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Full text of "Global Biodiversity: status of the Earth's living resources"

GLOBAL 

BIODIVERSITY 



STATUS OF THE EARTH'S LIVING RESOURCES 




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WORLD CONSERVATION MONITORING CENTRE 



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Global Biodiversity 

Status of the Earth's Living Resources 



A Report compiled by 

the 

World Conservation Monitoring Centre 

Editor: Brian Groombridge 



WORLD CONSERVATION 
MONITORING CENTRE 



in collaboration with 
The Natural History Museum, London 

and in association with 

lUCN - The World Conservation Union 

UNEP - United Nations Environment Programme 

WWF - World Wide Fund for Nature 

and the 

World Resources Institute 



^1^ 

NATURAL 
HISTORY 
MUSCUM 



p} 




With project sponsorship from 

Overseas Development Administration, UK 

and additional support from 

The Ministry of Foreign Affairs, The Netherlands 

The Ministry of the Environment, Denmark 

and 
The World Bank 



[3 



CHAPMAN & HALL 

London • Glasgow • New York • Tokyo • Melbourne • Madras 



1992 



Published by Chapman & Hall, 2-6 Boundary Row, London SEl 8HN 

Chapman & Hall, 2-6 Boundary Row, London SEl 8HN, UK 

Chapman & Hall, 29 West 35th Street, New York, NY 10001, USA 

Chapman & Hall Japan, Thomson Publishing Japan, Hirakawacho Nemoto Building, 6F, 1-7-11 
Hirakawa-cho, Chiyoda-ku, Tokyo 102, Japan 

Chapman & Hall Australia, Thomas Nelson Australia, 102 Dodds Street, South Melbourne, Victoria 3205, 
Australia 

Chapman & Hall India, R. Seshadri, 32 Second Main Road, CIT East, Madras 600 035, India 

This report is a contribution to GEMS - The Global Environment Monitoring System 

First edition 1992 

® 1992 World Conservation Monitoring Centre 

Reproduced from camera-ready copy prepared by WCMC. 

Printed in Great Britain by Unwin Brothers Limited, The Gresham Press, Old Woking, Surrey: a member of 

the Martins Printing Group. 

Recycled paper supplied by Robert Home Paper Co Ltd. 

ISBN 412 47240 6 

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted 
under UK Copyright Designs and Patents Act 1988, this publication may not be reproduced, stored, or 
transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the 
case of reprographic reproduction only in accordance with the terms of the licences issued by the Copyright 
Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate 
Reproduction Rights Organisation outside the UK. Enquiries concerning reproduction outside the terms stated 
here should be sent to the publishers at the London address printed on this page. 

The publisher makes no representation, express or implied with regard to the accuracy of the information 
contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that 
may be made. 

Citation: Worid Conservation Monitoring Centre (1992) Global Biodiversity: Status of the Earth's living 
resources. Chapman & Hall, London, xx -I- 594pp. 

Also available from lUCN Publications Services Unit, 181a Huntingdon Road, Cambridge, CB3 ODJ 

Cover Photos Mugger, Crocodylus palustris: Brian Groombridge 

Guzmania lingulata: D. Muleax 

Fish market, Indonesia: Tom Moss/WWF Photo library 
Henri Pittier National Park, Venezuela: Paul Goriup 

The designations of geographical entities in this book, and the presentation of the material, do not imply the 
expression of any opinion whatsoever on the part of WCMC or its sponsoring organisations concerning the 
legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of its frontiers 
or boundaries. In recent years geopolitical entities have become more fluid and this is not reflected consistently 
in the tables which were completed at different times and use data of different ages. 

A catalogue record for this book is available from the British Library 



Contents 

How to Use this Book viii 

World Conservation Monitoring Centre ix 

Acknowledgements ,,^„^^,^^, x 

Preface ^HHBHHHB xii 

Biodiversity - An Overview xiii 
Part 1. BIOLOGICAL DIVERSITY 
SYSTEMATICS AND DIVERSITY 

fe GENETIC DIVERSITY "^"^H 

The nature and origin of genetic variation 1 

Measuring genetic variation 1 

The interpretation of variation 3 

The environment and the distribution of genetic variation 3 

Conclusion 6 

2. SYSTEMATICS AND DIVERSITY 7 

Biological classification 7 

Phylogenetic relationships and their estimation 7 

From hierarchy to classification 7 

Taxonomic nomenclature and its regulation 9 

Major features of the hierarchy of life 10 

Systematics and the measurement of biodiversity II 

3. SPECIES CONCEPTS .:.^™.„„:. ...........,,„ ... 13 

What is a species? 13 

Early species concepts 13 

Evolutionary theory and polytypic species 13 

The biological species concept 14 

The phylogenetic species concept 15 

Species in practice 15 

Conclusion 16 

Current status 17 

Prediction from the existing partial inventory 20 

Other approaches to predicting patterns 23 

Uncharted realms of species richness 26 

Sampling the hyper-diverse but poorly known 31 

New data on tropical insects and what they convey 32 

Prospects for improved species richness estimates 36 

SPECIES DIVERSITY 

5. SPECIES DIVERSITY: AN INTRODUCTION ,«,,,«^,,,^^;«^.««,^. 40 



A brief history of diversity 40 

Measuring biological diversity 41 

The global distribution of species richness 43 

Sf)ecies and energy 45 

Explanations and hypotheses 46 



MICROORGANISMS „»,^«,,^.. - *^«*sy..^-K..:«!JBB»^^ 47 



Taxonomic scope 47 

Assessment of diversity 47 

Species concepts in microorganisms 47 

Extent of genetic diversity 49 

Regions and habitats of maximum diversity 49 

Role of microorganisms in biodiversity maintenance 50 

Role of microorganisms in biosphere ninctions 51 

Potential contribution of microorganisms to sustainable development 51 

The need for diversity amongst microorganisms 52 

Ex situ conservation of microorganisms 52 

The taxonomic challenge 52 

LOWER PLANT DIVERSITY 55 

Bryophytes 55 

Lichens 55 

Algae 57 



8. 


HIGHER PLANT DIVERSITY 


64 




The groups of higher plants 
The distribution of higher plants 


64 
65 


9. 


NEMATODES 


88 



Nematode diversity 88 

The ecological importance of nematodes 90 

10. DEEP-SEA INVERTEBRATES 93 

Deep-sea communities 93 

Ocean trenches 95 

Hydrothermal vents 98 

Cold seeps 100 

11. SOIL MACROFAUNA .„,„._ 103 

Soil and soil fauna 103 

Patterns of species richness 105 

General patterns of diversity 113 

12. FISHES 116 

The diversity of fishes 116 

Freshwater fishes: species richness and endemism 116 

Subterranean fishes 121 

Coral reef fishes 122 



13. 


HIGHER VERTEBRATES 


136 




The groups of higher vertebrates 
The distnbution of higher vertebrates 


136 

137 


14- 


ISLAND SPECIES 


147 


=-y 


Plants on oceanic islands 
Land snails 


148 
149 


15. 


CENTRES OF SPECIES DIVERSITY 


■.«E!:*>^;?f ¥>'!*«»:»«* x^A 



Introduction 154 

Methods of determining areas of conservation priority 154 

Centres of plant diversity 157 

Centres of avian endemism 161 



SPECIES LOSS 

16. SPECIES EXTINCTION SHBHHBBBHHHBHHF ' ^^^ 

How species become vulnerable to extinction 192 

A brier history of extinctions 196 

Extinctions in recent history 198 

Current and future extinction rates 202 

17. THREATENED SPECIES 234 

What is a threatened species? 234 

Globally threatened animals 236 

Aquatic habitats 242 

Threatened species on islands: plants 244 

Threatened species on islands: birds 245 

HABITATS AND ECOSYSTEMS 

18. GLOBAL HABITAT CLASSIFICATION 248 

Ecosystem mapping 248 

Estimating rates of change of ecosystems 250 

19. BIODIVERSITY AND GLOBAL CLIMATE CHANGE . -^i._.„o,^ 254 

Modelling global climate change 254 

Effects of climate change on vegetation zones and biodiversity 254 

20. TROPICAL MOIST FORESTS WSSBBT"^ 256 

What are tropical moist forests? 256 

The global area of tropical moist forest 257 

Factors involved in changes in forest cover 264 

Management practices in tropical forests 267 

Case studies 269 

21. GRASSLANDS ^"""^'"^■i^H^.__.__.™_,_...,..,. 280 



The world area of grassland 280 

Origins and floral diversity of grasslands 280 

The 20th century impact on grasslands 284 

Case studies 288 

22. WETLANDS . 293 

Global extent and distribution of wetlands 293 

Regional extent and distribution of wetlands 295 

Values and threats 297 

Loss of wetlands 298 

Conservation of wetlands 302 

23. CORAL REEFS 307 

Occurrence of reefs 307 

Values and threats 307 



24. MANvjROVt»o ,!ap3t^g»^35?aiaKK*aa8KsssaBH9Sfis*?saHes«'^'^-vs'^^ -^sk^^^^^ 

The mangrove habitat 324 

Value of mangroves ^"^ 

Threats to mangrove habitats 



324 
324 



Part 2. USES AND VALUES OF BIODIVERSITY 
USES OF BIOLOGICAL RESOURCES 

25. PLANT USE 331 

Food plants 331 

Timber 342 

Rattans 350 

Medicinal plants 350 

Ornamental plants 353 

26. ANIMAL USE 359 

Introduction 359 

Food: terrestrial animals 359 

Food: fisheries 365 

Non-food uses 374 

Domestic livestock 389 

VALUING BIODIVERSITY 

27. BIODIVERSITY AND ECONOMICS 407 

Valuing the environment 407 

Loss of biodiversity as an economic process 409 

Current uses of diverse resources 41 1 

Community use of wildlife resources 411 

Ecotourisra 413 

Existence values 415 

The valuation of diverse ecosystems 417 

The value of tropical forests 417 

The value of wetlands 421 

Preserving fiiture options 425 

The value of diversity in providing insurance: crop yields 426 

Sources of yield variability 429 

Crop insurance: the response to increased agricultural risk 430 

The value of agricultural genetic diversity 432 

The value of biodiversity in the production of pharmaceuticals 434 



Part 3. CONSERVATION AND MANAGEMENT OF BIODIVERSITY 
NATIONAL POLICIES AND INSTRUMENTS 

28. NATIONAL LEGISLATION 441 

The protection of wild flora 441 

The protection of wild fauna 442 

Limitations of species legislation 444 

The protection of natural habitats 444 

29. PROTECTED AREAS 447 

National protected area systems 447 

International protected area systems 459 

INTERNATIONAL POLICIES AND INSTRUMENTS 

30. MULTILATERAL TREATIES 479 
Multilateral treaties 479 



31. INTERNATIONAL POLICY AND LEGAL ASSISTANCE 490 

Funding 490 

International obligations: protected areas 494 

Intellectual property rights for biotechnology 495 

Regulated trading in wildlife products 499 

Regional seas programme 501 

32. INTERNATIONAL AID 506 

International development assistance 506 

Bilateral development assistance 507 

Multilateral development assistance 509 

International assistance in forest management 514 

The tropical forestry action plan (TFAP) 514 

The international tropical timber agreement (ITTA) 518 

Debt purchase 522 

33. MANAGEMENT OF INTERNATIONAL RESOURCES 528 

International fisheries management commissions 528 
Antarctica: the evolution of an international resource management regime 534 

BIODIVERSITY CONVENTION 

34. CURRENT PRACTICES IN CONSERVATION '"'iJiiMi Plgl^W 543 



In situ conservation of threatened plant species 545 

In situ conservation of crops and wild relatives of crops 546 

Institutions involved in ex situ conservation of plants 549 

Techniques for ex situ plant conservation 557 

In situ conservation of animals 561 

Ex situ conservation of animals 563 

Ex situ conservation of animal genetic resources 571 

Ejc situ conservation of microbial diversity 571 

35. THE CONVENTION ON BIOLOGICAL DIVERSITY 576 

Background 576 

The biodiversity convention 576 

The biodiversity country studies and unmet financial needs 579 

Future data needs: networking and global monitoring 581 



GLOSSARY fMlt- 585 



How to Use this Book 



An extensive review of global biodiversity obviously generates substantial quantities of data with the 
concomitant problem of how best to present this mass of material. Global Biodiversity is intended to be a 
source-book of information and analysis rather than be read cover to cover, so assisting the reader find his/her 
way around the book is essential. 

The primary means of accessing this wealth of information is through the Contents list (page iii). This is 
therefore very detailed and serves some of the function of an index (which it has not been practical to include 
because of excess length). The reader is urged to browse the Contents before dipping into the text. 

The book is divided into three Parts, each of which opens with a brief overview of its structure and contents. 
The Parts are then divided into ten Sections that group together Chapters that address a common theme. This 
structure is outlined below as a guide to the overall organisation of the book. 

Parti. Biological Diversity 

• Systematics and diversity 

• Species diversity 

• Species loss 

• Habitats and ecosystems 

Part 2. Uses and Values of Biodiversity 

• Uses of biological resources 

• Valuing biodiversity 

Part 3. Conservation and Management of Biodiversity 



• National policies and instruments 

• International policies and instruments 

• Current practices in conservation 

• Biodiversity Convention 

Individual Chapters are divided thematically by major sub-headings, and these are fiilly listed in the Contents, 
which is therefore the key entry point for access to the information. 

As far as possible, plain English has been used rather than scientific terminology, but when the use of obscure 
technical language has been unavoidable a definition has been provided in the Glossary. 



World Conservation Monitoring Centre 



The Earth's biological diversity and other natural resources provide many economic, social and aesthetic 
benefits to mankind. Effective programmes for sustainable human development must, therefore, incorporate 
conservation objectives. Responsible institutions and individuals need access to a service that provides factual 
information on conservation issues in a timely, focused and professional way. 

This service is provided by the World Conservation Monitoring Centre, Cambridge, UK. Established in 
1988 as a company limited by guarantee with charitable status, WCMC is managed as a joint-venture between 
the three partners in the World Conservation Strategy and its successor Caring For The Earth: lUCN - The 
World Conservation Union, UNEP - United Nations Environment Programme, and WWF - World Wide 
Fund for Nature. Its mission is to provide information on the status, security, management and utilisation of 
the world's biological diversity to support conservation and sustainable development. 

To implement this mission, WCMC maintains substantial databases on the status and distribution of plant and 
animal species of conservation and development interest; habitats of conservation concern, particularly tropical 
forests, coral reefs and wetlands; the global network of national parks and protected areas; and the international 
trade in wildlife species and their derivative products. Much of this information is managed with Geographic 
Information Systems, and is supported by an extensive bibliography of published and "grey" literature. WCMC 
is also involved in providing support for the expansion of national data management and monitoring capabilities 
in developing countries, and in developing communication networks for the flow of information. 

WCMC contributes its biodiversity data to GEMS - the Global Environment Monitoring System, co-ordinated 
by UNEP. GEMS is a collective programme of the world community to acquire, through global monitoring, 
and assessment, the data that are needed for the rational management of the environment. GEMS is an element 
of the United Nations Earthwatch programme. 

WCMC Biodiversity Report Team 

John McComb Project Manager 

Dr Brian Groombridge Editor and Research Co-ordinator 

Esther Byford Production Supervisor 

Crawford Allan Research 

John Rowland Research 

Dr Chris Magin Research 

Helen Smith Research 

Veronica Greenwood Production 

Lindsay Simpson Production 

Consultant Assistant Editors 

Martin Jenkins (general) 

Timothy M. Swanson (economics and policy) 

Hugh Synge (plants) 

WCMC Staff who contributed to the compilation and review process: 

Mike Adam, Clare Billington, Simon Blyth, Gillian Bunting, John Caldwell, Lorraine Collins, Dr Mark 
Collins, Mary Cordiner, Helen Corrigan, Robert Cubey, John Easy, Jeremy Harrison, Tim Inskipp, Dr 
Timothy Johnson, Beverley Lewis, Dr Richard Luxmoore, Lesley McGuffog, Sheila Millar, Dr Ronald I. 
Miller, James R. Paine, Dr Robin Pellew, Corinna Ravilious, Jonathan Rhind, Sarah Skinner, Jo Taylor, 
Dr Kerry Walter. 



Acknowledgements 



The production of this Report has been based largely upon the substantial biodiversity databases that WCMC 
manages, supplemented by a major world-wide data gathering and standardisation programme. This 
information is drawn from an extensive network of scientists, research workers, park managers, wildlife 
authorities, conservation bodies and government organisations. WCMC would like to express its thanks for 
the contributions of these individuals and agencies, too numerous to mention individually, without whose 
support we would not be able to operate. 

WCMC particularly recognises with gratitude the fundamental contribution of both the lUCN Species Survival 
Commission (SSC) and the Commission of National Parks and Protected Areas (CNPPA), whose conmiitment 
to WCMC over the years has enabled the Centre to expand its databases. Their data have been used extensively 
in the Report. WCMC also acknowledges the support of the lUCN Environmental Law Centre, whose legal 
data and expertise have contributed significantly. 

In compiling the Report itself, WCMC particularly acknowledges the major contributions of the following 
people whose names appear at the end of the relevant chapter (unattributed chapters were provided by WCMC 
staff): 

Dr John Akeroyd, Bruce Aylward, Dr Keith Banister, Dr Gordon Brent Ingram, Dr B.N.K. Davis, Victoria 
Drake, Alan Eddy, B.C. Eversham, Alix Flavelle, Shirra Freedman, D.J. Galloway, Sarah Gammage, 
Dr Stephen J.G. Hall, Dr P.N. Halpin, Peter Hammond, David Hanrahan, Dr Caroline Harcourt, Prof. D.L. 
Hawksworth, Richard J. Hornby, Nigel Howard, Martin Jenkins, David M. John, Sam Johnston, A.S. Jolliffe, 
E.A. Leadlay, Dr Rik Leemans, Mike Maunder, Sara Oldfield, Greg Rose, Timothy M. Swanson, Hugh 
Synge, Richard Thomas, Ian Tittley, Susan M. Wells, Dr P.S. Wyse Jackson, Dr R.I. Vane-Wright. 

The first four chapters were contributed by staff of The Natural History Museum, London. WCMC is 
especially grateful for their assistance, and for the efforts of John Peake (Associate Director, Scientific 
Development) in facilitating this collaboration. 

In addition, WCMC would like to express thanks to the following who have contributed to the compilation 
of this Report in a variety of ways: 

Dr Dennis Adams, Suraya Affiff, Dr J.Crinan Alexander, M. Altieri, Dr Chris Andrews, Dr Martin Angel, 
Prof. Peter Ashton, Margerita Astralaga. Dr Paul Bamps, Dr John Beard, Dr S. Beck, Dr Henk Beentje, 
Dr Colin J. Bibby, Dr Mike Bingham, Dr William Block, Dr Robert Boden, Dr A. Bogan, Dr Attila Borhidi, 
Dr Philippe Bouchet, Prof. Loutfy Boulos, Dr David Bramwell, Dr F.J. Breteler, Dr Harold Brookfield, 
Dr Dick Brummitt, David Brunner, Dr Frangoise Burhenne-Guilmin, Victor Bullen, Dr Yvonne A. Byron, 
Dr J. Cardiel, Dr Jan Cerovsky, Jim Chapman, Dr Arthur D. Chapman, Dr A. Cleef, P. Colman, Dr R. 
Cowie, Dr Quentin Cronk, Mike J. Crosby, James Culverwell II, Michael Dadd, Dr Patricia Davila, Stephen 
D. Davis, D.G. Debouck, Dr Jean-Jacques de Granville, Dr Robert DeFilipps, A. Delsaerdt, Nelly Diego, 
DrC. Dodson, Dr John Dransfield, DrJ. Duivenvoorden, M. Dulude, DrK. Emberton, Lynne Farrell, Prof. 
Philip M. Fearnside, Dr Richard Felger, Rosa M. Fonseca, Dr F.R. Fosberg, Dr F. Friedmann, Dr lb Friis, 
Dr John D. Gage, Dr F. Galena, Dr Rodrigo Gamez, Dr Sam M. Gan III, Dr Martin Gardner, N. Gardner, 
Dr Steve Gartlan, Dr Alwin Gentry, Dr David Given, Prof. C^sar G6mez Campo, Dr Roger Good, Dr R. 
Gopalan, Dr Frederick Grassle, Peter Green, O. Griffiths, Liz Guerin, Prof. Nimal Gunatilleke, Dr M. 
Hadfield, Dr S. Halloy, Dr Ole Hamann, Dr Alan Hamilton, Dr Stephen Harris, Melanie F. Heath, Dr A.N. 
Henry, Dr Derral Herbst, Prof. Vernon Heywood, Craig Hilton-Taylor, Dr A. Hoffmann, Dr Martin 
W. Holdgate, E. Hoyt, Dr Otto Huber, Prof. Dr Gordon Brent Ingram, Dr Frank Ingwersen, Dr Walter 
Ivantsoff, Prof. K. Iwatsuki, Dr Peter Wyse Jackson, Dr J. J^r^mie, Prof. Robert Johns, Dr Marshall 
Johnston, Dr M. Jorgensen, Dr Calestous Juma, Prof. Horng Jye-Su, Dr Ruth Kiew, Dr T. Killeen, Prof. 
V. Krassilov, Dr John Lambshead, Prof. Elias Landolt, Dr R. Lara, Dr John Leigh, Dr David Lellinger, 
Christine Leon, Blanca Ledn, Dr E. Lleras, Dr Paul V. Loiselle, Adrian J. Long, Francisco Lorea, 
Dr Rosemary Lowe-MacConnell, Lucio Lozado, Prof. Grenville Lucas, Olga Herrera-MacBryde, Dr Kathy 
MacKinnon, Jane MacKnight, Lynne Maclennan, Dr Domingo Madulid, Mike Maunder, Dr Niall McCarten, 



Dr Bill McDonald, Bob McDowall, Jeffrey A. McNeely, Dr Tim Messick, Robert Mill, Dr Kenton R. 
Miller, Dr Tony Miller, Danya Miskov, Lino Monroy, P. Mooney, Dr Norman Moore, Prof. P. Morat, 
Dr P.B. Mordan, Dr Scott Mori, Dr Larry Morse, Michael Moser, Fred Naggs, Dr David Neill, Dr B. 
Nelson, Dr Dan Nicholson, Dr Hans Nooteboom, Dr Rosa Ortiz, Dr Maria Tereza Jorge Padua, 
Dr Christopher Page, Dr W. Palacios, Dr Mark Perry, Prof. Ghillean T. Prance, Dr M. Prashanth, 
Robert Prescott-Allen, Han Qunli, Dr L. Ramella, Dr Orlando Rangel, Dr Peter Raven, Dr Tony Rebelo, 
Marcia Ricci, J. Robertson-Vernhes, Joyce Rushton, Dr B.D. Sharma, Samar Singh, Dr D.K. Singh, 
Dr Mark Skinner, Joel Smith, D. Smits, Dr Sy Sohmer, C. Sperling, Alison Stattersfield, Dr George 
Staples, Dr G. Stephens, Wendy Strahm, Dr Tod Stuessy, Prof. Dr H. Sukopp, Dr R.W. Sussman, Glen 
Swindlehurst, Lesley Taylor, Dr Simon Thirgood, Dr Duncan Thomas, Dr F. Thompson, Dr Jim Thorsell, 
Dr Mats Thulin, Dr S. Tillier, Simon Tonge, Dr Shigeru Tsuda, Dr Verena Tunnicliffe, Dr C. Ulloa, 
Dr E. Vajravelu, Dr Vu Van Dung, Dr Leo Vanhecke, Jane Villa-Lobos, Dr C. Villamil, Dr J.-F. Villiers, 
Dr David Wagner, Dr Warren H. Wagner, Dr H. Wald^n. Richard Warner, Dr Tom Wendt, Julie S. 
Wenslow, Dr Dagmar Werner, Dr Gerry Werren, Dr Tony Whitten, J.T. Williams, Julia Willison, Dr David 
S. Woodruff, Dr Richard Wunderlin, Prof. Wang Xianpu, Dr K.R. Young, Prof. Yang Zhouhuai, 

The authors are grateful for the assistance provided by the librarians of the Monks Wood Experimental Station, 
the University of Cambridge, the Natural History Museum (General, Zoological and Entomological) and the 
British Antarctic Survey. 

Finally, WCMC recognises with gratitude the substantial fmancial contributions made by our sponsors listed 
on the title page. Their confidence in our ability to complete such an ambitious project is appreciated. In 
particular, WCMC thanks the Overseas Development Administration, UK and especially David Turner, Ian 
Haines and Mark Lowcock, together with the Ministry of Foreign Affairs, The Netherlands, particularly Ton 
van der Zon and Egbert Pelinck. The Ministry of the Environment, Denmark, through the endorsement of 
Veit Koester, also contributed, whilst the World Bank, through Mohan Munasinghe has distributed copies 
into the developing world. WCMC expresses its sincere gratitude these organisations and individuals. 



Preface 

We Need Your Data for Future Editions of this Report 



In your hands you now hold the most comprehensive review of global biodiversity ever compiled. It represents 
the product of numerous scientists, consultants and research institutes each of whom has generously contributed 
data or assistance to the compilation of this Report, together with the substantial information holdings that 
WCMC already manages. Yet so vast and diverse are the Earth's living resources - the genes, species and 
ecosystems that comprise the planet's biotic wealth - and the threats that these resources now face, that this 
massive effort has barely scratched the surface. 

To build the information store on which this Report is based, we need your help. WCMC will continue to 
expand its global biodiversity database and intends to republish the Report every two years. This volume is 
therefore the first of a proposed series that will document changes to the status, utilisation and management 
of the world's biological resources. We need your contribution to fuel this expansion. We are embarked 
upon a long-term process, the aim of which is to mobilize the substantial amounts of data available throughout 
the world to encourage a more enlightened conservation practice. Your piece of the jigsaw puzzle may fit 
into the overall picture we are trying to create. If you are able to contribute data to expand this Report, we 
urgently want to hear from you - don't quibble with its deficiencies which inevitably are numerous; instead 
be more constructive by contributing your specialist knowledge to this global conservation effort. We plan to 
distribute the database itself later this year in machine-readable format, and it is not too late to include your 
information. 

The need for reliable quantitative information about the impact of people upon nature has never been greater. 
Good intelligence is the key to good decisions, whether about priorities, policies or investments. We need 
to develop data gathering and monitoring capabilities at the local and country levels, particularly in the 
developing world, and to build networks for the early-warning of new threats to biodiversity. The realisation 
of these needs is encompassed in Agenda 21 of the UN Conference on Environment and Development, in the 
Biodiversity Convention, and in the Global Biodiversity Strategy, but the basic common factor for the 
implementation of all these initiatives is good information. WCMC will make available its information to 
support these global enterprises, but to be really effective, we need your data and your participation. 

This process of expanding the global database through the networking of national centres must be linked 
directly into the Biodiversity Convention. Despite the delays and frustrations in its negotiation, which are 
discussed in Chapter 35, the Convention could provide a potent mechanism for implementing global 
conservation and sustainable use of biodiversity. Assuming a Convention is eventually agreed, its 
effectiveness will depend upon its access to reliable up-to-date scientific information. WCMC will mobilize 
its substantial data holdings to support the Convention: information will be its life-blood and WCMC will act 
as the catalyst for its operation by providing a massive blood transfusion. 



Robin Pellew World Conservation Monitoring Centre 

Director 219 Huntingdon Road 

Cambridge 
24 April 1992 CB3 ODL 

UK 



BIODIVERSITY: AN OVERVIEW 



This introduction is intended to map out in general terms 
some of the principal themes to be encountered in the field 
of biological diversity. It will provide a context for the 
remainder of the report, in which many of these themes 
are further developed. 

WHAT IS BIODIVERSITY? 

The word "biodiversity' is a contraction of biological 
diversity. Diversity is a concept which refers to the range 
of variation or differences among some set of entities; 
biological diversity thus refers to variety within the living 
world. The term 'biodiversity' is indeed commonly used 
to describe the number, variety and variability of living 
organisms. This very broad usage, embracing many dif- 
ferent parameters, is essentially a synonym of ~ Life on 
Earth'. 

Management requires measurement, and measures of diver- 
sity only become possible when some quantitative value can 
be ascribed to them and these values can be compared. It is 
thus necessary to try and disentangle some of the separate 
elements of which biodiversity is composed. 

It has become a widespread practice to define biodiversity 
in terms of genes, species and ecosystems, corresponding 
to three fundamental and hierarchically-related levels of 
biological organisation. 

Genetic diversity 

This represents the heritable variation within and between 
populations of organisms. Ultimately, this resides in vari- 
ations in the sequence of the four base-pairs which, as 
components of nucleic acids, constitute the genetic code. 

New genetic variation arises in individuals by gene and 
chromosome mutations, and in organisms with sexual 
reproduction can be spread through the population by 
recombination. It has been estimated that in humans and 
fruit flies alike, the number of possible combinations of 
different forms of each gene sequence exceeds the number 
of atoms in the universe. Other kinds of genetic diversity 
can be identified at all levels of organisation, including 
the amount of DNA per cell, and chromosome structure 
and number. 

This pool of genetic variation present within an inter- 
breeding population is acted upon by selection. Differen- 
tial survival results in changes of the frequency of genes 
within this pool, and this is equivalent to population 
evolution. The significance of genetic variation is thus 
clear: it enables both natural evolutionary change and 
artificial selective breeding to occur. 

Only a small fraction (often less than 1 %) of the genetic 
material of higher organisms is outwardly expressed in 
the form and function of the organism; the purpose of the 



remaining DNA and the significance of any variation 
within it is unclear. 

Each of the estimated 10 different genes distributed 
across the world's biota does not make an identical 
contribution to overall genetic diversity. In particular, 
those genes which control fundamental biochemical proc- 
esses are strongly conserved across different taxa and 
generally show httle variation, although such variation 
that does exist may exert a strong effect on the viabiUty 
of the organism; the converse is true of other genes. 
Further, an astonishing amount of molecular variation in 
the mammalian immune system, for example, is possible 
on the basis of a small number of inherited genes. 

Species diversity 

Perhaps because the living world is most widely consid- 
ered in terms of species, biodiversity is very commonly 
used as a synonym of species diversity, in particular of 
'species richness', which is the number of species in a 
site or habitat. Discussion of global biodiversity is typi- 
cally presented in terms of global numbers of species in 
different taxonomic groups. An estimated 1.7 million 
species have been described to date; estimates for the total 
number of species existing on earth at present vary from 
five million to nearly 100 million. A conservative working 
estimate suggests there might be around 12.5 milUon. In 
terms of species number alone, life on earth appears to 
consist essentially of insects and microorganisms. 

TTie species level is generally regarded as the most natural 
one at which to consider whole-organism diversity. Spe- 
cies are also the primary focus of evolutionary mecha- 
nisms, and the origination and extinction of species are 
the principal agents in governing biological diversity in 
most senses in which the latter can be defined. On the 
other hand, species cannot be recognised and enumerated 
by systematists with total precision, and the concept of 
what a species is differs considerably between groups of 
organisms. 

Further, a straightforward count of the number of species 
only provides a partial indication of biological diversity, 
for implicit within the term is the concept of degree or 
extent of variation; that is, organisms which differ widely 
from each other in some respect by definition contribute 
more to overall diversity than those which are very 
similar. 

The more different a species is from any other species (as 
indicated, for example, by an isolated position within the 
taxonomic hierarchy), then the greater its contribution to 
any overall measure of global biological diversity. Thus, 
the two species of Tuatara (genus Sphetiodon) in New 
Zealand, which are the only extant members of the reptile 
order Rhynchocephalia, are more important in this sense 
than members of some highly speciose family of lizards. 



Developing this argument, a site with many different 
higher taxa present can be said to possess more laxo- 
nomic diversity than another with fewer higher taxa but 
many more species. Marine habitats frequently have 
more different phyla but fewer species than terrestrial 
habitats; i.e. higher taxonomic diversity but lower 
species diversity. Measures under development endeav- 
our to incorporate quantification of the evolutionary 
uniqueness of species. 

The ecological importance of a species can have a direct 
effect on community structure, and thus on overall bio- 
logical diversity. For example, a species of tropical rain 
forest tree which supports an endemic invertebrate fauna 
of a hundred species evidently makes a greater contribu- 
tion to the maintenance of global biological diversity than 
a European alpine plant which may have no other species 
wholly dependent on it. 

Ecosystem diversity 

The quantitative assessment of diversity at the ecosystem, 
habitat or community level remains problematic. Whilst 
it is possible to define what is in principle meant by genetic 
and species diversity, and to produce various measures 
thereof, there is no unique definition and classification of 
ecosystems at the global level, and it is thus difficult in 
practice to assess ecosystem diversity other than on a local 
or regional basis and then only largely in terms of vege- 
tation. Ecosystems further differ from genes and species 
in that they explicitly include abiotic components, being 
partly determined by soil parent material and climate. 

Ecosystem diversity is often evaluated through measures 
of the diversity of the component species. . This may 
involve assessment of the relative abundance of different 
species as well as consideration of the types of species. In 
the first instance, the more equally abundant different 
species are, then in general the more diverse that area or 
habitat is considered to be. In the second instance, weight 
is given to the numbers of species in different size classes, 
at different trophic levels, or in different taxonomic 
groups. Thus a hypothetical ecosystem which consisted 
only of several species of plants, would be less diverse 
than one with the same number of species but which 
included animal herbivores and predators. As different 
weightings can be given to these different factors when 
estimating the diversity of particular areas, there is no one 
authoritative index for measuring diversity. This obvi- 
ously has important implications for the ranking of differ- 
ent areas. 

Biodiversity: its meaning and measurement 

The differences between these conceptual perspectives on 
the meaning of biodiversity, and the associated semantic 
problems, are not trivial. Management intended to main- 
tain one facet of biodiversity will not necessarily maintain 
another. For example, a timber extraction programme 
which is designed to conserve biodiversity in the sense of 
site species richness may well reduce biodiversity meas- 
ured as genetic variation within the tree species harvested. 
Clearly, the maintenance of different facets of biodiversity 



will require different management strategies and re- 
sources, and will meet different human needs. 

Even if complete knowledge of particular areas could be 
assumed, and standard definitions of diversity be derived, 
the ranking of such areas in terms of their importance with 
respect to biological diversity remains problematic. Much 
depends on the scale that is being used. Thus, the question 
of what contribution a given area tnakes to global biologi- 
cal diversity is very different from the question of what 
contribution it makes to local, national or regional bio- 
logical diversity. This is because, even using a relatively 
simplified measure, any given area contributes to biologi- 
cal diversity in at least two different ways - through its 
richness in numbers of species and through the endemism 
(or geographical uniqueness) of these species. The relative 
importance of these two factors will inevitably change at 
different geographical scales, and sites of high regional 
importance may have little significance at a global level. 
Neither of these factors include any explicit assessment of 
genetic diversity. 

Although the word biodiversity has already gained wide 
currency in the absence of a clear and unique meaning, 
greater precision will be required of its users in order that 
policy and programmes can be more efficiently defined in 
the future. 

BIODIVERSITY: CHANGES IN TIME AND 
SPACE 

Changes over time 

The fossil record of life in geological time is very incom- 
plete. There is marked variation between higher taxa and 
between species in different ecosystems in the extent to 
which individuals are susceptible to preservation and to 
subsequent discovery. Chance factors have played a large 
part, and interpretation by palaeontologists of the avail- 
able material is beset by differences of opinion. Thus, the 
record is relatively good for shallow-water hard-bodied 
marine invertebrates, but pwor for most other groups, such 
as plants in moist tropical uplands. 

Two salient points appear well-substantiated. Firstly, 
taxonomic diversity, as measured by the number of rec- 
ognised phyla of organisms, was greater in Cambrian 
times than in any later period. Secondly, and keeping in 
mind the difficulty of disentangling artifacts of the record 
from the underlying pattern, it appears that species diversity 
and number of families have undergone a net increase 
between the Cambrian and the Pleistocene epoch, although 
interrupted by isolated phases of mass extinction (few of 
which are reflected in the fossil record of plants). 

Changes in space 

In general, species diversity in natural habitats is high in 
warm areas and decreases with increasing latitude and 
altitude. On land, diversity is also usually higher in areas 
of high rainfall and lower in drier areas. The richest areas 
are undoubtedly tropical moist forests. If current estimates 
of the number of species (mainly insects) comprising the 
microfauna of tropical moist forests are credible, then 



these areas, which cover perhaps 7% of the world's 
surface area, may well contain over 90% of all species. 
If the diversity of larger organisms only is considered, 
then coral reefs and, for plants at least, areas with Medi- 
terranean climate in South Africa and Western Australia, 
may be as diverse. Gross genetic diversity and ecosystem 
diversity will, by definition, tend to be positively corre- 
lated with species diversity (although there are indications 
that some tropical species show more genetic diversity 
than related temperate species, and some habitat general- 
ises more than habitat specialists). 

The reasons for the large-scale geographic variation in 
species diversity, and in particular for the very high 
species diversity of tropical moist forests, are not fully 
understood and involve two interconnected questions: the 
origin of diversity through the evolution of species and 
the maintenance of diversity. Both these involve consid- 
eration of the present and historic (in a geological or 
evolutionary sense) conditions prevailing in particular 
areas, principally climatic but also edaphic and topo- 
graphic. Climatically benign conditions (warmth, mois- 
ture and relative aseasonality) over long periods of time 
appear to be particularly important. 

It is often assumed that areas with so-called climax 
ecosystems will be more diverse than areas at earlier 
successional stages. However, an area with a mosaic of 
systems at different successional stages will probably be 
more diverse than the same area at climax provided that 
each system occupies a sufficiently large area of its own. 
In many instances, human activities artificially maintain 
ecosystems at lower successional stages. In areas that have 
been under human influence for extended periods, notably 
in temperate regions, maintenance of existing levels of 
diversity may involve the maintenance of at least partially 
man-made landscapes and ecosystems, mixed with ade- 
quately sized areas of natural climax ecosystems. 

Loss of biodiversity 

The loss of biological diversity may take many forms but 
at its most fundamental and irreversible it involves the 
extinction of species. 

Over geological time, all species have a finite span of 
existence. Species extinction is therefore a natural process 
which occurs without the intervention of man. However, 
it is beyond question that extinctions caused directly or 
indirectly by man are occurring at a rate which far exceeds 
any reasonable estimates of background extinction rates, 
and which, to the extent that it is correlated with habitat 
perturbation, must be increasing. 

Unfortunately, quantifying rates of species extinction, 
both at present and historically, is difficult and predicting 
future rates with precision is impossible. 

Documenting definite species extinctions is only realistic 
under a relatively limited set of circumstances, where a 
described species is readily visible and has a well-defined 
range which can be surveyed repeatedly. Unsurprisingly, 
most documented extinctions are of species that are easy 



to record (e.g. land snails, birds) and inhabit sites which 
can be relatively easily inventoried (e.g. oceanic islands). 
The large number of extinct species on oceanic islands is 
not solely an artefact of recording, because island species 
are generally more prone to extinction as a result of human 
actions. 

Rather than being derived from observed extinctions, 
therefore, quoted global extinction rates are derix'ed from 
extrapolations of measured and predicted rates of habitat 
loss, and estimates of species richness in different habi- 
tats. These two estimates are interpreted in the light of a 
principle derived from island biogeography which states 
that the size of an area and of its species complement tend 
to have a predictable relationship; fewer species are able 
to persist in a number of small habitat fragments than in 
the original unfragmented habitat, and this can result in 
the extinction of species. 

Even on best available present knowledge, these estimates 
involve large degrees of uncertainty, and predictions of 
current and fu^are extinction rates should be interpreted 
with very considerable caution. Pursuit of increased ac- 
curacy in the estimation of global extinction rates, how- 
ever, whilst of great concern, is not a crucial activity; it 
is more important to recognise in general terms the extent 
to which populations and species which are not monitored 
are likely to be subject to fragmentation and extinction. 

Loss of biodiversity in the form of crop varieties and 
livestock breeds is of near zero significance in terms of 
overall global diversity, but genetic erosion in these 
populations is of particular human concern in so far as it 
has imphcations for food supply and the sustainability of 
locally-adapted agricultural practices. For domesticated 
populations, loss of wild relatives of crop or timber plants 
is of special concern for the same reason. These genetic 
resources may not only underlie the productivity of local 
agricultural systems but also, when incorporated in breed- 
ing programmes, provide the foundation of traits (disease 
resistance, nutritional value, hardiness, etc.) of global 
importance in intensive systems and which will assume 
even greater importance in the context of future climate 
change. 

Erosion of diversity in crop gene pools is difficult to 
demonstrate quantitatively, but tends to be indirectly 
assessed in terms of the increasing proportion of world 
cropland planted to high yielding, but genetically uniform, 
varieties. 

The causes of loss of biological diversity 

Species may be exterminated by man through a series of 
effects and agencies. These may be divided into two broad 
categories: direct (hunting, collection and persecution), 
and indirect (habitat destruction and modification). 

Overhunting is perhaps the most obvious direct cause of 
extinction in animals, as it has affected several large and 
well-known species. In terms of overall loss of biodiver- 
sity, however, it is undoubtedly far less imjxirtant than 
the indirect causes of habitat modification and loss. Nev- 



ertheless, as it self-evidently selectively affects species 
which are or have been considered a harvestable resource, 
it has important implications for the management of 
natural resources. 

Genetic diversity, as represented by genetic differences 
between discrete populations within wild species, is hable 
to reduction as a result of the same factors affecting 
species. The genetic diversity represented by populations 
of crop plants or livestock is liable to reduction as a result 
of mass production; the desired economies of scale de- 
mand high levels of uniformity. 

Virtually any form of sustained human activity results in 
some modification of the natural environment. This modi- 
fication will affect the relative abundance of species and 
in extreme cases may lead to extinction. This may result 
from the habitat being made unsuitable for the species (for 
example, clear-felling of forests or severe pollution of 
rivers), or through the habitat becoming fragmented. The 
latter has the effect of dividing previously contiguous 
populations of species into small sub-populations. If these 
are sufficiently small, then chance processes lead to raised 
probabilities of extinction within a relatively short time. 

A major, though at present largely unpredictable, change 
in natural environments is hkely to occur within the next 
century as a result of large-scale changes in global climate 
and weather patterns. There is a high probability that these 
will cause greatly elevated extinction rates, although their 
exact effects are at present unknown. 

MAINTAINING BIOLOGICAL DIVERSITY 

The maintenance of biological diversity at all levels is 
fundamentally the maintenance of viable populations of 
species or identifiable populations. This can be carried out 
either on site or off site. Some integrated management 
programmes have begun to link these basically dissimilar 
approaches. 

In situ conservation 

The maintenance of a significant proportion of the world's 
biological diversity at present only appears feasible by 
maintaining organisms in their wild state and within their 
existing range. This is generally preferable to other 
courses of action because it allows for continuing adapta- 
tion of wild populations by natural evolutionary processes 
and, in principle, for current utilisation practices to con- 
tinue (although these often require enhanced manage- 
ment). 

Ex situ conservation 

Viable populations of many organisms can be maintained 
in cultivation or in captivity. Plants may also be main- 
tained in seed banks and germplasm collections; similar 
techniques are under development for animals (storage of 
embryos, eggs, sperm) but are more problematic. In any 
event, ex situ conservation is clearly only feasible at 
present for a small percentage of organisms. It is ex- 
tremely costly in the case of most animals, and while it 
would in principle be possible to conserve a very large 



proportion of higher plants ex situ, this would still amount 
to a small percentage of the world's organisms. It often 
involves a loss of genetic diversity through founder effects 
and the high probability of inbreeding. 

WHY CONSERVE BIOLOGICAL DIVERSITY ? 

This question can be asked from a number of different 
perspectives, all conditioned by a variety of cultural and 
economic factors. The various answers given, arguing for 
the maintenance of biological diversity, have tended to 
become increasingly confused. Different goals have dif- 
ferent implications for the elements and extent of biologi- 
cal diversity that must be maintained. Among these goals 
are the following: 

• the present and potential use of elements of biodiversity 
as biological resources 

• the maintenance of the biosphere in a state supportive 
of human life 

• the maintenance of biological diversity per se, in 
particular of all presently living species. 

Biological diversity as a resource 

It is evident that a certain level of biological diversity is 
necessary to provide the material basis of human hfe: at 
one level to maintain the biosphere as a functioning system 
and, at another, to provide the basic materials for agricul- 
ture and other utilitarian needs. 

Food 

The most important direct use of other species is as food. 
Although a relatively large number of plant species, 
perhaps a few thousand, have been used as foodstuffs, and 
a greater number are believed to be edible, only a small 
percentage of these are nutritionally significant on a global 
level, and only very few of these have been intensively 
managed on a commercial scale. Similarly, very many 
animal species are eaten (mostly fishes), but only a very 
small percentage are globally of nutritional significance. 
A few dozen species, mostly mammals, are managed in 
some kind of husbandry system, and a handful of these 
are globally significant. 

It is clear that successful cultivation of agricultural crops 
on a large scale requires a suite of other organisms (chiefly 
soil microorganisms and, in a few cases, pollinators) but 
these probably amount to a statistically insignificant per- 
centage of global biological diversity. Highly productive 
agricultural systems also require the virtual absence of 
some elements of biological diversity (pest species) from 
given sites. 

Whilst relatively little diversity is currently used in com- 
mercial food production, the very high probability of 
global climate change, predicted to result in large-scale 
shifts in natural vegetation and in agricultural systems, has 
focused attention on the need for conservation of plant 
genetic resources in order to maintain crop productivity 
under different climatic regimes. This ' insurance value' 
of diversity is also evident in contemporary conditions, 
where increased genetic uniformity is correlated with 
increased crop yield variation. 



Pharmaceuticals 

Medicinal drugs derived from natural sources make an 
important global contribution to health care. An estimated 
80% of people in less-developed countries rely on tradi- 
tional medicines for primary health care; this shows no 
signs of decline despite availability of western medicine. 
Some 120 chemicals extracted in pure form from around 
90 species are used in medicines throughout the world. 
Many of these cannot be manufactured synthetically: the 
cardiac stimulant digitoxin, the most widely used car- 
diotonic in western medicine, is extracted direct from 
dried Digitalis (foxglove); synthetic vincristine, used to 
treat childhood leukaemia is only 20% as efficacious as 
the natural product derived from Catharanthus roseus 
(Rosy Periwinkle). 

As with agriculture, and excluding traditional medicines, 
at present only a very small percentage of the world's 
biodiversity contributes on a global scale to health care. 
Many argue that technological advances within the phar- 
maceutical industry, and in particular those involving the 
design and manufacture of synthetic drugs, will mean that 
this contribution is more likely to fall than rise. However, 
natural diversity might be increasingly valued for the 
^blueprints' it provides for new synthetic drugs. 

Other material values of biological diversity 

Many natural or semi-natural ecosystems, some of which 
may be of high biological diversity, are of considerable 
benefit to man. Examples are: 

• the role of forests in watershed regulation and stabili- 
sation of soils in erosion-prone areas 

• the role of mangroves in coastal zone stabilisation and 
as nursery areas for fisheries species 

• the role of coral reefs in supporting important subsis- 
tence fisheries 

• the role of natural ecosystems protected as national 
parks in generating income from wildlife tourism. 

In general, however, these values are only indirectly 
related to biological diversity. That is, a certain level of 
species richness is required for these functions but there 
is not necessarily a direct correlation between the value 
of the ecosystem and its diversity, nor in all cases do a 
particular set of species have to be present. Thus, man- 
grove ecosystems are generally of far lower diversity than 
adjacent lowland terrestrial forests but in resource terms 
are likely to be of comparable value. The savannas of east 
and southern Africa, which are of great importance in 
generating revenues from tourism, are less diverse than 
the moist forests in these countries which have far less 
potential for tourism. 

The precautionary principle 

While it is evident that at present a relatively small 
proportion of the world's biological diversity is actively 
exploited by man, other elements of biological diversity 
may be important for different reasons: 

• they have values which are unused or unknown at 
present but which could enhance the material well-be- 



ing of mankind if these values were discovered and 
exploited 

• they may become useful or vital at some time in the 
future owing to changing circumstance. 

These factors support a precautionary line in maintain- 
ing biological diversity - that is, actually or potentially 
useful resources should not be lost simply because we 
do not know about or value them at present. However, 
although this precautionary argument has wide applica- 
bility it has limited force. It is based on estimates of the 
potential value of a given element of biological diversity 
which must be balanced against the actual cost of 
maintaining it or refraining from destroying it. Thus, 
unless a given element is identified as vital, it must have 
a finite value and there must therefore come a point at 
which the projected costs required to maintain it will 
outweigh any probable benefits. The fact that these 
costs and benefits are rarely if ever precisely quantifi- 
able means that such calculations will involve the esti- 
mation of probabihties and risks. 

Conclusions on resource values 

Experience and general ecological theory indicate that no 
single species is indispensable in maintaining basic eco- 
logical processes on a global scale and that, in general 
terms, the rarer a species is, the less likely it is to play an 
important ecological role on even a local level. In other 
words, every species has a finite resource value and, 
although in some cases this value may be very high, in the 
case of increasingly rare species it tends to zero. 

Similarly, with respect to species which may be directly 
useful to man, chiefly as food and pharmaceuticals, the 
vast majority of species can be said with high probability 
to have little potential. Experience enables us to identify 
those groups of taxa where there is a higher probability 
of value (e.g. wild relatives of crop species, and certain 
plant families for pharmaceuticals). 

General conclusions to be drawn from the above discus- 
sion may be that considering species only as material 
resources, it would be more cost-effective to: 

• maintain systems and areas rich in species than those 
poor in species 

• maintain those known to be useful, or regarded as 
having a high probability of being useful, than to 
maintain other species. 

These conclusions indicate that resource values of biodi- 
versity, and in particular the cost-benefit approach to 
conservation, do not of themselves provide justification 
for the wide-ranging approach to biodiversity conserva- 
tion that many seek to pursue. Such arguments must 
have limited applicability and limited force, and consid- 
erable caution must be exercised when citing them, es- 
pecially when extrapolating from the particular (the 
rationale for maintaining particular species or a certain 
level of biological diversity) to the general (that all bio- 
logical diversity is inherently valuable as a resource 
and must therefore be preserved). 



Biodiversity and the biosphere 

Human activities are affecting the biosphere on a global 
scale. It is important in the present context to estabhsh the 
extent to which losses in biological diversity may contrib- 
ute to these changes in having an impact on man. 

One of the most obvious of such global changes is the 
perturbation of the carbon cycle, leading to a steady 
increase in atmospheric CO2 levels. This will probably 
have far-reaching, although at present unpredictable, ef- 
fects on global climate patterns which may in turn have 
serious consequences for human welfare. 

A significant part of this is ascribable to industrial proc- 
esses, especially the burning of fossil hydrocarbon fuels 
for energy generation. However, it is believed that altera- 
tion of existing natural or semi-natural ecosystems is also 
important. In particular the large-scale destruction of 
tropical moist forests is implicated, both in contributing 
to atmospheric CO2 through burning and in decreasing the 
carbon-fixing potential of the biosphere. The high risk of 
serious consequences for humans of global climate 
changes is itself a strong argument for decreasing rates of 
forest clearance. It must, however, be stressed that this 
argument applies to tropical moist forest as ' forest ' , rather 
than as ~a highly diverse ecosystem'. Diversity is impor- 
tant only to the extent that it contributes to the system 
functioning as a carbon sink and the argument applies 
equally to other systems with a similarly high capacity for 
carbon fixation, such as tropical freshwater swamps, 
although these are far less diverse than tropical moist 
forest. In more general terms, there appears to be no direct 
or obvious link between the importance of an ecosystem 
in maintaining essential global ecological processes and 
its diversity, although more research is required. 

Non-resource values of biological diversity 

It is evident that resource-based arguments for the main- 
tenance of biological diversity have very considerable but 
finite force; therefore any fundamental justification for 
striving to maintain all currently existing biological diver- 
sity must lie outside the realm of material resource values. 
Such justification usually devolves onto two principles - 
ethics and aesthetics - which themselves lie outside the 
realm of science. 

Ethics 

For some cultures, ethical beliefs provide the strongest 
grounds for maintaining biological diversity, and indeed 
in some eastern countries much of the remaining diversity 
in densely populated areas can be attributed directly to 
rehgious practices. However, without recourse to an 
absolutist moral code, it is difficult to argue compellingly 
for an ethical imperative for the maintenance of all 
existing biological diversity. Whilst the killing of any 
living organism may be morally unacceptable to some 
people, there are problems in extending this argument to 
the conservation of biological diversity. At an extreme 
level, any individual organism that is not genetically 
identical to another represents a facet of this diversity, and 



a strict ethical argument would proscribe its destruction. 
It may be understandable to object to the killing of an 
elephant on moral grounds, but is it any less moral to eat 
wheat, which is grown from genetically diverse seeds, 
than to eat potatoes, most of which are grown from 
genetically identical clones? Similarly, there are difficul- 
ties in demonstrating that a species, which is to some 
extent a human construct, has any greater ' right' to 
existence as an entity than any one of the individuals of 
which it is comprised. 

Neverthess, the fact remains that ethics provides a pow- 
erful argument against the destruction of biological diver- 
sity. In practice, this argument is often contingent on other 
grounds, particularly the precautionary principle. For 
example, it may be considered immoral to destroy some- 
thing which is now, or may be in the future, regarded as 
valuable to others. This is embodied in the " stewardship' 
argument. The principle of inter-generational responsibil- 
ity underpins the ethical case for conservation in the 
developed world, although it may be of little practical 
relevance to a desperate farmer faced with the reality of 
survival in a developing country. 

Aesthetics 

Arguments for the maintenance of biological diversity for 
its aesthetic appeal are compelling but have limited force, 
as they must be dependent on relative aesthetic judge- 
ments. Such judgements could presumably discard some 
organisms (those not visible, for example) as not worthy 
of being maintained. They are also unlikely to hold sway 
in the face of counter arguments that certainly exist for 
the destruction in the wild of harmful organisms, such as 
malarial Plasmodium species. Further, because genetic 
diversity is not susceptible to aesthetic appreciation, aes- 
thetic criteria can be applied only to species and ecosystem 
aspects of biodiversity. 

Regardless of individual aesthetic judgements, it is un- 
doubtedly the case that humans very strongly favour 
variety in most areas of their experience. This need is 
particularly evident in the realm of the natural world. That 
is, diversity itself, and biological diversity in particular, 
is held in some poorly-defmable but fundamental sense to 
be a highly desirable phenomenon. This is no mere notion, 
but a need that is very deeply felt, and a fundamental part 
of the spiritual life of many people. It is not important that 
the reasons for this cannot be fully articulated; the need 
is strongly manifest and should have force in determining 
action. 

Overall, while it is evident that neither ethical nor aes- 
thetic arguments provide of themselves sufficient grounds 
for attempting to maintain all existing biological diversity, 
a more general and pragmatic approach recognises that 
different but equally valid arguments (resource values, 
precautionary values, ethics and aesthetics, and simple 
self-interest) apply in different cases, and between them 
provide an overwhelmingly powerful case for biodiversity 
conservation. 



PART 1 
BIOLOGICAL DIVERSITY 



Part 1 introduces some of the principal elements comprising biological diversity. 
Where appropriate, it discusses the ways in which they are measured, their patterns of 
distribution in space and the changes they have undergone over time, and notes their 
ecological importance. The main emphasis is on diversity at the species level. The 
chapters in Part 1 are grouped into four sections. 

The first section (Chapters 1-4) is concerned broadly with the science of systematics 
as the primary approach to biodiversity. The opening three chapters cover: genetic 
diversity among species and populations, the scope and practice of systematics, and 
the meanings of the word 'species'. Although most debate about biodiversity has been 
in terms of species, it is important to recognise that the 'species' is not a standard 
unit; the way species are defined differs between groups and between taxonomists. 
The fourth chapter deals in considerable detail with the complex topic of global 
species numbers: how many species have been named and how many species probably 
exist but are as yet unknown and undescribed? There is considerable uncertainty about 
the number of valid described species, and extreme uncertainty about the global 
species total: conservative working estimates suggest 1.7 million described species and 
12.5 million in total (estimates of the latter range up to 100 million). 

The second section (Chapters 5-15) presents a review of biodiversity at the species 
level. Chapter 5 provides a general introduction to the subject of species diversity, 
while Chapters 6 to 14 present a series of case studies of different taxonomic or 
ecological groups. Many of the data sets presented here are entirely new. No attempt 
has been made systematically to cover all organisms in a consistent manner. The 
groups included and the kinds of data presented have to a great extent been dictated 
by the availability of information and expertise, although we have tried to cover some 
groups and communities that are less familiar, or highly diverse, or both. Species 
richness of tropical forest insects is discussed at length in Chapter 4, along with an 
outline of sampling procedures which could result in much-improved data on their 
distribution. Groups that have not received detailed review will be considered in 
future editions of this report. 

In this section. Chapter 8, on ferns, gymnosperms and flowering plants, and Chapter 
13, on vertebrates (excluding fishes), include large data tables which attempt to give 
an estimate, for each major group, of the total number of species in each country of 
the world, and an estimate of the number endemic (restricted) to each country. 
Chapter 12 includes data tables of freshwater fish species number and endemism in 
rivers and lakes. 

This section closes with a discussion (Chapter 15) of some of the ways in which data 
on species distribution can be analysed to identify sites or areas which are particularly 
rich in species or contain a high proportion of endemic species. Conservation of these 
areas will be particularly important in efforts to maintain global biodiversity. This 
approach is illustrated by data derived from two global-level projects dealing with 
plants and with birds. 



The third section contains two chapters which deal with trends in species diversity 
over time. Chapter 16 introduces the phenomenon of extinction; while extinctions in 
paiaeontological time are discussed, the main emphasis is on historical and recent 
extinction, and the problems of predicting current and future rates of species loss. An 
attempt to list the animal species known to have become extinct since 1600 is included 
in this chapter. Chapter 17 discusses species threatened with extinction, in particular 
those which have been assigned to one of the lUCN threatened species categories. It 
covers the taxonomic, habitat and geographic distribution of species listed by lUCN as 
threatened, and discusses the factors leading to population decline. 

The fourth and final section moves on to look at the habitat and ecosystem level of 
biodiversity. The opening chapter (18) introduces the theme of global community 
classifications, and notes some of the conceptual and practical difficulties which hinder 
their construction. Chapter 19 briefly outlines evidence for global climate change, and 
its predicted impact on protected areas. Both these chapters are illustrated by full 
colour maps. 

Chapters 20 to 24 in turn cover five ecosystem types: tropical rain forest, grassland, 
wetlands, coral reefs and mangrove forest. A selection of systems which are species- 
rich or under particular threat have been included; no attempt has been made 
systematically to review all ecosystems (others will be included in future editions). 
Chapter 20, on tropical forests, discusses in some detail the various attempts that have 
been made to estimate the rate at which this habitat is being modified, and the 
difficulties inherent in such estimation. This should be read in conjunction with 
Chapter 4, on species inventory, and Chapter 16, which in discussing estimates of 
current and future rates of extinction, notes that no precise quantitative link can be 
made between species number in tropical forests, rates of forest loss, and rates of 
species extinction. 



Genetic Diversity 



1. GENETIC DIVERSITY 

This section introduces concepts from genetics necessary for 
an understanding of the generation and maintenance of 
biological diversity. 

THE NATURE AND ORIGBS OF GENETIC 
VARIATION 

Genes are the blueprints that make us and all the other 
organisms around us what we are. They consist of a 
discrete segment of deoxyribonucleic acid (DNA), a linear 
molecule composed of sequences of four different 
nucleotide bases. From the seemingly simple code contained 
in the sequence of these four bases of DNA comes the 
overwhelming complexity and diversity of the living world. 

Living organisms can be divided very broadly into 
eukaryotes, in which the cell nucleus is bounded by a 
membrane, contains a number of organelles, and has its 
DNA combined with proteins to form chromosomes, and 
prokaryotes, in which these features are lacking. All higher 
organisms are eukaryotes; bacteria are prokaryotes. 

Bacteria generally have a single copy of each of their genes 
located on a single piece of DNA and usually they tend to 
reproduce asexually, that is without the coming together of 
genetic information from another individual. Sometimes 
bacteria obtain some or all of the genetic material from 
other individuals in a process analogous to sexual 
reproduction in animals and plants. Thus, concepts of 
species developed principally with reference to higher 
organisms do not apply exactly to bacteria. Work is just 
beginning to characterise the nature and extent of genetic 
variation in a few bacteria. Given the huge diversity that 
has evolved over three billion years it is not surprising that 
bacteria appear to be a very complex group. 

Genes are arranged linearly along the DNA and in most 
eukaryote organisms there are something like 50,000 of 
them. The actual quantity of DNA in each cell of different 
species of eukaryotes varies over three orders of magnitude 
(Fig. 1.1). Much of this DNA is not coding for anything 
and it is still an active area of research to understand what, 
if anything, all this apparently 'extra' DNA is doing. Our 
ignorance of its function, however, does not stop it from 
being useful for answering some kinds of questions, as 
discussed below. In most of the organisms we can see with 
the naked eye (animals and plants) the DNA of a cell is 
divided among a number of chromosomes. Humans have 23 
different chromosomes. These chromosomes generally exist 
in two copies within each cell of the body and the organism 
is then said to be diploid; thus humans have a total of 46 
chromosomes per cell. For the majority of organisms, 
which have sexual reproduction, one of these copies comes 
from the mother and the other from the father. Sex in 
genetic terms is just this, the coming together of genetic 
information from separate individuals. In this way genetic 
differences from different individuals may be combined in 
their offspring to produce new combinations upon which 
evolutionary processes can work. Asexually reproducing 
organisms must wait for the occurrence of different 
mutations in the same lineage to achieve these new 
combinations of genes. 



Mutations are changes in the DNA. They occur in many 
ways. Mutations produce variation and variation is the raw 
material of evolution. The same gene can exist in a number 
of variants and these variants are called alleles. If the two 
copies of a particular gene possessed by an individual are 
different alleles, the individual is said to be heterozygous at 
that gene. If the two copies are the same allele the 
individual is homozygous at that gene. A population of a 
species that has more than one sillelic form of a particular 
gene is said to be polymorphic for that gene. If there are 
two alleles for a gene there are two possible homozygotes 
and one heterozygote. If there are three alleles, there are 
three homozygotes and three heterozygotes. For four alleles 
there are four homozygotes and six heterozygotes, and so 
on. Now consider the possibilities when we look at two 
polymorphic genes, and three, and on to the thousands that 
are polymorphic in most outbreeding organisms. 

The number of possible combinations is vast - much larger 
than the number of individuals making up a species. This is 
the variation that the evolutionary process works on, and 
that provides the production attributes which agricultural 
development seeks to incorporate into crop varieties and 
livestock breeds. 

The material below considers what is known of the 
implications of all this variation, how it changes and 
spreads, and the effects of human activities on genetic 
diversity and evolutionary processes. 

MEASURING GENETIC VARIATION 

Measurements of genetic variation are useful for studies of 
two broad classes of problems. One of these is the testing 
of theories about the nature of the forces acting on genetic- 
variants - the nuts and bolts of evolution. There is a large 
body of mathematical and statistical theory about the 
genetics of populations, the basis of which was formulated 
by 1930. Only now, with the advent of DNA technology, 
do we have sufficiently powerful tools fo begin rigorously 
testing these theories and their more recent elaborations. 
The other class of problems uses measures of genetic 
variation as a tool for understanding relationships among 
organisms and the diversity within and divergence between 
them. 

There are necessarily important connections between the 
two sets of problems. Indeed, the central debate in 
evolutionary genetics is about whether most of the genetic 
variation seen in natural populations is maintained by 
natural selection or is neutral and therefore is subject only 
to the laws of chance. The issues at stake in this debate are 
crucial to the understanding of the mechanisms of the 
evolutionary process but they are not so important in the 
very practical matters of assessing differences between 
individuals, populations and species that are our main 
concerns here. 

Allozymes 

The first widely applicable technique for measuring genetic 
variation does so at one remove from the DNA itself. This 



Part 1. Biological Diversity 



Figure 1.1 Range of DNA content in euloryote organisms 



PROT 1 STS 
Eug lenozoa 
CI I iophora 


1 1 i 1 1 1 11 






























FUNGI 

ANIMALS 

Sponges 

Anne 1 1 ds 

Mol 1 uses 

Crustaceans 

1 nsects 

Echinoderms 

Agnathes 

Sharks/ Rays 

Bony Fish 

Amphibians 

Rept i 1 es 

Birds 

Mamma 1 s 

PLANTS 










^ 




■ i 










^^^^* 


















^ 




















- 




Algae 

Pter idophytes 

Gymnosperms 

Angiosperms 














-.. . .1 1 1 M 1 III 1 1 1 1 1 1 II 


1 1 1 


Mini 1 1 1 1 1 1 1 il 1 1 1 1 1 1 il 



1,000 
Range of DNA content 



100,000 



1000,000 
Range 



Source: from data tabulated by Li, W. and Graur, D. 1991 . Fundamentals of Molecular Evolution. Sinauer Associates Inc., Sunderland, Mass. 



technique is protein electrophoresis and it depends on the 
differences in electrical charge between variants of specific 
enzymes (allozymes) coded for by DNA. These charge 
variants migrate at different rates in gels subjected to an 
electric field and can therefore be differentiated from one 
another. It was this method that first revealed that on 
average 20-30% of the proteins of most organisms exist in 
more than one allelic form. This level of variation was not 
expected and the search for adequate explanations for it has 
been a major force in evolutionary genetics for more than 
20 years. 

By measuring the frequencies of different variants in groups 
of individuals sampled from different areas we can quantify 
the amount of variation within and between individuals and 
thereby get a picture of the geographic structure of the 
species in genetic terms. Not all changes in DNA result in 
a charge change which allows variants to be separated on a 
gel but this method still provides a good approximation to 
changes at the DNA level, at least within species and 
between closely related species. At greater taxonomic 
distances the probability of two different variants showing 
the same mobility in the gel system becomes high enough 
for the method to break down. Nevertheless, analysis of 
allozyme frequencies still has an important role to play in 
the study of intraspecific variation and the bulk of available 
data on genetic variation comes from studies of frequencies 
of electrophoretic variants of a number of enzymes. 



Very recently development of DNA technology has 
provided us with the means to sample genetic variation 
directly at the DNA level. At present, however, these 
methods are more expensive and generally more difficult to 
perform than allozyme techniques. Therefore there are not 
yet the large amounts of data on within-species variation 
available from allozyme studies. This situation is changing 
rapidly as the necessary technology becomes more widely 
available and less expensive. The following sections give 
brief descriptions of the main techniques of use in 
phylogenetic and population genetic studies. 

Because different parts of the DNA evolve at different rates 
we can choose to study particular segments to answer 
particular questions. Some genes change very slowly and 
can be used to study relationships among groups of 
organisms which diverged from one another hundreds or 
even thousands of millions of years ago. Other regions of 
DNA change at such a rapid rate that every individual in a 
population, except for identical twins and other such clones, 
is distinct. Still other regions of DNA show intermediate 
levels of variability which are useful for studies of variation 
within and between populations of a species, or of variation 
between closely related species. 

Restriction fragment polymorphisms (RFLPs) 

The DNA-based techniques most widely used for studies of 



Genetic Diversity 



within- and between-population variation make use of the 
properties of enzymes derived from various species of 
bacteria which use them to protect themselves from 
infection by viruses by cutting (restricting) invading viral 
DNA. These restriction enzymes are very specific in the 
DNA sequence they recognise and cut, and they form the 
backbone of the technology of DNA manipulation. If DNA 
from an individual is extracted and cut with a restriction 
enzyme and the resulting fragments separated by length in 
an electrophoretic gel a pattern is obtained. Another 
individual may have a change in its DNA which produces 
an additional site recognised by the enzyme, or it might 
have changed in such a way that a recognition site has 
disappeared, thereby changing the pattern of restriction 
fragments seen on a gel. By repeating this process with 
other individuals and restriction enzymes, patterns of 
variation can be seen and analyzed to estimate the amount 
of variation in the DNA sequences among the individuals. 
These restriction fragment length polymorphisms (RFLPs) 
are very useful for determining the geographic structure of 
populations. By measuring the frequencies of different 
patterns in populations of a species we can estimate the 
amount of gene flow or genetic cohesion among the 
populations. 

DNA sequencing and the polymerase chain reaction 

Another more powerful (and more expensive) method of 
assessing genetic variation is to sequence a portion of the 
DNA itself. With the advent of the polymerase chain 
reaction technique (PCR), which can be used to make 
millions of copies of a particular region of DNA, it is now 
possible to obtain DNA sequence data from a wider variety 
of organisms much more quickly than was possible 
previously. The exquisite sensitivity of the PCR permits the 
amplification of a sequence from minute amounts of starting 
material - as little as a single cell. This has very important 
implications for obtaining data from very small organisms 
which contain too little tissue to use with RFLPs, and from 
larger organisms without having to kill or otherwise injure 
them. A minute drop of blood or a hair root or a feather 
are now adequate material for DNA sequence-based work. 
This has obvious importance in dealing with rare and 
endangered species. 

THE INTERPRETATION OF VARIATION 

Different measures of variation can be used to investigate 
relationships ranging from very distant groups, such as 
phyla, to closely related individuals within a population. 

Often an understanding of relationships among closely 
related individuals is necessary for understanding behaviour 
and evolutionary processes within a species. Similarly, with 
breeding programmes for endangered species it is important 
to know the degree of genetic relatedness of individuals so 
that deleterious effects from inbreeding can be minimised. 
The technique of genetic fingerprinting can provide this 
information. Fingerprinting makes use of a common but 
peculiar group of DNA sequences known as minisatellites. 
These are dispersed throughout the genome and consist of 
tandemly repeated copies of short sequence units. High 
levels of variation in the numbers of these repeated units 
are exploited in fingerprinting to identify close relatives. 



Biologists have long wanted to know if the genetic 
differences between species were of a different sort from 
the differences between individuals within a species. The 
answer appears to be that interspecific differences are not 
different in kind from intraspecific variation. Animal 
species usually differ at a large number of genes; single 
mutafions are seldom, if ever, responsible for speciation 
events. The genetics of speciation is not discussed here 
although information on genetic distance between species- 
level populations in selected vertebrate genera, derived from 
methods outlined above, is show in Fig. 1.2. 

In an outbreeding species every individual has a unique 
combination of alleles and the shuffling of genes that occurs 
in sexual reproduction insures that every future individual 
will be unique as well. If every individual is unique, what 
use are genetic data in making decisions about conservation 
problems? This question gets us to the heart of some 
fundamental problems in biology. Our knowledge of how a 
genotype is translated into a phenotype, a body, is very 
sketchy and this is an area of major research effort in 
biology. Genetic criteria for uniqueness and justification for 
conservation are not simple problems. In the sections below 
we will outline some of the issues, the problems and 
prospects for the use of genetic data in conservation. 

THE ENVIRONMENT AND THE DISTRIBUTION OF 
GENETIC VARIATION 

The earth is not a homogeneous place. This obvious fact 
has profound implications for the ways in which organisms 
live and evolve and is very probably responsible for much 
of the diversity of life around us. Limitations of the extent 
of particular habitats and differences in the ways in which 
organisms get their livings contribute in part to the large 
differences in the amounts and distributions of genetic 
variation which we observe. The following sections describe 
some of the basics of population genetics theory. 

Gene flow and range expansion 

One organism's minor inconvenience to free movement can 
be another's insurmountable barrier. These barriers can be 
physical, as for an animal which cannot cross a small 
stream, or behavioural, as for a small rodent which refuses 
to cross a small gap between patches of forest, or a plant 
reliant on a particular species of animal for pollination or 
dispersal of its seeds. Behavioural traits can have a large 
influence on the distribution of variation within a species. 
Even organisms which range over vast areas of ocean can 
have very different genetic population structures as a result 
of behavioural differences. An example of the extremes 
possible are the North American Eel which inhabits streams 
along 4000km of coastline and the Humpback Whales of the 
North Pacific and North Atlantic Oceans. The eels migrate 
to the Sargasso Sea to reproduce as one massive population 
and as a consequence the individuals inhabiting streams 
show no geographic differentiation. Other fish species 
inhabiting the same streams, but which do not leave their 
home streams to spawn, show substantial genefic 
differentiation. Humpback Whales on the other hand show 
genetically distinct subpopulations within ocean basins 
despite their ability to roam over huge distances. This 
differentiation is apparently the result of female traditions 



Part 1. Biological Diversity 



in migratory destinations. The eels then show a very high 
rate of gene flow while the humpbacks have a low rate of 
gene flow among subpopulations, despite ranging over 
comparable areas. 

These differences in rates of gene flow and population 
structuring have major effects on the course of evolution. 
A few broad generalisations are possible, though subject to 
all sorts of caveats in particular situations. Species 
inhabiting large geographic areas and showing high rates of 
gene flow show very little or no local differentiation. 
Conversely, species with low rates of gene flow are often 
divided into distinct populations. At least some of this 
distinctness represents adaptation to the local enviroimient. 
Adaptations of this sort are familiar to us all in varieties of 
crop plants and domesticated animals which, as a result of 
artificial selection by humans, perform better in particular 
climates and agricultural regimes. Natural selection can 
work in a similar way in producing populations with 
adaptations to local conditions. 

The Earth has only very recently (in geological and 
evolutionary terms) emerged from an ice age. This and 
other events in the planet's history have had, and continue 
to have, major effects on the nature and distribution of 
living things. Much of the northern hemisphere was under 
thick ice 10,000 years ago. Most of that ice is now gone 
and in its place is forest, prairie, lakes and tundra, all 
teeming with life which has managed to colonise these 
newly available habitats. Natural processes of change are 
still visibly occurring in these regions, suggesting that 
populations inhabiting them are not likely to be in genetic 
equilibrium. This means that patterns and amounts of 
genetic variation reflect historical factors as well as the 
present-day situation. 

Genetically effective population size 

The number of individuals we can count in a population at 
any given time can be a surprisingly deceptive measure of 
the size of that population in genetic terms. At one extreme 
are organisms with vegetative or asexual reproduction such 
as aspen where we can stand in a forest surrounded by 
genetically identical individuals and a large area can be 
populated by only a handfiil of clones. A number of other 
factors commonly found in nature tend to reduce the 
genetically effective size of populations below that of the 
observed census size. Organisms with limited dispersal 
abilities tend to mate with individuals who are more closely 
related to themselves than the average for the population at 
large. This inbreeding reduces the overall genetic variation 
of the population relative to what it would have been if 
individuals mated at random across the whole population. 
Variation in number of offspring produced by different 
individuals in a population produces the same effect. If 
some individuals have many offspring while others have 
few or none the genetic variation of the population is 
reduced relative-to what it would have been if everyone had 
the same number of offspring. Similarly, populations which 
fluctuate in size or pass through a bottleneck of small 
population size can also show reduced genetic variation 
relative to that expected, all else being equal. Population 
geneticists have developed mathematical formulae to take 
account of these complicating factors in order to express 



population sizes of different organisms in comparable terms 
- the genetically effective population size. All these factors, 
and others too, can be operating and indicate the 
complexities of understanding genetic population structure 
of natural populations. We now have the tools with which 
to study this structure. Much remains to be done before we 
can hope to have a deep understanding of the structures of 
natural populations. 

One of the most dramatic examples of the potential discord 
between our visual impression of a species and its genetic 
reality is the Cheetah. This cat was until quite recently 
widely distributed throughout Africa and Asia. It has 
undergone a severe reduction in its range and numbers but 
is still found in widely separated areas of Africa. Recent 
surveys of genetic variation in the Cheetah have found 
almost no variation - individuals from widely separated 
parts of the species range are genetically almost identical. 
These results indicate a severe population bottleneck and 
subsequent inbreeding. Cheetahs both in the wild and in 
captive populations show pronounced effects of inbreeding 
not seen in other wide ranging carnivores. This inbreeding 
shows itself in reproductive difficulties such as very low 
numbers of sperm, many with morphological aberrations, 
and high susceptibility to epizootic diseases resulting from 
very low amounts of genetic diversity in their immune 
systems. The bottleneck responsible for these difficulties 
may well have been due to events following the retreat of 
the last ice sheet thousands of years ago. Human assaults on 
the Cheetah's range and numbers have certainly not aided 
its recovery from the effects of this botfleneck. Similar 
effects of inbreeding resulting from recent population 
bottlenecks are seen in relictual populations of lions in the 
Gir Forest Sanctuary of western India and in the 
Ngorongoro Crater in the Serengeti of Kenya. 

Outbreeding depression is the converse of inbreeding 
depression. If individuals have differentiated genetically 
over their range, the mating of individuals from different 
parts of that range can result in deleterious effects. This is 
presumably because genes from one area do not necessarily 
work harmoniously with genes from another area. The 
experimental difficulties involved in trying to understand 
these effects are great but we do have observations attesting 
to their existence in a number of plant species. Several 
experiments have demonstrated an 'optimal outcrossing 
distance', that is fertilization by pollen from distances 
greater than the optimum results in reduced fitness, just as 
fertilization by pollen from individuals close by can result 
in inbreeding depression. There are a few dramatic 
examples of outbreeding depression in animal populations. 
In Czechoslovakia, Turkish and Nubian Ibex were mixed 
with the local Tatra Mountain Ibex and the hybrids were so 
poorly adapted that the entire population went extinct. 

The genetic effects of habitat alteration and 
fragmentation 

Human activities cause genetic changes in species by 
altering their population structures. Disruption of dispersal 
and migration routes and reduction of population sizes are 
the most obvious factors. As with natural processes, effects 
of particular activities vary depending on the species 
considered, some may be affected virtually not at all while 



Genetic Diversity 



Figure 1.2 Means and ranges of genetic distance between species in selected 
vertebrate genera 



CercocebusC 63 

GeomysC 103 

Per omyscusC 1903 

Las i urusC 153 

DipodomysC553 

MacacaC 153 

Spermophi I usC 33 

NeotomaC 33 

ThomomysC 103 

_ PaploC53 

- VireoC1D3 

AmmodramusC 33 
Vermi voraC 53 

Par use 3D 
AnasC^53 

Zonotr ichi aC 33 

ToxostomaC 33 

DendroicaCB53 

CatharusC 63 

AnserC 33 

Geosp i zaC 153 

AythyaC33 

~ Anol isC723 

BipesC33 

Lacerta(;33 

UmaC33 

_ CrotaphytusC 53 

- PlethodonC3253 

Hy laC213 

Liter iaC1203 

HydromantesC 103 

RanaC213 

ScaphiopusC 103 

_ TarichaC33 

~ Lepomi.sC453 

NotropisC 10B13 

MenidiaC 103 

EtheostomaC 33 

Bathygobi usC33 

CoregonusC53 

ThoburniaC33 

Hypente I 1 umC33 

CampostomaC 53 
Cypr i nodonC 1 03 



Mean 




0.4 



Range 



OB 1.2 

Genetic Distance 



Note: The numbers of pairwise comparisons of species are in parentheses. 

Source: Avise, J.C. and Aguardro, C.F. 1982. A comparalive summary of genetic distances in the vertebrates. In: Hecht, M.K., Wallace, B. and 

Prance, G.T. (Eds), Evolutionary Biology. Volume 15. Plenum Press, New York. 



Others may be devastated. For example, many tropical 
forest trees occur at very low densities over wide areas and 



rely on particular species of insects or birds for pollination. 
Fragmentation of the forest results in very small numbers 



Part 1. Biological Diversity 



of individuals in each patch. If their pollinators are unable 
to cross the gaps between patches, severe inbreeding or 
failure to reproduce can result. So even if accidents of 
nature do not remove these rare individuals from isolated 
patches of forest, they are genetically speaking dead, 
despite appearances to the contrary. Other species in the 
same isolated patches of forest may maintain large 
genetically effective population sizes, either by being 
present in higher densities within patches or by having 
better dispersal abilities between patches, or both. Of 
course, not all species are adversely affected by habitat 
fragmentation, especially those dependent on 'edge' habitats 
such as where forests and open country meet. Species that 
thrive in these circumstances range from animals usually 
perceived as desirable like White-tailed Deer, to the vectors 
of a number of the most devastating human parasites and 
diseases. 

The effects of small population size depend on the breeding 
system of the species and the duration of the bottleneck. If 
population size expands rapidly immediately after a 
bottleneck, relatively very little genetic variation will be 
lost. If the bottleneck lasts for many generations or 
recovery is very slow a great deal of variation can be lost. 
Of course a population which remains at a very small size 
for an extended period is very likely to go extinct as a 
result of demographic accidents, probably before deleterious 
genetic effects manifest themselves. 

If habitat fragmentation eliminates gene flow between parts 
of a species' range these newly isolated populations have 
independent evolutionary fiitures. What this means for the 
long-term fiiture for a species is difficult to predict. It is 



certainly time to put some serious effort into trying to find 
out. 

CONCLUSION 

The genetic diversity inherent in most species provides the 
raw material to respond rapidly to changed circumstances. 
This response may not always be adequate and it may not 
be in the best interests of humans, as when agricultural 
pests and human pathogens develop resistance to our control 
measures. Change is, of course, the normal state of affairs 
in the living world. What makes our present situation 
unique is the rapidity and scale of the change. Our 
fragmentation and destruction of habitats constitutes a 
massive uncontrolled experiment in ecology smd genetics. 
We are beginning to understand in outline what needs to be 
done to mitigate at least some of the negative effects of this 
experiment. Knowledge of the population structures, i.e. the 
distribution and amount of genetic variation, of a wide 
range of organisms is necessary, as is a much deeper 
understanding of the biological significance of different 
sorts of variation. 

References 

Avise, J.C. and Aguardro, C.F. 1982. A comparative summary of 

genetic distances in the vertebrates. In: Hecht, M.K., Wallace, B. 

and Prance, G.T. (Eds), Evolutionary Biology. Volume 15. Plenum 

Press, New York. 
Li, W.-H. and Graur, D. 1991. Fundamentals of MoUcular Evolution. 

Sinauer Associates Inc., Sunderland, Mass. 

Contributed by Richard Thomas, Molecitlar Biology Unit, 
The Natural History Museum (Loruion). 



2. SYSTEMATICS AND DIVERSITY 



Systematics and Diversity 



This chapter provides a short introduction to systematics: 
the branch of biological science responsible for recognising, 
comparing, classifying and naming the millions of different 
sorts of organisms that exist. As such, systematics provides 
the basic framework for the whole of biology, and is the 
fundamental discipline of biodiversity. The work can be 
divided into a number of activities, including classification, 
identification and nomenclature. These are often grouped as 
taxonomy, broadly defined as the classification and naming 
of organisms. This chapter gives the background for 
Chapter 3, which discusses some key theoretical and 
practical problems arising from the concept of the species. 

BIOLOGICAL CLASSIFICATION 

The ultimate task of systematics is to document and 
understand the extent and significance of biological 
diversity. Within this framework, taxonomy performs four 
basic functions: differentiation (recognition of taxa), 
identification (universal diagnosis of taxa), symbolisation 
(application of universal names), and comparison (relative 
relationships of taxa). Vernacular or folk taxonomies 
provide limited local systems for the first three but have 
little to tell us about the last. 

Individuals and characters are the most basic units of 
biological classification. On the basis of features held in 
common (attributes or characters), individuals can be 
grouped together into a large number of different classes. 
These classes are of two kinds (often regarded as sharply 
distinct, although in reality they form a continuum). On the 
one hand, individual organisms can be divided into such 
groups as freshwater, marine, terrestrial, planktonic, 
nocturnal, pollinators, etc. Alternatively, they can be placed 
into taxonomic categories of species, genera, families, 
orders and so on. The former are regarded as artificial 
classes, constructed only to serve a particular purpose, 
whereas the latter are seen, ideally, as natural groups. 

Natural groups comprise individuals with a very large 
number of attributes in common, whereas individuals 
belonging to artificial groups have relatively few shared 
characters. Thus the essential difference between, for 
example, 'marine animals' and Mammalia is that individuals 
of the latter class have far more in common than those of 
the former. A natural group, being based on a large number 
of characters, can be used for a far wider range of 
generalisations and predictions than an artificial group. 

Artificial and general classifications are not restricted to 
biology. Biology, however, has a unique theory of its own, 
the theory of organic evolution. Ideas about evolution can 
be divided into a general theory of descent with 
modification and special theories about the processes of that 
descent (natural selection, neutral theory, etc.). Modern 
systematists consider that the general theory of evolution 
not only provides a compelling justification for seeking one 
natural, general classification for living organisms but also 
suggests the basis on which that classification can be most 
securely founded: the hierarchic pattern of the ancestor- 
descendant sequence, or phylogenetic relationships. 



PHYLOGENETIC RELATIONSHIPS AND THEIR 
ESTIMATION 

In the past, many biologists have denied that we have 
access to sufficient or appropriate information to determine 
the phylogenetic relationships of organisms. In the last 25 
years, however, spectacular advances in such areas as 
molecular biology threaten to overwhelm us with suitable 
data. Moreover, during this same period great advances 
have also occurred in the theory of systematics and methods 
of data analysis. 

In an absolute sense, being part of remote history, 
phylogenetic relationships cannot be known. What is done 
instead is to estimate the most basic feature of the ancestor- 
descendant sequence, the pattern of branching points or 
nodes. Relationships are defined in terms of common 
ancestry. If two species are considered to have a common 
ancestor which they do not share with a third species, then 
the first two are considered to be more closely related to 
each other than either is to the third. This represents the 
fundamental three-taxon problem, basic to all phylogenetic 
(or cladistic) analysis 

Cladistic analysis rests on three basic assumptions: features 
shared by organisms (homologies) form a hierarchic 
pattern; the hierarchic pattern can be expressed by 
branching diagrams (cladograms); and the nodes in a 
cladogram symbolise the homologies shared by the 
organisms subtended by that node (groups). Where data are 
in conflict (as they usually are, to a greater or lesser 
extent), parsimony is used to find the best supported or 
most efficient solution. 

Cladistics differs from other methods of classification 
because, based on these principles, only special 
resemblances are used as evidence of relationship or group 
membership. This is in sharp contrast to methods such as 
phenetics, in which all resemblances, including character 
absences, are regarded as equally informative. Some of the 
principles involved here are illustrated in Fig. 2.1. 
Cladistics has been at the centre of heated debate, but is 
now widely acknowledged to be the best way of 
approximating the branching patterns of phylogenetic 
history. 

FROM HIERARCHY TO CLASSIFICATION 

Once a justified hierarchy of phylogenetic relationships has 
been established, what relationship should exist between the 
hierarchy and classification? Organisms are divided into 
kingdoms (animals, plants, etc.), kingdoms into phyla 
(Arthropoda, Chordata), phyla into classes (Crustacea, 
Mammalia), classes into orders (Decapoda, Rodentia), 
families (Cancridae, Muridae), genera (Cancer, Rattus) and 
species (Rattus norvegicus, Rattus rattus). Each group 
contains the entirety of one or more groups at a lower level. 
The categories most often used are shown in Table 2.1, and 
see Fig. 2.2. Multiple membership of categories is not 
permitted (thus an organism cannot belong to two or more 
orders, genera or species at once, with the possible 
exception of hybrids). 



1. Biological Diversity 



Figure 2.1 Establishing the 

phylogenetic hierarchy 











Crarocters 








laxa 





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3 4 


s 


6 




UMt 




G 




S 


G 


" 




ALL 1 GATOR 


w 


E 




S 





« 




TUNA FISH 








- - 


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SHAfK 




- 




- - 


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SmRK TW« FISH MAN ALLlG*TOH SHARE TUNA F I SH MAN ALLIGATOR 





Notes: Establishing the phylogenetic hierarchy - overall similarity or 
special resemblance? In this simple example of a four taxon problem, 
the characters are the amino acids (guanine, lucine, serine etc) found 
to vary at eight homologous positions in the amino acid sequence of 
myoglobin A in man (taxon A), an alligator (6), a tuna fish (C) and a 
shark (D) (note that the positions 0-4 in man and alligator have no 
equivalent in tune or shark, and that position is also represented in 
man). If both presences and absences are counted as equally 
informative, the branching diagram on the left most efficiently 
summarises the data, but if only presences (special resemblances) are 
counted, the cladogram on the right is best. The first solution is that of 
the phenetic school of classification, which would continue to accept 
the *fish* as a natural group. The second solution is that of the cladistic 
school of classification, which would wish to recognise that, in terms 
of recency of common ancestry, there is good evidence that the tuna 
fish is more closely related to man and alligator than it is to the early- 
diverging shark. As a result, the fish is seen to be a paraphyletic 
group, of little or no value on natural (phylogenetic) classification (see 
also text; based on Patterson, 1980). 

Groups which, on the evidence of shared unique characters 
(special resemblances), are considered to contain all the 
living descendants of a common ancestor are called 
monophyletic groups; the mammals are an example. Use of 
characters which have evolved more than once leads to the 
formation of polyphyletic groups (groups of organisms 
which have multiple origins, such as placing birds and 
turtles together because they have beaks). If groups are 
formed on the basis of unspecialised or non-unique 
characters, such as reptiles (which can only be recognised 
collectively as members of the amniote vertebrates that are 
not mammals or birds), these are termed paraphyletic 
groups. 

These distinctions are important because they relate to a 
continuing debate over the relationship between genealogical 
hierarchy (as discovered by cladistic analysis of taxonomic 
characters) and formal classification. Most taxonomists 
agree that polyphyletic groups once recognised should be 
abandoned (although some remain in use, such as 
lophophores, a false grouping of the animal phyla 
Phoronida, Ectoprocta and Brachiopoda). But many 
paraphyletic groups continue to be very widely used, such 
as the invertebrates (Metazoa minus Chordata), fish 
(Chordata minus Tetrapoda) and Reptilia (Amniota minus 
birds and mammals). 

Nevertheless, Darwin's view that our classifications should 



correspond to genealogies is becoming more and more 
widely accepted. In the last 2-3 decades much progress has 
been made in discovering the phylogenetic relationships of 
organisms but far more needs to be done. In what follows 
it is therefore necessary to appreciate the ideal of hierarchic 
classification based on phylogenetic relationships and the 
compromise that most existing classifications still represent. 



The taxonomic hierarchy 



Table 2.1 

KINGDOM 

DIVISION (Botany) or PHYLUM (Zoology) 
CLASS 
ORDER 
FAMILY 
GENUS 
SPECIES 
Subspecies 

Variety (Botany) 

Form (Botany) 



Note: The categories of the taxonomic hierarehy in descending order 
of rank and inclusiveness. There are a few additional less commonly- 
used categories, (subphylum, superfamily, tribe, etc.). 



Figure 2.2 



Basic principles of 
classification 




Notes: Diagram to illustrate the basic principles for turning a scheme 
of phylogenetic relationship into a classification (based on Goodrich, 
1919. The Evolution of Living Organisms). According to Goodrich, 
"individuals are grouped into species, species into genera, these again 
into families, orders, classes and phyla, divisions of increasing size and 
importance ... the only "fixed points" in a phylogenetic system of 
classification are the points of bifurcation, where one branch diverges 
from another ... it is here that our divisions should be made." 
Goodrich's formulation of the problem remains appropriate today, 
except that to avoid mis-matches in the ranking of higher categories, 
division should proceed from top downward, not from the terminals 
(species) upwards. Simple principles of this sort allow us to translate 
the phylogenetic hierarchy into a classification hierarchy, although 
some compromises and exceptions are still widely accepted in practice, 
notably through continued recognition of paraphyletic groups such as 
invertebrates, fish and reptiles (see text), and problems created by 
hybridization (particularly in plant taxonomy). 



Systematics and Diversity 



TAXONOMIC NOMENCLATURE AND ITS 
REGULATION 

A separate problem from classification, but often confused 
with it, is taxonomic nomenclature. The ultimate goal of 
scientific nomenclature is a universal system of 
unambiguous names for all recognised taxa. Scientific 
names are basic to all biology, and biodiversity is no 
exception. In particular, their exact significance has 
important implications for conventions, red lists, export 
controls, licences or any other legal instruments used to 
manage biological diversity. 

Taxonomic nomenclature is controlled by voluntary 
application of internationally agreed rules or codes. 
Separate codes apply to the animal kingdom, plants 
(including fungi), and bacteria. In this section the operation 
of the zoological code will be outlined and the other codes 
briefly compared by noting a few of their differences. 

International Code of Zoological Nomenclature 

The formation and application of names at the rank of 
species (including subspecies), genus and family are 
regulated by the International Code of Zoological 
Nomenclature (the Code), and by the use of type specimens. 
Cases in dispute are settled through submissions to the 
International Commission on Zoological Nomenclature 
(ICZN). Names in use below the rank of subspecies (for 
polymorphic forms, seasonal variations, hybrids etc.) and 
above the rank of superfamily (orders, classes, phyla etc.) 
lie outside the scope of the zoological code, and are simply 
regulated through usage. This might appear unsatisfactory, 
but in practice it gives rise to few difficulties. The major 
problems occur with the names of species and, to a lesser 
extent, genera and families. 

The zoological code depends on two operational principles - 
availability and priority - and also governs the formation 
of names. To be considered nomenclaturally valid, a species 
name must be introduced in combination with a generic 
name, and in Latinised form. The species name follows the 
generic, never takes a capital, and is usually printed, as 
with the generic name, in italics (e.g. Homo sapiens, Rattus 
norvegicus, Papilio machaon). If a species is considered 
divisible into two or more taxonomically distinct subspecies, 
formal trinomens can be introduced. The subspecies 
including the population originally described is designated 
by tautonymy (Papilio machaon machaon); other subspecies 
receive distinguishing third names (Papilio machaon 
britannicus). 

Availability 

For a name of a subspecies, species, genus or family to be 
recognised within zoological nomenclature, a number of 
requirements must be met. If all these are satisfied, the 
name is said to be available; if not, the name is considered 
unavailable for the purposes of nomenclature. For a species 
name these requirements normally include: a statement that 
the name is proposed for a newly recognised species or 
subspecies; an indication of how the new taxon differs from 
other, related species; and proposal of the name in Latinised 
binominal form (i.e. the new species name must be 
proposed in combination with a generic name). These are 



some of the basic ingredients of the description, which must 
be properly published, in printed form. 

Priority 

The second basic principle is priority. If what is currently 
considered a single species, genus or family has received 
two or more available names independently, how would you 
choose between them? The basic principle oi priority simply 
directs that, wherever possible or practical, the oldest or 
senior available name must be used. Binominal 
nomenclature for animals was first consistently introduced 
in the 10th edition of Linnaeus's Systema Naturae, 
published in 1758, and this gives a baseline for priority. 
For zoological nomenclature it is therefore utmecessary to 
consider names published in any work before 1758 (with 
the exception of a single work on spiders published in 
1757). 

Name, author and date 

The two principles of availability and priority come together 
in the original published description. It is for this reason 
that, when a name is mentioned formally (as in a 
catalogue), the original author of the name and year-date of 
publication should also be mentioned; thus: Papilio 
machaon Lirmaeus, 1758. 

Types and their function 

Species and other taxa are concepts about the organisation 
of the natural world, whereas names are artefacts, symbols 
intended to designate those concepts. As taxonomic 
concepts change, difficulties arise with the application of 
existing names. One of the commonest problems occurs 
when there are more names available than taxa to be 
designated. Which old names apply to which newly 
circumscribed taxa? Objectivity in the application of names 
is achieved by the use of type specimens. 

The code strongly recommends that in original descriptions 
the author selects a particular specimen as the type (strictly 
holotype) and ensures that it is clearly so labelled and 
preserved in a permanent place (normally a museum) so that 
it can be studied again in the future. What is the purpose of 
such types'' It is quite commonly supposed, by those 
unfamiliar with biological nomenclature, that the type 
specimen represents some sort of 'standard' (typical) for 
defining the species, perhaps analogous to the standard 
metre or standard kilogram used to calibrate rulers or 
weights. Nothing could be further from the truth. The type 
specimen is simply the name-bearer - it is the specimen to 
which the original name is attached. In cases of doubt over 
identification with a particular species concept, if you can 
decide to which concept the type specimen fits, then the 
name automatically follows. Where more than one name is 
found to apply, then priority will normally determine which 
one is to be used; the other names are synonyms. 

Why do names change? 

Everyone who makes regular use of biological 
classifications soon becomes aware that 'official' names can 
change. The instability of scientific names is irritating and, 
as conservation and wildlife trade legislation becomes more 
complex, can lead to real difficulties. Some systematists, 
embarrassed that instability gives taxonomy a bad name, 
have proposed that a stabilised 'official list' should be 



1. Biological Diversity 



created (for one of the latest rounds of discussion, see 
Hawksworth, 1991). 

Changes in nomenclature occur for two basic reasons: 
problems with names and their application (homonymy, 
synonymy, and misidentification, as normally decided by 
interpretation of the international code), and revisions of the 
system of classification necessary to reflect new scientific 
discoveries about taxa and their natural relationships. 
Frequently these problems are compounded. While 
responsible efforts to avoid 'unnecessary' changes brought 
about by slavish application of the code are to be 
encouraged (because taxonomy is a science to which 
nomenclature ought to be subservient), it is futile to imagine 
that some fixed, permanently stable list of names can be 
drawn up. 

To insist on fixity would be far more damaging to 
biological science than to accept the minor irritation that, as 
our understanding of natural classification changes and 
steadily improves, it is necessary to adjust nomenclature 
accordingly. However, there are situations where automatic 
application of the code can lead to changes considered so 
unacceptable that the normal rulings of the code are best set 
aside. Such cases are submitted to 77ie International 
Commission on Zoological Nomenclature, an international 
panel of experts in animal nomenclature whose role is to 
decide on the best acfion in such cases, and then publish 
their decisions through the Bulletin of Zoological 
Nomenclature. 

International Code of Botanical Nomenclature 

This code governs the names of fungi as well as green 
plants. The ICBN operates in a broadly similar way to the 
zoological code, but differs in many details. One obvious 
difference is the 'double citation' whereby, if there has been 
any change in taxonomic assignment or rank of a taxon 
since its original proposal, the name is formally to be cited 
with the original author's name in parentheses, followed by 
the name of the taxonomist who proposed the change. 
Thus the plant known in English as the scentless mayweed 
was named by Linnaeus as Matricaria inodora. Later, it 
was moved by Schultz-Bipontinus to a separate genus, 
Tripleurospermum. This is the accepted name today, and its 
authority is formally quoted as Tripleurospermum inodorum 
(L.) Sch-Bip. Another difference is that tautonyms are not 
permitted for species names. Thus a name like Bison bison, 
acceptable under the zoological code, would not be 
acceptable in botany. (Tautonymous names below the rank 
of species do, however, occur in botany, being created 
automatically when plant species are first named; these so- 
called antonyms apply to varieties and subspecies.) Unlike 
zoological nomenclature, to establish a valid botanical name 
it is essential that the original description includes a Latin 
diagnosis. 

Cultivars are specifically the subject of an additional code, 
the International Code of Nomenclature for Cultivated 
Plants. Because of biological and other peculiarities, a 
number of special provisions also apply to fungi, lichens, 
plant hybrids and certain other groupings. One example is 
that the name of a lichen is taken to apply to the fungal 
part, should it be necessary to consider priority over the 



application of names to its constituent algal or fungal 
elements. At a more fundamental level, there are subtle but 
important differences between the botanical and zoological 
codes regarding availability and the significance of types. 
Changes in the botanical code, and appeals against the strict 
application of its provisions, must be directed to the 
Nomenclature Section of an International Botanical 
Congress, for decision in plenary session. 

Codes for the nomenclature of bacteria, actinomycetes, 
and viruses 

Names for bacteria and actinomycetes are controlled by the 
ICNB, the International Code of Nomenclature for Bacteria, 
itself controlled by the International Committee for 
Systematic Bacteriology. In some respects the bacterial code 
is similar to the botanical code (e.g. double citation) but 
there are many differences in detail. A particularly 
important development occurred recently when the 
nomenclatural starting date for all bacteria was revised to 1 
January 1980, to coincide with publication of the Approved 
List of Bacterial Names (Skerman, McGovern and Sneath, 
1980). 

The names of viruses present exceptional difficulties, and 
no international or standard system has been followed. 
During the 1966 International Congress for Microbiology 
the problem was addressed by an International Committee 
on Nomenclature of Viruses (ICNV). This produced a 
report. Classification and Nomenclature of Viruses (Wildy , 
1971), including recommendations for rules. Since then the 
ICNV has become the International Committee on 
Taxonomy of Viruses (ICTV), revising and re-revising the 
rules and recommendations of Wildy's report. An almost 
complete statement is to be found in Matthews' (1979) 
report. Classification and Nomenclature of Viruses, the 
nearest approach yet to an international code for viral 
nomenclature. 

MAJOR FEATURES OF THE HIERARCHY OF LIFE 

The evidence of molecular biology, notably the universality 
of the genetic code, strongly favours the idea that all 
modern life on Earth is monophyletic. 

Ernst Haeckel (1866) was amongst the first to recognise the 
enormous diversity of bacteria and other unicellular 
organisms, separating many of these life forms (together 
with many others that would no longer be included) into a 
major group, the Protista, equal in rank to the plants and 
animals. This group is no longer formally recognised; some 
'protists' are currently classified amongst the prokaryotes. 
This basal, paraphyletic assemblage comprises the 
eubacteria (for which there is good evidence of monophyly) 
and archaebacteria (which may or may not form a natural 
group). The prokaryotes represent an evolutionary grade in 
which DNA is not organised within a nuclear envelope. 

The higher organisms, the eukaryotes, form a clade 
characterised by possession of a double nuclear membrane. 
The eukaryote clade includes the three major groups of 
macro-organisms, the green plants, fungi and smimals, 
together with many unicellular and other simple organisms 
now often referred to as 'protists'. The protists include the 



10 



Systematics and Diversity 



myxomycetes (slime moulds), protozoans and various 
groups of algae, including green algae (chlorophytes), 
chromists (chrysophytes, golden brown algae etc.), and 
rhodophytes or red algae; the chlorophytes form a 
monophyletic group with the green plants (Bremer, 1985). 

Plants 

A major group, comprising the green algae and the land 
plant kingdom, can be recognised as a natural group. Of 
three primary divisions, the Chlorophyta (green algae) 
comprise a complex paraphyletic group from within which 
the land plants (embryophytes) have arisen. The most basal 
groups of land plants are the liverworts and hornworts, and 
then the mosses. The next level of organisation is 
represented by the tracheopytes (characterised by the 
possession of vascular tissue), including lycopods, horsetails 
and ferns. Beyond this level are the seed plants 
(spermatophytes), including cycads. Ginkgo, conifers, a 
group comprised of fp/iedro, Gnetum and Welwitschia, and 
finally the flowering plants (angiosperms). The angiosperms 
are a vast and complex assemblage, traditionally divided 
into the monocotyledons (probably monophyletic) and the 
dicotyledons (paraphyletic). 

Fungi 

The fungi form a major kingdom, divisible into the 
Oomycetes and the true fiingi, the Eumycota. According to 
Tehler (1988), the true fungi (identifiable as a natural group 
on the basis of 25S RNA and chitin cell walls) can be 
divided into four divisions, one of which includes the 
Dicaryomycotina. The dicaryomycetes are themselves 
divided into three classes: the Ascomycotina (moulds, 
yeasts), Protobasidiomycotina,and Basidiomycotina (smuts, 
rusts, bracket fiingi, mushrooms, toadstools). A number of 
poorly-known fungal groups probably do not fit into this 
scheme, but the 'fungi-imperfecti ' (Deuteromycotina) are an 
unnatural assemblage of forms (including many moulds) 
unknown in their sexual stage, most of which are believed 
to be non-sexual stages of ascomycetes and basidiomycetes. 

Animals 

The higher, multicellular animals (Mesozoa and Metazoa) 
are usually regarded as monophyletic, the principal basal 
members being the mesozoans and poriferans (sponges), 
followed by coelenterates (jelly fish and cnidarians) and 
platyhelminths (flatworms). The molluscs, arthropods 
(including insects), echinoderms (starfish, sea urchins etc.) 
and vertebrates are conventionally grouped together at the 
apex of the animal hierarchy. 

In conclusion, although some major features are discernible, 
our knowledge of the hierarchical pattern of life, even at 
this most general level, appears very limited. However, 
new molecular evidence, such as the 18S rRNA data studied 
by Lake (1990) and others, holds the promise of yielding 
far greater understanding. Margulis and Schwartz (1988) 
should be consulted for further information on all the 
recognised phyla of organisms, their biology, relationships 
and taxonomy. 

SYSTEMATICS AND THE MEASUREMENT OF 
BIODIVERSTTY 

Ecologists have measured diversity either by estimating 



species richness (number of species) in an area, or by one 
or more indexes combining species richness and relative 
abundance within an area. Some attempts have also been 
made to measure change in species richness (species 
turnover) between areas. These solutions to the problem of 
measuring biodiversity are limited because species richness 
takes no account of the differences between species in 
relation to their place in the natural hierarchy, and because 
relative abundance is not a fixed property of species, 
varying widely from time to time and place to place. 
Furthermore, in many environments most taxa cu^e virtujdly 
or even completely unknown. 

For some time conservationists have called for a 
measurement of diversity more clearly related to overjdl 
genetic difference. For example, regarding the problem of 
differential extinction, lUCN/UNEP/WWF (1980) noted 
that "the size of the potential genetic loss is related to the 
taxonomic hierarchy because ... different positions in this 
hierarchy reflect greater or lesser degrees of genetic 
difference ... the current taxonomic hierarchy provides the 
only convenient rule of thumb for determining the relative 
size of a potential loss of genetic material." 

Measurements of diversity are now being proposed that 
either attempt to measure genetic difference directly, or 
indirectly through use of the taxonomic (cladistic) hierarchy 
(Williams et al., 1991; Faith, in press). Apaut from 
scientific debate still not fully resolved, the latter approach 
is more practical because we already have a "rule of 
thumb" taxonomic hierarchy (which is being steadily 
improved through the application of cladistic analysis, 
notably to molecular data), whereas reliable estimates of 
overall genetic differences between taxa are virtually non- 
existent. 

Based on the shared and unshared nodes between taxa 
(equivalent to position in the taxonomic hierarchy), a 
number of taxonomic diversity indices have now been 
developed. Of these, the most distinct are root weight, 
higher taxon richness and taxonomic dispersion. The first 
places highest individual value on taxa which separate 
closest to the root of the cladogram and comprise only one 
or relatively few species; in effect this gives high weighting 
to relict groups. Higher taxon richness favours taxa 
according to their rank and number of included species. 
Dispersion, the most complex of the measures proposed so 
far (Williams et at., 1991), endeavours to select an even 
spread of taxa across the hierarchy, sampling a mixture of 
high, low and intermediate ranking groups. See Fig. 2.3 for 
illustration of these concepts. 

For a given group these measures, together with simple 
species richness if desired, can be used to compare the 
biotic diversity of any number of sites. The measures can 
also be expressed as percentages. Thus a site with viable 
populations of all species in a group would have a diversity 
score of 100%, while a site without any species of the 
group in question would score zero. In reality, of course, 
most sites have only a selection of species, and so receive 
various intermediate scores. 

Such assessments allow us to compare all sites with each 
other, and rank them individually from highest to lowest 



11 



1. Biological Diversity 



Figure 2.3 Measures of biodiversity 



Notes: The practical need for measures of biodiversity. Assume there 
is a small zoo keeping six species of vertebrates: a shark, a bony fish 
(salmon), a rat, a turtle, a bird and a snake but only half can be 
maintained in future (each one costs the same). If the objective is to 
display as 'good' a sample of biodiversity as possible, which three 
should be selected? Accepting the phylogenetic relationships in the 
diagram, species richness offers no help - all 20 possible choices are 
the same. Taxjc diversity measures will help us choose, but the result 
will be dependent on which index we use. Root-weight selects shark, 
bony fish and rat. Higher taxon richness selects a shark, bony fish plus 
one of the remainder. Taxic dispersion chooses shark and rat plus bird 
or snake. Dispersion is prx>bably the criterion that corresponds most 
closely to an intuitive notion of diversity. 

diversity. However, if we then takt some action on this 
(such as conserving a particular site), the same measures 
are unlikely to be directly comparable for making a second 
decision (such as choosing a second conservation site). This 
is because, in most real situations at least, there will be 
considerable overlap in the presence of species at particular 
sites. 



In a seminal work on the measurement of diversity, 
Whittaker (1972) introduced the concepts of alpha, beta and 
gamma diversity. The measurements just described, giving 
diversity values for single sites, are examples of alpha 
diversity. The beta and gamma diversity concepts relate to 
changes in diversity between sites at local (beta) and 
geographical (gamma) scales. An essential part of these 
relational concepts is the idea of species turnover - the 
degree to which species present at one site are replaced by 
others at different sites. For use in assessing the relative 
value of multiple sites for the conservation of biodiversity, 
the idea of species turnover is translated into the principle 



of complementarity, implemented in combination with a 
taxonomic diversity index. This is returned to in 
Chapter 15. 

References 

Bremer, K. 1985. Summary of green plant phylogeny and 

classification. Cladistics 1:369-385. 
Faith. D. (in press). Conservation evaluation and phylogenetic 

diversity. Biological conservation. 
Goodrich, E.S. 1919. The Evolution of Living Organisms. Jack and 

Nelson, London. 
Haeckel, E. 1866. Generelle Morphologic der Organismen, 2. Berlin. 
Hawksworth, D.L. (Ed.) 1991. Improving the stability of names: needs 

and options. Koellz Scientific Books, Koenigstein. (Regnum 

Vegetabile 123). 
International Code of Nomenclature for Bacteria. 1975. American 

Society for Microbiology, Washington. 
International Code of Botanical Nomenclature. 1988. International 

Association for Plant Taxonomy (Europe). 
International Code of Nomenclature for Cultivated Plants. 1980. 

International Commission for the Nomenclature of Cultivated 

Plants, lUBS. 
International Code of Zoological Nomenclature. 1985. International 

Trust for Zoological Nomenclature, London. 
lUCN/UNEPAVWF 1980. World Conservation Strategy: living 

resource conservation /or sustainable development. Gland, 

Switzerland. 
Lake, J. A. 1990. Origin of the Metazoa. Proceedings of the National 

Academy of Science USA 87:763-766. 
Margulis. L. and Schwartz, K.V. 1988. Five Kingdoms: an illustrated 

guide to the phyla of life on earth. W.H. Freeman, New York. 
Matthews, R.E.F. 1979. Classification and nomenclature of viruses. 

Third report of the International Committee on Taxonomy and 

Viruses. Intervirology 12:131-296. 
Patterson. C. 1980. Cladistics. Biologist 27:234-240. 
Skerman. V.D.B., McGowem. V. and Sneath, P.H.A. (Eds) 1980. 

Approved list of bacterial names. International Journal of 

Systematic Bacteriology 30:225-420. 
Tehler, A. 1988. A cladislic outline of the EumycoU. Cladistics ^JlTl- 

111. 
Whittaker, R.H. 1972. Evolution and measurement of species diversity 

Tocon 21:213-251 
Wildy, P. 1971. Classification and nomenclature of viruses. In: 

Melnick, J.C. (Ed.), Monographsin VirologyS. London: Academic 

Press, London. 
Williams, P.H., Humphries, C.J. and Vane-Wright, R.I. I99I. 

Measuring biodiversity: taxonomic relatedness for conservation 

priorities. Australian Systematic Botany, 4:665-679. 
Williams, P.H. (unpublished). Afrotropical antelopes - priority areas 

for biodiversity. Progress report to the Natural History Museum, 

London, WCMC and lUCN-SSC. 

Abridged from a document written by R.l. Vane-Wright, 
Biodiversity Programme, TJie Natural History Museum 
(London). 



12 



3. SPECIES CONCEPTS 



Species Concepts 



An understanding of the species concept is basic to an 
understanding of biological diversity because species are 
almost universally used as the units in which diversity is 
measured. 

WHAT IS A SPECIES? 

This simple question has troubled biologists for more than 
two centuries. Although accepted so widely as a 'natural', 
basic or fundamental unit, many conflicting definitions of 
species have been coined, and agreement is still lacking. 
The range of definitions reflects, to a large degree, the 
differing interests and differing theories of individual 
scientists about the origin of diversity itself - literally from 
Genesis to Darwin and DNA. This process has not stopped, 
continuing for example with the debate over the importance 
of neutralism or selectionism in the evolutionary process. 
Furthermore, many scientists have entered the debate from 
practical knowledge of particular groups of animals or 
plants. As there are major differences in the biology of 
different groups, with consequent variations in the patterns 
and processes of species formation, it is hardly surprising 
that species and species concepts are heterogeneous both in 
theory and practice. 

One of the most fundamental aspects of the problem is 
variation. Most if not all animals and plants show variation, 
every individual often being demonstrably unique. Within 
a population variation can be continuous (such as height or 
weight) or discontinuous (such as sex or handedness), 
enviromnental in origin (such as human language) or 
genetic (such as blood group). Variation can also be seen in 
time between successive generations (seasonal variation), 
and in space across allopatric populations (geographical 
variation: clines, demes, races and subspecies). 

The species problem is, in part, a history of how biologists 
have tried to manage this problem of variation. In 
particular, how can we classify variable organisms into 
discrete groups, tempered by knowledge of the existence, 
origin and maintenance of that variation? Modern species 
concepts divide into two main groups, those concerned with 
process and those concerned with pattern. We thus need to 
examine the processes of segregation, isolation and 
recognition responsible for the differentiation and cohesion 
of populations, and the patterns we perceive through 
comparison of the products of those differentiation 
processes. 

EARLY SPECIES CONCEPTS 

The word 'species' literally means outward or visible form. 
Conspicuous natural species have long been recognised by 
people of many local cultures. With the emergence of 
natural science in the 17th and 18th centuries, attempts 
were made to cataloguethe whole of biological diversity, in 
all its manifestations and variations. Early approaches to 
dealing with the species problem were influenced by two 
very different philosophical views, essentialism and 
nominalism. In practice, however, both were usually 
abandoned in the face of increasing empirical knowledge of 
the life cycles of organisms and how they reproduce. 



According to the typological species concept, based on 
essentialist principles, which was widely adopted during 
much of the 18th and 19th centuries, every organism 
corresponds to some idealised plan. The task of the 
taxonomist involved recognising each fundamental design, 
and describing, diagnosing or divining the essential features 
of those designs or 'types', so that individual organisms 
could be assigned to them. 

In practice this often led to arbitrary divisions. Very 
different plants or animals were often lumped together 
because they shared certain 'essential' features; this was 
particularly evident amongst higher taxa, such as Linnaeus's 
group Vermes. By the same token, what we would now 
recognise as different forms of one and the same animal or 
plant were often separated because they conformed to 
different idealised types - in its most extreme manifestation, 
in many higher taxa two different sexes exist which 
according to this view could be classified as separate 
species, plainly a nonsensical view. 

The most extreme opposing view states that only individuals 
exist in nature. Taxonomic groups are seen as man-made 
abstractions allowing us the convenience of being able to 
refer to large numbers of individuals collectively, and 
nothing more. They have no objective or independent basis 
but are merely convenient 'pigeon-holes' for dividing up or 
handling diversity. 

Few scientists now accept that this nominalist approach is 
applicable to species, but it is still widely considered to 
apply to higher taxa. Most cladists and other taxonomists 
concerned with natural classification deny nominalism at all 
levels - the kingdom is seen as 'real' as the species 
(Loevtrup, 1987). Some cladists, however, deny reality to 
the species level, seeing species as only something in the 
process of becoming, while higher taxa are considered 
permanent real entities. With such deep divisions in the 
philosophical views of taxonomists, it is hardly surprising 
that there is still no agreement over the species concept. 

EVOLUTIONARY THEORY AND POLYTYPIC 
SPECIES 

Evolution and genetics 

Following the emergence of Darwinism in the 1860s, and 
the general acceptance of the theory of evolution, the 
typological approach began to be questioned. Darwin 
himself suggested that "our classifications will become, so 
far as possible, genealogies". To Darwin, species were no 
different from other taxa (a view currently advocated by 
Nelson, 1989), and he expressed relief at being freed from 
"the vain search for the undiscovered and undiscoverable 
essence of the term species". Darwin, however, had no 
reliable theory of inheritance. With the development of 
genetics and population biology, including statistics, 
scientists began to develop rational explanations for the 
origin and inheritance of variation, and apply this 
understanding to a radically different view of the nature of 
taxa - and species in particular. 



13 



1. Biological Diversity 



Polytypic species 

One of the first major impacts of population thinking on 
taxonomy was the concept of polytypic species. According 
to this idea, many widespread species-level taxa show more 
or less discontinuous geographical variation describable by 
the use of trinomens, or subspecies. Previously such 
variation was recognised haphazardly by the occasional 
naming of 'varieties' or, alternatively, by the description of 
increasingly large numbers of allopatric species, many of 
which differed only in details of coloration or other 
superficial characters. Such patterns were seen to reflect 
both common ancestry and local adaptation, as species were 
thought to spread from their geographical places of origin 
and differentiate under the influence of natural selection. 
Subspecies were seen virtually as 'species in the making'. 
This approach, including the trinominal nomenclature 
(genus, species and subspecies), was preadapted to become 
the basis of an influential new vision of the species. 

THE BIOLOGICAL SPECIES CONCEPT 

The biological species concept is particularly associated 
with the work of three zoologists, Theodozius Dobzhansky, 
Julian Huxley and Ernst Mayr. This view concentrates not 
on logical classes or plans but on the idea of the species as 
a process, a closed reproductive community or breeding 
system. According to Mayr (1969), species are groups of 
interbreeding [or potentially interbreeding] natural 
populations that are reproductively isolated from other such 
groups. The basic idea of a biological species is that of a 
'pool' of genes available for re-combination through sexual 
reproduction, but not with genes belonging to other gene 
pools, from which they are 'protected' by a variety of 
recognition and isolation mechanisms (behavioural, 
physiological, genetical, etc.). Thus the biological species 
to which a given individual belongs is determined by the 
limits of the populations with which it interbreeds, or 
potentially interbreeds. 

The biological species concept, or some variant of it, is 
probably the most widely accepted view of the species held 
by biologists today. Extreme versions of the concept, such 
as Huxley's (1940) definition of species as "distinct self- 
perpetuating units with an objective existence in nature, and 
therefore on a different theoretical footing from genera or 
families or other higher categories" approach the 
evolutionary species concept, in which species are seen as 
the fundamental units of evolution (rather than haphazard 
by-products of it). 

Recently, certain proponents of the biological species 
concept have split into two 'camps': those supportive of the 
idea that species distinctness is mainly brought about and 
maintained by selection for isolating mechanisms (isolation 
concept), and those emphasising greater importance for 
inherent mate-recognition systems in this role (the 
recognition concept). The debate has led to further 
proposals, such the cohesion concept. According to 
Templeton (1989) this idea draws on all three major 
variants of the biological species (the evolutionary, isolation 
and recognition concepts), and defines species as the "most 
inclusive population of individuals having the potential for 
phenotypic cohesion through intrinsic cohesion 



mechanisms". The intrinsic mechanisms relate to gene flow 
and ecological equivalence. 

All variations of the biological species concept suffer from 
a number of practical shortcomings and limitations. They 
are inapplicable to the very large number of animals and 
plants that reproduce with otdy irregular genetic 
recombination, or without it altogether (asexual or agamo- 
species). In sexually reproducing species the limits of 
genetic re-combination are rarely known and have to be 
inferred from indirect evidence, and there is further 
uncertainty regarding species limits when the concept is 
applied over wide geographical ranges or over time. 

Superspecies and syngameons 

As already noted, the biological species concept was 
developed by zoologists from the idea of grouping allopatric 
(not overlapping geographically), modestly differentiated 
races or subspecies into single polytypic species. This 
system was elaborated to include a further concept, that of 
the superspecies, consisting of assemblages of more 
strongly differentiated groups of populations, or 
semispecies. Semispecies have geographically 
non-overlapping but contiguous (parapatric) distributions, 
permitting gene exchange at their boundaries. Most 
significantly, they are seen as ecological equivalents, and 
thus unable to coexist as stable, fully differentiated species. 

Following Turesson, botanists have long recognised a 
related concept, the syngameon, whereby groups of 
sympatric (geographically overlapping) semispecies coexist. 
Gene flow may be slight or extensive, and their continued 
existence depends on ecological vicariance , occupying stable 
and distinct local habitats (such as contiguous forest and 
open formations). If such a patchy environment is destroyed 
and replaced by a different ecosystem, the separate 
semispecies usually fuse through hybridisation. 

The advent of genetic fingerprinting techniques has now 
permitted zoologists to appreciate that gene flow between 
more or less closely related but perfectly 'good' sympatric 
species of animals may be commonplace. One of the most 
recent discoveries of this kind is reported by Templeton 
(1991), who quotes work showing that significant gene 
exchange can occur between Bison and certain species of 
Bos (domestic cattle). This example demonstrates that 
species sufficiently distinct to have been placed in different 
genera can have this type of relationship, empirically 
violating the most basic tenet of the biological species 
concept, the separateness of gene pools. 

Tokogenetic and phylogenetic relationships 

In order to understand continuing disagreements over the 
significance and definition of species, it is necessary to 
appreciate that two quite separate goals are being pursued. 
Species serve as the basis for describing and cataloguing the 
elements of biodiversity, and in our attempts to discover the 
historical relationships of those diverse elements. Species 
are also widely regarded as fundamental units of evolution, 
being both the products of speciation and the things which 
are thought to speciate. Thus the single word, species, 
serves the needs of systematics (discovery of empirical 



14 



Species Concepts 



patterns) and the needs of population biology (formulation 
of process theories). Once the existence of these two 
separate goals is acknowledged, it becomes easier to make 
sense of the multiplicity of species concepts, many of which 
represent only differences of emphasis within the two major 
divisions. 

Another way to think about this problem is to consider two 
major sorts of genetic relationships: those between 
individuals (tokogenetic, or blood relationships) and those 
between taxa (phylogenetic, or historical relationships). 
What is truly unique about species may simply be that they 
lie at the junction of both types of relationship (Nixon and 
Wheeler, 1990). Higher taxa, and their interrelations, 
represent a fixed, historical past. Below the species, at the 
level of demes and populations, all is change, with mutation 
and genetic recombination affecting every new life cycle, 
every generation of individuals. Species exist at a dynamic 
limit between the two, with tokogenetic processes 
maintaining cohesion yet allowing change, while historical 
accidents fragment species into separate phylogenetic 
lineages. Such ideas form the basis of yet another species 
concept, that of phylogenetic species. 

THE PHYLOGENETIC SPECIES CONCEPT 

According to this view, species are irreducible clusters of 
organisms diagnosably distinct from other such clusters, and 
within which there are parental networks of ancestry and 
descent. Nixon and Wheeler (1990) have defined the 
concept as "the smallest aggregation of populations (sexual 
reproduction) or lineages (asexual reproduction) diagnosable 
by a unique combination of character states in comparable 
individuals". 

This view of species places the emphasis not on 
reproductive process but on the most general aspect of 
taxonomic diversification, that of differentiation. In some 
cases differentiation results in reproductive isolation but in 
many cases it does not. Thus the existence of reproductive 
isolation is evidence of diagnostic characters but new 
characters which become fixed within a population do not 
necessarily affect reproductive isolation. 

An inherent danger in such a view is that, by reductio ad 
absurdum, every population, stage, morph or even 
individual organism could be elevated to separate species 
status. For this type of definition to be operational it would 
also be essential to emphasise the critical importance of 
reproductive community, or cohesion, more or less in 
Templeton's sense. Even then, a consequence of applying 
the phylogenetic species concept, compared with the 
biological species concept, would be a very large increase 
in the number of species recognised (Nelson and Platnick, 
1981). 

SPECIES IN PRACTICE 



debatable specific or subspecific status, with evidence of 
hybridisation in contact zones. His cladistic analyses suggest 
that many biologically defined 'subspecies' that hybridise on 
contact are less closely related to each other by descent than 
they are to other, ftill 'species' with disjunct distributions. 

Thus, as accepted under the phylogenetic species concept, 
species separable on phylogenetic criteria may be 
interfertile, while polytypic species recognised on biological 
(interbreeding) criteria may not be the 'units of evolution'. 
At the practical level, these alternative approaches give rise 
to major differences in the classification and status given to 
populations and groups of populations. As already noted, 
the phylogenetic concept or approach leads to the 
recognition of far more species (and fewer subspecies) than 
the biological species concept. In terms of formal 
classification, it lacks the major practical advantage of 
trinomens - we would tend to lose sight of the wood for the 
trees. 

Subspecies 

Many species of geographically variable and conspicuous 
organisms, such as birds, have been subdivided into 
numerous subspecies. Butterflies, for example, are thought 
to comprise about 17,500 full species, but the number of 
currently recognised subspecies approaches 100,000. Many 
of these subspecific taxa (particularly those from small 
islands or isolated mountains) are fully diagnosable - that is, 
virtually every individual can be reliably identified to 
subspecies, regardless of knowledge of where it was found. 
Such subspecies would qualify as species under a 
phylogenetic species concept. 

On the other hand, this is not true for all so-called 
subspecies, notably many of those described ft'om large 
islands or continental areas. In many of these cases 
subspecies are only recognised on a statistical basis, so that 
individuals cannot be reliably diagnosed, and only identified 
with the aid of knowing where they came ft'om. Typically, 
this represents the phenomenon of clinal geographic 
variation. At the extreme, the most distant populations in 
long clines may be so distinct that in areas of overlap they 
may behave as separate biological species and be fully 
diagnosable locally (rassenkreis and ring species: Mayr, 
1963). Even in less extreme situations, the opposite ends of 
a cline may be more strikingly distinct than related, fully 
diagnosable subspecies, or even full species. 

The implications of this are that for the assessment of 
biodiversity there is no easy answer to 'the subspecies 
problem' any more than there is to the species problem. 
Species status bears no direct or simple relationship to 
degree of phenetic differentiation, or to any measure such 
as genetic distance. Species (and subspecies) are determined 
by relational properties, not by absolute criteria, be they 
essences, reproductive mechanisms or distance measures. 



Empirical consequences of different concepts 

Cracraft (1989) has provided some examples of the striking 
differences that can arise in evolutionary and taxonomic 
conclusions, dependent on the species concept applied. 
Cracrafl's examples all concern parapatric birds of 



The state of the science 

At the broadest scale, we know very few organisms well 
enough to consider the subtle, albeit highly significant, 
interpretations that such insights as the phylogenetic species 
concept or the syngameon might lead us to consider. In 



15 



I. Biological Diversity 



particular, the vast majority of named species are known 
only from morphology and limited knowledge of their 
geographical distributions. For these species we know 
virtually nothing about their individual breeding systems, 
gene flow, ecology or even, in most cases, their cladistic 
relationships. Such species are often referred to as 
morphospecies. 

The present state of taxonomy, carried out by different 
scientists working at different times to different theories and 
philosophies and on imperfectly known groups of widely 
differing size, taxonomic apparency and life-cycle 
characteristics, ensures that species currently recognised are 
not comparable entities. Following the successive rise of 
population biology and phylogenetic systematics, there is 
some prospect if not of harmonising species concepts at 
least of clarifying what is meant by a particular scientist in 
a particular context. 

CONCLUSION 

For the present we have to manage with a very imperfect 
and inconsistent system of classification, even at the 
supposedly fundamental level of species. In practice we 
have not advanced much beyond the position outlined long 
ago, that a species is what a competent systematist says it 
is (Regan, 1926). Although much can and should be done 
to improve this state of affairs, a lack of certainty should be 
accepted as inherent to the subject. 

However, this strong limitation on the use of species as 
comparable units is all too often forgotten when species 
numbers are handled in aggregate, as with many practical 
conservation issues or theoretical discussions of 
biodiversity. Conclusions reached on this basis run a risk of 
being inaccurate, spurious or even completely misleading. 



If species, instead of being treated like independent and 
equivalent units of diversity, are placed in their proper 
relational context of the entire hierarchical classification, 
some of the problems caused by this limitation can be 
avoided. 

References 

Cracrafl, J. 1989. Speciation and its ontology: the empirical 
consequences of alternative species concepts for understanding 
patterns and processes of differentiation. In: Otte, D. and Endler, 
J. A. (Eds), Speciation and its Consequences. Sinauer, Sunderland, 
Mass. Pp. 28-59. 

Huxley, J.S. 1940. Introductory: towards the new systematics. In: 
Huxley, J. (Ed.), The New Systematics. Oxford University Press, 
London. Pp. 1-46. 

Loevtnip, S. 1987. On species and other taxa. Cladistics 3:157-177. 

Mayr, E. 1963. Animal Species and Evolution. Harvard University 
Press, Cambridge, Mass. 

Mayr, E. 1969. Principles of Systematic Zoology. McGraw-Hill, New 
York. 

Nelson, G. 1989. Species and taxa: systematics and evolution. In: 
Otte, D. and Endler, J. A. (Eds), Speciation and its Consequences. 
Sinauer, Sunderland, Mass. Pp. 60-81. 

Nelson, G. and Platnick, N. 1981. Systematics and biogeography: 
cladistics and vicariance . Columbia University Press, New York. 

Nixon, K.C. and Wheeler, Q.D. 1990. An amplification of the 
phylogenetic species concept. Cladistics 6:21 1-223. 

Regan, C.T. 1926. Organic evolution. Report of the British Association 
for the Advancement of Science 1925:75-86. 

Templelon, A.R. 1989. The meaning of species and speciation: a 
genetic perspective. In: Otte, D. and Endler, J. A. (Eds), Speciation 
and its Consequences. Sinauer, Sunderland, Mass. Pp.3-27. 

Templeton, A.R. 1991. Genetics and conservation biology. In: Seitz, 
A. and Loeschcke, V. (Eds). Species Conservation: a population- 
biological approach . Birkhauser, Basel. Pp. 15-29. 



Text written by R.I. Vane-Wright, Biodiversity Programme, 
The Natural History Museum (London). 



16 



4. SPECIES INVENTORY 



Species Inventory 



The objective of this section is to explore how far global 
biodiversity may have been accounted for by taxonomic 
description, emphasising diversity at the species level. This 
is done with reference to the total number of species 
currently recognised (itself very imprecisely known) and the 
degree to which we can estimate the completeness of 
taxonomic knowledge. 

Existing knowledge of geographical and other variation in 
species richness provides a useful starting point, but this 
knowledge is heavily biased. Unfortunately, our 
understanding of the best-known taxonomic groups and 
best-known parts of the world remains an insufficient basis 
for predicting more general patterns, or for rigorously 
testing explanations for such patterns as have been 
identified. Any estimation that may be made of the overall 
extent of global species richness remains staggeringly 
imprecise. Even so, for at least multi-celled animals and 
green plants, and perhaps for all eukaryotes (i.e. all of life 
except for microorganisms such as bacteria) it is possible to 
predicate useful lower and (with less confidence) upper 
limits to the extent of regional and global species richness 
of the major groups. Also, it is now reasonably clear just 
what the major gaps in our understanding are, so that we 
have a good idea of which new data are needed to improve 
on present estimates. Work in progress that involves 
intensive sampling of species-rich groups (e.g. insects) in 
especially species-rich areas (e.g. moist tropicid forests) 
promises to provide a much more reliable picture of major 
global species richness patterns and a more reliable basis 
for estimating the number of species with which we share 
the planet. 

It must be emphasised that data discussed in this section that 
may be pertinent to species richness estimates should not, 
in the current poor state of knowledge, be applied directly 
to estimations of possible species extinction rates via loss or 
degradation of habitat. Existing data on range sizes, 
patchiness of distribution and population structure of the 
poorly-known organisms discussed here are such that no 
direct coimection between numbers of species present at one 
site or in one region and the threat posed to the continued 
existence of any one of those species by the loss of a given 
area of habitat can be made. 

CURRENT STATUS 

Here we consider how many extant species of organisms 
have already been described and assess at what rate the 
existing inventory is growing and improving. 

The number of described species 

The number of species which have been described and the 
number currently regarded as valid are not precisely known 
for many groups of organisms. For the best known groups, 
all of which are relatively small (e.g. birds with 9,881 
species, Sibley and Monroe, 1990), catalogues and counts 
are very complete. Variations in published figures are 
largely because of differences in whether certain taxa are 
regarded as 'good' species or not. Accurate figures for 
currently recognised species are also available for some 



groups (e.g. bacteria with 3,058 recognised species as of 
1991) in which it can be assumed a major proportion 
remains undescribed. Much improved counts have recently 
become available for some substantially larger groups, such 
as the vascular plants (260,000 species in total) and fungi 
(70,000 species). Counts for animal groups with many 
described species, as Tables 4. 1 and 4.2 illustrate, mostly 
remain much less precise. Disparities between the various 
figures very recently furnished for individual groups such 
as the molluscs, annelids and platyhelminths (Table 4.1) and 
Diptera (Table 4.2) are particularly striking. On 
investigation, only some of the apparent discrepancies turn 
out to be because of differences in the year up to which 
counts had been made; others appear to result from 
confusion between the number of nominal species (i.e. all 
species that have ever received a separate name no matter 
what their current status) and the often much lower number 
of species recognised as valid, as well as from simple 
miscalculation or oversight. Some of the largest groups 
(e.g. the insect orders Coleoptera and Diptera) are, in fact, 
relatively well catalogued, but animal taxonomists have 
tended to place little emphasis on providing accurate tallies 
of described species that are regarded as valid at any 
particular point in time. Largely as a result, figures for the 
biota as a whole that have been published in recent years 
vary considerably, from around 1.4 million to more than 
1.8 million. This imprecision is far exceeded by that 
involved in the attempts to estimate total species richness 
(including as yet undiscovered and undescribed species) 
discussed below, but it is in some respects more surprising. 
Estimates for numbers of currently recognised and 
described species are given here, mostly rounded to the 
nearest five thousand, for the groups that make the largest 
contributions (see Table 4.3 and Fig. 4.5) - but without any 
pretence to high accuracy. In arriving at these figures 
relevant specialist opinion, as well as the most recent 
literature, was taken into account. Including all of the 
smaller groups not listed in Table 4.3, the overall figure 
reached is approximately 1.7 million. A more accurate 
count is likely to produce a somewhat higher figure. 

Deflciencies of the existing database 

The evidently low priority accorded by taxonomists to 
keeping track of how many species have been described 
stems in large measure from the knowledge that the 
biological significance of these data is slight. For all but the 
best known groups, if a species count is a measure of 
anything it is of taxonomic effort expended, and this is 
clearly seen to be arbitrary by most biological criteria. Even 
in terms of the taxa that ostensibly have been dealt with by 
the descriptive process much uncertainty exists, as 
catalogues of described species, however carefiiUy 
compiled, include the results of poor taxonomy as well as 
good. When careful reassessments (taxonomic revisions) are 
made, it is common to find that a relatively high proportion 
of previously recognised 'species' are not, in fact, distinct. 
To put it in taxonomists' jargon, most parts of the existing 
inventory contain substantial amounts of unrecognised or at 
least unreported synonymy. In some groups, further 
imprecision arises from a fundamental lack of agreement as 
to just what constitutes a species. 



17 



1. Biological Diversity 



Table 4.1 


Estimated numbers of described extant species 


in majo 


r animal groups 




Mayr et ml. Barnes 


May 


May 


Brusca & Brusca 




(1953) (1989) 


(1988) 


11990) 


(1990) 


'Protozoa' 




260,000 


32,000 


35,000 


Porifera 


4,500 5,000 


10,000 




9,000 


Cnidaha 


9,000 9,000 


10,000 


9,600 


9,000 


Platyhelminthes 


6,000 12,700 


- 


- 


20,000 


Rotifera 


1,500 1,500 


- 


- 


1,800 


Nematoda 


10,000 12,000 


1,000,000 ? 


- 


12,000 


Ectoprocta 


3,300 4,000 


4,000 


- 


4,500 


Echinodermata 


4,000 6,000 


6,000 


6,000 


6,000 


Urochordata 


1,600 1,250 


- 


1,600 


3,000 


Vertebrata 


37,790 49,933 


43,300 


42,900 


47,000 


Chelicerata 


35,000 68,000 


63,000 




65,000 


Crustacea 


25,000 42,000 


39,000 


- 


32,000 


'Myriapods' 


13,000 10,500 




- 


13,120 


Hexapods 


850,000 751,012 


1,000,000 ? 


790,000 


827,175 + 


Mollusca 


80,000 50,000 


100,000 


45,000 


100,000 + 


Annelida 


7,000 8,700 


15,000 


- 


15,000 



Notes: 'Protozoa', a paraphyletic group, is used in the ^traditionaP zoological sense. TTie 'Myriapods' consist of the Chilopoda (centipedes) and 
Diplopoda (millipedes) together. Apart from two exceptionally high figures - those for Protozoa and Nematoda - provided by May (1988), who 
presumably intended these as estimates of actual rather than described species, most estimates, even the highest of a range for any given group, 
are probably conservative. The extent of the great variation in totals for some groups is inexplicable. For example, while Brusca and Brusca (1990) 
suggest 100,0(X)+ as a likely figure for described species of molluscs a totalling of the figures given for the individual mollusc classes by the same 
authors provides a total of around 50, (XK). 

Table 4.2 Number of described species in the four major insect orders 



Southwood 


Arnett 


(1978) 


(1985) 


350,000 


290,000 


1 20,000 


98,500 


100,000 


103,000 


120,000 


1 1 2,000 



Coleoptera 
Diptera 
Hymenoptera 
Lepidoptera 

Notes: Some recent estimates of the number of described species in the four major insect orders. An accurate figure for Hymenoptera is probably 
not very different from any of the fairly consistent estimates shown, while one for Diptera probably lies towards the middle of the very wide range 
indicated here. The estimates for Coleoptera and Lepidoptera, on the other hand, are probably all far too low. 



May 


Brusca & Brusca 


(1988) 


(1990) 


300,000 


300,000 + 


85,000 


1 50,000 


110,000 


125,000 


110,000 


1 20,000 



The existing inventory of described species may, as 
discussed below, provide a poor basis for estimating the 
true extent of global species richness. However, where 
extrapolative methods are adopted that do involve the use of 
described species counts, the accuracy with which the 
counts have been made will often have a substantial 
influence on results. For example, let us assume that our 
approach to estimating global species richness is to (1) 
estimate what proportion of the biota belongs to a particular 
group, (2) estimate what proportion of species in that group 
has already been described, juid (3) use these estimates and 
the number of described species in the group to calculate a 
total for all groups. Should the group chosen be the 
Coleoptera our estimates might be that this group contains 
(say) 20% of all living species, and that (say) only one in 
every five or even ten Coleoptera species has been 
described. Recent published estimates for the number of 
described species of Coleoptera, like those for most other 
large groups, are extremely variable. Several put the figure 



at around 300,000 species (Table 4.4), although thorough 
counts of a sample of coleopterous families suggest that 
400,000 is a likely minimum. If the figure of 300,000 does, 
in fact, represent an underestimate of the order of 100,000 
species its use in the calculations outlined above would lead 
to underestimation of the biota as a whole by as much as 
five million. 

Current rates of growth 

Current rates of description of new species and other taxa 
and how these rates vary from group to group can tell us a 
good deal about how the task of inventorying biotic 
diversity is proceeding. Whether or not rates of description 
have any value for predicting just how much of the task 
remains to be done is another matter, considered below. 
Numbers of newly described species recorded in the 
Zoological Record for a range of animal groups, for each 
year between 1979 and 1988, are given in Table 4.5. The 



18 



Species Inventory 



Table 4.3 Numbers of species in the groups of organisms likely to include in excess 
of 100,000 species (plus vertebrates) 





DESCRIBED 




SPECIES 


Viruses 


5,000 


Bacteria 


4,000 


Fungi 


70,000 


Protozoans 


40,000 


Algae 


40,000 


Plants 


250,000 


(Embryophytes) 




Vertebrates 


45,000 


Nematodes 


15,000 


Molluscs 


70,000 


Crustaceans 


40,000 


Arachnids 


75,000 


Insects 


950,000 



ESTIMATED SPECIES 
HIGHEST FIGURE WORKING FIGURE 



500,000 + 

3,000,000 + 

1,500,000 + 

100,000 + 

10,000,000 + 

500,000 + 

50,000 + 

1,000,000 + 

180,000 + 

150,000 + 

1,000,000 + 

100,000,000 + 



500,000 


sv 


400,000 


MaO'e/Sy 


1,000,000 


Te/Sy 


200,000 


Ma/Te/Sy 


200,000 


Ma 


300,000 


Te 


50,000 


Ma/Te 


500,000 


Ma/Te/Sy 


200,000 


Ma/Te 


150,000 


Ma 


750,000 


Te 


3,000,000 


Te 



Notes: The figures for described species (mostly given to the nearest 5,000) were arrived at by consulting relevant specialists as well as by critically 
reviewing the literature. The 'highest figure' estimates for existing species, many of them frankly speculative, are the highest encountered during 
a survey of recent literature. The 'working figure' estimates are conservative. The figure for bacteria has been arbitrarily 'capped' at 100 undescribed 
to 1 described species on the grounds that projections involving mote than two orders of magnitude are inJierently unsafe. The biggest question marks 
lie over the true numbers of species of viruses, bacteria and algae. Substantial upward revisions from the working figures for these groups may prove 
justified with time. The figures for fungi, protozoans and nematodes are also insecurely based. Note that the Fungi and Protozoa are used in the 
'traditional' sense, while Bacteria includes cyanobacteria. The figures for 'insects' include all hexapods, and that for described insect species assumes 
totals of 400,000 for Coleoptera, 150,000 for Lepidoptera, 130,000 for Hymenoptera and 120,000 for Diptera. The final column in the table gives 
an indication of where the major proportion of species in each group is concentrated. All groups listed include at least some symbionts (Sy), 
obligately associated as parasites, mutualists or commensals with other organisms, and all (except for viruses) have at least some free-living 
representatives in marine (Ma), terrestrial (Te) and freshwater systems. Despite high local species richness in some groups, the overall contribution 
of freshwater species to group totals is relatively small, unsurprising in view of the fact that freshwater covers well below 1 % of the earth's surface. 



most Striking aspect of these figures is the extremely low 
variation between years. Indeed, the yearly overall totals 
(for all groups included in the Zoological Record) for the 
years 1979-1988 show a standard deviation of less than one- 
twentieth of the mean annual figure. Description rates for 
many of the individual groups listed in Table 4.5 are almost 
equally invariant through this decade. 

Description rates can tell us roughly how quickly various 
parts of the taxonomic inventory are growing. As the 
description of new species in most groups is accompanied 
by continuing reappraisal of the existing inventory, the rate 
of description of new species is rarely precisely the same as 
the rate of increase in the number of recognised species. 
The description rate may be substantially higher; in some of 
the larger groups of insects, for example, the current rate 
at which previously described species disappear into 
synonymy is around one-quarter to one-third the rate at 
which new species are described. Unfortunately, for some 
groups, newly recognised synonymies are not systematically 
reported or recorded in abstracting journals, so that the 
extent of the disparity between rates of description and rates 
of growth in number of recognised species is extremely 
difficult to assess. 

How current description rates for a range of groups 
compare with earlier rates is indicated in Table 4.6. In 
relation to averages for the post-Liimean period, and with 
the exception of groups such as birds where few new 
species are being discovered, current rates are uniformly 
high. For some groups, such as nematodes, current rates 



are as high as or even higher than they have ever been, but 
the average figures conceal the fact that the period of 
maximum species description for a number of groups is 
well in the past. Detailed information on how taxonomic 
activity, as reflected in description rates, has varied through 
time is available in a range of reviews dealing with 
individual groups, and a summary of this has been provided 
by Simon (1983). The picture for groups such as the birds 
is predictable, with most species described early on and half 
of the present day total of 9,000 or so recognised species 
having been reached by 1843 (see Fig. 4.1). After a 
sometimes rather slow start, description of new species in 
some groups has otherwise proceeded at a fairly steady rate, 
while in others there has been a marked decline after a peak 
of activity which in many instances falls towards the end of 
the 19th century. Groups in which the maximum activity is 
taking place now include some of the better-known as well 
as those, such as nematodes and fungi, in which only a 
small fraction of species is likely to have been described so 
far. 

Description rates or growth rates do not, of course, 
necessarily provide a good measure of taxonomic effort 
expended or of how effective this is (see below). A rough 
and ready way of determining how such effort is being 
applied is to look at publication rates (Barnes, 1989, May 
1988). Most instructive, perhaps, is to compare publication 
rates for various groups with their size, both in terms of 
currently recognised species and also projected overall 
species totals. Publication data from the Zoological Record 
quoted by May (1988) reveal, not surprisingly, that the 



19 



1. Biological Diversity 



Table 4.4 Number of species in various families of beetles (Coleoptera) 







DESCRIBED SPECIES 




ACTUAL SPECIES 






Arnett 


Lawrence 


All Sources 


Arnett 






119671 


(1982) 


(1990) 


(1967) 




Byrrhidae 


154 


c. 300 


319 


300 


TEMP 


Derodontidae 


10 


19 


20 


19 


TEMP 


Dtscolomidae 


30 


c. 400 


443 


50 


TROP 


Dryopidae 


178 


c. 200 


253 


300 


trop 


Elmidae 


263 


c. 700 


1,170 


350 


trop 


Limnichidae 


67 


c. 200 


297 


80 


trop 


Lymexylidae 


37 


c. 50 


64 


100 


trop 


These families in total 


739 


c. 1,869 


2,566 


1,195 




All Coleoptera 


219.409 


340,500 


? 


290,199 





Notes: Number of described species in various families of beetles (Coleoptera) compared with one laxonomisl's estimates (Arnett, 1967) for actual 
numbers of existing species in these families. Three sets of figures for numbers of described species are provided. Ametl's (1985) estimates of 
described species were based on catalogues published between 1910 and 1915 while Lawrence's (1982) estimates were based on more up-to-date 
sources. The 1990 figures are based on direct counts from the most recent catalogues available supplemented by Zoological Record entries for 
subsequently described species and new synonymies to June 1990. A small part of the increase in numbers of Elmidae recognised in 1990 is due 
to species transferred from Dryopidae. If the 7 families for which the 1990 total of described species is 2,566 were representative of the Coleoptera 
as a whole in terms of growth since the 1910-1915 period (Ametl's figures) total described beetle species regarded as valid up-dated to 1990 should 
be 761,845 (i.e. 219,409 x 2566/739). Using the more up-lo-date estimate (Lawrence, 1982) as starting point the 1990 lolal for Coleoptera should 
be 467,481 fi.e. 340,500 x 2566/1869). In fact, recent species description rates for some of the families in the table (e.g. Elmidae and Limnichidae) 
are likely to be well above average for the Coleoptera as a whole, so both extrapolations may produce overestimates. No accurate count has been 
made for the whole Order but the actual number of described Coleoptera species regarded as valid as of 1990 is probably in the region of 400,000. 
The table illustrates the way in which cautious taxonomists are strongly influenced by the number of species already known when predicting the 
number that might actually exist. For relatively well-known beetle groups, largely those in which most species occur in temperate regions, this may 
not lead to drastic underestimation, but clearly may do so in the case of less well- known groups in which most species are tropical. TEMP = family 
shows a strong bias away from the Tropics; TROP = family shows a strong bias towards the Tropics; trop = family with a weaker tropical bias. 



ratio of papers published to number of species already 
described has been high in recent years for vertebrates, 
varying from around two papers per species in mammals to 
one paper for every two or three species in fish. Leaving 
aside these well-known groups, the number of papers 
published per recognised species per year is more or less 
inversely correlated with the size of the group in terms of 
described species. For example, in all major groups 
including fewer than 50,(X)0 described species the ratio of 
publications to species is below 1 :50 and often below 1:10, 
whereas ratios are generally much higher, exceeding 1 : 100 
in the case of the Coleoptera, in groups containing a greater 
number of described species. 

Despite this evident bias in taxonomic attention against 
groups containing many described species, actual growth 
rates, i.e. number of new species described in relation to 
the number already described (see Table 4.6), currently 
vary remarkably little. 



of the world's species and, more importantly, that described 
species represent a very biased sample. Is it then possible 
to use these figures for described species in any way at all 
as a basis for projecting actual world totals? 

If we examine the available data on absolute rates of 
description and how these have varied through time, and on 
how the overall taxonomic effort is and has been 
apportioned between the major groups of organisms, we 
might justifiably conclude that they tell us very little about 
the size of the descriptive task that remains. However, a 
careful scrutiny of these data can help to demonstrate the 
biases that exist in the inventory as it stands, and may help 
to reveal what underlies them. This may be helpfiil in 
making initial judgements as to where the major sources of 
unexplored diversity are to be found. It may also prove 
useful in assessing the likely accuracy of species richness 
estimates, such as those of taxonomic specialists considered 
below, that are difficult to evaluate in any other way. 



PREDICTION FROM THE EXISTING PARTIAL 
INVENTORY 

Inherent limitations 

The total number of species so far described, of course, 
gives us some idea of the minimum extent of global species 
richness, while knowledge of how described species in the 
better-known groups are distributed gives us an impression 
of the way in which species richness is allocated between 
regions, ecosystems, etc. However, there is every indication 
that described species do not account for the major portion 



Perhaps the most obvious among biases in how taxonomic 
effort is applied are those that stem from everyday human 
interests and preoccupations. Large organisms, those that 
are considered particularly attractive (flowering plants, 
butterflies, etc.) or appealing in some other way, those most 
closely resembling humans themselves (vertebrates, 
especially mammals), and those that have a direct impact on 
human affairs, usually as pests of one kind or another, are 
all favoured objects of study and description. By 
association, certain other groups such as fleas and lice - 
because they are parasites of birds and mammals - may also 
receive a relatively large share of attention. 



20 



Species Inventory 



Table 4.5 Number of new species listed in the Zoological Record 1979-1988 





1979 


1980 


1981 


1982 


1983 


1984 


1985 


1986 


1987 


1988 


Protozoa 


463 


309 


353 


280 


272 


374 


432 


385 


315 


377 


Platyhelminthes 


293 


357 


341 


290 


307 


340 


359 


336 


297 


243 


Nematoda 


407 


389 


364 


422 


383 


354 


365 


367 


331 


258 


Annelida 


234 


114 


215 


186 


127 


208 


200 


149 


161 


131 


Mollusca 


338 


355 


391 


239 


344 


316 


419 


412 


392 


419 


'Other' invertebrates 


180 


214 


341 


174 


303 


353 


187 


252 


195 


339 


Crustacea 


645 


638 


763 


736 


695 


599 


700 


843 


708 


660 


Arachnida 


1,610 


1,523 


1,199 


1,182 


1,145 


1,504 


1,353 


1,185 


1,488 


1,307 


'Other' arthropods 


98 


57 


120 


154 


119 


123 


55 


94 


146 


122 


Hemiptera 


1,277 


1,115 


1,191 


981 


1,275 


1,038 


1,072 


1,162 


903 


1,016 


Lepidoptera 


675 


445 


506 


580 


631 


685 


658 


915 


623 


699 


Diptera 


1,019 


1,015 


1,130 


899 


973 


928 


1,115 


1,095 


1,303 


1,000 


Hymenoptera 


1,167 


1,134 


1,086 


1,031 


1,215 


1,496 


857 


1,184 


1,084 


1,705 


Coleoptera 


2,116 


2,804 


2,243 


2,454 


1,960 


2,259 


2,220 


2,843 


2,130 


2,051 


Other Insecta 


725 


824 


992 


878 


1,331 


1,030 


836 


822 


1,110 


703 


Pisces 


183 


241 


273 


240 


260 


223 


220 


204 


234 


229 


Other Chordata 


146 


170 


134 


186 


177 


168 


230 


117 


191 


138 



Source: Zoological Record Online, data search organised and carried out by BfOSlS UK. 

Notes: Number of new species listed in the Zoological Record 1979 to 1988 (Vols 1 16-125), showing Iho remarkable constancy of description rates 
in the larger animal groups. The figures given are for newly described species. While extinct groups such as the Trilobita are excluded, fossil species 
(mostly relatively few in number) of extant groups (e.g. Mollusca, Insecta, Pisces) are included in the counts. As new synonymies are not accounted 
for the figures do not provide a precise measure of growth in numbers of described species regarded as valid. The 'other' invertebrates category 
includes all extant non- arthropod groups not otherwise listed. The 'other' arthropod category includes all taxa listed in Section 12 of the Zoological 
Record; in major part these are Chilopoda (centipedes) and Diplopoda (millipedes). The other Chordates category includes reptiles, mammals, 
amphibia and birds. 



Other strong biases have more to do with taxonomic taste 
and fashion, and the ease with which the organisms are 
found, collected, studied and preserved as specimens. 

Organisms that can be studied without complex procedures 
or expensive equipment, that are not too small, that exhibit 
distinctive characteristics and can be readily sorted tend to 
be dealt with preferentially. These various biases have 
influenced the historical pattern of description, starting with 
Liimaeus himself, who described very few small organisms, 
and confirmed by Gaston (1991b) who showed a clear 
relationship between body size and date of description in the 
approximately 4,000 species of British beetles. 

It is also evident that most areas distant from the centres of 
human population as well as more obviously inaccessible 
regions such as the ocean depths are rather poorly 
inventoried. It should also be noted that most taxonomists, 
however much they may travel, remain based in the cities 
of the north temperate zone. Recent patterns of description 
for birds and mammals suggest that the few species that 
remain to be discovered in such well-known groups will 
almost certainly turn out to be tropical. Despite clear 
indications that the greater part of global species richness is 
to be found in the tropics, it is evident (no precise counts 
are available) that, in terms of described species, those of 
tropical origin are considerably outnumbered by those from 
temperate and boreal regions. An analysis of recent 
description data for insects (Gaston, unpublished) reveals 
that, for this speciose group at least, the bias against 
tropical species is still not being redressed. In some groups, 
the rate at which new species are described may be 



determined, at least in part, by what material is immediately 
available for study, which in turn depends on its general 
accessibility in nature. However, this can scarcely be the 
major influence on description rates in those groups (e.g. 
the larger insect orders) for which the world's museums 
already contain hundreds of thousands of undescribed 
species. 

Time-series of species descriptions 

Changes in the rate at which new species have been and are 
being described have been used to make an estimation of 
the likely future growth of each of the major groups of 
organisms. Various statistical procedures can be used to 
identify trends and project description rates forwards (May, 
1990), with different techniques sometimes producing very 
different results (Frank and Curtis, 1979; Simon, 1983). 
Not surprisingly perhaps, attempts to use trends in 
description rates to predict global species richness of major 
contributors (i.e. excluding groups such as birds, mammals, 
etc.) or of the biota as a whole have been singularly 
unsuccessful (see Erwin, 1991). First of all, as a glance at 
Table 4.5 reveals, very few trends in description rates can 
be observed over the short term. Longer term trends, where 
they are evident, are often erratic but, except for a few 
small groups, commonly involve an increase in the pace of 
description over time. Species description in the least 
apparent and least tractable groups often gets off to a slow 
start but once this gets going, description rates may be 
more or less monotonic. 

For those few groups in which species description is 



21 



1. Biological Diversity 

Table 4.6 Current species description rates for various animal groups and for fungi 



Vertebrates 

Birds 

Mammals 

Amphibians and 

Reptiles 

Fish 
Molluscs 
Sponges 
Cnidarians 
Platyhelminths 
Ectoprocts 
Annelids 
Protozoans 
Crustaceans 
Insects 

Lepidoptera 

Coleoptera 

Diptera 

Hymenoptera 
Arachnids 
Fungi 
Nematodes 



SPECIES 


"GROWTH- 


CURRENT 


PROPORTION 


DESCRIBED 


RATE 


RATE/ 


OF SPECIES 


PER ANNUM 


PER ANNUM 


OVERALL 


DESCRIBED 


(1978-19871 


(1978-1987) 


RATE 


TO DATE 


367 


0.82 


1.90 


High 


5 


0.05 


0.13 


Very high 


26 


0.59 


1.37 


" 


105 


1.17 


2.72 


High 


231 


1.22 


2.83 


- 


366 


0.52 


1.22 


Moderate 


50 


0.56 


1.30 


" 


57 


0.63 


1.48 


H 


316 


1.58 


3.68 


l» 


58 


1.29 


3.00 


•* 


173 


1.15 


2.57 


" 


356 


0.88 


2.00 


Moderate/low 


699 


1.74 


3.91 


" 


7,222 


0.76 


1.77 


Low 


642 


0.43 


1.00 


Moderate/high 


2,308 


0.57 


1.34 


Low 


1,048 


0.87 


2.03 


Low/very low 


1,196 


0.92 


2.14 


" 


1,350 


1.80 


4.19 


" 


1,700 


2.43 


5.67 


Very low 


364 


2.43 


5.65 


" 



Notes: Current species description r^tes for various animal groups and for fungi, expressed as number of species described per annum (mean of 
years 1978-1987) (Column 1), compared with number of already described species (figures from column 1 (x 1(X)) divided by number of described 
species) (Column 2), and with an approximation to average description rates for the whole of the period since 1758 (mean number of species 
described per annum 1 978- 1 987 divided by mean number of species currently recognised as valid described per annum between 1 758 and the present) 
(Column 3). The fourth coluitm provides an indication of the proportion of each group that is likely to have been described so far; very high = c. 
90% or mote already described; high = c. 50-90%; moderate = c. 20-50%; low = c. 10-20%; very low = less than 10% 



nearing completion, description rates may be expected to 
have some predictive value. Even here, however, they are 
likely to tell us what we already know, and may be 
distinctly misleading. Growth curves based on time-series 
of species descriptions are a convenient way of portraying 
the relevant data. The time-series for the very well-known 
groups such as birds generally forms a classic S-shaped 
growth curve (see Fig. 4.1, but note that here the curve is 
not S-shaped as the vertical axis is on a logarithmic scale). 
Any other form of curve indicates that the group in question 
is unlikely to be almost completely inventoried, but may tell 
us little else. We may note that birds are exceptional among 
relatively high-ranking taxa in that the description of new 
species has slowed to a trickle. Even mammal species (see 
Table 4.6) are still being described at a rather high rate that 
gives no clear sign of an asymptote, although it is fairly 
certain that the number of species awaiting discovery is 
relatively low. Some slowing down of the rate, finally, is 
perhaps indicated by figures for the last decade or so, with 
an average of 37 mammal species described per year from 
1978 to 1982 and 20.5 per year from 1983 to 1988. 

There are various ways of gathering the data for time-series 
graphs, and these can have significant effects on our ability 
to predict. For example, the number of species recognised 
within a group at any one time can be assessed from 



contemporary taxonomic works. However, over the past 
120 years, there have been major changes in how species 
status is evaluated, which can make the figures 
non-comparable and the curves uncertain. 

A better curve is usually obtained by making a cumulative 
graph of the dates of first description of all currently 
recognised species. In the case of the 120 or so species of 
crows (Fig. 4.2A), for example, we see a truncated version 
of the S-shaped curve, with nearly 10% of all currently 
recognised crow species having been described within the 
decade 1758-1767. With the curve for crows flat for the last 
quarter century it would be a bold person who would 
predict a rise to even 130 species, let alone a higher figure. 
However, such dramatic shifts can occur, even in relatively 
well-known groups. 

An example is provided by a group of blue butterflies (Fig. 
4.2C), subject of a recent major revision (Eliot and 
Kawazoe, 1983). Linnaeus knew only one species, the 
familiar European Holly Blue Celastrina argiolus, and the 
time-series is very slow up until the decade ending 1877. 
After that it goes through a rapid growth-phase, and then 
flattens at about the same time as the curve for the crows. 
Since 1967, however, there has been a new burst of species 
description, bringing the current total to a point at least 



22 



Figure 4.1 Discovery curves for species 
from 1758 to 1970 



Birds 




175B 1843 

Arachnids and Crustaceans 



1970 




0.001 



175B 



19601970 



Source: Following May (1990) after Simon (1983). 
Notes: Numbers of known species (expressed as a fraction of those 
known in 1970 on a logarithmic scale) are plotted against time. The 
vertical and horizontal lines show the points at which half of the 1970 
totals had been reached. Although a trickle of new species of birds 
continues to be described the shape of the curve for birds as a whole 
resembles that for crows. The curve for Arachnida + Crustacea (i.e. 
the majority of non-insect arthropods) shows that up to 1970 
description of new species had an ever-increasing pace, with the 1960 
total doubled by 1970. Description of new species in these groups now 
proceeds at a steady rate of some 2,000 per annum (see Table 4.5). 

33% higher than the plateau level. The explanation here is 
not poor taxonomy or a change in species concept, but a 
combination of exceptionally painstaking work coupled with 
vigorous collecting in previously inaccessible parts of 
Southeast Asia, where these butterflies form many island or 
mountain endemics. 



Species Inventory 

OTHERAPPROACHESTOPREDICTING PATTERNS 

Estimates by taxonomic specialists 

The opinions of taxonomists specialising in particular 
groups of organisms have traditionally played a considerable 
part in the formulation of views on the extent ^md pattern of 
species richness at every scale. Indeed, the preliminary 
tentative working figures for global species richness of the 
major groups used in this section have inevitably been 
influenced by the opinions and estimates of relevant 
taxonomists. However, the simple approach of collating 
views based on the specialist knowledge of the taxonomic 
community has not been systematically pursued, a major 
exception being the recent essay by Gaston (1991a) to 
assemble and interpret a cross-section of taxonomists' 
opinions concerning likely global insect species richness. 

The approach adopted by Gaston has the merit of involving 
a large number of data points so that no one estimate has an 
overriding effect on the overall result. In addition, the 
sources are experienced taxonomists whose work generally 
involves exposure to at least part of the richness of species 
located in poorly studied regions. This said, it is likely that 
the way in which taxonomists actually arrive at their 
conclusions is quite varied, may be distinctly idiosyncratic 
and tends to the conservative. Indeed, the generally rather 
poor track record for such estimates suggests a possible 
correlation between the degree to which any given 
taxonomist has been exposed to relevant data (e.g. 
representative samples from many areas, including some of 
the richest) and the extent to which he or she is prepared to 
extrapolate beyond the relatively sure ground of already 
described species. Very early estimates by such as John Ray 
who, in the late 17th century, considered that the insects of 
the world as a whole might amount to some 10,000-20,000 
species, may lend some support to this view. 

To the extent that taxonomists work largely with what 
happens to come their way, it is likely that the collections 
they examine do not fully represent the richness to be found 
in less-known regions of the world, such as the tropics. In 
making their assessments of overall species richness it is 
also likely that they make some use, however 
unsystematically, of described to undescribed species ratios 
(see also below) in the small groups with which they are 
most familiar. If the group already contains (say) 100 
nominal species, and the taxonomist in question is aware 
that 10 of these are not 'good' but is also aware of a further 
60 undescribed species, the new provisional total for the 
group will be 150 species, representing an increase of 50%. 
The value of this figure for generalising will, of course, 
depend very much on how typical the sample group is and 
how well the available material represents its true size. 

Nevertheless, if accepted for what they are, and if we 
accept also that recent estimates by taxonomists are based, 
in comparison with their predecessors, on a relatively 
extensive (if still fragmentary) coverage of the world, the 
surely conservative figures produced by the cautious and 
pragmatic approach may have considerable value as 
minimum estimates. 

Gaston's conclusions have attracted strong criticism (Erwin, 



23 



1. Biological Diversity 



1991), the main focus of which is that the reliability of 
results obtained in this way is impossible to judge; 
taxonomists' estimates represent opinions that have been 
arrived at in ways that we cannot know. The arguments for 
and against have broadened to include the merits of other 
approaches as well as the usefulness of collated opinion, 
providing an area of active debate (see Gaston, 1992). 

First principles and empirical relationships 

The broad understanding we have of how life evolved and 
how species interact could be used to estimate, from first 
principles, how many species are likely to be found in a 
given region or in the world as a whole (May, 1988). 
General rules concerning; body size relations, commonness 
and rarity, range sizes, and the relationship between species 
numbers and area have all been used to suggest explanations 
for observed species richness patterns and why there are so 
many (or so few) species overall. Understandably, only 
tentative use has been made of rules of this type for actually 
predicting major species richness patterns for poorly-known 
groups. Any real test of their predictive power in these 
areas awaits the provision of many more data concerning 
the exceptionally diverse but little-known groups than are 
available at the moment. This applies, for example, to the 
empirical rules, derived mainly from the larger terrestrial 
animals, that describe the way in which species numbers 
increase with decreasing size. Using only described species 
these rules begin to break down at body lengths of below 
about 1cm. Arbitrary extrapolation to smaller size classes 
(down to lengths of about 0.2mm) that are poorly 
represented among described species produces an estimated 
global total for terrestrial animals of around 10 million 
species (May, 1988). 

The use that may be made of other empirical relations that 
concern the structure of food webs, and the numbers of 
parasitic or other symbiotic species that are typically 
associated with individual host species, has also been well 
reviewed by May (1988, 1990). While rules concerning the 
number of levels in food webs are sufficiently well 
established to form the basis for relatively reliable 
generalisation, the same cannot be said for the numbers of 
species and overall numbers of links involved in webs of 
various types. Species richness patterns involving parasite, 
parasitoid or (less often) predator species and their hosts or 
prey have received much attention. In well-known regions 
such as the British Isles it is possible to calculate the 
approximate number of potential host species for a given 
group of, for example, parasites and relate this to the 
overall number of species of these parasites that are present. 
If we take British vascular plants (2,089 species) and the 
insects that directly exploit them (assuming this to be 
around 25% of the British total or c. 5,500 species) as an 
example, we can derive a ratio, in this case of around 2.6 
(associated insect species) to 1 (plant species). This type of 
simple relationship tells us very little, of course, about 
host-specificity. Nevertheless, the question of host- 
specificity levels, rather than any empirical relationship 
between the number of hosts and the number of associated 
parasites, has received some attention as a possible means 
of predicting overall numbers of parasite species. The 



difficulties involved in evaluating such patchy 
host-specificity data as exist and using them for 
extrapolative purposes are great (see May, 1990 for 
discussion). 

Keeping to vascular plants and their associates as the 
example, we see that the most useful data on how many 
species may be effectively specialised to one host come 
from detailed single species studies. Intensive studies, 
whether of oak trees or passion vines (see May, 1990), may 
help to reveal something of the processes underlying the 
way in which these plants are exploited, while at the same 
time elucidating a series of contrasting patterns. However, 
they cannot be expected to provide what is required for any 
prediction of overall numbers of plant associated species. 
The simple questions for which answers are needed here 
are; how many species depend on the average plant species 
throughout its range, and how many species depend on the 
same average plant species in one place at one time? For 
practical purposes it is also advantageous if these data can 
be related to sampling phenomena, so that it is known what 
proportion of the associated species present at one place are 
obtained in a particular type of sample. 

As far as species associated with green plants are concerned 
there are indications that patterns vary with moisture, 
latitudinal and other gradients. Host-specificity levels may 
also tend to be lower where plant species richness is 
especially high, particularly when the plants in question are 
trees, as in tropical moist forests. Indeed, there are strong 
suggestions that the general architecture of forests may be 
a better predictor of the number of small animal species and 
fiingi present in a given area than is the number of different 
vascular plant species that occur. 

Taxon to taxon and region to region relationships 

Using some aspect or aspects of the diversity profile of a 
well-known group such as birds or mammals as a reference 
point, a variety of simple extrapolations to other less 
well-known groups may be made. We may use butterflies, 
a well-known group, as an example. Of the roughly 22,000 
species of insects to be found in Britain some 67 are 
butterflies. The number of described species of butterflies 
in the world is fairly accurately known at around 17,500, 
the true figure almost certainly not exceeding 20,000 or so. 
If the ratio of butterfly species to all insect species is the 
same globally as it is in Britain then the world insect 
species total should lie at around 22,000 x 17,500/67, that 
is 5.75 million. 

A more involved extrapolation may be made by taking 
tropical to extratropical ratios as the point of departure. For 
both birds and mammals, for example, there are roughly 
two to three times as many tropical as non-tropical species. 
To extrapolate successfully from this we need to have a 
good estimate of the proportion of described species that are 
from extra-tropical areas in the more significant of the less 
well-known groups, coupled with a good estimate as to the 
proportion of extra-tropical species that have been 
described. In practice our estimates for the first are unlikely 
to be very accurate and for the second unreliable. However, 



24 



Species Inventory 



Figure 4.2 Time series of first descriptions of currently recognised species in 
decades from tlie time of Linnaeus (1758) to 1987 




1757 1767 1777 17S7 1797 1807 



Source: Data for crows (Corvidae) based on Goodwin, 1986, Crows of the World, London; BM(NH), thai for milkweed butterflies (Danainae) on 
Ackery and Vane- Wright, 1 984, Milkweed Butterflies, London; BM(NH), and that for the Lycaenopsis group of blue butterflies (Lycaenidae on Eliot 
and Kawazoe, 1983, Blue Butterflies of the Lycaenopsis Group. London; BM(NH). 

Notes: Asterisks on each curve indicate the points at which half of the 1987 totals had been reached. All three of the groups depicted are 
'well-known' with few if any species left to be discovered and described. The rate at which new species of crows (Corvidae) were recognised and 
described declined steadily from the mid 1800s so that 90% were known by around 1880. Description of milkweed butterflies (Danainae) followed 
a largely similar pattern, with 90% of the apparently settled total achieved by 1937 and maintained for the next three decades also reached by around 
1880. However, intensive studies over the past two decades have led to a further (and unpredicted) small burst of description. After a much slower 
start, the Lycaenopsis group of blue butterflies (Lycaenopsis) also reached a seemingly stable plateau (by around 1920). As with the milkweeds an 
unpredicted burst of description, although in this instance a much larger one, has characterised the last decade or so. 



again taking insects as the example, if we take one million 
as the rough number of described species, and assume that 
(1) roughly 60% of described insect species are from 
temperate and boreal regions, and (2) 40% of extra-tropical 
species have been described, then ratios of two or three 
tropical species to one extratropical species give us world 
insect species totals in the range 4.5-6 million. There are 
few suitable data points to use for microorganisms and 
some of the other groups such as nematodes and mites 
discussed below, even for north temperate sites and regions, 
but extrapolations based on the pattern of species richness 
in vascular plants, various vertebrate groups and on 
butterflies all produce roughly the same kinds of answers 
for the remainder of the biota, including the insects. 

All such calculations, of course, depend on how similar 
bird, mammal, butterfly or other patterns used in 
calculations are to those found in the much richer but less 
well-known groups. If we were, in fact, confident that 
patterns found in groups such as birds were universal we 
would be close to achieving reasonable understanding of the 
global picture. But just how 'typical' are these well-studied 
groups with respect to species richness patterns, including 



their local species richness in tropical as opposed to 
temperate areas, and the rates at which species accumulate 
as the area considered is enlarged? We know enough to be 
clear that latitudinal gradients of species richness are not the 
same in all major groups (although species richness does 
generally increase dramatically with reducing latitude). 
Turnover rates also vary substantially from group to group, 
although evidence presently available (mostly of course for 
well-known groups) fails to reveal any clear correlation 
between these rates and size or other significant biological 
attributes that might suggest large average differences 
between (say) mammals and small invertebrates. A more 
rapid turnover in tropical as opposed to temperate regions 
does, however, seem to be indicated by the evidence, and 
various explanations for this have been advanced. 

However, in the absence of data that might be used for 
more direct approaches to calculating species richness in the 
largest and most poorly-known groups, simple 
extrapolations from well-known groups are likely to provide 
us with the most securely based, if very conservative, 
estimates attainable at present. To do distinctly better it will 
be necessary to identify clearly which of the poorly-known 



25 



/. Biological Diversity 



groups might eventually make a major contribution to the 
taxonomic inventory (see below), and gather fresh relevant 
data by direct sampling from nature. 

The relationship between the number of described and 
undescribed species in any group requires comment. The 
usefulness of this relationship as a means of predicting the 
number of species in a group depends on the extent to 
which representative samples are available and the accuracy 
with which the proportion of species that are undescribed 
can be ascertained. In practice, the latter is generally time- 
consuming and difficult, if not impossible. Unfortunately, 
where most feasible (e.g. in very small groups and groups 
in which most species have already been described), the 
results obtained will tend to be uninformative. Where the 
approach is potentially most valuable (e.g. very speciose 
groups in which 75% or more of the species remain 
undescribed), it is most difficult to apply. Here, there is a 
premium on accuracy, but this can otdy be achieved by 
someone who has close familiarity with all of the described 
species that might be present in the sample. Nevertheless, 
the effort may be worth making for groups likely to make 
a major contribution to global species richness. Any 
indication as to whether undescribed species are, for 
example, around three times as numerous (i.e. 75% 
undescribed) or (say) 19 times (i.e. 95% undescribed) as 
numerous as described species would be of considerable 
value. 

UNCHARTED REALMS OF SPECIES RICHNESS 

Here we turn away from the existing taxonomic inventory 
and knowledge of species richness patterns in well-known 
groups to consider directly where the major part of as yet 
unassessed species richness might lie. For which 
ecosystems, taxonomic or other groups are there indications 
of great unassessed species richness? Is it possible to 
pinpoint the areas that it is essential to take into account if 
global totals are to be roughly estimated? Included in the 
discussion are the principal among the biological 'new 
frontiers' that have attracted attention in recent years. 
Evidence or the presumption that local species richness is 
at least sometimes high provides the first hint that a 
taxonomic group or a type of community might make a 
large contribution to the global species total. However, in 
sifting the stronger indications out from less telling 
anecdotes or the merely hyperbolic, it is helpful to 
remember that high local species richness, although 
necessary, by no means provides a sufficient demonstration 
that the group in question makes a particularly large 
contribution overall. 

The marine realm 

The oceans, occupying over two-thirds of the Earth's 
surface, have been described by Colinvaux (1980) as 
making up "a vast desert, desperately short of nutrients and 
with hving things spread most thinly through them". This 
blunt description, dismal as it may seem, nonetheless 
provides an effective summary of what is known of marine 
productivity, turnover time and biomass. Average biomass 
(per unit area) in the seas has been estimated to be of the 
order of one thousandth that on dry land while marine 
productivity (again per unit area) is about one-fifUi of the 



average for terrestrial systems (Valiela, 1984). In absolute 
terms it has been calculated, for example, that the world's 
seas produce some 92,000 million tons of plant tissue per 
annum, as against 272,000 million tons for dry land plants. 
Although new data may necessitate some revision of figures 
of this type they are unlikely to change the general picture. 
Against this background it may be unsurprising that there 
are few data to suggest that the oceans contribute more than 
a small fraction to the world total of species, at least of 
multicellular animals and plants. In contrast, the marine 
realm makes an exceptional contribution to biotic diversity 
at higher levels (all major eukaryote groups are represented 
and more than 80% of all phyla are restricted to the seas). 

Of all currently described species it has been estimated that 
somewhat less than 15% are marine. The views of relevant 
taxonomists (see Barnes, 1989, etc.), supported by the 
generally rather high proportion of described species in 
samples taken from poorly studied areas, suggest that fairly 
high percentages of the marine 'macrofauna' (mostly 
species of molluscs, crustaceans and polychaete worms) and 
multicellular algae are already known. The position with 
regard to smaller organisms, including nematodes and 
protists, is very much less certain. Moderately high species 
richness at the local level can be found in some inshore 
communities where productivity is high, those of tropical 
reef systems providing good and well documented 
examples. However, total areas occupied by these rich 
communities are small and many of the species have fairly 
large ranges; thus local species richness of the apparently 
relatively well-described littoral and shallow water marine 
communities is not reflected in especially high regional or 
global described species totals. 

Although the ranges occupied by most marine organisms are 
poorly understood, patterns observed in the better-known 
groups suggest that turnover of species, the rate at which 
species numbers increase with increasing area, may be 
generally lower in the seas, perhaps especially in the open 
oceans and the ocean depths. Unlike the continents the 
oceans are contiguous; also the deep sea appears to have 
few areas sufficiently isolated for boundaries to be defined 
and thus few limits to dispersal which, even for small 
sediment-dwelling animals, may be through planktonic 
larvae. Although volumetrically great, the seas are also 
architecturally not very varied. As noted above, systematists 
working on most marine groups (see Barnes, 1989) appear 
reluctant to suggest that large numbers remain to be 
described and, compared to terrestrial arthropods, for 
example, this may well be true for such groups as 
Echinodermata, the larger MoUusca and Crustacea, etc., as 
well as fishes. 

The deep sea is one of the more remarkable biological 'new 
frontiers' that has become evident in the past few decades 
(see Grassle, 1989, 1991; Grassle et al., 1991). Although 
some parts of the deep sea floor are apparently poor in 
species, high local species richness of macrofauna in deep 
sea sediments appears to be the rule over the fairly large 
areas that have now been investigated in the Gulf of 
Mexico, the West Atlantic (Grassle, 1991) and elsewhere. 
This is manifest mostly among polychaete aimelids, certain 
groups of Crustacea and, to a lesser extent, molluscs. Low 
productivity, sediment patchiness and ease of immigration 



26 



Species Inventory 



are among the factors suggested to explain this diversity. 
Distinct depth and sediment type assemblages have also 
been shown to occur,, but there is little indication in the 
macrofauna of high turnover across all spatial scales. 
Indeed, the major part of local species richness seems to be 
exhibited at a very small scale, so that the majority of 
species to be found at one site are obtained by very few 
samples. The smaller organisms or meiofauna of deep ocean 
sediments often equal the macrofauna in biomass and are 
present in much greater abundance, the major component 
being nematodes. However, whether meiofaunal species 
richness equals or possibly exceeds that of the macrofauna 
remains to be established. Although relevant data may be 
forthcoming from studies in progress, as yet how nematode 
species of deep ocean sediments accumulate as we move 
from site to site is more or less unknown. 

Although these new data on the deep sea, coupled with 
recent discoveries of a whole new realm of protistan, 
bacterial and other picoplankton suggest that total marine 
biotic diversity could be considerably greater than 
previously assumed, evidence to support the contention that 
this richness rivals that found in tropical forests, except 
perhaps at the smallest of scales (i.e. the range below Im^ 
is wanting. New data on both pelagic and benthic 
microorganisms and the deep sea meiofauna may yet 
confound this view, but the evidence so far suggests that the 
oceans, including their poorly explored depths, contribute 
less to total global species richness, by an order of 
magnitude or more, than do moist tropical forests. 

Parasites 

Parasite loads for a few large animals (mostly vertebrates) 
and some green plants may be high, involving many 
parasites that are specific to a single host or a narrow range 
of host species. However, the overall numbers of large 
animal and large vascular plant symbionts, unless there are 
many more unknown than we suppose, are insufficient in 
themselves to make a very large contribution to global 
species richness. In contrast, very little is known 
concerning loads and levels of host-specificity with respect 
to the microorganisms, small nematodes, mites and others 
that are associated as parasites with members of the most 
species-rich groups, such as terrestrial arthropods. In 
relatively well-known areas such as the British Isles the 
recorded numbers of such parasites are low, but even here 
it is not unusual for small invertebrate animals to turn out 
on close examination to possess previously unknown 
parasites. Clearly, if there are many such undetected 
parasite species, their numbers could lead to a considerable 
inflation of global species figures. For example, if each 
insect species has, on average, one completely specific 
associated parasite or other syrabiont this would entail at 
least doubling estimates of insect species to obtain a 
minimum figure for overall global species richness. As yet 
there is little evidence that this may be necessary, as where 
a range of insects and other small potential host species 
have been relatively well studied, large numbers of 
host-specific parasites have not been found. We may note 
that such negative results (absence of parasites) often go 
um-emarked and unreported. There is also an inevitable 
general tendency for host ranges to be underestimated. In 
addition, it is reasonable to assume that the sometimes high 



parasite loads observed in widely distributed pest species 
are not, in fact, typical, and furnish a poor basis for 
extrapolation. We should also not be too eager to generalise 
from the situation in large vertebrates and vascular plants 
whose size and bodily complexity furnish many potential 
niches for exploitation. The great majority of organisms, 
small in size, clearly offer very different opportunities to 
potential parasites. On first principles, levels of parasitism 
may be expected to vary very widely, depending rot only 
on the size of the host but also its defences and its 
population structure. Potential hosts that are very hard to 
find will generally have few obligate parasites. 

Fungi and microorganisms 

Although far fewer species have been described than of 
green plants it has long been considered likely that the fungi 
(using the term in its traditional non-phylogenetic sense) 
might eventually prove to be the most species-rich of all 
groups, insects excepted. Interestingly, at a time when only 
a few thousand species of fiingi had been described, some 
19th cenmry mycologists early on recognised the likelihood 
that some hundreds of thousands might actually exist. 
However, with around 70,000 described species now 
recognised, we are still not in a position to say much more 
than this about the size of the group. In the absence of good 
data on tropical fungal communities, on latitudinal or other 
gradients in diversity, and how the numbers of fiingus 
species accumulate as we move from one spatial scale to 
another, any estimates of overall fungus species richness 
can only be tentative. 

In a thorough review of the significance and possible 
magnitude of ftingal diversity, Hawksworth (1991, and see 
this report) has settled on 1.5 million as a conservative 
estimate for the world's species of fungi. This figure was 
arrived at by taking into account several types of evidence, 
but finds its most firm basis in the relationship between the 
number of species of fungi known to occur in the British 
Isles and the number of British species of vascular plants. 
The list of fungus species recorded from the British Isles 
currently stands at around 12,000. Taking a figure of 2,089 
(i.e. garden species, etc. excluded) for British vascular 
plant species, we arrive at an approximately 6:1 ratio in 
favour of the fungi. Applying this ratio to a conservative 
global figure for vascular plant species of 270,000 yields a 
global total for fiingi of around 1.6 million species. 

As already discussed above, the reliability of extrapolations 
made in this way depends on the extent to which species 
richness patterns are shared, in this instance between fungi 
and vascular plants. At least some fungus species have 
extremely large ranges; should average range size in fiingi 
be significantly greater than the average in vascular plants, 
some lowering of the 1 .5 million figure for fungi would be 
in order. Similarly, should fungi exhibit a less steep 
latimdinal gradient in species richness than that found in 
vascular plants, this should also point to a lower figure. 
Data on tropical fungi remain extremely scant, but we may 
note that the rather low proportions of undescribed species 
found in recent tropical collections as yet provide no 
indication of especially great tropical diversity. 

Taking a cautious approach similar to that adopted here 



27 



/. Biological Diversity 



towards other poorly-known groups, a minimum figure for 
global fuDgus species might be put at around half a million. 
An alternative, less cautious but well-supported, approach 
is presented in Chapter 6 of this book. The arbitrary 
'working figure' of one million incorporated in Table 4.3 
represents a compromise between this and the 1.5 million 
estimate given by Hawksworth (1991). 

Microorganisms, including the smaller fungi, algae and 
'protozoans', as well as bacteria and viruses, present the 
greatest challenge to any serious attempt to assess the 
overall scale of global species richness. The great genetic 
diversity and general significance of microorganisms is 
highlighted in Chapter 6, where the problem of applying to 
them the species concepts that are more or less consistently 
used for many larger organisms is also discussed. 

What is clearly an immense diversity of very small 
organisms, perhaps especially bacteria, viruses and 
unicellular algae, remains largely unaccounted for by the 
existing taxonomic inventory. However, whether the 
diversity of these organisms, often lacking sexual processes 
and many of them clonal, is best expressed in terms of the 
number of phenetic groups recognised as species is a moot 
point. The comparability of, for example, viral 'species' 
and those of multi-cellular organisms, in which sexual 
reproduction predominates, is very questionable. Virtually 
nothing is known of any latitudinal or other gradients of 
diversity that microorganisms might exhibit while, even in 
temperate regions, at no scale is species richness well 
documented. Probable range sizes are also known for very 
few species, but very small organisms (and those with very 
small dispersal stages, such as fiingal spores) are known, in 
some instances, to have very broad if not cosmopolitan 
distributions. Coupled with a generous measure of caution 
in extrapolating too far from the known, all of these 
considerations are reflected in the arbitrary 'working 
figures' for species richness of microorganism groups given 
in Table 4.3. 

Nematodes, mites and insects 

Despite a considerable increase in resources devoted to 
nematode taxonomy over the past few decades and a 
commensurate surge in the rate of description of new 
nematode taxa, this group of worms probably still remains 
the least well inventoried group of metazoan animals. 
Although relatively early attention had been devoted to 
some of the larger and, in human terms, more significant 
parasitic species, up until 1860 only 80 species of plant, 
soil and freshwater species had been described. This 
compares with an annual rate of around 140 species of the 
same groups described in the 1960s and the present overall 
description rate (including parasitic and marine taxa) of 
more than 300 species per annum. The current total of 
described species is very uncertain but has been estimated 
to stand at around 15,000. 

Nematodes 

Indications that nematode species richness may be of an 
extremely high order stem more than anything from the 
abundance of free-living forms (a few millions of 
individuals may be present in Ikm^ of suitable soil or mud) 
and the great number of free-living species that may be 



found in samples taken from a very small area. Two 
hundred or more species have been reported from samples 
of just a few cm' of coastal mud. 

While parasitic species totals may prove to be significantly 
high (see above), and free-living terrestrial and freshwater 
species also very numerous (Poinar, 1983), recent work on 
estuarine, shallow-water and deep-sea sediment nematodes 
suggests that the marine reiilm (see above) could make an 
even greater contribution to a total count of the world's 
nematodes. However, how high levels of species richness 
at the smallest scales bear on the question of the overall 
number of nematode species remains unclear. Good data on 
species turnover in both terrestrial and marine nematode 
assemblages are conspicuously lacking, as is any indication 
that assemblages of tropical nematodes are especially rich. 
In the absence of any direct indication of massive 
unaccounted for species richness at larger scales a 
somewhat cautious approach to estimating the likely overall 
number of nematode species is probably advisable. 
However, it would be surprising if this number were not at 
least some hundreds of thousands. 

As in the case of protists and other microorganisms the 
taxonomic study of nematodes is made difficult by 
uncertainties with regard to the application of species 
concepts. Many species are entirely uniparental or contain 
some uniparental populations. Apart from their frequently 
very small size, the sorting to species of nematode samples 
is often hampered by a very low incidence of diagnostic 
males. At best, species recognition is beset by many 
difficulties and may, in some instances, remain frankly 
subjective. 

Mites 

In the case of mites (Acari) there are fewer problems with 
interpreting species limits but, as with nematodes, the 
number (around 30,000 or so) of described species clearly 
represents only a small proportion of the actual total. 
Knowledge of tropical mite faunas in particular is very 
scant, lagging well behind that of other arachnids, including 
spiders. Reliable quantitative sample data that give anything 
more than a hint of what mite species richness might be at 
any site in the tropics appear to be unavailable. However, 
it may be reasonable to expect that free-living terrestrial 
mites, although flightless and differing from insects in 
various other respects, do roughly follow patterns, in terms 
of coexistence, range sizes, turnover, etc., already 
tentatively established for certain insect groups. If so, and 
despite the fact that we have a less complete knowledge of 
temperate mites than, say, of beetles, it is difficult to 
envisage a world total of less than a few hundred thousand 
species. Suggestions that the global number of mite species 
is in the region of one million or even higher may prove 
defensible once good data for tropical sites are forthcoming. 

Insects 

There is abundant evidence to suggest that insects exhibit 
high species richness at most scales (i.e. from a few m^ to 
ecosystems) except perhaps the very smallest. The number 
of already recognised and described species - around one 
million - is sufficient to establish that insects comprise a 
substantial portion of the world's species. Most insect 
groups are taxonomically tractable and the rate at which the 



28 



Species Inventory 



process of inventoryiDg advances depends largely on the 
level of resources devoted to the task. Samples containing 
many species can often be fairly rapidly as well as reliably 
sorted, and this makes several major insect groups suitable 
for a range of species richness studies, even when most of 
the species being examined are undescribed. Some of the 
ways in which data from samples of tropical insects may be 
used to tackle the problem of assessing insect global species 
richness are discussed below. We may note, however, that 
attaining any reasonably accurate idea of what proportion of 
species in total are insects is less easy. This is likely to 
depend as much on achieving advances in estimating the 
diversity of microorganisms and other poorly understood 
groups as on better data for the insects themselves. 

Tropical forest canopies: the height of tropical diversity? 

Tropical forests have long been known to harbour a great 
richness of life and, although they cover only 6% of the 
earth's land surface, it has been widely supposed that they 
may contain as many species of organisms as, or even more 
than, the rest of the world together. One part of these 
forests, the world of the tree tops, has tended to evade close 
inspection by biologists but, with the development over the 
past two decades of new methods for studying forest canopy 
organisms, notably (but not only) the use of insecticide 
fogging techniques, canopy communities even in tall 
tropical forests have become much more accessible (Erwin, 
1990). 

There is now sufficient information to indicate that local 
species richness of many of the insect and other arthropod 
groups that have been the main focus of recent attention are 
very high in tropical forest canopies, much higher (often by 
a factor of 10 or more at the level of a single tree) than in 
temperate forests. It is equally clear that not only are a high 
proportion of the species undescribed (this is the case for all 
strata in moist tropical forests) but a proportion of them are 
not or are only exceptionally found at lower levels. Data 
have now been gathered that give some idea of the usual 
sort of numbers of species of at least some of the more 
important insect groups (notably Coleopteraand Hemiptera) 
to be found in various neotropical and palaeotropical forest 
canopies at the level of individual trees and small quadrats 
(e.g. 12 X 12m), up to about the one hectare level. 

Fewer data are available to allow confident estimation of 
canopy species numbers at a larger scale within relatively 
uniform tropical forest. Indications are that much of the 
patchiness in the canopy is at or below the one hectare level 
and that samples from adjacent hectares are about as 
different in species composition as samples taken several 
kilometres apart. The picture that is beginning to emerge is 
of a mosaic less defined by tree species than by a variety of 
other factors, including the condition of each tree, and the 
patchwork distribution of resources, including epiphytes, 
that manifests itself at a much smaller scale than an 
individual tree canopy. Some data are available to show that 
adjacent but radically different forest types have very 
different canopy faunas but inadequate sampling does not 
allow any even remotely accurate estimation as yet of the 
extent of 'turnover' in moving from one forest type to 
another, or whether this is higher or lower than species 
turnover in the forest's lower strata. 



In sum, quite enough is known to indicate that high local 
species richness (although not of all groups) and 
considerable patchiness at quite a small scale are typical of 
tropical forest canopy arthropod communities. How large a 
contribution canopy-dwelling species or species that are 
present in canopy samples (not exactly the same thing) 
make to overall arthropod species richness at one site is less 
clear. The contribution made by canopy species to faunas at 
regional and other scales is even less well understood, 
despite claims that the canopy is where maximum tropical 
biodiversity occurs (Erwin, 1990). 

Against this background, it is rather surprising that 
speculations as to the number of species of arthropods that 
might be found overall in the canopies of tropical forests 
(Erwin, 1982, etc.) have come to occupy centre stage in 
recent general discussion (May, 1988, 1990; Stork, 1988; 
etc.) of the possible magnitude of the global species 
inventory. At the same time, and stemming from the view 
that tropical forest canopies harbour an unparalleled 
diversity of life, suggestiops that the global species total for 
terrestrial arthropods alone may be as high as 50 or even 
100 million have also been widely reported, and have found 
expression in a number of reports concerned with the 
conservation of biotic diversity (Wolf, 1987; Reid and 
Miller, 1989; National Science Board, 1989; etc.). The 
attention paid to these suggestions perhaps justifies a closer 
look at data that may give some hints as to the likely 
richness of tropical forest canopy arthropod assemblages. 

Tropical forest canopies: reassessment of the evidence 

Critical examination of the available data (many of them 
still unpublished) might usefully begin with some evaluation 
of how fiiUy the richness of canopy arthropod assemblages 
is reflected in samples that are routinely studied. Most of 
the significant data points come from insecticide fogging 
studies. The proportion of species that might be expected to 
be obtained by this technique has been the subject of some 
discussion (Adis et al., 1984; Erwin, 1990; Stork, 1991; 
etc.), but without firm conclusions being reached. However, 
restricting attention to adult stages only, we know that some 
species that mine or burrow within living or dead plant or 
fungal tissue and some of the fauna of suspended litter and 
soil are poorly collected by fogging, as are certain 
arthropods that are firmly attached (e.g. scale-insects) to 
leaf surfaces, along with an uncertain proportion of the 
larger species of some groups that may escape capture by 
flight. On the other hand, species that are present as 
'tourists', most of them presumably resting on exposed 
surfaces or in flight, seem to be well sampled locally. 
Characteristically, their pattern of occurrence in the canopy 
is patchy and unpredictable, with the result that tourist 
species accumulate steadily as sample size is increased. A 
good number of groups (e.g. ladybirds, ants, adult psyllid 
bugs, etc.) seem to be sufficiently well sampled by fogging 
that results give an accurate impression of the relative and 
even absolute abundance of individual species, as well as a 
good account of which species are present. 

However, canopy samples obtained by means other than the 
application of insecticides reveal that a proportion of true 
canopy species are not or are not readily taken by fogging. 
The most telling evidence for this comes from studies 



29 



1. Biological Diversity 



(Hammond, 1990; Hammond and Stork, unpublished) 
where canopy fogging has been carried out in tandem with 
additional extensive sampling of both canopy and lower 
forest strata by other means. In such instances we find a 
certain number of species well represented in, for example, 
baited traps or interception traps placed in the canopy, but 
absent from traps of the same type operated at ground level 
as well as from fogging samples. 

Ignoring the proportion of species (probably rather small) 
that are not well sampled by the technique, how much 
fogging is necessary to give a reliable picture of the size of 
a local canopy arthropod community, and how are its 
components distributed? A number of studies in both 
temperate and tropical countries suggest that, with an 
appropriate pattern of sampling (including adequate seasonal 
coverage) relatively few trees or quadrats may be needed. 
Particularly good evidence on this point is emerging from 
the results of a fogging programme carried out in a 
relatively uniform tract of lowland tropical forest in 
Sulawesi (Hammond and Stork, unpublished). In this study 
a number of samples, covering all seasons, were taken from 
each of 20 different 12 x 12m quadrats distributed through 
a 500ha study area. A strong indication that a representative 
sample of the canopy insects present in the study area was 
obtained is furnished by the rate at which species 
accumulated with sampling effort (see Fig. 4.3). 

How near are we to determining the proportion of all 
arthropod species present in a given tropical forest that are 
likely to be taken by canopy fogging, and is this more or 
less a constant? If canopy samples are to be used as a 
means of directly estimating overall species richness of a 
forest, either locally or at a larger scale, it is clearly vital 
that the relationship between numbers of species present in 
the canopy emd the number of species found overall be 
roughly understood. If canopy samples are to be used for 
comparing local species richness directly it would obviously 
be helpful if proportions varied little from one place to 
another. Finally, if global figures for arthropod species 
richness are to be derived from canopy fogging data (see 
below) these will be on a particularly sure basis if the 
number of species present in canopy samples is a very high 
as well as constant and a known proportion of the whole. 
That this is the case, for neotropical forests at least, has 
been asserted by Erwin (1991) who in earlier work (1982) 
suggested that canopy arthropod communities were at least 
twice as rich overall as those of the forest strata below. 
Working from first principles, this sort of relationship 
might seem unlikely. Most of the production of living tissue 
in a forest starts off in the canopy, but most of this - fallen 
leaves, fruit and wood, insect, bird and other excrement, 
and whole fallen trees - ends up forming a rich mosaic of 
resources on the forest floor. Not surprisingly, the 
abundance and biomass of arthropods is greatly skewed in 
favour of the lowest levels in a forest. Strictly comparable 
figures for both canopy and forest floor are not available, 
deriving as they do from fogging samples for the canopy 
(undersampling internal and concealed feeders, etc.) and a 
range of different 'standing crop' methods for the forest 
floor. For example, in neotropical forests investigated by 
Adis and Schubart (1985), disregarding the Collembola ani 
mites which made up 60-80% of the individuals in soil/litter 
samples, an average of around 30 times as many arthropods 



were found, per m', in the soil/litter layer as in the canopy. 
Methods used in studies such as this are known to 
undersample small arthropods, mites and springtails in 
particular, because of poor extraction from soil and other 
substrates, and also ignore or underplay the large 
contribution made by significant but patchily distributed 
resources such as csu'rion, fallen fruit, large fungus fruiting 
bodies and decaying wood. 

Both baited traps and those not involving attractants (e.g. 
Malaise traps and window traps) collect far fewer 
individuals and species at canopy level than on the ground. 
This is a common finding of studies in several countries. 
Some tropical studies (e.g. Hammond, 1990), for example, 
show a relationship of around three species of Coleoptera 
in ground-level Malaise trap samples to one for the same 
trapping effort in the canopy. A much higher ground to 
canopy ratio is characteristic for some other groups (e.g. 
Hymenoptera) and higher ratios all round are generally 
found in catches from interception or other traps that do not 
favour plant-climbing species. 

Apart from temperate forests where the overall proportion 
of species present at a site that can be found in the canopy 
probably rarely exceeds 20 % , the most compelling evidence 
for much lower local species richness in the canopy than at 
other levels comes from the Sulawesi study already 
mentioned (Hammond, 1990), where as complete aa 
inventory as possible was made of the Coleoptera and some 
other insect groups found in the 500ha study area. The 
extensive canopy fogging that formed part of the sampling 
and inventorying programme produced around 30% of the 
beetle species found in total, and around 20% of those 
conservatively estimated actually to occur in the study area. 

More than three-quarters of the species taken by fogging in 
the Sulawesi study were also present in samples of various 
types taken at ground level. Analysis of their pattern of 
occurrence in all ground and canopy-level samples suggests 
that many of these were present in the canopy only as 
'tourists', and that overall less than two-thirds of species 
found in the canopy belong to the canopy fauna proper, 
either as 'specialists' (species largely restricted to the 
canopy) or 'generalists' (species found regularly both in the 
canopy and at lower levels). Making allowance for canopy 
species not obtained by fogging, canopy species proper 
amount to at most 20% of the area's species, of which no 
more than half (i.e. probably less than 10% of the total 
fauna) may be regarded as canopy specialists. 

Results from other palaeotropical and from neotropical sites 
suggest that although canopy insect species richness in 
tropical moist forests is somewhat variable, it is not 
exceptionally low at the Sulawesi site. Somewhat higher 
levels of local species richness might be expected, however, 
in canopies that contain more tree species and forests in 
which canopy, understorey and ground layers are more 
clearly demarcated. Data available for temperate forests 
suggests relatively weak stratification, a very small canopy 
specialist component and a 'typical' overall canopy to 
ground arthropod species ratio of around 1:10 or more. 
Variation is to be expected in tropical forests, with the 
lowest ground to canopy ratios most likely to be found 
where the ground component is relatively small (e.g. dry 



30 



Species Inventory 



Figure 4.3 Accumulation of beetle species in canopy samples 



0) 

o 

a 
in 



o 

0) 
(0 

o 



0) 

> 



e 

Z! 
U 

u 
< 







Canopy 


beetles of various gui Ids including tour is 


50 








^ -^ 


40 


- 




10 





30 


^ 




- 


^// 


8 
6 


■f^ 


20 






4 


/ One canopy herbivore gui Id 




^ 1 




2 


./ 


10 






a 






March 5 July 10 Decentoer 15 





1 1 


1 1 1 


1 1 


1 1 1 1 1 1 1 1 1 



March 5 July 10 Oecerrtoer 15 

Number of Samp I es 

Notes: Beetle species in canopy fogging samples from a single tropical site and how these accumulate with increased sampling effort. The upper 
curve is for a 'representative' selection of 51 species (out of 900 beetle species in the total sample) comprised of 23 'regular' canopy species and 
28 that are present in the canopy as 'tourists'. It shows a steady decrease in increments with sampling effort but no distinct flattening. The inset curve 
is for some of the species - the 10 members of a herbivore guild (broad-nosed leaf-chewing weevils that are all either canopy specialists or generalist 
species regularly feeding in the canopy) - included in the upper curve . This shows how, with a dataset restricted to canopy species proper, the species 
accumulate much mote rapidly, in this case reaching a plateau after 5 (out of 15) samples had been taken. 



forests) or, conversely, where the canopy component is 
high as a consequence of great stratification, as may be the 
case in some of the tallest closed-canopy moist forests. The 
ratios found for Coleoptera in Sulawesi (about one in five 
species belong to the canopy fauna proper, about one in ten 
species are canopy specialists) may not be modal for 
tropical forests, but further results are needed before any 
firm view on what 'typical' ratios are can be taken. 

Despite the large numbers of arthropod and other species to 
be found in tropical forest canopies, there are few data 
providing any clear support for the view that the upper 
levels of tropical forests are truly the "heart of biotic 
diversity". If anywhere, it would seem more likely that this 
is to be found on and under the forest floor. 

SAMPLING THE HYPER-DIVERSE BUT POORLY 
KNOWN 

Knowledge of large organisms and some temperate regions 
provide an inadequate basis on which to extrapolate with 
any confidence to groups and areas that are poorly-known. 
Well-established species richness patterns exhibited by 
groups such as birds are, of course, a useful starting point 
in attempts to gauge better the species richness of less 
well-known groups, but there is every reason to suppose 
that they provide no more than general guidance. 
Well-known organisms are a biased sample of the biota. 
Apart from being mostly large, they may also be 



unrepresentative in many other ways. Vascular plants, for 
example, may be much less dependent on surface moisture 
levels than many small animals. Butterflies, unlike the 
majority of insects, are all essentially herbivorous. 

Taxonomic groups, functional groups and ecosystems that 
might be expected to make the largest contributions to 
global species richness have been briefly surveyed above. 
For some of these, there are strong indications of 
considerable diversity that is as yet unaccounted for by the 
taxonomic inventory, while for others the hints are more 
vague. Many more data for these poorly-known groups and 
areas of the world are needed for the magnitude of their 
contributions to biodiversity to be even roughly assessed. 
How some of these data might be gathered and applied to 
species richness estimates is discussed below. 

What, where and how 

Almost any new data on species richness patterns in the 
groups discussed in the previous section are likely to prove 
useful, but the pace at which our understanding of these 
patterns improves will depend heavily on which data we 
choose to gather first, and on how economical and effective 
the methods are that we adopt. 

The questions of what and where to sample and how best to 
gather sample data to improve our knowledge of major 
species richness patterns has been well reviewed in a recent 



31 



1. Biological Diversity 



report (Solbrig, 1991) where the need to focus efforts on 
high diversity groups and ecosystems is highlighted. More 
precise proposals with regard to the choice of sites for 
intensive study and the choice of indicator or focal groups 
(see below) have been advanced by di Castri et at. (in 
press). Clearly, there is an urgent need for better data on all 
of the hyper-diverse groups: insects, nematodes, fungi, 
bacteria, etc.. However, it is equally clear that we cannot 
expect progress to be made at an even rate on all fronts. 
The point of departure varies from group to group, as does 
the ease and reliability with which good sample data may be 
obtained. Some groups are distinctly more tractable than 
others, in the sense that large samples may be rapidly and 
reliably sorted to species. 

To make the most of the considerable effort involved in 
gathering species richness data for groups of any size, two 
complementary approaches are necessary. The intensive 
approach entails in-depth studies, inevitably feasible for 
large groups at only a few sites, aimed at establishing the 
number of species present as precisely as possible. If 
coupled with appropriate quantitative sampling, the process 
of intensively inventorying a single site may be exploited to 
identify and calibrate methods that are needed for studies of 
a more extensive type. Thus, complete site inventories are 
needed to furnish the 'knowns' against which sampling 
methods can be calibrated and more extensive sample data 
compared. The actual methods used for inventorying will, 
of course, vary from group to group, habitat to habitat, and 
biome to biome. 



For the purposes of this discussion, perhaps the most 
important distinction to make is between ratios that are 
extrapolated from one site to another and those that are used 
to extrapolate across spatial scales. Some of the different 
kinds of ratio that may be extrapolated from site to site 
have already been mentioned above while discussing the 
intensive/extensive approach to obtaining species richness 
data. Most commonly, when dealing with sites of a 
generally similar type, ratios used will be those relating less 
complete (sample/focal group) data to more complete 
(inventory/larger group) data. Here, the reliability of 
extrapolation will depend in part on how extensively the 
ratio has been calibrated, but also of relevance is the notion 
of comparing like with like. For example, a ratio that has 
been shown to obtain at a series of sites in the moist tropics 
might well be considered unlikely to hold at temperate sites. 

It goes almost without saying that species richness data for 
poorly-known groups that we may wish to use as the basis 
for extrapolation will generally relate to single sites, as few 
reliable data for larger areas are available. If we start with 
single site data and wish to extrapolate to species richness 
of such groups at the regional or global level, we face a 
dilemma, as the ratios needed can only come from the few 
very well-known groups of organisms in which species 
number relationships across spatial scales are more or less 
established. Such ratios, derived as they are from groups 
which in the main may be expected to have quite different 
species turnover rates, should be used only with the greatest 
caution. 



The current emphasis on terrestrial arthropods in 
biodiversity research is perhaps to be explained as much by 
the general amenability of these animals to study as by the 
likely size of their contribution to the global species 
inventory. 

In extensive studies of hyper-diverse groups it may often 
prove necessary to deal with just part of the group rather 
than treat it in its entirety. In such instances the 'indicator' 
group or groups chosen need to be as 'representative' as 
possible. It is also helpful if, in species terms, they 
constitute a more or less unvarying proportion of the group 
as a whole. 

Where to look first if we aim to advance rapidly our 
knowledge of species richness patterns in the ultra-diverse 
groups is fairly clear. In the marine realm there is an 
evident need for many more data from the ocean depths. 
For terrestrial organisms in general the most urgent 
requirement is for more data from the moist tropics. 
Despite their undoubted richness, tropical forests remain the 
least well studied of major terrestrial ecosystems. 

Kinds of extrapolation 

Extrapolation of one sort or another is likely to be 
employed at every stage in the process of assembling and 
interpreting species richness data on poorly studied groups 
of organisms or regions. Although all extrapolative 
procedures involve the same assumption: that a ratio 
obtaining in a known situation holds in an unknown one, 
some kinds of extrapolation may, in practice, be seen to be 
more trustworthy than others. 



It is, of course, possible to extrapolate directly from species 
richness data for a single site or even a single sample to 
species richness at the ecosystem, regional or global level. 
Naturally enough, approaches that offer the possibility of 
moving from sample or site figures to global figures in a 
single step are tempting to use. However, given its 
inevitably speculative nature, extrapolation in this way is 
probably best avoided. The limitations of methods that 
involve empirical species richness relationships between 
very different groups of organisms (e.g. vascular plants and 
insects, butterflies and nematodes), host specificity levels, 
and proportions of species remaining undescribed have 
already been discussed. In some instances, ratios made use 
of (e.g. host: parasite species numbers) are likely to be 
extremely poorly calibrated. In most cases, the extrapolation 
from site to region or globe involves the essentially unsafe 
(and often unstated) assumption that the relationships used 
scale evenly (see May, 1990). 

NEW DATA ON TROPICAL INSECTS AND WHAT 
THEY CONVEY 

It is widely assumed that insect species outnumber all 
others. The belief is not without some foundation, as more 
than half of all described species are insects, and it is 
evident that at least several times as many remain 
undescribed. Ultimately, however, the question of the size 
of the contribution that insects make to the global species 
inventory is not to be settled by data on the insects 
themselves. A much improved understanding of 
microorganismal diversity and a better appreciation of 
species richness in groups such as the fungi and nematodes 
is needed for the insect contribution to be seen in 



32 



Species Inventory 



perspective. This said, the insect part of the equation is a 
matter of obvious interest, particularly if we concede that an 
approximate answer to the question of how many insect 
species there are is within reach. 

In comparison with other speciose groups such as 
nematodes or mites, knowledge of tropical insects is 
relatively advanced. Although the actual evidence remains 
fragmentary and anecdotal in the main, it has long been 
recognised that the tropics, and moist tropical forests in 
particular, contain far greater numbers of species than 
extra-tropical regions. Arguably, therefore, a reasonably 
accurate estimate of the number of tropical insect species 
would provide a good indication of the scale of insect 
species richness overall. For some of the smaller and 
best-known insect groups, such as butterflies and 
dragonflies, tropical species richness patterns are, in fact, 
rather well understood. The same cannot be said of the 
largest insect groups, although enough is known concerning 
a range of family-level taxa to suggest that the proportional 
representation of these groups (Coleoptera, Diptera and 
Hymenoptera) in the tropics may differ significantly from 
that in well-studied parts of the temperate regions. 

New quantitative data, including a number not yet referred 
to in print, are beginning to both broaden and give greater 
precision to our understanding of tropical insect species 
richness and how it is distributed. However, few hard data 
on the number of species of any of the major insect groups 
to be found at individual tropical sites have yet emerged. 
Only for the very best-known groups, such as butterflies, is 
there any sound appreciation of turnover rates and the 
relationship between single site and regional species 
richness. 

In spite of these difficulties, two datasets concerning the 
number of species of major insect groups present in large 
samples taken at moist tropical sites have already been used 
(Erwin, 1982; Hodkinson and Casson, 1991) to generate 
estimates for total tropical and also global insect (or 
arthropod) species richness. The estimates produced from 
these now widely quoted studies, both of them involving 
explicit assumptions, but with regard to ratios of very 
different kinds, are strikingly divergent, with Hodkinson 
and Casson arriving at a figure of around two million for 
insects globally and Erwin at a figure of 30 million for 
arthropods in the tropics alone. If correct, the first figure 
implies that around half of all insect species have already 
been described, while the second would suggest that 
undescribed insect species outnumber those described by a 
factor of 30 or more. However, not too much significance 
need be read into the discrepancy between the results, as 
both approaches entail the use of ratios that are essentially 
uncalibrated. Recognising this, Erwin's (1982) original 
calculations have been tentatively reworked by others (e.g. 
Stork, 1988; May, 1990), illustrating well how ostensibly 
reasonable but different assumptions will produce widely 
varying results from the same chain of reasoning. The same 
applies, if with less force, to Hodkinson and Casson's 
calculations (see below). 

Hodkinson and Casson use a single data point - the number 
of species of bugs (Hemiptera sensu lata) in samples from 
the Dumoga area of N. Sulawesi, Indonesia. They suggest 



that the bug samples studied "contained a significantly high 
proportion of the species present", but there is good reason 
to suppose that the recorded total of 1,690 species 
represents a considerable underestimate. However, for the 
first of the two separate calculations employed by 
Hodkinson and Casson, the extent to which their data 
accurately reflect the size and composition of the bug fauna 
of their study area is not directly relevant. They begin by 
estimating the ratio of undescribed to described species in 
the Dumoga sample of bugs and then, treating this as a 
subsample of the world bug fauna, extrapolate directly to a 
global figure for the group. Only two considerations are of 
significance here: the accuracy of the undescribed to 
described ratio for Dumoga bugs, and whether the Dumoga 
sample is in fact representative in global terms. On the 
second count, we lack the data to make any reasonable 
judgement, but with regard to the first it is clear that the 
estimates on which the ratio is based, as might be expected, 
are in no way precise. In fact, the figure of 62.5 for the 
percentage of species undescribed could well turn out to be 
rather conservative. 

The second line of attack adopted by Hodkinson and Casson 
begins with the number of undescribed species of Hemiptera 
(see discussion above) considered to occur in the Dumoga 
area (i.e. 62.5% of 1,690 = 1,056) and the ostensibly 
empirical relationship between this and the number of tree 
species found there, estimated to be around 500. Direct 
extrapolation to the tropics as a whole (with an estimated 
50,000 tree species) yields a figure of 105,600 undescribed 
tropical bug species. Added to the 81,7(X) species of bugs 
already described, this furnishes a total of 187,300, no 
allowance being made for undescribed extratropical species. 
It should be noted that the relationship presumed to exist 
between the numbers of bug species and numbers of tree 
species present in a given area includes the hidden 
assumption that this scales evenly, that is to say that an area 
containing, for example, 5,000 tree species may be 
expected to contain 10 times as many (rather than 5 or 20 
times as many) bug species as an area with 5(X) tree 
species. This problem of scaling is as relevant to empirical 
relationships of the type considered here as it is to those 
based on host-specificity (see discussion in May, 1990). 

For both sets of calculations Hodkinson and Casson scale 
up to global insect species overall by using figures of 7.5% 
or 10% for the proportion of the world's insects that are 
Hemiptera. The first of these figures represents the 
proportion of described insects that are Hemiptera, more 
reasonably put at around 8.5%, and the second is the 
proportion of insect species in Bornean canopy fogging 
samples that are bugs. Both are probably over-estimates. 
Bugs, like several other mainly plant-associated groups, are 
known to be over-represented in fogging samples; for a 
number of reasons, including their taxonomic apparency, it 
may be reasonable to assume that bugs are proportionately 
better described than the insects as a whole. Taking a figure 
of 5% (rather than 7.5% or 10%) as the proportion of 
insects that are bugs and applying this to the revised bug 
estimates produced above, we see that it is possible to reach 
figures for world insects in the range 6.5 to 11 million 
rather than the two million or so that Hodkinson and 
Casson conclude with. 



33 



1. Biological Diversity 



The ostensible basis for the estimate of 30 million tropical 
arthropods obtained by Erwin (1982) is an interesting study 
of the beetles (of some 1 ,200 species) obtained by fogging 
the canopies of 19 individual trees of the neotropical species 
Luhea seemannii (Erwin and Scott, 1980). In the light of 
how little is known of insect species:tree species 
relationships, this might seem an unlikely source for an 
estimate of tropical arthropod species richness. However, 
closer examination of the chain of reasoning adopted by 
Erwin reveals that the data obtained from the field on Luhea 
insects play a relatively minor part in the calculations. Of 
much greater significance in terms of the results are two 
major assumptions that are unrelated to the field data. The 
first of these, and one which we are far ft-om being in a 
position to test concerns average levels of host-specificity in 
tree-dwelling tropical insects (see also May, 1990). The 
second assumption, one that, at least at the local level, is 
much easier to test, concerns the proportion of tropical 
forest species that are to be found in the canopy. Other 
factors involved in Erwin's chain of argument, including the 
proportion of canopy arthropods that are beetles, and the 
number of species of tropical trees, are less problematic, as 
the figures used may reasonably be expected to be of the 
right general order. It should be added that further implicit 
rather than explicit assumptions that relate to problems of 
scaling (see discussion in May, 1990) are involved. 

The role played by the estimate of 163 for the number of 
beetle species specialised on the average species of tropical 
tree in Erwin's estimate is crucial. Essentially, it is this that 
generates the very high figure for tropical insect species 
richness that eventually emerges from his chain of 
calculations. Unfortunately, although there are good reasons 
to suppose that the degree of host-specificity exhibited by 
tropical canopy insects is generally low, there are few data 
that give even a hint as to what actual levels of 
host-specificity might be. More importantly, and as has 
already been noted, the use of host-specificity data for 
species richness calculations is beset with problems (see 
discussion in May, 1990). Even in the British Isles, where 
the host ranges and preferences of canopy-dwelling insects 
are relatively well documented, specificity data are far too 
imprecise to be used for any calculation of the number of 
tree-associated insect species. 

Bearing these limitations in mind, reworking of Erwin's 
calculations may be viewed as of little practical value. 
However, it should be noted that truly staggering numbers 
are generated if the ratio of tropical canopy beetle species 
to tropical beetle species overall is revised in the light of 
findings discussed above. If the 1:4 or so canopy to total 
ratio found to obtain in Sulawesi is substituted for Erwin's 
2:3, but all else in Erwin's chain of calculations is left as it 
is, we arrive at an estimate for tropical forest arthropods 
alone of around 100 million, rather than 30 million. If we 
should conclude, reasonably enough in view of what is 
known of tropical canopy insects, that beetles are typically 
less than 40% of canopy arthropod species, let us say 25% 
(see Stork, 1987), the estimate for tropical arthropods rises 
again to approaching 200 million. 

Some of the relationships used by Erwin are important ones 
for almost any kind of estimates of global insect species 
richness that we might envisage, and some of these, for 



example the proportion of tropical forest beetles that are to 
be found in the canopy, are also amenable to test. However, 
this is far from true for the key relationship that Erwin 
employs, concerning numbers of beetle species that are 
effectively specialised on individual species of tree. In fact, 
it would seem likely that only when we know most of the 
answers that we are actually seeking, i.e. the number of 
species of insects to be found in the tropics and how many 
of them are found in the canopy, will we be in a position to 
start gaining some idea of how many are exclusively 
associated with the average tropical tree species. 

The methods of estimating tropical insect species richness 
used by Erwin on the one hand and Hodkinson and Casson 
on the other have been discussed in some detail here with 
the intention of stressing the problems involved in the 
short-cut approach. Any extrapolatory route, from sample 
or inventory data to a summary for the tropics as a whole, 
that avoids the explicit use of ratios concerning relative 
species richness at different spatial scales is bound to be 
tempting. However, if the alternative is to invoke 
relationships that cannot be calibrated, the temptation is 
perhaps best avoided. 

The valuable datasets (Casson, 1988; Erwin and Scott, 
1980) on which the Hodkinson and Casson and Erwin 
estimates discussed above were based are just a part of a 
whole crop of new data that have recently become available 
for tropical insects. Although most results pertain to rather 
narrow taxonomic groupings, they are nevertheless leading 
to a steady improvement in our overall understanding of 
such questions as altitudinal gradients in species richness, 
species turnover at small spatial scales, and the contribution 
made by elevational assemblages and pronouncedly different 
but adjacent forest types to species richness at the level of 
the 'extended site'. 

Data of a particularly extensive type have come from one 
recent large study based on an area of moist tropical forest 
in northern Sulawesi, Indonesia. The work of analysing 
results is still in progress, but many data concerning local 
species richness of beetles (Hammond, 1990) have already 
become available. The full dataset for beetles includes the 
results of quantitative sampling by a variety of means 
through all seasons of one year, as well as an inventory of 
species found within the principal study area (SOOha of 
relatively uniform lowland forest). Valuable if less 
comprehensive data for several other insect groups, e.g. 
Hemiptera (Casson, 1988) and Hymenoptera(Noyes, 1989) 
are also available. The data firom this study offer the 
possibility, for the first time, of (1) establishing a figure for 
overall local species richness of some major insect groups 
at a tropical moist forest site, (2) assessing what proportion 
of species is found in the canopy as opposed to lower layers 
(see above), and (3) of calibrating a range of sampling 
methods against knowns (total inventory results) in a 
tropical forest setting. Finally, the detailed sample data and 
inventory provide a comprehensive enough picture of the 
assemblage of insects present that, with sufficient general 
knowledge of their biology, it is possible to assess the 
proportions that belong to different functional groups, and 
that are associated with particular microhabitats and the 
various forest strata. The biases of various sampling 
methods with respect to these and other characteristics, such 



34 



Species Inventory 



as body size and taxonomic group membership, may also be 
determined. 

The findings of most direct relevance to overall tropical 
insect species richness to emerge so far from this study are: 

• Species richness of Coleoptera at this tropical site, at 
scales of Iha up to around 500ha is some five times 
greater than the average for a range of temperate forest 
sites. The species richness of Hemiptera, in relation to 
temperate sites, may be of the same general order, while 
that of Lepidoptera and Hymenoptera is also higher than 
in temperate forests, but by a less certain factor 
(probably between two and four) 

• The numbers of species of some major insect groups and 
of insects overall that are found in the canopy are low 
compared with numbers found at ground level 

• For an equivalent intensity and pattern of sampling, some 
of the sampling methods used obtain the same proportion 
of species present as they do at comparable sites in 
temperate regions (see Fig. 4.4). 

In the long term, the last of these findings may turn out to 
be the most significant. Following calibration against the 
Sulawesi site inventory, simple 'sampling packages' that 
have already been shown reliably to reflect local species 
richness of Coleoptera and/or other major insect groups at 
'known' temperate sites, might reasonably be expected to 
provide a good indication of species richness at other moist 
tropical sites. In fact, a number of trials of these sampling 
packages at a range of sites in the Indo-Australian and New 
World tropics have now been made. Assuming that the 
results being obtained (Hammond, unpublished) are reliable, 
they suggest ratios for the number of Coleoptera species 
between the tropical sites investigated and average 
temperate forests, that vary, except for one small tropical 
island with substantially lower beetle species richness, from 
around 3:1 to 8:1. 

New data on the overall species richness of major groups at 
single well-defined sites make an obvious contribution to 
our general understanding of the pattern of insect species 
richness in the tropics. Furthermore, if accurate, they 
provide us with the essential base-line from which improved 
estimates of tropical insect species richness might eventually 
grow. For the moment, our poor understanding of species 
turnover in the tropics means that we have little to go on, 
if we wish to use single site data for extrapolation to 
regional or global figures. 

Of course, starting with the ratio of five beetle species at a 
moist tropical site to one at a temperate site, crude 
extrapolation to a global insect species total is possible, but 
to do this it is necessary to make a series of major 
assumptions, not the least of which concern the proportion 
of insect species that are beetles and, as we have noted, 
species turnover rates. For a start, we may repeat the 
simple extrapolation made earlier on, based on the 
assumption that we are already able roughly to estimate the 
number of extratropical beetle species. If we take 400,000 
as the number of described beetle species, and assume (no 
good count is available) that roughly 50% of described 
beetle species are from extratropical regions, and make an 
educated guess that around 50% of extratropical species 



have been described, an overall ratio of five tropical beetle 

Figure 4.4 Beetle species richness: 
tropical vs temperate 



Tropical Forest 




Notes: Comparison of beetle species richness in comparable sets of 
samples from single tropical and temperate sites, showing a 
relationship of around 5 lo 1 . Tne graph depicts accumulative numbers 
of species over time collected by representative single Malaise traps of 
modest size (see Hammond, 1990). Tropical data are for moist lowland 
forest in N Sulawesi and temperate data for mixed deciduous woodland 
in southern Britain (Hammond, unpublished). Traps chosen for 
illustration are those produci.ig total beetle species nearest to the means 
of 412 per trap for Sulawesi (9 traps) and 83 for Britain (5 traps). 

species to one extratropical species yields a world total for 
beetles of 2.4 million, of which two million are tropical and 
0.4 million extratropical species. If we then take the 
proportion of insect species that are beetles (see below) to 
be 33 % , the figure we reach for insect species globally is 
around 7.2 million. This, of course, involves the dubious 
assumption that the tropical to temperate ratio scales evenly 
from site upwards, in both tropical and extratropical 
regions. Assuming much higher species turnover rates in 
the tropics, but bearing in mind that the extratropical 
component includes contributions from broad latitudinal 
bands in both southern and northern hemispheres, a tropical 
turnover 'factor' may be brought into play. If we take this 
to be (say) 1.3 and apply it to the calculation already made 
our figure for insect species worldwide i£ 9.4 million. 

An alternative approach is to take the beetle species total 
for the Sulawesi site, and scale up directly to a figure for 
the tropics as a whole, using available data on tropical 
species turnover for relatively well-known groups as a 
rough guide. Using information patched together from many 
groups, including the best-known families of beetles 
themselves, an extrapolation may be made from the 
Sulawesi site inventory of 6,000 or so beetle species to 
28,000 for the northern part of Sulawesi, to 70,000 
(Sulawesi as a whole), 700,000 (Asian tropics) and finally 
1.8 million beetle species for the entire moist tropics. Using 
the same figure for extratropical beetles as before, we reach 
a global beetle species figure of 2.3 million beetle species 
and, assuming (as before) that beetles comprise 33 % of the 
global insect species inventory, 6.9 million insect species 
worldwide. 

Finally, we might compare these results with those obtained 
by a Hodkinson and Casson type approach to the Sulawesi 
beetle data. In fact, no estimate is available for the 
proportion of species undescribed in the sample as a whole, 



35 



1. Biological Diversity 

Figure 4.5 Major groups of organisms: described species as proportions of the global 
total 

Vertebrates (2.7%) 
Nematodes (0.9%) f"'*"*^ (Embryophytes) (14.3%) 

Molluscs (4.2%) ^^ ^^^^^^^ 

Other invertebrates (4.0%) /K \^. /\. ^'°^^ ^^"^^^ 

Other arthropods (1.2%) y\/ \ \^^ / jK, Protozoans (2.4%) 

Crustaceans (2.4%) //^^ v \^ , ^ /\c-,^na/> 

V ' / / \ \ . V \^ / / / \ Fungi (4.2%) 

Bacteria (0.2%) 

Arachnids (4.5%) / / \ w \ w /// v.-.«iHr . Viruses (0.3%) 



Other insects (8.9%) 



Diptera(7.1%) 




Coleoptera (23.8%) 



Hymenoptera (7.7%) 



Lepidoptera (8.9%) 



Notes: Proportions of major groups of organisms in terms of described species (estimated to total approximately 1 .7 million). Groups included in 
the pie-chart are those considered likely to contain in excess of 100,000 species when as yet undescribed species are taken into account, along with 
vertebrates for comparison. Numbers of described species used in this diagram are those given in Table 4.3, with the exception of plants for which 
an earlier lower estimate of 240,000 was used. 



but assuming this (on the basis of a small and probably 
unrepresentative sample) to be 75%, we generate a world 
figure of 1.6 million species for Coleoptera and, using the 
33% formula from above, one of approaching five million 
for insect species worldwide. 

Of course, all of the more significant ratios used in these 
simple calculations derive, at best, from informed guesses, 
but they are not simply plucked from the air. First-hand 
experience of how heterogeneity manifests itself at very 
small scales at tropical sites, and a feel for the extent of the 
contribution made by the different elements (e.g. elevational 
assemblages and different forest types) involved at more 
'extended' sites may provide particularly useful guidance. 
Knowledge of vicariance patterns, especially as they differ 
between the three major tropical regions, may also be of 
considerable assistance. Finally, an awareness of the biases 
of various sampling methods, and the many factors that 
influence how well sampled and studied particular groups 
are likely to be, will be of great help when attempting to 
grasp the significance of fragmentary data. 

The more important ratios used, those concerning the 
proportional representation of the major insect groups in 
terms of species and tropical to extratropical relationships, 
in the simple extrapolations made above were derived by 
patching together small fragments of data from many 



sources. The conclusions reached and assumptions used in 
reaching them cannot be detailed here, but it should be 
mentioned that higher tropical to temperate ratios were 
assumed for Coleoptera, Hemiptera and Lepidoptera, as 
opposed to Diptera and Hymenoptera (see Gaston, 1991a). 
The relative species richness of what seem certain to be the 
three largest insect groups was based on separate 
assessments of their possible overall species richnesses in 
both tropical and extratropical regions. 'Working figures' 
arrived at for the percentage of insects overall that are 
Coleoptera, Hymenoptera and Diptera in extratropical 
regions were 25%, 30% and 30% respectively, while those 
for the tropics were 35%, 27% and 20%, yielding (if we 
assume a 5:1 tropical to extratropical ratio for beetle 
species) overall working figures of 33 % Coleoptera, 27.5 % 
Hymenoptera and around 22 % Diptera. 

PROSPECTS FOR IMPROVED SPECIES RICHNESS 
ESTIMATES 

Currently available estimates of species richness for all but 
the best-known groups such as birds, and best-known 
regions such as northern Europe, all involve substantial 
margins of error. By simple extrapolation from the 
well-known, only a very rough idea may be gained of how 
many species exist overall. The many uncertainties, 
especially with respect to microorganisms, make an upper 



36 



Species Inventory 



Figure 4.6 Major groups of organisms: possibly-existing species as proportions of the 
global total 

Vertebrates (0.4%) Plants (Embryophytes) (2.4%) 
Nematodes (4.0%) '^'S^- '^ ■^'^'^ 

Molluscs (1 .6%) 
Other Invertebrates (1.1%) 
Other arthropods (0.5%) 
Crustaceans (1 .2%) 



Protozoans (1 .6%) 

Fungi (8.0%) 



Arachnids (6.0%) 



Other Insects (4.0%) 



Bacteria (3.2%) 
Viruses (4.0%) 



Dlptera(12.9%) 




'Coleoptera (24.9%) 



Hymenoptera (1 9.3%) 



Lepldoptera (3.2%) 



Notts: Possible proportions of major groups of organisms based on conservative estimates (see Table 4.3) providing a total for all groups of 
approximately 12.5 million species. All groups considered likely to contain in excess of 100,000 species are picked out in the pie-chart, along with 
vertebrates for comparison. 



bound to the size of the global species inventory particularly 
difficult to establish. Despite numerous indications that this 
could be very great, claims that extant species number 
many tens of millions or even more can not be supported, 
for the moment, by any firm evidence. However, a lower 
bound to the global figure is much easier to set, and the 
available data, some of them discussed above, suggests that 
this might safely be put at a level considerably higher than 
the current described species total (approaching two 
million), perhaps at around eight million. The 'working 
figure' adopted here of 12.5 million species for the biota as 
a whole (see Fig. 4.6), arrived at by examining the data for 
each major group separately, is an avowedly conservative 
one. 

In a situation where the most species-rich groups are at the 
same time the least known, an unwillingness to take into 
account anything but incontrovertible evidence is always 
likely to result in underestimation, as the record of early 
attempts to estimate the scale of global species richness well 
illustrates. Nevertheless, if we are to have any confidence 
in species richness estimates, there is no real alternative to 
working forwards by steadily enlarging the area of knowns. 
While new observations concerning little-known taxonomic 
groups and poorly explored habitats continually alert us to 
additional possibilities of as yet unassessed species richness, 
it would be naive to make too much of each and every 
anecdote. 



To speed up the rate at which our understanding of species 
richness patterns and the overall dimensions of global 
biodiversity grows, it will be necessary to identify key 
questions and, if feasible, turn our attention first to them. 
The most obvious general line of attack is to focus efforts 
on the groups of organisms and parts of the globe that seem 
most likely 'o make the greatest overall contribution to the 
species inventory. New and pertinent data are needed for all 
of the ultra-diverse groups, but quicker and more substantial 
returns for efforts made are to be expected from some 
groups rather than others. If the main emphasis of this 
section has been on terrestrial arthropods, it is not because 
these animals (however numerous their species) can supply 
all of the answers, but rather because answers to key 
questions concerning their patterns of species richness are 
seen to be distinctly and not too distantly attainable. 



Perhaps the greatest need is for good sample data on 
microorganisms and fungi. Because of seasonality and 
difficulties in detecting and/or culturing small species, 
exhaustive inventories may not be achievable but, in line 
with recent recommendations, these should be attempted at 
representative sites in the major biomes. If tropical to 
temperate species richness ratios are to be established for 
these groups, there will be a need to develop sampling 
methods and protocols that allow reliable comparison 
between sites without a complete inventory being taken. 



37 



1. Biological Diversity 



For nematodes there is a pressing need for data on the 
species richness of free-living forms in both marine and 
terrestrial enviroimients, including the moist tropics. Sample 
data that allow some estimation of species turnover at least 
at relatively small scales (i.e. in the m' to km^ range) are a 
particular need, while any results concerning the less easily 
addressed problem of turnover at larger scales would be of 
great value. As in the case of microorganisms, advances in 
both the theory and practice of species recognition and 
discrimination will be needed if data gathered are to be 
truly informative. 

In the case of terrestrial arthropods, the more tractable 
groups that are also large and 'representative' (e.g. 
Coleoptera) may be expected to receive considerable 
attention. For some of these groups, sampling programmes 
at various tropical and other sites, are already well 
advanced. While there is a need for the analysis of results 
already obtained to be speeded up, this should not be 
allowed to stand in the way of the application of the best of 
the methods so far developed at many additional sites. 

For some of the major terrestrial arthropod groups, e.g. 
Diptera and Acari (mites), data on the numbers of species 
to be found at any one location in the moist tropics remain 
extremely limited and largely anecdotal. Reasonably reliable 
estimates of the species richness of these groups at single 
tropical sites are eminently attainable, and the acquisition of 
the appropriate datasets is a particular priority. Another 
clear need is for a better understanding of the proportional 
representation, in species terms, of the major terrestrial 
arthropod groups at single sites, and how this varies from 
region to region. 

A separate agenda of research is needed for the 
investigation of species richness patterns in the marine 
realm. Here, data from the ocean depths remain too 
fragmentary for any confident estimation of the contribution 
that this 'new frontier' might make to marine or overall 
global species richness. There is a particularly urgent need 
for results that give some idea of species turnover in 
deep-ocean sediment assemblages, especially at the larger 
spatial scales. 

Attention has been directed in this section almost entirely 
towards species, which for sound theoretical as well as 
operational reasons are often considered "central to the 
concept of biodiversity" (Reid and Miller, 1989). However, 
it should be stressed that a species count falls far short of 
any full assessment of biotic diversity, which expresses 
itself at a number of levels, from genes to ecosystems 
(Solbrig, 1991). 

Our perception of the full dimensions of biotic diversity 
remains very hazy, but there is much of an immediate 
nature that can be done and is being done to remedy the 
situation. Indeed, there is every reason to suppose that 
advances in our understanding of some significant species 
richness patterns will be made very rapidly. Of course, we 
shall not get to know, even appro.ximately, how many other 
species we share the planet with overnight, but we may 
reasonably expect our global species estimates to be made 



with steadily increasing confidence and precision. 
References 

Ackery "nd Vane-Wright. 1984. Milkweed Butterflies. BM(NH), 

London 
Adis, J., Lubin, Y.D. and Montgomery, G.G. 1984. Arthropods from 

the canopy of inundated and terra firma forests near Manaus, 

Brazil, with critical considerations of the Pyrethrum-fogging 

technique. Studies on Neotropical Fauna and the Environment 

19:223-236. 
Adis, J. and Schubart, H.O.R. 1985. Ecological research on 

arthropods in central Amazonian forest ecosystems with 

recommendations for study procedures. In: Cooley, J.H. and 

Golley, F.B. (Eds), Trends in Ecological Research for the 1980s. 

NATO Conference Series, Series 1: Ecology. Plenum Press, 

London. Pp.1 1 1-144. 
Amett, R.H. 1967. Present and future systematica of the Coleoptera in 

North America. Annals of the Entomological Society of America 

60:162-170. 
Amett, R.H. 1985. American insects: handbook of the insects of 

America north of Mexico. Van Noslrand Reinhold, New York. 
Barnes. R.D. 1989. Diversity of organisms: how much do we know? 

American Zoologist 29; 1075-1084. 
Brusca, R.C. and Brusca, G.J. 1990. Invertebrates. Sinauer, 

Sunderland, Massachusetts. 
Casson, D. 1988. Studies on the Hemiptera communities of 

Dumoga-Bone National Park, Sulawesi. M.Phil. Thesis. Liverpool 

Polytechnic . 
di Castri, F., Vemhes, I.R. and Younes, T. C>n press). A proposal for 

an international network on inventorying and monitoring of 

biodiversity. Biology International, Special Issue 21. 
Colinvaux.P. 1980. Why Big Fierce Animals Are Rare. Pelican Books, 

London. 
Eliot, J.N. and Kawazo^, A. 1983. Blue Butterflies of the Lycaenopsis 

Group. BM(NH) Umdoa. 
Erwin, T.L. 1982. Tropical forests: their richness in Coleoptera and 

other arthropod species. Coleopterists' Btdletin 36:74-75. 
Erwin, T.L. 1990. Canopy arthropod biodiversity: a chronology of 

sampling techniques and results. Revista Peruana de Entomologta 

32:71-77. 
Erwin, T.L. 1991. How many species are there? Revisited. 

Conservation Biology 5:1-4. 
Erwin, T.L. and Scott, J.C. 1980. Seasonal and size patterns, trophic 

structure and richness of Coleoptera in the tropical arboreal 

ecosystem: the fauna of the tree Luehea seemannii Triana and 

Planch in the Canal Zone in Panama. Coleopterists' Bulletin 

34:305-322. 
Frank, J.H. and Curtis, G.A. 1979. Trend lines and the number of 

species of Staphylinidae. Coleopterists' Bulletin 33:133-149. 
Gaston, K.J. 1991a. The magnitude of global insect species richness. 

Conservation Biology 5:283-296. 
Gaston, K.J. 1991b. Body size and probability of description; the 

beetle fauna of Britain. Ecological Entomology 16:505-508. 
Gaston, K.J. 1992. Estimates of the near-imponderable: a reply to 

Erwin. Conservation Biology 5:564-566. 
Goodwin. 1986. Crows of the World. BM(NH), London. 
Grassle, J.F. 1989. Species diversity in deep-sea communities. TREE 

4:12-15. 
Grassle, J.F. 1991. Deep-sea benthic biodiversity. Bioscience 

41:464-469. 
Grassle, J.F., Laserre, P., Mclnlyre, A.D. and Ray, C.G. 1991. 

Marine biodiversity and ecosystem fiinction. Biology Interruuional, 

Special Issue 23:'t-iv. 1-19. lUBS, Paris. 
Hammond, P.M. 1990. Insect abundance and diversity in the 

Dumoga-Bone National Park, N. Sulawesi, with special reference 

to the beetle fauna of lowland rain forest in the Toraul region. In: 

Knight, W.J. and Holloway, J.D. (Eds), Insects and the Rain 

Forests of South East Asia (Wallacea). Royal Entomological 

Society, London. Pp. 197-254. 
Hawksworth, D.L. 1991. The fUngal dimension of biodiversity: 

magnitude, significance and conservation. Mycological Research 

95:641-655. 



38 



Species Inventory 



Hodkinson, I.D. and Casson, D. 1991 . A lesser predilection for bugs; 

Hemiptera (Insecu) diversity in tropical rain forests. Biological 

Journal of the Linnean Society of London 43:101-109. 
Lawrence, J. F. 1982.Coleoptera. In: Parker, S. P. (Ed.), Synopsis and 

Classification ofUving Organisms. McGraw-Hill, New York. Pp. 

482-553. 
May, R.M. 1988. How many species are there on earth? Science 

241:1441-1449. 
May, R.M. 1990. How many species? Philosophical Transactions of 

the Royal Society 8330:293-304. 
Mayr, E., Linsley, E.G. and Usinger, R.L 1953. Method and 

principles of systematic zoology. McGraw-Hill, New York. 
National Science Board 1989. Loss of Biological Diversity: a global 

crisis requiring international solutions. National Science 

Foundation, Washington, DC. 
Noyes, J.S. 1989. The diversity of Hymenoptera in the tropics with 

special reference to Parasitica in Sulawesi. Ecological Entomology 

14:197-207. 
Poinar, G.O. 1983. The Natural History of Nematodes. Prentice Hall, 

Englewood Cliffs, NJ. 
Reid, W.V. and Miller, K.R. 1989. Keeping options alive. The 

scientific basis for conserving biodiversity. World Resources 

Institute, Washington, DC. 
Sibley, C.G. and Monroe, B.L. Jr 1990. Distribution and Taxonomy 

of Birds of the World. Yale University Pr«ss, Yale. 
Simon, H.R. 1983. Research and publication trends in systematic 

zoology. Ph.D. thesis. The City University, London. 



Solbrig, O. (Ed.) 1991 . From genes to ecosystems: a research agenda 

for biodiversity. Report of an lUBS-SCOPE-UNESCO workshop, 

Harvard Forest, Petersham, Ma. USA, June 27-July 1, 1991. 

lUBS, Cambridge, Mass. 
Stork, N.E. 1987. Guild structure of arthropods from Bomean rain 

forest trees. Ecological Entomology 12:69-80. 
Stork, N.E. 1988. Insect diversity: facts, fiction and speculation. 

Biological Journal of the Linnean Society of London 35:321-337. 
Stork, N.E. 1991. The composition of the arthropod fauna of Bomean 

lowland rain forest trees. Journal of Tropical Ecology 7:161-180. 
Soulhwood, T.R.E. 1978. The components of diversity. In Mound, 

LA. and Waloff, N. (Eds), Diversity of Insect Faunas. Symposia 

of the Royal Entomological Society of London. 9. Blackwell 

Scientific Publications, Oxford. 
Valiela, I. 1984. Marine Ecological Processes. Springer Verlag, New 

York. 
Wolf, E.C. 1987. On the brink of extinction: conserving the diversity 

of life. [WorldWatch Paper No. 78). WorldWatch Institute, 

Washington, DC. 

Abridged from a docitment provided by Peter Hammond, 
Environmental Quality Programme, The Natural History 
Museum (London). 

Data presented in Table 4.5 retrieved from Zoological 
Record Online by BIOSIS, UK. 



39 



1. Biological Diversity 

5. SPECIES DIVERSITY: AN INTRODUCTION 



A BRIEF fflSTORY OF DrVERSITY 

Knowledge of the history of diversity through geological 
time is based on analysis of the fossil record. Because the 
fossil record gives only a very incomplete and highly biased 
view of the past history of life on earth, the reconstruction 
of that history has been, and continues to be, the subject of 
great debate. It is generally accepted that the fossil record 
can give a reasonable insight into past diversity in terms of 
taxonomic richness, particularly at higher taxonomic levels. 
However, it is far more difficult to derive other, more 
ecologically based, measures of diversity from it, as these 
require the reconstruction of palaeoenvirotunents, a far 
more contentious exercise than palaeotaxonomy. 

While detailed patterns of taxonomic richness through the 
earth's history remain debatable, the overall outline is 
generally accepted. There are believed to have been 
relatively few species in total during the Palaeozoic and 
early Mesozoic; since then, that is for the past hundred 
million years, diversity has increased markedly. This recent 
diversification has passed through one major extinction 
event, at the Cretaceous-Tertiary boundary, and probably 
two minor events since then (see Chapter 16). Apart from 
these, the diversification appears to have continued more or 
less unabated, with the world apparently reaching its highest 
ever level of species richness during the Pliocene and 
Pleistocene, when climatic change and the advent of 
organised human activity finally halted the process. 
Significantly, however, diversity at higher taxonomic levels 
does not conform with this pattern, as evinced by the far 
higher number of animal phyla present in the early 
Cambrian than today (see below). 

The early history of Life - the Precambrian 

Recent consensus suggests that cellular life on the planet (in 
the form of procaryotes, at least some of which were 
probably very similar to living cyanobacteria) originated 
sometime between 3,900 and 3,400 million years ago 
(Mya). The origin of the earliest eucaryotes has proved 
difficult to establish, but it is generally accepted that the 
Precambrian microfossils known as 'acritarchs', which are 
recorded as far back as 1400 Mya, are almost certainly the 
cysts of marine algae and the earliest known eucaryotes. If 
this analysis is correct, then life on earth consisted only of 
procaryotes for at least 2,000 million years, or well over 
half its history. There is sufficient morphological variation 
in the fossil remains to permit some analysis of changes in 
diversity of these presumed early procaryotes in the late 
Proterozoic era. Vidal and Knoll (1983) have hypothesised 
a gradual increase in diversity from 1400 Mya to 750 Mya, 
when there was a peak of around 30 taxa in the fossil 
record, followed almost immediately by a sharp drop to 
around 10 taxa, possibly owing to a period of glaciation. 
After this there is an exponential increase in diversity, 
corresponding with the start of the Phanerozoic era. 

The early Phanerozoic 

For many years it was assumed that metazoans 
(multicellular organisms with internal organs) originated in 



the Cambrian era at the base of the Phanerozoic. This is 
now known not to be the case, as a wide range of fossil 
metazoans is now known from well before this time, 
including recognisable arthropods and possibly 
echinoderms. Most fossils from this time, however, appear 
completely unrelated to extant forms, and consist mainly of 
enigmatic frond- and disc-shaped soft-bodied animals: the 
so-called Ediacaran fauna. 

The lower Cambrian marks a dramatic change from this 
early fauna, with the sudden appearance in the fossil record 
of a wide range of metazoans, many with czdcareous 
skeletons. It is generally accepted that this represents a 
genuine explosion of diversity which took place over only 
a few million years, and is not an artefact of the fossil 
record. The lower Cambrian thus represents the most 
important period of high-level diversification in the history 
of animal life on earth. Very many phyla may have existed 
at this time, no more than five of which have origins 
traceable to before the Cambrian-Precambrian boundary. 
These include every well-skeletalised animal phylum living 
today (with the possible exception of the Bryozoa), 
indicating that virtually no new animal phyla have appeared 
during the many subsequent evolutionary radiations. 
Perhaps most significantly, no new animal phyla appeared 
with the colonisation of land, some 50-100 million years 
after the Cambrian radiation. 

The Cambrian appears to have represented not only a peak 
of diversification but perhaps also a peak of higher order 
taxonomic diversity, as suggested by the presence of many 
more animal phyla than the 35 or so now extant. 

Changes in diversity of marine animal taxa through the 
Phanerozoic 

Although the number of phyla has decreased markedly since 
the Cambrian, diversity at all lower taxonomic levels has 
either increased overall or in a few cases remained more or 
less level. 

The number of orders (of marine animals) present in the 
fossil record climbed steadily through the Cambrian and 
Ordovician, levelling off towards the end of the Ordovician 
to a figure of between 125 and 140, which has been 
maintained throughout the Phanerozoic. 

The diversity of families represented in the fossil record 
shows a similar pattern of increase through the Cambrian 
and Ordovician, levelling off at around 500, a figure which 
was maintained until the late Permian mass-extinction (see 
Chapter 16). This extinction event resulted in the loss of 
around 300 families; subsequent to this, family diversity has 
increased to the modern level, with a number of temporary 
reversals in the form of the series of extinction events 
outlined in Chapter 16. 

The trend in number of species in the fossil record is even 
more extreme. From the early Cambrian until the mid- 
Cretaceous, the number of marine species remained low; 
since then, that is in the past 100 million years, it has 
probably increased by a factor of 10. 



40 



Species Diversity: An Introduction 



Diversity patterns in terrestrial animals 

Colonisation of land by animals has occurred many times; 
although the oldest body fossils of terrestrial animals date 
from the early Devonian, it is generally accepted that the 
primary period of land invasion by animals was the 
Silurian. 

The overwhelming number of described extant species of 
terrestrial animals are insects and arachnids. The fossil 
record for both these groups is generally scanty. 

Some attempt has been made, however, to chart changes in 
insect diversity at the generic level. Insects first appear in 
the fossil record in the Carboniferous. The number of 
genera then increased through much of the Palaeozoic and 
first part of the Mesozoic, interrupted by a sharp drop 
coinciding with the late Permian mass extinction, and then 
levelling off during the late Triassic. Diversity then doubled 
during the Cenozoic or Tertiary, coincident with the 
radiation of the angiosperms. 

The fossil record of terrestrial vertebrates is much better, 
particularly that of tetrapods. The bird record is much less 
substantial than that for other groups, probably because 
their light slceletons have been less frequently preserved. 
Terrestrial vertebrates first appear in the fossil record in the 
late Devonian. Diversity remained relatively low during the 
Palaeozoic, with around 50 families, and actually declined 
overall during the early Mesozoic. From the mid- 
Cretaceous the number of families started to increase 
rapidly, reaching a Recent pealc of around 340. Diversity of 
genera follows this overall pattern in a more exaggerated 
form. These trends are shown in Fig. 5.1. 



Figure 5.1 Fossil diversity: terrestrial 
vertebrates 

Birds 
: Mammals 
m Rsptilas 
■ Amphtians 



60 



50 



40 



O 



30 - 



20 - 



10 • 




421406 380 



266 246 213 144 

MiKon years 



65 



Source: Adapted from Signer, P.W. 1990. The geological history of 
diversity. Annual Review of Ecology and Systematics 21 . 
Note; Diversity is here measured in terms of number of taxonomic 
orders present. 

Diversity patterns in vascular plants 

It is generally accepted that vascular terrestrial plants first 



arose in the Silurian, although some palaeobotanists argue 
for a Late Ordovician origin. Diversity increased during the 
Silurian, and then more rapidly during the Devonian, owing 
to the first appearance of seed-bearing plants, leading to a 
peak of over 40 genera during the late Devonian. Diversity 
then declined slightly, but started to increase markedly 
during the Carboniferous, with at least 200 species recorded 
by the mid Carboniferous. Following this, diversity 
increased only slowly until the end of the Permian. There 
was a minor decrease in diversity at the end of the Permian, 
coinciding with or preceding the mass extinction of animjd 
species, followed by a rapid rebound to previous levels. 
Diversity then continued increasing slowly, reaching around 
250 species in the early Cretaceous. Starting at the mid- 
Cretaceous, diversity began increasing at an accelerating 
pace. 

This overall pattern masks important changes with time in 
the composition of the flora, most notably in the relative 
importance of the three main groups of tracheophytes: the 
pteridophytes, gymnospermsand angiosperms. The Silurian 
and early Devonian are marked by a radiation of primitive 
pteridophytes. During the Carboniferous, more advanced 
pteridophytes and gymnosperms developed and underwent 
extensive diversification. Following the late Permian 
extinction event, pteridophytes were largely replaced 
(although ferns remain abundant) by gymnosperms which 
became the dominant group until the mid-Cretaceous. The 
dramatic increase in plant diversity since then is entirely 
due to the radiation of the angiosperms which first appeared 
in the lower Cretaceous. These trends are shown in Fig. 
5.2. 



Figure 5.2 Fossil diversity: terrestriail 
plants 




4a Me 360 2ae 24e 213 

Ulon years 

Source: Adapted from Signor, P.W. 1990. The geological history of 

diversity. Annual Review of Ecology and Systematics 21 . 

Note: Diversity is here measured in terms of number of species 

present. 

MEASURING BIOLOGICAL DIVERSITY 

A central problem in the maintenance of biological diversity 
is an assessment of the relative importance, in terms of 
diversity, of different areas, habitats or ecosystems. Only 
by understanding this can priorities in conservation efforts 
be usefully assigned. However, this importance can be 
assessed in different, though related, ways. The first, and 
most obvious, makes reference to its 'intrinsic' diversity, so 
that an area with higher diversity is deemed more important 
than one with lower diversity. The second attempts an 



41 



1. Biological Diversity 



assessment of the contribution any given area makes to 
theoverall diversity of a given geographic region, such as a 
country, continent or, ultimately, to the world overall. 
From this perspective, some areas with lower intrinsic 
diversity may be more important than others with higher 
diversity. This will be discussed further below; see also 
Chapters 2 and IS. 

Assessments of diversity pose considerable problems, both 
practical tmd theoretical. In the first instance, the concept 
of diversity in an ecological context has to be made clear. 

Local biological diversity 

Species richness 

Biological diversity measures for particular areas, habitats 
or ecosystems are often largely reduced to a straightforward 
measure of species richness. In its most ideal form this 
would consist of a complete catalogue of all species 
occurring in the area under consideration. In practice this 
is clearly unrealistic outside very small areas which will be 
of only limited interest in a global context. Even with small 
sites, a complete enumeration of all species will be 
impossible to carry out if micro-organisms are included. 

Species richness measures will therefore in practice be 
based on samples. Such samples could consist of complete 
catalogues of all species in a particular, generally 
taxonomic, group (e.g. all birds, all ferns) or may consists 
of measures of species density (i.e. all the species in a 
sample plot of standard area) or of numerical species 
richness, defined as the number of species per specified 
number of individuals or biomass. 

Although straightforward measures of species richness may 
convey relatively little ecologically important information, 
in practice because they are the most easily derived, they 
are perhaps the most useful index for comparisons of 
biological diversity on a large scale. 

Species abundance 

From an ecological viewpoint, simple species richness 
indices have limited value. More meaningful measures of 
diversity take into account the relative abundance of the 
species concerned. In general, the more equally abundant 
the species in the area or ecosystem under consideration 
are, the more diverse it is considered to be. A number of 
models have been developed which derive diversity indices 
from measures of species abundance. As different 
mathematical and biological assumptions are made in these 
models, they will often generate different diversity 
measures from the same sets of data. Thus there is no one 
authoritative index for measuring diversity. 

Taxic diversity 

Furthermore, weight can also be given to the relative 
abundance of species in various categories, for example in 
different size classes, at different trophic levels, in different 
taxonomic groups, or with different growth forms. Thus a 
hypothetical ecosystem which consisted only of several 
species of primary producers, such as photosynthesising 
plants, would be less diverse than one with the same 
number of species but which included herbivores and 
predators. Similarly, an ecosystem with representatives 



from four different phyla would be more diverse than one 
with representative of only two. 

Based on cladistic analysis, a nutaber of taxonomic 
diversity indices have now been developed. Some of these 
give higher weight to so-called relict groups, that is 
taxonomic groups not closely related to other living groups 
and consisting of few species; others favour higher 
taxonomic groups with large numbers of species. The most 
complex measure so far developed is taxonomic dispersion, 
which endeavours to select an even spread of taxa in any 
given group. 

Comparisons of different areas 

Once a measure of diversity has been decided upon, it 
should be possible to compare the diversity of different 
areas. Such comparisons may not, however, be 
straightforward. 

Diversity measures for ecological entities such as 
communities, habitats and ecosystems make the assumption 
that these entities are not site-specific, that is that they 
occur in essentially the same form over a wide area or in a 
number of different places. In practice, species composition 
and species abundance are very rarely constant either in 
space or in time; thus the existence of communities or 
ecosystems definable by species composition is seriously 
questioned by many ecologists. This therefore undermines 
the extent to which diversity measures derived from 
particular sites can be used as a basis for generalisation. 
Nevertheless, these ecological concepts still retain 
considerable force, even if they cannot be rigorously 
defined, and much discussion of biological diversity is 
couched in terms of comparisons between different habitats 
and ecosystems. 

Species/area relationships 

The relative diversity of different sites will often depend on 
the scale at which diversity is measured. Thus Im^ of semi- 
natural European chalk grassland will contain many more 
plant species than Im^ of lowland Amazonian rain forest 
whereas for an area of, say, Ikm^ or more this will be 
reversed. This is because as an area is sampled the number 
of species recorded increases with the size of the area, but 
this rate of increase varies from area to area. 

A wide range of observations has demonstrated that, as a 
general rule, the number of species recorded in an area 
increases with the size of the area, and that this increase 
tends to follow a predictable pattern, known as the 
Arrhenius relationship, whereby: 



logS = c + zIog/4 



where 5 = number of species, A = area and c and z are 
constants. 

The slope of the relationship (z in the equation above) 
varies considerably between surveys, although is generally 
between 0.15 and 0.40, and some surveys do not fit the 
relationship at all. This relationship is shown graphically in 
Fig. 5.3. 



42 



Species Diversity: An Introduction 



Figure 5.3 A typical species-area plot 



2 
in 








% 


.^^^ 


« 








^^ 




y 








]Hk 




tl 








j^ m 




Q 

U1 






^^^ 


^% 









%^ 








L 












tl 
















































C 


^^ 










a 


^^ 













% 


1 






1 1 



Log area Cfia) 

Note; The data are plotted on logarithmic axes resulting in a straight 
line graph, the slope of which (z) indicates the rate at which species 
number changes in step with changing area. 

The most widely quoted generalisation from this finding is 
that a ten-fold reduction in an area (i.e. loss of 90% of 
habitat) will result in the loss of from c. 30% (with z = 
0.15) to c. 60% (with z = 0.40) of the species present. 
This is often reduced to the rule-of-thumb that a ten-fold 
decrease in area leads to a loss of half the species present. 

The causes of the species-area relationship appear to be 
relatively straightforward, and involve a combination of 
sampling effects and environmental heterogeneity. On a 
small scale, the increase in number of species with an 
increase in area is probably overwhelmingly a result of the 
former: that is, put very crudely, a given habitat in which 
species are randomly distributed will become increasingly 
more completely sampled as the area sampled increases. At 
larger scales, environmental heterogeneity will be more 
important: that is, as the area sampled increases, so 
different habitats with different species in them will be 
included in the sample. 

Diversity at different scales 

Thus the overall diversity of any given area will be a 
reflection both of the range of habitats it includes and the 
diversity of the component habitats. The greater the 
differences between the various component habitats in terms 
of species composition, then the greater the overall diversity 
will be. The differences between habitats are referred to as 
beta 08) diversity, while the diversity within a site or habitat 
is alpha (a) diversity. Thus an area with a wide range of 
dissimilar habitats will have a high |S-diversity, even if each 
of its constituent habitats may have low a-diversity. 
Differences in site diversity over large areas, such as 
continents, are sometimes referred to as gamma (y) 
diversity. 

An area with relatively low species diversity may therefore 
still make an important contribution to the overall diversity 
of the larger region it is found in if it contains a significant 
number of species which do not occur elsewhere 
(endemics). Oceanic islands (see Chapter 14) and 
continental montane regions are examples of geographical 
entities which typically have comparatively low species 
diversity but high rates of endemism. 



Assessing the relative importance of areas with high species 
diversity and low rates of endemism compared to areas with 
lower rates of diversity and high endemism remains an 
intractable problem. Attempts have been made to 
circumvent this by using somewhat different approaches, 
such as Critical Faunal Analyses, but these also generally 
do not generate unequivocal results (Chapter 15). 

TBOS GLOBAL DISTMBUTION OF SPECIES 
RICHNESS 

Analysis of worldwide trends in biological diversity almost 
always treats this in terms of species richness, as this is the 
only indicator of diversity for which anything approaching 
adequate data is available on a global scale. Biological 
diversity is not evenly distributed around the globe. 

Latitudinal gradients 

The single most obvious pattern in the global distribution of 
species is that overall species richness increases with 
decreasing latitude. At its crudest this means that there are 
far more species per unit area and in total in the tropics 
than there are in temperate regions and far more species in 
temperate regions than there are in polar regions. 

Not only does this apply as an overall general rule, it also 
holds within the great majority of higher taxa (at order level 
or higher), and within most equivalent habitats, although the 
most obvious and frequently cited are forests and shallow- 
water marine benthic communities, with, respectively, 
tropical moist forests and coral reefs being renowned for 
their remarkably high levels of species diversity. 

This overall pattern masks a large number of minor trends 
where species richness in particular taxonomic groups or in 
particular habitats may show no significant latitudinal 
variation, or may actually decrease with decreasing latitude; 
nevertheless it remains a phenomenon of overwhelming 
biogeographical importance. 

As well as latitude, changes in diversity can also be 
correlated with a many other variables, some of which are 
discussed briefly below. For some of these it is not easy to 
establish a significant relationship because there are often 
confounding variables, and because there are too few 
comparable datasets. 

The maps in Fig. 5.4 demonstrate broad gradients in 
species richness in frogs (left) and trees (right) in the 
Americas (data extracted from Duellman, 1988 and Gentry, 
1988). For these groups in this part of the world, climatic 
factors appear to play a large part in determining such 
gradients. 

Elevational gradients 

In terrestrial ecosystems, diversity generally decreases with 
increasing altitude. This phenomenon is most apparent at 
extremes of altitude, with highest regions at all latitudes 
having very low species diversity. There are fewer 
examples showing gradients of species richness with 
altitude, although amongst vertebrates this has been 
demonstrated for bird species in New Guinea (Kikkawa and 



43 



1. Biological Diversity 



Figure 5.4 Gradients in species richness: frogs and trees in tlie Americas 




44 



Williams, 1971 cited in Brown) and. on the Amazonian 
slope of the Andes in Peru (Terborgh, 1977). Gentry (1988) 
demonstrates it for woody plants in tropical forests, 
although notes that the data for upland sites are very 
incomplete. Suggestions have been made that, in tropical 
forests at least, diversity may be higher at mid-altitudes 
than in lower areas. However, there appear to be no 
substantiating data for this 'mid-altitude bulge' as a general 
phenomenon, although it has been noted in particular cases 
such as a desert mountain in Arizona where diversity at 
lower and higher altitudes is believed limited by aridity and 
low temperate respectively (Brown, 1988). 

The decrease in straightforward species numbers with 
increasing altitude may in part be a reflection of species- 
area relationships, as available area generally decreases with 
increasing altitude, and number of species is closely related 
to area. Measurement of species numbers in standard -sized 
plots, such as those of Gentry (1988) take account of this, 
demonstrating that the relationship between altitude and 
species diversity is real, although not necessarily 
discounting the role that decreased available area may play 
in causing this phenomenon. It should also be noted that fi 
diversity will often be higher in areas of varied topography 
because of increased environmental heterogeneity. 

Precipitation gradients 

Precipitation is generally believed to be an important factor 
governing terrestrial diversity. However, the relationship 
between precipitation and diversity is not straightforward, 
and it seems that seasonality in precipitation may be as 
important as absolute amount. As with altitude, the 
relationship between precipitation and diversity is most 
apparent at one extreme, as highly arid environments are 
well-known to be much less diverse than less arid, or more 
mesic, environments at similar altitudes and latitudes. There 
are, however, apparently few quantifiable data to 
demonstrate this. Gentry (1988) in his study of forest 
diversity, demonstrated a strong correlation between plant 
species richness and absolute annual precipitation. 
However, he notes that this correlation may not apply at all 
in the Palaeotropics, and that there were strong indications 
that the length and severity of the dry season were more 
important than absolute annual rainfall. In the Neotropics, 
there is a strong relationship between annual rainfall and 
strength of the dry season, which is much less marked in 
the Palaeotropics. The importance of seasonality was borne 
out by a preliminary study of a Brazilian site with a 
relatively low, evenly-distributed aimual rainfall, which 
showed a much higher species diversity than would be 
expected from total rainfall measures alone. Moreover, 
there appears to be a marked tailing-off of increasing 
diversity with increasing rainfall at high rainfalls, with little 
or no increase in diversity once rainfall exceeded 4,000- 
4,500mm per year. 

However, it should be noted that the limits on diversity may 
in fact represent a limitation of sampling technique: in the 
two most diverse sites sampled (in areas of year-round 
rainfall of 3,000-4,000mm p. a.), diversity was so high in 
the plots sampled (in one site 300 species > 10cm diameter 
out of 606 individual plants in one plot), that it seems likely 
that only by increasing the size of the survey plots would 



Species Diversity: An Introduction 

any further trends be discerned (Gentry, 1988). 

Nutrient levels 

Although there are few studies of global trends in diversity 
and soil nutrients, the relationship between plant community 
richness and tropical soil nutrient levels has been the subject 
of considerable interest. The data that are available indicate 
that the relationship may not be straightforward. Studies in 
Southeast Asia indicate that diversity may be highest at 
intermediary levels of nutrition, with a decrease at higher 
levels, while in the Neotropics diversity generally seems to 
increase with increasing nutrient levels, being most strongly 
correlated with Potassium (K) levels. This overall trend is 
apparently also shown by a variety of other organisms, 
including bats, birds and butterflies. In general, however, 
diversity in tropical forest ecosystems seems much less 
strongly dependent on nutrient levels than other factors, 
notably latitude, altitude and precipitation (Gentry, 1988). 

The relationship between nutrient levels and diversity in 
other ecosystems is also complex: declines in diversity with 
increasing nutrient levels of temperate freshwater habitats 
(eutrophication) and grasslands are well-documented,butit 
is difficult to draw general conclusions from these (Brown, 
1988). 

Salinity gradients 

In aquatic ecosystems, salinity appears to act as a strong 
'normalising' factor on diversity. Thus, in coastal areas, 
diversity almost invariably declines when salinity deviates 
from 'normal' sea water (i.e. 35 ppt), while in freshwaters 
diversity decreases when salinity increases above c. 2 ppt; 
this results in a bimodal distribution of diversity with 
increasing salinity (Brown, 1988). 

Islands 

The study of diversity on islands, both real and theoretical, 
has been an important factor in much of biogeography and 
conservation biology. In particular the equilibrium theories 
of island biogeography elaborated by MacArthur and 
Wilson (1967) have had an important influence on both 
disciplines. More recently discussion in this, as in many 
other areas of ecology, has tended to move away from 
assumptions of equilibrium to more realistic, but far more 
complex, non-equilibrium theories. 

SPECIES AND ENERGY 

The relationship between diversity and productivity has 
been the subject of long-standing debate in ecology. Recent 
studies have indicated that available energy is strongly 
correlated with species diversity on a large-scale, at least in 
terrestrial ecosystems. A study of North American tree 
species (Currie and Paquin, 1987) demonstrated that 
realised annual evapotranspiration, a measure of available 
energy, statistically explained 76% of the variation in 
species richness across the continent. Such recent studies 
have shown that diversity gradients in tree species are more 
closely related to indices of climatic productivity than to 
other geographical parameters, including latitude (Adams, 
1989). These results could be used to predict accurately tree 



45 



1. Biological Diversity 



species richness patterns in Great Britain and Ireland. 
Preliminary analysis of the diversity of terrestrial 
vertebrates in North America apparently yielded very 
similar results. 

EXPLANATIONS AND HYPOTHESES 

The explanation of geographic and temporal variation in 
species diversity is one of the central problems of biology. 
It has also proved one of the most intractable. The problem 
has generated an enormous amount of literature in which 
many different hypotheses have been proposed to attempt to 
account for it; these hypotheses often operate at different 
levels of explanation and much confusion has arisen as a 
result. It is beyond the scope of this report to attempt a 
thorough review of the subject, although, ultimately, an 
understanding of the importance of biological diversity 
should rest on an understanding of how and why it has the 
form that it does. 

It is self-evident that, ultimately, all non-random patterns in 
species diversity must depend on past or present variations 
in the physical environment. How such variations result in 
the patterns observed is often far from clear. It is evident, 
however, that any complete explanation must involve both 
historical events and current ecological processes - the 
former implicit in any explanation of the origin of diversity, 
the latter in explanations of its maintenance, these being 



two separate, although intimately linked, problems. The 
relative importance of these two factors in determining 
present patterns is still a subject of considerable debate. 

References 

Adams, I.M. 1989. Species diversity and productivity of trees. Planu 

today Nov.-Dec. 183-187. 
Brown, J.H. 1988. Species diversity. In: Myers, A. A. and Gillet, P.S. 

(Eds), Analytical Biogeography . Chapman and Hall, London. 
Currie, D.I. and Paquin, V, 1987. Large-scale biogeographical 

patterns of species rictiness of trees. Nature 329:326-327. 
Duellman, W.E. 1988. Patterns of species diversity in anuran 

amphibians in the American tropcis. Annals of the Missouri 

Botanical Garden 75:70-104. 
Gentry, A.H. 1988. Changes in plant community diversity andfloristic 

composition of environmental and geographical gradients. Annals 

of the Missouri Botanical Garden 75:1-34. 
Kikkawa, J. and Williams, E.E. 1971. Altitudinal distribution of land 

birds in New Guinea. Search 2:64-69. 
MacArthur, R.H. and Wilson, E.O. 1967. The Theory of Island 

Biogeography . Princeton University Press, Princeton. 
Signer, P.W. 1990. The geological history of diversity. /4wma//fevi>H' 

of Ecology and Systematics 21:509-539. 
Terborgh, J. 1977. Bird species diversity on an Andean elevational 

gradient. Ecology 58:1007-1019. 
Vidal, G. and Knoll, A.H. 1982. Radiations and extinctions of 

plankton in the late Proterozoic and early Cambrian. Nature 

297:57-60. 

Chapter contributed by Martin Jenkins. 



46 



6. MICROORGANISMS 



Microorganisms 



TAXONOMIC SCOPE 

This section provides an overview of the phylogenetically 
extremely diverse groups collectively regarded as 
'microorganisms'. This term is misleading as by no means 
all are microscopic. The definition accepted here is: 
organisms which either belong to phyla many members of 
which cannot be seen by the unaided eye, or where 
microscopic examination, and in many cases growth in pure 
culture, is essential for identification (Hawksworth, 1992). 
Some of the themes touched on here with specific reference 
to microorganisms are developed ft-om a broader 
perspective elsewhere in the report (Chapter 4). The 
glossary should be consulted for definitions of certain 
terms. 

The classification of the various microorganism groups at 
the rank of kingdom, and both below and above that level, 
is currently in a state of flux. For the purposes of this 
contribution, the terms algae, bacteria, fiingi, protozoa, and 
viruses are treated in their traditional non-phylogenetic 
sense, with some minor modifications (Table 6.1). 
However, as the macroalgae (charophytes and seaweeds) 
and the lichen-forming fungi (lichens) are discussed 
elsewhere in this publication (Chapter 7), these 
non-taxonomic groupings are given only brief mention here. 

ASSESSMENT OF DIVERSITY 

The diversity of microorganisms in terms of the numbers of 
species currently known, and those estimated to occur in the 
world, was considered by leading specialists in the various 
groups at an lUBS/IUMS workshop in 1991 (see below; 
Hawksworth and Colwell, 1992 and in prep.). While the 
total number of known species is reliably estimated at 
159,000 (Table 6.1), considerable difficulty arises in the 
estimation of those which remain undescribed. 
Nevertheless, the conclusion that less than 5%, and 
probably less than 3 % , of the world's microorganisms have 
been described is not expected to be unduly pessimistic. 

Algae 

While the number of recognised algal species can be 
asserted with some confidence, the estimated world figure 
of 350,000 now proposed has large error margins - indeed 
it has been hinted that the chromophyte algae alone might 
eventually prove to comprise either 100,000 or up to 10 
million species, the diatoms being the most speciose 
(Andersen, in press). The terrestrial algal species, 
especially those on bark and rocks, and minute ocean 
species have received particularly scant attention. Further, 
the marine picoplankton, which can make up to 25% of the 
phytoplankton biomass in polar waters, were first 
recognised only in 1980. 



primarily as a result of the application of molecular 
techniques (Liesack and Stackebrandt, 1992), that there are 
enormous numbers of as yet uncultured bacteria to be found 
in soils, deep sea sediments, as mutualists in protozoans and 
other organisms and, most importantly, in the digestive 
tracts and pockets of a wide variety of animals - including 
most insects (Triiper, in press). It has been sugge."!ted that 
one genus of wall-less bacteria inhabiting insect guts, the 
mollicute Spiroplasma, may prove to be the largest genus 
on Earth with well over one million species (Whitcomb and 
Hackett, 1989). 

Fungi 

The number of fungi estimated to occur in the world has 
recently been conservatively estimated at 1 .5 million species 
(Hawksworth, 1991a). This figure contrasts markedly with 
the 70,000 now described - that figure has been increased 
from the 69,000 cited by Hawksworth (,op. cit.) to allow for 
fungi newly published since 1990. The 1.5 million figure is 
conservative as in the calculations leading to it: (1) a 
modest world estimate of vascular plants was employed, (2) 
no special allowance was made for fiingi to be expected on 
the large numbers of insects now postulated, (3) the UK 
vascular plant:fungus ratio of 1:6 used must be an 
underestimate as additional fiingi continue to be found in 
that country, and (4) no provision was made for any 
proportionately increased numbers in the tropics or polar 
regions. Whether an upward revision of the 1.5 million 
figure is defensible must await in-depth studies of particular 
tropical sites. See Chapter 4 for an alternative view. 

Protozoa 

Corliss (1991) estimated the number of known non-fossil 
protozoan species at 40,000. No calculated predictions of 
the number of world species have been prepared, but many 
groups, such as the heterotrophic heterokonts in soil, have 
scarcely been investigated. The total world estimated 
number of 100,000 used here could prove to be a gross 
understatement. 

Viruses 

No comprehensive catalogue of the world's known viruses 
currently exists, but it is expected that about 5,000 will be 
recognised in a compilation being planned by the 
International Committee on the Taxonomy of Viruses for 
publication in 1993. The estimate of 500,000 species 
presented here reflects the substantial numbers of new 
viruses to be expected on yet unstudied non-crop plants, and 
especially insects. Also scarcely investigated are viruses 
only recently recognised as frequent in marine plankton, 
plasmids in fungi, and phages on bacteria - not least on 
'unculturable' bacteria. 

SPECIES CONCEPTS IN MICROORGANISMS 



Bacteria 

The number of bacterial species accepted in the Approved 
List of Bacterial Names was 3,058 in July 1991 (Triiper, 
1992); the figure of 4,0{X) in Table 6. 1 has been increased 
to allow for cyanobacteria. Perceptions of the true number 
of bacteria in the world have changed dramatically during 
the last 5-10 years. It has become increasingly evident. 



Comparisons of species numbers between microorganisms 
and macroorganisms, and indeed also between the different 
microorganism groups, are complicated by variations in 
species concepts. While the idea of the 'biological species' 
is not without appeal to microbiologists, in practice in the 
majority of cases it is not readily applicable. This difficulty 
arises both because sexual processes are absent or difficult 



47 



1. Biological Diversity 



Table 6.1 













GROUP 



Estimates of the number of described species and possible 
undescribed species of microorganisms 



Algae 

Bacteria (incl. cyanobacteria and 
'unculturables') 

Fungi (incl. yeasts, lichen-fornning 
fungi, slime moulds, and 
oomycetes) 



DESCRIBED 


ESTIMATED 


SPECIES 


SPECIES 


40,000 


350,000 


4,000 


3,000,000 


70,000 


1,500,000 



PER CENT 
KNOWN 



11.0 
0.1 



5.0 



Protozoa (proctoctists, excl. algae 
and oomycete fungi) 

Viruses (incl. plasmids, phages, 
etc.) 



40,000 



5,000 



100,000 
500,000 



40.0 



1.0 



TOTAL 



159,000 



5,450,000 



3.0 



Source: Based primarily on data in Hawlcswonh, D.L. and Colwell, R.R., (Eds) (in prep). Biodiversity amongst mictxMrganisms and its 
significance. Biodiversity and Conservation 1. 



to detect in many microorganism groups, and fiirther when 
they are known to occur it is often impractical to determine 
breeding groups. In practice microbiologists tend to be 
pragmatic, recognising as 'species' specimens or strains 
with a high degree of morphological, biochemical, or 
molecular similarity and which produce replicating lineages. 
The scale of characters used is inversely proportionate to 
the size and number of morphological characters. In the 
bacteria and yeasts suites of assimilation, substrate 
utilisation, and cultural attributes are extensively used, 
while these feature to a much lesser extent in algae, 
filamentous fungi, and protozoa. 

Stress is invariably placed on the recognition of marked 
discontinuities in several characters, but emphasising those 
features which are relevant in human terms - for example 
the ability to cause diseases in particular animals or plants, 
to form toxins, to conduct economically important 
fermentations, or to produce desired chemical products. 

Clones, the progeny derived from a single cell and which 
do not exhibit any genomic variation or recombination, are 
to be found in all microorganism groups. However, these 
are not always easy to recognise, and the practice has been 
to accept as species clones fulfilling the requirements of 
distinctness normally associated with that rank. Clones are 
frequently opportunistic organisms well-adapted to 
particular ecological niches; in the case of the conidial 
fiingi, clones are derived from a part of the life-cycle of 
sexually reproducing species in which the sexual stage has 
sometimes been entirely lost. 

Particular aspects of the use of species concepts in the 
different microorganism groups are considered further 
below: 

Algae 

The biological species concept is theoretically usable in 
those algae which are entirely sexual or have such stages in 
their life cycles, but experimental verification is rarely 
practical as many species caimot be readily grown in pure 



culture. Its application in practice has thus been extremely 
limited. In large groups such as the diatoms and coccoliths, 
while sexual stages are known or expected to occur, in 
reality morphological species concepts have to be used, 
increasingly employing characters only visible by the 
Scaiming Electron Microscope (SEM). In eight algal 
classes, however, sexual reproduction is entirely unknown. 
Chemical characteristics are extensively used as aids to 
species differentiation in certain groups (Kessler, 1985). 
Mating complex studies and molecular approaches are also 
increasingly being used. The latter approaches are 
illustrating that considerably diverse taxa are sometimes 
grouped in the same genus or species, although the 
converse situation is also known. An overview of species 
concepts in algae is provided in Andersen (1992). 

Bacteria 

As sexual differentiation does not occur in bacteria and 
most reproduction is asexual, and further, as recombination 
between different strains is difficult to detect, species 
concepts in bacteria have largely been based on overall 
similarities. Since the early 1960s, numerical taxonomic 
studies utilising 50 to several hundred biochemical and 
cultural tests have played a major role in defining bacterial 
species. Similarity coefficients are computed, and phenetic 
groups formed at about the 80-85% similarity level are 
generally taken as equivalent to species (Austin and Priest, 
1986; Sneath, 1989). The advent of molecular techniques 
has enabled species concepts derived from phenetic methods 
to be reassessed. DNA homologies of 20-50% are found 
between species in the same genus, and 60-70% between 
subspecies within the same species (Johnson, 1989). The 
International Commission on Systematic Bacteriology 
recommends that a minimal DNA homology of 70% be 
required for species-level treatment (Wayne, 1987). 

Fungi 

A consequence of the wealth of morphological characters in 
fiingi is that species continue to be mostly distinguished by 
marked discontinuities between those features. The 
assimilative and predominant phase is haploid, and most 



48 



Microorganisms 



fungi are either sexual or derived from ancestors that were 
so. Despite the considerable literature on speciation in fungi 
(Burnett, 1983), the delimitation of populations from a 
biological standpoint remains in its infancy. As particular 
examples are studied in depth, it is becoming increasingly 
apparent that several discrete reproductively isolated groups 
are not uncommonly present within single morphospecies 
(Brasier, 1986). Mycologists have been reluctant to 
recognise such groups at the rank of species, but this can be 
expected to change where particular groups also have other 
important features such as pathogenicity to different crops. 
While a wide range of biochemical and molecular 
techniques are currently being employed in the fungi 
(Hawksworth and Bridge, 1988), the application of many of 
these is limited to the 20% of the known species which can 
be grown in pure culture. Where DNA homology studies 
have been conducted, notably in yeasts and certain 
economically significant genera such as Aspergillus, the 
differences between morphological species tend to be in the 
20-50% range (Kurtzman, 1985), as they are in bacteria. 

Protozoa 

In contradistinction to the fiingi, many protozoan species 
are diploid. In numerous groups information on life-cycles 
and sexuality are still lacking, rendering it difficult to apply 
a biological species concept. Clonal protozoans are, 
however, often described as species, while in contrast, as 
in the case of fungi, morphologically defined species may 
be found on more critical analysis to consist of a number of 
discrete gene pools. 

Viruses 

While some biologists are reluctant to recognise viruses as 
'living', that they are functional biological entities is 
inescapable. They possess genomes, replicate, evolve, 
occupy specific ecological niches, and exhibit intrinsic 
variability. Ultrastructure, serological tests, physical and 
chemical structure and features, and the ability to infect 
particular hosts are used in species separation. The species 
concept in virology has been analysed by Regenmortel 
(1990). He took a pragmatic stance and defined a virus 
species as a polythetic class of viruses constituting a 
replicating lineage and occupying a particular ecological 
niche. This definition has the attraction of being applicable 
both to groups which are able to undergo recombination and 
those which are clonal. 

EXTENT OF GENETIC DIVERSITY 

The extent of genetic diversity exhibited by microorganism 
groups is vast in comparison to that of macroorganisms. 
This conclusion was to be expected bearing in mind that the 
earliest bacteria probably arose around 3.5 billion years ago 
on an Earth formed only one billion years earlier, whereas 
the first land plants, for example, did not emerge until 
about 0.4 billion years ago; i.e. microorganisms have had 
nine times as long to diverge as land plants. 

This diversity is illustrated to some extent in terms of the 
numbers of phyla recognised, but most forcefully at the 
molecular level. Of the 95 phyla accepted by Margulis and 
Schwartz (1988), 52 belong to the microorganisms as 
defined here (less the virus groups not considered by those 
authors). More significantly, the study of 16S-Iike rRNAs 



in prokaryotes led to the suggestion that they should be split 
into two separate groups, Archaebacteria and Eubacteria, 
and that these were roughly equivalent to the Eukaryotes. 
Recognising that most biologists would be unwilling to 
accept plants and animals as belonging to the same 
kingdom, the higher rank of "domain" has been applied to 
these three groups, i.e. the domains Archaea, Bacteria, and 
Eucarya (Woese et al., 1990). Studies with the gut 
protozoan Giardia lamblia, however, have fiirther 
demonstrated that at least some eukaryotic microorganisms 
are much more remote from each other than had hitherto 
been assumed; for example, on the basis of 16S-like 
rRNAs, the crustacean Artemia salina and Homo sapiens 
are ten times closer to each other than either are to Giardia 
(Sogin, 1991). 

The extent of genetic diversity now demonstrated between 
the higher ranks of microorganisms is reflected also at the 
species level. Both the genetic diversity within single 
microbial species, and that between several species referred 
to the same genus, can also be vast in comparison with 
macroorganism groups. This is especially true at the DNA 
homology level where 20-50% similarities are regularly 
encountered between species (see above), whereas primate 
'species' may still be regarded as distinct although sharing 
90-1-% DNA homology. 

One consequence of the considerable genetic diversity 
within microbial species is that in certain microorganism 
groups infraspecific categories are utilised to an extent not 
otherwise seen outside the higher vertebrates. These include 
subspecies, pathovars, 'special forms', and serotypes. In 
addition, complex race notations have been developed 
within particular species of major medical or plant 
pathogenic importance. This tradition has developed as a 
pragmatic response to the need to label populations to a 
finer degree because of the different effects they have on 
humans or their crops. 

From this discussion it will be apparent that if identical 
DNA homology criteria were used for species separations 
in both macro- and microorganisms, the numbers of known 
and estimated species in Table 6. 1 would have to be inflated 
by not less than an order of magnitude. 

REGIONS AND HABITATS OF MAXIMUM 
DIVERSITY 

The variety of ecological niches exploited by the major 
groups of macro- and microorganisms is directly related to 
their geological age; ecology recapitulates phylogeny (Price, 
1988). The greatest niche breadth is consequently seen in 
the bacteria, and then, in declining sequence, in the algae 
and protozoa, fungi, animals, and plants. 

While there is every reason to suppose that regions and 
habitats with a maximum diversity of macroorganisms will 
also be particularly rich in microorganisms - a consequence 
of the larger numbers of host-specific parasites, mutualists, 
and saprobes to be expected - there are additional habitats 
of no importance for macroorganisms which are important 
for the conservation of microorganism diversity. 

Amongst the bacteria are species able to grow in extreme 



49 



/. Biological Diversity 



saline substrata or at high sugar (low water activity) 
concentrations, ones which thrive at high concentrations of 
heavy metals, sulphur, or other generally toxic compounds, 
major groups restricted to anaerobic situations, and ones 
able to tolerate or even thrive at extremely high (e.g. 
Thermotoga lives at 90°C) or low temperatures (e.g. at or 
below freezing point in the Antarctic). 

Triiper (in press) identified the following environments as 
ones dominated by microorganisms or ones which are 
strongly influenced or stabilised by them: 

• hypersaline neutral and alkaline lakes (salt lakes and 
soda lakes), e.g. East African rift valley lakes, the Dead 
Sea 

• hot springs (hydrotherms, fiimaroles, solfatoras) which 
have not been disturbed 

• natural leaching environments (acid crater lakes, acid 
mine waters) 

• peat mosses, permafrost tundra, cypress and mangrove 
swamps 

• stratified (meromictic) lakes 

• hot deserts (sand and rocks) which have not been 
disturbed) 

• bare lichen-encrusted rock areas (with associated bacteria 
and fungi), in all climatic regions 

• estuaries (salt marshes, mud flats, beaches) 

• deep sea envirorunents (hydrothermal vents, hypothermal 
zones, manganese nodule areas). 

Extreme enviroimients also continue to be a particularly rich 
source of previously unknown microorganisms belonging to 
diverse groups. Even though not all the species are known, 
it is evident that due accord needs to be given to extreme 
environments when drawing up international, national, or 
regional plans for the establishment of protected areas. 

As a consequence of the antiquity of the groups, there is a 
tendency for microorganisms to have much broader 
geographic ranges than macroorganisms. Biogeographic 
studies, except in the case of lichens and macroalgae, are 
rarely undertaken. However, there is no reason to suppose 
that while there are a considerable number of almost 
cosmopolitan species, many others do not have 
geographically restricted ranges. This is certainly true for 
the fungi, but current perceptions of distributions on a 
global scale are skewed by inadequate sampling. 
Mycologists, for example, would take in their stride the 
discovery of a species previously known only from Europe 
in an undisturbed habitat in Australia, whereas a similar 
event would cause amazement among workers in most other 
groups. 

Conversely, detailed biogeographic analyses from the world 
level down to national mapping programmes, clearly 
demonstrate that in the fungi numerous species are narrowly 
restricted geographically. Studies on the numbers of species 
of particular families and genera of fungi in different 
geographic regions can potentially lead to the recognition of 
centres of maximum diversity, as demonstrated for certain 
ascomycete groups by Pirozynski and Weresub (1979). A 
shortage of authoritative inventories and surveys currently 



limits the utilisation of such approaches in site-selection. 

ROLE OF MICROORGANISMS IN BIODIVERSITY 
MAINTENANCE 

Microorganisms have played a major role in the evolution 
and diversification of macroorganisms. They contributed 
key organelles such as mitochondria and chloroplasts to 
eukaryotic cells, and as mutualists are either involved in 
nutrient-supply or perform other biochemical processes on 
which they depend (Margulis and Fester, 1991). Bacteria, 
fungi, and protozoa in the guts of insects and herbivorous 
mammals perform crucial roles in their digestive processes, 
particularly in the breakdown of celluloses and lignins, and 
without which they could not exist (Smith and Douglas, 
1987). About 85% of the Earth's vascular plants form 
mycorrhizas with fungi. This life-style is often obligate in 
nature, the mycorrhizas being crucial to the absorption of 
growth-limiting nutrients (Read, 1991). The very existence 
of many macroorganisms is consequently dependent on the 
continued availability of the mutualistic microorganisms 
they require. 

In the marine environment, up to 80% of the biomass and 
productivity in open waters is contributed by ultraplanktonic 
algae (Andersen, 1992). Further, dinoflagellates form 
mutualisms with coelenterate stony corals, and the outer 
ridges of major reefs taking the full force of the oceans are 
formed by crustose coralline algae cementing detritus 
together (Round, 1981). In the absence of these mutualistic 
microorganisms, coral reef ecosystems simply could not 
exist (Smith and Douglas, 1987). Without the coral 
mutualists one of the most biologically diverse habitats on 
Earth would never have been formed. 

At the ecosystem function level, food networks of all life on 
Earth are ultimately dependent on microorganisms. This 
holds for terrestrial and marine ecosystems (Andersen, 
1992; Grassle et al., 1991; Price, 1988), yet ecologists and 
conservationists only exceptionally take it into account. 

The greatest biomass in soil, on the basis of current 
evidence, is that of the microorganisms, especially the fungi 
(Lee, 1991; Lynch and Hobbie, 1988). These play a variety 
of roles related to the maintenance of soil structure and 
composition both through the biodegradation and 
incorporation of dead plant and animal remains, and by 
extra-cellular fungal polysaccharides which bind soil 
particles together, thus increasing soil aggregation and 
stability (Lai, 1991). 

Microorganisms also contribute to the maintenance of 
ecosystem structure through natural biocontrol. Plant 
pathogenic microorganisms can limit plants that would 
otherwise expand explosively in the absence of their 
co-existing pathogens. Similarly, entomogenous 
microorganisms can limit the populations of insects that 
would otherwise become major pests (e.g. defoliants) of 
trees or other plants. In these two cases, if their targets 
have crucial ecological roles, the loss of the containing 
microorganism would lead to major changes in the 
ecosystem. 



50 



Microorganisms 



ROLE OF MICROORGA^fISMS DV BIOSPHERE 
FUNCTIONS 

Bacteria shaped the early atmosphere of Earth, the start of 
life coinciding with a fall in carbon dioxide and an increase 
in methane at around 3.8 billion years ago. The 
photosyntheticcyanobacteriawere subsequently instrumental 
in producing oxygen, and microorganisms on land would 
have increasingly removed carbon dioxide from the early 
atmosphere in rock weathering (Lovelock, 1988). In the 
absence of these activities there would have been no 
macroorganisms or humans. Microorganisms continue to 
play a major role in the maintenance of the biosphere and 
global ecology through the various biogeochemical cycles. 
They perform unique and indispensable roles in the 
circulation of matter in the world (Stolz et al., 1989). The 
principed biogeochemical cycles with which they are 
involved are: 

Carbon 

It has been estimated that about 40% of the carbon fixed by 
photosynthesis on the Earth is carried out by algae and 
cyanobacteria, especially those in oceans and seas. Bacteria 
also fix atmospheric carbon dioxide anaerobically and in 
methanogenesis. Methanogenic archaean bacteria generate 
about 58 % of the Earth's methane. Conversely, wood-decay 
fungi are instrumental in releasing around 85 billion tonnes 
of carbon (as carbon dioxide) into the atmosphere each 
year. Ruminant gut microbial populations also produce 
methane, and other methyl gases are produced by fungi 
during wood decay. The tissues of microorganisms ftirther 
have roles as carbon sinks, and their removal of carbon 
from the atmosphere in rock weathering is an on-going 
process. 

Nitrogen 

The Earth's nitrogen cycle is dependent on bacteria 
(including cyanobacteria) for nitrogen fixation, the oxidation 
of ammonia, nitrification, and nitrate reduction. The 
magnitude of the amounts involved is staggering: each year 
bacteria fix 240 Tg of nitrogen, release 210 Tg of nitrogen 
by denitrification, and release 75 Tg of ammonia (Triiper, 
1992). 

Sulphur 

The sulphur cycle on Earth is dependent on sulphur- 
reducing bacteria for the reduction of sulphate into 
hydrogen sulphide, on purple and green photosynthetic 
bacteria for the oxidation of sulphides to sulphur, and 
sulphur oxidising bacteria for the conversion of sulphur to 
sulphates. Bacteria are also involved in the biogenesis of 
dimethylsulphide, a substance of particular relevance as a 
greenhouse gas and postulated as performing an 
equilibrating function for the planet (Lovelock, 1988). 

Minerals 

Microorganisms of various types, including algae, bacteria, 
fungi, and protozoa, are important in the production of a 
wide range of biogenic minerals, notably in the processes 
of rock weathering. These include diverse kinds of 
carbonates, phosphates, oxalates, sulphates, silicates, 
sulphides, and further oxides of iron and manganese 
(Krumbein, 1983; Leadbeater and Riding, 1986; Stolz et 
al.. 1989). 



POTENTIAL CONTRIBUTION OF 
MICROORGANISMS TO SUSTAINABLE 
DEVELOPMENT 

Microorganisms have the potential to contribute to 
sustainable development in multifarious ways (Hawksworth, 
1991i>; Persley, 1990). Production on existing agricultural 
land may be increased through: 

• the selection and introduction of the most efficacious 
nitrogen-fixing Rhizobium strains into legume crops 

• the enhancement of natural nitrogen fixation by the 
application of cyanobacterial inocula, either directly or 
through mutualists (e.g. improvement of cyanobacteria 
of Azolla for use in rice-fields) 

• the use of bacteria and fiingi as biocontrol agents for 
insect pests, plant pathogens, disease vectors, and 
noxious weeds 

• the mass production of the most efficacious mycorrhizal 
(and in the future almost certainly also beneficial 
endophytic) fungi for inoculation into seeds or seedlings 
on or prior to planting. 

Genes from bacteria amd fungi with useful properties, for 
example the production of an insecticidal metabolite or 
enzyme, can be cloned and inserted into the genome of a 
crop plant by an increasing range of methods. Indeed, a 
plasmid in the crown gall bacterium Agrobacterium 
tumefaciens is well-established as a practical mechanism by 
which genes from any source can now be engineered into 
over 20 major world crops. 

A wide array of pharmaceutical and other industrial 
products are already obtained from microorganisms grown 
under factory conditions. These include, for example, 
organic acids, vitamins, antibiotics, anti-inflammatory 
drugs, immunoregulators(e.g. cyclosporin from a saprobic 
fungus which is now routinely used in human transplant 
surgery), food colourings, fragrances, and food 
preservatives. The discovery and studies of the actions of 
naturally occurring compounds can also lead to 
semi-synthetic drugs of great potential, as in the case of 
ivermectin first used against helminths parasitic on livestock 
but now also employed in humans against onchocerciasis 
(river blindness). 

In addition, cellulosic and lignosic wastes from agricultural 
and industrial sources can be biodegraded by 
microorganisms and converted to animal feedstuffs. 

Waste-water treatments using anaerobic bacteria and 
filter-feeding ciliates reduce pressure on freshwater 
supplies. Microorganisms are crucial to the fiinctioning of 
sewage filter-beds. Bacteria can also be employed in the 
removal of toxic chemicals, especially heavy metals, from 
liquid waste; any valuable metals can be recovered for 
reuse. The bioremediation of major oil spills at sea can be 
achieved by applying nitrogen fertilizers which encourage 
the natu rally presenthydrocarbondegradingmicroorganisms 
to proliferate. 

Biogas (methane) production from a variety of agricultural 
and other wastes for use as fiiel is dependent on anaerobic 
bacteria. This has the potential to reduce the pressure on 



51 



I. Biological Diversity 



forests by providing an alternative energy supply. 

An expanded range of sources of food for humans can be 
derived both from the mass-production of certain algae and 
filamentous fungi (e.g. the Fusarium graminearum strain in 
'Quom'), and through the increased use of waste materials 
for the commercial production of a wide range of edible 
macroAingi. 

The design and development of technologies to increase the 
utilisation of microorganisms for human benefit therefore 
merit interpretation as activities integral to the formulation 
of long-term sustainable development programmes. 

THE NEED FOR DIVERSITY AMONGST 
MICROORGANISMS 

While sufficient diversity of microorganisms to enable the 
various functions necessary for ecosystem maintenance and 
the operation of biogeochemical cycles is clearly crucial, 
the extent to which individual species are important is less 
certain. In monitoring microorganisms with reference to the 
conservation of biodiversity in macroorganisms, the 
maintenance of functional groups rather than individual 
species can be presumed to be limiting - except where a 
particular microorganism is a keystone species. 

There has been considerable debate as to the significance of 
fiinctional redundancy in ecosystem function and 
maintenance (Solbrig, 1991). The presence of a wide 
variety of species able to perform similar roles is 
unquestionably beneficial as it provides an ecosystem with 
increased resilience to perturbations. For example, in the 
caseofectomycorrhizas of temperate and boreal forests, the 
ability of a tree to form associations with a variety of fungi 
(over 100 in the case of Betula) enables that tree to grow 
satisfactorily even if only a few of the candidate 
mycorrhizal fiingi are present in a particular soil. Further, 
if the mycorrhizal species are differentially sensitive to 
pollutants, the tree can continue provided at least some of 
those fiingi can tolerate the ambient pollution levels. In the 
event that too many species from a functional group are 
eliminated, at some point an ecosystem will start to break 
down irretrievably. In this regard, the implications for trees 
of the recently reported widespread and dramatic losses of 
ectomycorrhizal fiingi in Europe are of particular concern 
(laenike, 1991). 

Single microorganisms can also function as keystone species 
crucial to the maintenance of particular ecosystems. This 
applies to marine environments such as coral reefs, kelp 
forests formed by Macrocystis in temperate waters, and 
lichen-dominateddeserts, heaths and rocks. Microorganisms 
are most important as keystone organisms when they 
function as mutualistic symbionts in organisms that 
dominate an ecosystem, and in low productivity/high 
diversity systems (Solbrig, 1991). Examples include 
dinoflagellates in corals, endomycorrhizal fungi in tropical 
forest trees, and nitrogen-fixing bacteria in tree roots. 

Individual microorganisms which are major parasites can 
also fiinction as keystone species through natural biocontrol 
processes. For instance, trypanosomes in East Africa keep 
cattle out of wide areas and so may limit soil degradation. 



The present state of ignorance of the biology, ecology, and 
biochemical activities of so many microorganisms is 
comparable to that of their role in food-webs (cf above). It 
is consequently often difficult or impossible to assert 
whether a particular microorganism is functionally 
redundant or a keystone species. Thus, while the presence 
of a variety of lignosic wood decay fungi might at first be 
assumed to be a case of functional redundancy, in practice 
the species of wood attacked can be restricted, and in most 
instances the specific enzymes being formed are unknown. 
Several species of fungi with different but complementary 
properties may need to work simultaneously or 
successionally in the decay of a single log. Furthermore, 
one or more of the decay fungi in that log might be a 
source of digestive enzymes for an insect of ecological 
importance in that ecosystem (Martin, 1987). 

EX SITU CONSERVATION OF MICROORGANISMS 

A wide range of techniques is available for the preservation 
of microorganism strains, freeze-drying (lyophilisation) and 
storage in liquid nitrogen (cryopreservation) being the most 
efficacious for long-term storage. Although not all 
microorganisms can yet be preserved by such methods, the 
development of programmable coolers and cryomicroscopy 
is enabling protocols to be devised for the successfiil 
cryopreservation of organisms previously considered 
recalcitrant. Even where species cannot be grown in pure 
culture, host tissue including them (e.g. plant leaves 
infected with rust fungi) or samples of the substrate itself 
(e.g. soil) can be conserved by cryopreservation. A survey 
of the existing technology is provided by Kirsop and Doyle 
(1991), and the Worid Federation for Culture Collections 
(1990) has issued guidelines for the establishment and 
operation of such collections. 

Further information on ex situ culture collection is provided 
in Part 3. 

THE TAXONOMIC CHALLENGE 

Studies on the biodiversity and roles of almost all 
microorganism groups are frustrated by an inadequate 
taxonomic base. Not only are there vast numbers of species 
yet to be described, there are few modern monographs, 
keys, and other readily available aids, and 
disproportionately few taxonomists so that assistance with 
identifications is difficult to obtain. This issue requires 
priority attention at national, regional, and international 
levels. It is clearly unrealistic for most countries even to 
contemplate the provision of comprehensive microorganism 
identification services. However, attention could be focused 
on strengthening existing centres of expertise, developing 
north-south and south-south linkages, establishing networks 
of centres and specialists, and endeavouring to ensure that 
research agendas are complementary and collaborative. 

Action to improve the knowledge base 

An lUBS/SCOPE workshop on Ecosystem Function of 
Biological Diversity held in Washington DC in June 1989 
recognised that the issue of microbial diversity and its 
function had been neglected and was in urgent need of 
attention; the workshop recommended that FUBS and lUMS 



52 



Microorganisms 



(International Union of Microbiological Societies) establish 
a cooperative programme to address this problem (Di Castri 
and Younes, 1990). 

An lUBS/IUMS workshop on Biodiversity amongst 
Microorganisms and its Relevance was therefore convened 
in Amsterdam 7-8 September 1991. Representatives of 
relevant international scientific organisationsconcerned with 
different groups of microorganisms, together with other 
specialists, presented overviews of the current knowledge 
base (Hawksworth and Colwell, in prep.). A 14-point action 
statement, MICROBIAL DIVERSITY 21, was drawn up 
detailing the remedial work necessary to raise to an 
appropriate level our knowledge of the biodiversity of 
microorganisms and its relevance. The various action points 
are currently being developed and costed, but it must be 
recognised that substantial international resources will be 
required to implement this programme at the level necessary 
for it to realise its objectives. This Chapter draws heavily 
on the presentations and discussions which took place 
during the lUBS/IUMS workshop and the proceedings 
(Hawksworth and Colwell, in prep.) should be consulted for 
further information on many of the topics discussed here. 

References 

Andersen, R.A. (in press). The diversity of eukaryotic algae. 

Biodiversity and Conservation 1 . 
Austin, B. and Priest, F. 1986. Modem Bacterial Taxonomy. Van 

Nostrand Reinhold, Wokingham. 145pp. 
Brasier, CM. 1986. The dynamics of fungal specialion. In: Rayner, 

A.D.M., Brasier, CM. and Moore, D. (Eds), Evolutionary Biology 

of the Fungi. Cambridge University Press, Cambridge. Pp. 23 1-260. 
Burnett, J.H. 1983. Specialion in fungi. Transactions of the British 

Mycological Society 81:1-14. 
Corliss, J.O. 1991. Introduction to the protozoa. In: Harrison, F.W. 

and Corliss, J.O. (Eds), Microscopic Anatomy of Invertebrates, 1. 

Wiley-Liss, New York. Pp. 1-12. 
Di Castri, F. and Younfes, T. 1990. Ecosystem function of biological 

diversity. Biology International, Special Issue 22:1-20. 
Grassle, J.F., Lasserre, P., Mclntyre, A.D. and Ray, G.C 1991. 

Marine biodiversity and ecosystem function. Biology International, 

Special Issue 23:\-\9. 
Hawksworth, D.L. 1991a. The fungal dimension of biodiversity: 

magnitude, significance, and conservation. Mycological Research 

95:641-655. 
Hawksworth, D.L. (Ed.) 1991b. The Biodiversity of Microorganisms 

and Invertebrates: its role in sustainable agriculture. CAB 

International, Wallingford. 302pp. 
Hawksworth, D.L. (in press). Biodiversity in microorganisms and its 

role in ecosystem function. In: Solbrig, O.T. and van Emden, H.A. 

(Eds), Biological Diversity and Global Change. Springer Verlag, 

New York. 
Hawksworth, D.L. and Bridge, P.D. 1988. Recent and iiiture 

developments in techniques of value in the systematics of fungi. 

Mycosystema 1:5-19. 
Hawksworth, D.L. and Colwell. R.R. 1992 Biodiversity amongst 

microorganisms and its relevance. Biology International 24:\\-\5. 
Hawksworth, D.L. and Colwell, R.R., (Eds) (in prep). Biodiversity 

amongst microorganisms and its significance. Biodiversity and 

Conservation 1 . 
laenike, I. 1991. Mass extinction of European fungi. Trends in 

Ecology and Evolution 6:174-175. 
Johnson, J.L. 1989. Nucleic acids in bacterial classification. In: Holt, 

J.G. (Ed.), Bergey's Manual of Systematic Bacteriology, 4. 

Williams and Wilkins, Baltimore. Pp.2306-2308. 
Kessler, E. 1985 ["1984"). A general review on the contribution of 

chemotaxonomy to the systematics of green algae. In: Irvine, 

D.E.G. and John, D.M. (Eds), Systematics of the Green Algae. 

Academic Press, London. Pp. 391-407. 



Kirsop, B.E. and Doyle, A. (Eds) 1991. Maintenance of 

Microorganisms, 2nd edn. Academic Press, London. 308pp. 
Krumbein, W.E. (Ed.) 1983. Microbial Geochemistry. Blackwell 

Scientific Publications, Oxford. 330pp. 
Kurtzman, CP. 1985. Molecular taxonomy of fijngi. In: Bennett, J.W. 

and Lasure, L.L. (Eds), Gene Manipulations in Fungi. Academic 

Press, Orlando. Pp. 35-63. 
Lai, R. 1991. Soil conservation and biodiversity. In: Hawksworth, 

D.L. (Ed.), The Biodiversity of Microorganisms and Invertebrates: 

its role in sustainable agriculture. CAB International, Wallingford. 

Pp. 89-104. 
Leadbealer, S.C and Riding, R. (Eds) 1986. Biomineralizalion in 

Lower Plants and Animals. Clarendon Press, Oxford. 401pp. 
Lee, K.E. 1991. The diversity of soil organisms. In: Hawksworth, 

D.L. (Ed.), The Biodiversity of Microorganisms and Invertebrates: 

its role in sustainable agriculture . CAB International, Wallingford. 

Pp.73-87. 
Liesack, W. and Stackebrandt, E. (in press). Unculturable microbes 

detected by molecular sequences and probes. Biodiversity and 

Conservation I . 
Lovelock, J.M. 1988. The Ages of Gaia. Oxford University Press, 

Oxford. 252pp. 
Lynch, J.M. and Hobbie, J.E. (Eds) 1988. Microorganisms in Action: 

concepts and applications in microbial ecology, 2nd edn. Blackwell 

Scientific Publications, Oxford. 
Margulis, L. and Fester, R. (Eds) 1991. Symbiosis as a Source of 

Evolutionary Innovation. Massachusetts Institute of Technology 

Press, Cambridge, Mass. 454pp. 
Margulis, L. and Schwartz, K.V. 1988. Five Kingdoms. An illustrated 

guide to the phyla of life on Earth, 2nd edn. W.H, Freeman, New 

York. 376pp. 
Martin, M.M. 1987. Invertebrate-Microbial Interactions. Ingested 
fungal enzymes in arthropod biology. Comstock Publishing 

Associates, Ithaca. 148pp. 
Persley.G.J. (Ed.) \99G. Agricultural Biotechnology: opportunities for 

international development. CAB International, Wallingford. 495pp. 
Pirozynski, K.A. and Weresub, L.K. 1979. A biogeographic view of 

the history of ascomycetes and the development of pleomorphism. 

In: Kendrick, [W.l B. (Ed.), 77i^ Whole Fungus, 1. National 

Museums of Canada, Ottawa. Pp. 93-123. 
Price, P.W. 1988. An overview of organismal interactions in 

ecosystems in evolutionary and ecological time. Agriculture, 

Ecosystems and Environment 24:369-377. 
Read, D.J. 1991. Mycorrhizas in ecosystems- nature's response to the 

"Law of the Minimum". In: Hawksworth, D.L., (Ed.), Frontiers in 

Mycology. CAB International, Wallingford. Pp. 101-130. 
Regenmortel.M.H.V. van 1990. Virus species, a much overlooked but 

essential concept in virus classification. Intervirology 31:241-254. 
Round, F.E. 1981 . The Ecology of Algae . Cambridge University Press, 

New York. {Not seen.] 
Smith, DC. and Douglas, A.E. 1987. The Biology of Symbiosis. 

Edward Arnold, London. 302pp. 
Snealh, P.H.A. 1989. Numerical taxonomy. In: Holt, J.C (Ed.), 

Bergey's Manual of Systematic Bacteriology, 4. Williams and 

Wilkins, Baltimore. Pp.2303-2305. 
Sogin, M.L. 1991 . The phylogenetic significance of sequence diversity 

and length variations in eukaryotic small subunit ribosomal RNA 

coding regions. In: Warren, L. and Koprowski, H. (Eds), New 

Perspectives on Evolution. Wiley-Liss, New York. Pp. 175-188. 
Solbrig, O.T. (Ed.) 1991. From Genes to Ecosystems: a research 

agenda for biodiversity. International Union of Biological Sciences, 

Cambridge, Mass. 124pp. 
Stolz, J.F., Bolkin, D.B. and Dastoor, M.N. 1989. The integral 

biosphere. In: Rambler, M.B., Margulis, L. and Fester, R. (Eds), 

Global Ecology. Academic Press, San Diego. Pp. 31-49. 
Takishima, Y., Shimura, J., Udagawa, Y. and Sugawara, H. 1989. 

Guide to World Data Center on Microorganisms with a List of 

Culture Collections in the World. World Data Center on 

Microorganisms, Sailama. 249pp. 
Truper, H.G. (in press). The prokaryoles, an overview with respect to 

biodiversity and environmental Importance. Biodiversity and 

Conservation I . 



53 



1. Biological Diversity 

Wayne, L.G. (Ed.) 1987. Report of the ad hoc committee on World Federation for Culture Collections 1990. Guidelines for the 
reconciliation of approaches to bacterial systematics. Inlemaiiona! EstablishmenI and Operation oj Collections of Cultures of 

Journal of Systematic Bacteriology 37:463-464. Microorganisms. World Federation for Culture Collections, 

Whitcomb, R.F. and Hackett, K.J. 1989. Why are there so many Campinas. 16pp. 

species of mollicutes? An essay on prokaryote diversity. In: 
Knutson, L. and Stoner, A.K. (Eds), Biotic Diversity and 

Germplasm Presentation: Global Imperatives. Kluwer Academic j,,,-^ ^g^„^„ ^^ prepared by Professor D.L. Hawksworth. 

Publishers, Dordrecht. Pp. 205-240. , , ^ , .. / ■ i ; „•, , jjv^ 

„ „ „ J. ^ j>.n. . .« ■ ,nr.n ^ J ^1 International Mycological Institute, UK. 

Woese,C.R.,Kandler,0. and Wheehs.M.L. 1990. Towards a natural ■' ° 

system of organisms: proposal for the domains Archaea, Bacteria, 
and Eucarya. Proceedings of the National Academy of Sciences, 
USA 87:4567-4579. 



54 



7. LOWER PLANT DIVERSITY 



Lower Plant Diversity 



The term 'lower plants' is a convenient but imprecise label 
for a disparate group of plants and plant-like organisms 
which are defined primarily by their lack of vascular tissue 
(the transport system for water and nutrients within higher 
plants). Under this heading we here discuss bryophytes, 
lichens and larger algae. Many authorities would only 
include the first of these among the 'true' plants (defined as 
those developing from an embryo; see Chapter 8). The 
lichens are composite organisms, not true plants, discussed 
here for convenience. 



show little adaptation to desiccation, either physiologically 
or by reduction from perennial to aimual growth cycles. In 
general, therefore, liverworts reach their maximum 
diversity and only achieve dominance in highly oceanic 
regions. There are fewer recognised genera than in the 
mosses but this is offset to a degree by the much larger 
numbers of species in some of them (e.g. Frullania, with 
up to 400 species; Plagiochila, with about 500). For 
convenience, the Hornworts (Anthocerotae) are included 
here with the liverworts. 



BRYOPHYTES 

The bryophytes comprise some 14,000 species, consisting 
of 8,000 mosses and 6,000 liverworts. This is a very 
diverse group of plants containing several classes that are 
only distantly related. These classes, and their main 
subdivisions (orders) vary in their evolutionary history and 
geographical points of origin, and hence vary also in their 
current regions of maximum abundance and diversity. On 
a global scale, therefore, a more accurate assessment of 
areas of biodiversity should rely more on numbers of taxa 
within major taxonomic divisions of the bryophytes than on 
the oversimplified picture derived from crude summations 
of the whole group. Nevertheless, as with other plants, 
certain areas of the world are recognised as being 
particularly rich in bryophyte species, usually (but by no 
means always) the same areas where mosses and/or 
liverworts form more than 50% of the active biomass. In 
general terms, although bryophytes occur almost throughout 
the world, the majority of taxa are distributed in areas of 
high oceanicity, i.e. with cool or temperate, consistently 
moist climates. Their maximum diversity is to be found in 
regions where such conditions have persisted over 
geological time, and where tectonic factors have brought 
about an amalgamation of several regional floras. The 
regions of high species richness are noted in Table 7.1. 

In contrast to many groups of mosses, liverworts generally 
(with the exception of the highly adapted Marchantiales) 



Table 7.1 Regions of high bryophyte 
diversity 



REGION 




SPECIES 






(approximate) 


Indo-Australian archipelago 




3,000 


{esp. New Guinea, Sulawesi a 


nd Borneo) 




South America 




3,000 


(temperate, montane) 






S Australasia 




2,400 


(esp. Tasmania and New Zealand) 




N America 




2,000 


(Pacific, subarctic) 






NE Asia 




2,000 


(Pacific, subarctic) 






Himalayas 




2,000 


E. Africa 




2,000 


(and adjacent islands) 






Europe 




1,800 


(Atlantic areas, incl. British Isles) 






British Isles 




1,000 



Both mosses and liverworts (and hornworts) consist of 
major divisions into orders and families that may have 
widely different habitat preferences. There are too many 
such divisions to detail here, but the more significant 
groups (orders and families) are listed in Tables 7.2 and 7.3 
to provide a reasonably representative picture. 

LICHENS 

Lichens are composite organisms consisting of a usually 
dominant fungal partner in symbiosis with one or more 
photosynthetic partners, the resulting composite, organised 
structures behaving as independent entities. The fiingal 
partner (mycobiont) is, in most cases, an ascomycete, rarely 
a basidiomycete, while the autotrophic partner (photobiont) 
may be a green alga or a cyanobacterium. Lichen 
photobionts come from a small number of genera most of 
which occur widely in nature while lichen mycobionts are 
exclusively lichen-forming and are taxonomically diverse, 
many coming from orders that also have non lichen forming 
taxa. The lichen symbiosis is one of the most successfiil 
known in nature. Of the 46 orders in the Ascomycotina 
some 16 have lichenised taxa to a greater or lesser degree, 
and out of some 238 families, 81 consist entirely of lichens 
or at least have some lichenised taxa. Lichenisation is a 
polyphyletic process that has occurred at many different 
times. 

Currently, the consensus of known lichenised taxa world 
wide varies from 13,500 to 17,0{X). On the basis of recent 
monographic revision of a number of widespread lichen 
genera, and the collection of lichens from areas of the 
world previously unknown or little known lichenologically, 
it is safe to assume that a realistic world total for lichens 
will be closer to 17,000 and possibly even to 20,000. It 
seems probable that at present we know 50-70% of the 
world's lichens, though future discoveries of short-lived, 
fast-growing lichens on leaves and on bryophytes, and of 
Southern Hemisphere microlichens, could substantially alter 
this estimate (Galloway, 1992). 

Although for higher plants the tropics are regarded as major 
sites of biodiversity, much less is known about tropical 
lichens whose biodiversity tends to be richest in canopy 
vegetation, which is still very poorly sampled in many 
tropical areas. Temperate areas of the world, on the other 
hand, with their wide variations of habitat, geology and 
climate are known to be major sites of lichen diversity. Of 
great importance are the temperate rainforests of the 
Southern Hemisphere, especially South America, New 
Zealand, Tasmania, south eastern Australia and the 
highlands of the tropical Pacific islands. 



55 



1. Biological Diversity 

Table 7.2 Selected orders and families of mosses 

FAMILIES GENERA DISTRIBUTION AND ECOLOGY 



Sphagnales 
1 



Cosmopolitan. About 80 species. Maximum diversity in cool oceanic regions of N 
Hemisphere; c. 40 spp in W Europe, similar in N America; 13 in SE Asia and Pacific; 
15 in tropical S America; 13 in E. Africa; < 6 in Australasia? Terrestrial, mainly 
calcifuge. 



Polytrichales 




2 


21 


Bryales 




85 families inci: 




Dicranaceae 


45 


Pottiaceae 


>70 



Calymperaceae 


12 


Grimmiaceae 


12 


Bryaceae 


20 


Orthotrichaceae 


21 


Spiridentaceae 


2 


Hypnodendraceae 


2 


Amblystegiaceae 


21 


Pterobryacaae 


30 


Meteoriaceae 


19 


Hookeriaceae 


27 


Sematophyllaceae 


49 


Brachytheciaceae 


c30 


Hypnaceae 


40 



Old and diverse group with regional endemism and widely differing areas of 
diversity. About 200 species. 



Most mosses; about 7,000 species. 

Cosmopolitan; tropical montane and high latitude; greatest diversity probably in W 
Europe, N America and NE Asia. Mainly calcifuge. 

Cosmopolitan; most diverse in, Mediterranean or continental climates, extending to 
semi-deserts; principally in temperate to subarctic N Hemisphere but strongly 
represented in Australasia and Africa. Xerophytic on soil and rocks, rarely epiphytic, 
many annuals. 

Lowland tropics and subtropics. Greatest diversity in SE Asia and W Pacific; absent 
from cool temperate regions. 

Mostly subarctic and alpine. Highest diversity in W Europe and N America. 

Cosmopolitan; most numerous in cool temperate to polar regions; ecologically 
important in polar deserts. 

Ecologically very important in the epiphytic biome of the montane tropics. Major 
diversity in W Pacific (esp. New Guinea) with other areas in Australasia, S America, 
E Africa. Mainly photophilic epiphytes. 

Endemic to W Pacific (esp. New Guinea). Epiphytes. 

Endemic to W Pacific and Australasia. Epiphytes and lignicoles. 

Mainly cool temperate to arctic with high diversity in NW Europe, N America and NE 
Asia. Hygrophilous and subaquatic. 

Tropical montane rainforests, especially abundant in SE Asia and W Pacific where 
many genera endemic. Frondose epiphytes. 

Tropical montane rainforests, especially SE Asia and W Pacific. Pendulous epiphytes. 

Greatest diversity in the humid tropics, especially S America and SE Asia with 
significant endemism in both. Hygrophilous. 

Temperate to tropical montane. Maximum diversity in SE Asia/W Pacific (esp. 
Indonesia, Papua New Guinea) and tropical America. Mainly acidophilous, lignicolous 
and epiphytic. 

Temperate to arctic. Greatest diversity in N America, NW Europe and NE Asia. 
Mainly ground-dwelling. 

Cosmopolitan but with strong regional speciation in all of the areas mentioned 
above. 



Other regions of important local, lichen biodiversity are the 
unique coastal fog lichen communities (nebeloasen) found 
in northern Chile, Peru, Baja California and Namibia, 
where members of the family Roccellaceae are particularly 
well-developed. 

Islands also often show high lichen biodiversity in 
comparison with large continental areas, not only islands 
surrounded by water, but biogeographical islands (i.e. areas 
of habitat or climate diversity such as rock outcrops, 
mountains or ranges in an otherwise uniform forest or 



grassland landscape). Lichens are particularly successful 
pioneer colonisers, and so are important components of 
vegetation in many harsh enviroimients of the world, such 
as alpine and polar regions, in hot and cold deserts, and in 
often toxic, mineralised environments. 

Comparative figures of lichen diversity for a number of 
areas are presented in Table 7.4. The information is derived 
from published accounts of varying age and reliability, most 
of which are recorded in the bibliography of Hawksworth 
and Ahti (1990), and from unpublished data. 



56 



Lower Plant Diversity 



Table 7.3 Selected orders and families of liverworts (including hornworts) 



FAMILIES 



GENERA 



DISTRIBUTION AND ECOLOGY 



Calobryales 




2 


2 


Treubiales 




1 


2 


Jungermanniales 




39 families inch 




Herbertaceae 


4 


Lepidoziaceae 


24 


Lophoziaceae 


18 


Jungermanniaceae 


11 


Gymnomitriaceae 


3 


Schistochilaceae 


2 


Lophocoleaceae 


15 


Plagiochilaceae 


6 


Radulaceae 


1 


Lejeuneaceae 


c. 70 


Frullaniaceae 


3 



Living fossils with disjunct distributions, all in moist temperate habitats. 



An ancient group best represented in the W Pacific. 



The 'leafy liverworts'. 

Confined to oceanic regions, mainly tropical and subtropical montane but 2 spp. in 
W Europe. 

Greatest richness In W Pacific and temperate S Hemisphere. Mainly humicolous 

and llgnlcolous. 

Widespread In cool oceanic regions: W Europe, NW North America, NE Asia, S 
America, Australasia. 

Cool temperate to subarctic regions. Terrlcolous and strongly hygrophilous. 

Arctic and alpine preferences: main diversity In the cool N Hemisphere, especially 
W Europe. 

Almost confined to montane forests around the W Pacific. 

Cosmopolitan. Mainly ground-dwelling. 

Plagiochila Is most Important genus with large numbers of species in tropical 
montane rainforests. Very strongly represented in SE Asia and W Pacific. 

Cosmopolitan, but greatest diversity in rainforest vegetation: SE Asia, S America. 

Extremely diverse and Important family, especially within the tropics; greatest 
diversity in W Pacific, Indonesia and tropical America. In Europe almost confined 
to the Atlantic seaboard. Mainly cortlcolous and epiphyllous 

Frullania, with over 400 species. Is the most important genus. Greatest diversity 
in the montane tropics of SE Asia and America. Mainly strongly photophilic 
epiphytes but also epiirthic etc. 



Metzgerlales 




5 families IncI: 




Dllaenaceae 


11 


Aneuraceae 


2 


Metzgeriaceae 


1 


Marchantiales 





30 



Thalloid liverworts, strongly hygrophilous. 

Comparatively few species, more or less evenly distributed. Soil-dwelling, mainly 
riparian 

Montane forests; SE Asia, S America, W Europe and N America. Hygrophilous, 
mainly on soil, rooks and rotting wood 

Widely distributed. 

Thalloid liverworts 

Mediterranean type climate: W Mediterranean, S Africa, India. Xerophytic 
tendencies. Includes some 'weedy' cosmopolitan species. 



Anthocerotales 



Hornworts 

Widespread. Epiphylls maximum diversity in the W Pacific. Terrestrial 
hygrophytes, epiphytes and epiphylls. 



ALGAE 

Chlorophyta (Green Algae) 

The class Chlorophyta is cosmopolitan in distribution and 
occurs in marine and brackish water, freshwater, and 
terrestrial enviroimjents. It comprises approximately 1,040 
species in 170 genera and contains eight orders (Silva, 
1982) some of which have restricted geographical 



distributions. Many of the larger Chlorophyta are restricted 
to either marine or freshwater conditions; a few are 
sufficiently tolerant to be found in both environments. Table 
7.5 lists the orders and constituent families of the larger 
Chlorophyta (excluding unicellular forms) and indicates 
their broad geographical distributions and salinity 
tolerances. 

The largest family, the Cladophoraceae, occurs globally and 



57 



1. Biological Diversity 



Table 7.4 Lichen diversity 



USA and Canada 


401 


3409 


Australia 


299 


2499 


France 


181 


2200 


Sweden and Norway 


216 


2142 


West Indies 


173 


1751 


United Kingdom 


250 


1600 


New Zealand 


243 


1162 


India 


163 


1150 


Mexico 


130 


997 


Philippines 


137 


974 


Argentina 


122 


942 


Sardinia 


178 


901 


Hawaii 


104 


750 


Tasmania 


173 


655 


East Africa (macrolichens) 


79 


639 


Central America 


120 


635 


Guianas 


165 


600 


New Guinea 


137 


537 


Galapagos 


80 


196 


Juan Fernandez 


31 


194 


Ecuador 


160 


? 



in a wide range of salinities; the next largest family, the 
Codiaceae, is restricted to the marine environment and does 
not occur in the colder waters of the polar regions. 
Temperature-dependent distribution is clearly seen at both 
order and family levels. The Acrosiphoniaceae is restricted 
to colder waters in contrast to the Siphonocladales, 
Caulerpaceaeand Udoteaceae' which occur only in tropical 
and subtropical waters. 

Of the selected floras assessed for species diversity (Table 

7.8), the North Atlantic, the tropical/subtropical western 
Atlantic, and the Japanese region of the Pacific are the most 
species-diverse. Although the green seaweed flora of 
southern Australia is not so species-diverse, it probably 
contains the highest number of endemics (46% of the total). 
Particularly impoverished floras are those of the tropical 
west coast of Africa (e.g. Gambia to Angola) and the west 
coast of South America (e.g. Colombia, Peru), areas where 
there are major cold water upwellings. Other impoverished 
floras include those of small isolated islands (e.g. 
Macquarie Island) and the polar regions. 

Phaeophyceae (Brown Algae) 

The Phaeophyceae are global in distribution, occurring in 
polar, temperate and tropical zones. The brown algae are 
principally marine plants, with only very few species in 
freshwater. The class contains about 265 genera and in 
excess of 1,500 species arranged in 14 orders (Wynne, 
1982, Table 7.6). 



Table 7.5 Orders and families of larger green algae 

FAMILIES GEN SPP DISTRIBUTION ECOLOGY 



Ulotrichales 


1 


16 


80 


Global 


Mostly freshwater 


Ulvales 

Capsosiphonaceae 
Percursariaceae 
Ulvaceae 
Monostromaceae 


5 


12 

1 
1 
6 
3 


3 

1 

86 

12 


Global 


Brackish water 

Brackish water 

Mostly seawater/brackish water 

seawater/brackish water 


Prasiolales 


1 


3 


40 


Global 


Seawater/brackish water/freshwater 


Acrosiphoniales 
Codiolaceae 
Acrosiphoniaceae 


2 


4 

16 

2 


3 


Cold waters 
Cold waters 
Cold waters 


Seawater/brackish water 
Seawater/brackish water 
Seawater/brackish water 


Cladophorales 
Cladophorales 
Anadyomenaceae 


2 


20 

14 

6 


300 
26 


Global 
Tropical/subtropical 


Seawater 
Seawater 


Siphonocladales 
Siphonocladaceae 
Valoniaceae 


2 


12 
8 
4 


48 
35 


Tropical 
Tropical 
Tropical 


Seawater 
Seawater 
Seawater 


Bryopsidales 
Bryopsidaceae 
Ostroebiaceae 
Dichotomosiphonaceae 
Caulerpaceae' 
Udoteaceae 
Codiaceae' * 


6 


24 
6 

1 
1 
1 
13 
1 


60 

6 

1 

75 

87 

100 


Global 
Shells 

Tropical/subtropical 
Tropical/subtropical 
Global 


Seawater 
Seawater 

Seawater 
Seawater 
Seawater 


Dasycladaceae"" 


1 


11 


50 


Tropical /subtropical 


Seawater 



Notes: * Temperate in southern hemisphere, ** one relict genus in inland brackish water, *•* not polar waters. GEN = genera, SPP = species. 



58 



Lower Plant Diversity 



Table 7.6 Orders and families of brown algae 

FAMILIES GENERA SPECIES DISTRIBUTION 



ECOLOGY 



Ectocarpales 
Ectocarpaceae 
Ralfsiaceae 
Sorocarpaceae 

Chordarlales 

Mvrionenrtataceae 

Elachistaceae 

Corynophloeaceae 

Spermatochnaceae 

Acrotrichaceae 

Chordariaceae 

Ischigiaceae 

Chordariopsidaceae 

Notheiaceae 

Splachnidiaceae 

Cutleriales 

Tilopteridales 

Sphacelariales 
Sphacelariaceae 
Stypocaulaceae 
Cladostephaceae 
Choristocarpaceae 

Dictyotales 

Sporochnales 

Desmarestiales 
Desmarestiaceae 
Arthrocladiaceae 

Dictyoslphonales 
Myriotrlohaceae 
GIraudlaceae 
Striariaceae 
Delameriaceae 
Punctiariaceae 
Chnoosporaceae 
Dlctyosiphonaceae 

Scytosiphonales 

Laminariales 
Chordaceae 
Laminariaceae 
Lessoniaceae 
Alariaceae 

Fucales 
Fucaceae 

Himanthaliaceae 

Hormoseiraceae 

Phyllosporaceae 

Sargassaceae 

Cystoseiraceae 

Durvilleales 

Ascoseirales 



10 



29 

17 

2 

11 
5 
5 
S 
1 

29 
1 
1 
1 
1 

3 

2 

5 
4 

1 

2 

16 



3 
1 

1 
1 
9 
4 
17 
1 
2 



1 

15 

8 

7 



Global 
Global 



N Atlantic - 



10 



Global 



N Atlantic 
Global 
Limited 
S Africa 
Australasia 
S Africa 

Warm waters 

N Atlantic 

Global 

Global 

Global 

N Atlantic/Australasia 

N Atlantic/Mediterranean 

Tropical/subtropical ■ 

Warm waters 

Cold waters 
Cold waters 
N Atlantic/Mediterranean 

N Atlantic/Mediterranean 
N Atlantic/Mediterranean 



Temperate 
Tropical/subtropical 
N Hemisphere 



Temperate/polar 

N Atlantic 

Temperate/polar 

NE Pacific/S Hemisphere 

Temperate/polar 





7 




N Hemisphere 




1 
1 
6 
6 
16 


1 
1 


NE Atlantic 

Australasia 

Australasia 

Tropical/temperate 

Tropical/temperate 


1 


1 


4 


Australasia/Antarctic 


1 


1 


1 


Antarctic 



Marine 
Marine 
Marine 
Marine 

Marine 
Marine 
Marine 
Marine 
Marine 
Marine 
Marine 
Marine 
Marine 
Marine 

Marine 

Marine 

Marine 
Marine 
Marine 
Marine 
Marine 

Marine 

Marine 

Marine 
Marine 
Marine 

Marine 
Marine 
Marine 
Marine 
Marine 
Marine 
Marine 
Marine 

Marine 

Marine 
Marine 
Marine 
Marine 
Marine 

Marine 

Marine 

Brackish 

Marine 

Marine 

Marine 

Marine 

Marine 

Marine 

Marine 



The more primitive orders (Ectocarpales, Chordariales) are 
global in distribution, although some of the constituent 
families, particularly the smaller ones (e.g., Sorocarpaceae) 
are geographically restricted. The small orders Cutleriales, 
Dictyotales and Tilopteridales are limited, respectively, to 



warmer waters, the tropics and subtropics, and the North 
Atlantic, while the Durvilleales and Ascoseirales occur only 
in Australasia and Antarctica. The kelps (order 
Laminariales) are disjunctly distributed in temperate waters 
of both northern and southern hemispheres. In the most 



59 



1. Biological Diversity 



Table 7.7 Orders and families of red algae 

FAMILIES GENERA SPECIES DISTRIBUTION 



ECOLOGY 



Bangiophycideae 



Porphyridiales 
Porphyridiaceae 
Goniotrichaceae 
Phragmonemataceae 


4 


7 
3 
4 




Bangiales 

Erythropeltidaceae 

Bangiaceae 

Boldiaceae 


3 


6 

? 
1 


1 


Compsopogonales 


1 


1 


12 


Rhodochaeteles 


1 


1 


1 



Marine/freshwater 

Marlne/brackish/freshwater 

Freshwater 

Marine/freshwater 

Marine 

Marine/brackish/freshwater 



Marine 



Nemaliales 


13 






Global 


Marine/brackish/freshwater 


Acrochaetiaceae 




1 




Global 


Marine/brackish/froshwater 


Batrachospermaceae 




3 






Freshwater 


Lemaneaoeae 




1 






Freshwater 


Thoreaceae 




2 






Freshwater 


Helminthocladiaceae 




3 






Marine 


Nemaliaceae 




4 






Marine 


Dermatonemaceae 




2 






Marine 


Chaetangiaceae 




7 






Marine 


Naccariaceae 




3 






Marine 


Bonnemaisoniaceae 




5 






Marine 


Gelidiaceae 




2 






Marine 


Gelidiellaceae 




1 






Marine 


Wurdemanniaceae 




1 


1 




Marine 


Cryptonemiales 


13 






Global 


Marine 


Weeksiaceae 




3 






Marino 


Dumontiaceae 




6 






Marine 


Choreocolacaceae 




2 


3 




Marine 


Cryptonenniaceae 




20 




Global 


Marine 


Corynomorphaceae 




1 


1 




Marine 


Pseudoanemoniaceae 




2 




S Hemisphere 


Marina 


Kallynneniaceae 




10 


70 


Global 


Marine 


Endocladiaceae 




2 






Marine 


Crossocarpaceae 




4 


6 




Marine 


Glojosiphoniaceae 




2 






Marine 


Tichocarpceae 




1 


1 


NW Pacific 


Marine 


Pterocladiophilaceae 




1 


1 




Marine 


Peyssonneliaceae 






? 




Marine 


Corallinales 


1 


30 


400 


Global 


Marina 


Hildenbrandiales 


1 


1 






Marine/bracklsh/f rash water 


Gigartinales 


27 








Marine 


Gymnophleaceae 




4 


30 




Marine 


Gracilariaceae 




7 






Marine 


Sebdeniaceae 




1 


2 




Marine 


Calosiphoniaceae 




2 


3 




Marine 


Petrocelidaceae 




2 






Marine 


Phyllophoraceae 




4 






Marine 


Gigartinaceae 




4 






Marine 


Chondriellaceae 




1 


1 


Juan Fernandez 


Marine 


Polyideaceae 




2 






Marine 


Nizymeniaceae 




2 


3 


S Australia 


Marine 


Rhizophyllidaceae 




3 


12 




Marine 


Acrotylaceae 




5 


5 


S Hemisphere 


Marine 


Plocamiaoeae 




2 






Marine 


Phacelocarpaceae 




2 




S Hemisphere 


Marine 


Sarcodiaceae 




4 






Marine 


Furcellariaceae 




3 


5 




Marine 


Solieriaceae 




? 






Marine 


IHypneaceae 




3 






Marine 


Rissoellaceae 




1 


1 


Mediterranean 
60 


Marine 



Table 7.7 Orders and families of red algae (continued) 



Lower Plant Diversity 



FAMILIES GENERA SPECIES DISTRIBUTION 



ECOLOGY 



Rhabdoniaceae 




5 






Marine 


Cubiculosporaceae 




1 


1 




Marine 


Rhodophyllidaceaa 




3 






Marine 


Mychodeaceae 




1 


11 


S Australia 


Marine 


Dicranemaceae 




4 




S Australia 


Marine 


Ahnfeitiaies 


1 


1 






Marine 


Rhodymeniales 


2 








Marine 


Rhodymeniaceae 




30 






Marine 


Champlaceae 




6 






Marine 


Palmariales 


1 


4 






Marine 


Ceramiales 


4 






Global 


Marine 


Ceramiaceae 




100 




Global 


Marine/brackish* /fresh water* 


Oelesseriaceae 




100 


300 


Global 


Marine/freshwater* 


Dasyaceae 




12 


100 




Marine 


Rhodomelaceae 




100 


500 




Marine/brackish* 


Note: * A few species only. 













advanced order, the Fucales, the family Cystoseiraceae 
occurs widely in the tropical and temperate zones, whereas 
the family Sargassaceae is mostly confined to the tropical 
waters. Other families have more circumscribed 
distributions, the Hormoseiraceae and Phyllosporaceae 
occurring otdy in Australasia; the Fucaceae is restricted to 
the northern hemisphere and the monotypic Himeinthaliaceae 
is endemic to the north-eastern Atlantic. 



of Red Algae are those of California and Chile. Although 
precise data are not available for southern Australia, it is 
probably also species-rich, with 75% of species and 30% of 
genera endemic to the area. Species-poor floras are those 
referred to previously on the tropical west coasts of Africa 
and South America where there are cold-water upwellings. 
Red algae floras decrease in species abundance in cool 
waters. 



Brown algae attain greatest species richness in the Japanese 
region of the Pacific, the North Atlantic and, to a lesser 
extent, southern Australia. The last region, however, is 
probably highest in endemics, with 18% of genera and 54% 
of species endemic while only 26 % of the flora comprises 
widespread species. Species-depauperate floras are, as in 
the Chlorophyta, those in cold-water upwelling areas (e.g. 
Angola, Colombia and Peru), on isolated islands 
(Ascension, St Helens), or a combination of both (e.g. 
Macquarie Island). 

Rhodophyta (Red Algae) 

The Rhodophyta is the largest of the three main seaweed 
groups, with over 555 genera (Dixon, 1982, Table 7.7); it 
contains more species than the Chlorophyta (Green) and 
Phaeophyceae (Brown) together. The Rhodophyta is divided 
into two subclasses, the subclass Bangiophycideae, the 
smaller of the two, occurs throughout the world in marine, 
brackish and freshwater environments. The subclass 
Florideophycideae comprises eight orders and is 
predominantly marine. None of the orders is clearly 
circumscribed geographically; some small families (e.g. 
Mychodeaceae, Phacelocarpaceae) are restricted in 
occurrence to Australia or the southern hemisphere 
generally. The larger families are widely distributed. 

As with the Green and Brown Algae, the most species-rich 
floras are those of the Japanese Pacific region, the tropical 
and subtropical western Atlantic, and the North Atlantic 
(including temperate and arctic regions). Other rich floras 



General remarks on marine algal floras 

The most species-rich algal flora assessed is that of the 
Japanese region of the Pacific (1,503 species. Table 7.8). 
The North Atlantic and tropical and subtropical western 
Atlantic are also species-rich, with over 1,000 species 
recorded. 

In the North Atlantic, eastern and western seaboards differ 
in diversity. The western (American) coastline is relatively 
species-poor; 65 % of the North Atlantic flora is restricted 
to the eastern (European) coast, 35% is common to both 
coasts, and only 5% restricted to the American coast. A 
reduction in species also occurs from south to north, with 
the Arctic flora the least diverse and characterised by 
hardy, cosmopolitan species and very low endemism. The 
flora of the British Isles is relatively species-rich (over 700) 
exceeding that north western Pacific America and one of the 
richest of the 18 floras assessed. The flora of the Eastern 
Mediterranean is probably much richer than indicated by the 
430 species listed for Aegean Greece. The latter flora is 
fairly high in endemics (20% of the total species, while 
28% of all species are Mediterranean-Atlantic in 
distribution). 

The flora of the tropical and subtropical regions of the 
Atlantic contrast with those in higher latitudes to the north 
in having the most species-diverse area on the western 
(American) side, where 1,058 species are recorded. On the 
eastern (tropical African) side the number is only about 
300. Similar comparison of the Chlorophyta (green algae) 



61 



1. Biological Diversity 



and Phaeophyta (brown algae) floras (groups having better 
data for subtropical and tropical Africa) shows 253 species 
of green algae from the west and 153 from the east, and 
150 species of brown algae from the west and 125 from the 
east. The flora of tropical west Africa contains 56% of 
species that also occur in the Indian Ocean and 58% of 
species in the Pacific Ocean. 

Moderately rich floras are those of Chile (temperate), 
North-west America (temperate), California (subtropical) 
and tropical East Africa. The flora of southern Australia 
probably also falls into this group, but is probably much 
higher in endemics. 

Species-poor floras generally occur in polar waters, and on 
isolated islands - the further from the nearest landmass the 
poorer the flora (e.g. St Helena with only 68 species). 
Potential for endemism exists in water masses isolated from 
the main oceans, such as the Mediterranean Sea (which only 
has very small water exchange with the Atlantic Ocean), the 
Black Sea (for similar reasons), and the Caspian Sea (now 
completely isolated and brackish, but retaining an 



impoverished seaweed flora). 

An important characteristic of many tropical and subtropical 
regions is the occurrence of coral reefs; algae are a major 
constituent of these long-stable ecosystems and the sheltered 
lagoons they protect. Coral reefs support a unique and 
generally diverse algal flora that includes many crustose 
coralline algae whose numbers are likely to increase with 
further study. Mangrove areas are also restricted to the 
tropics and subtropics and support a well-defined and 
interesting algal vegetation, contrasting with that of 
saltmarshes in the temperate zones, which are generally 
more species-poor. Sandy coastlines are floristically 
depauperate areas and often form barriers to seaweed 
dispersal. Some anthropomorphic changes to the coastline 
involving creation of additional habitats have locally 
enhanced species diversity; pollution, in contrast, has 
reduced species diversity, especially in lagoons, mangrove 
areas and coral reefs. In the latter, pollution-tolerant weedy 
species appear to outcompete and replace pollution-sensitive 
species. Land reclamation, rice-paddies and salt-pan 
development have led to the loss of algal habitat in many 
coastal areas in the tropics. 



Tgible 7.8 Diversity of marine algal (seaweed) floras 



FLORA 



CHLOROPHYTA PHAEOPHYCEAE RHODOPHYTA TOTAL 

GENERA SPECIES GENERA SPECIES GENERA SPECIES GENERA SPECIES 



Japan 


60 


234 


108 


379 


267 


900 


475 


1503 


N Atlantic 


67 


253 


127 


324 


193 


539 


387 


1116 


W Atlantic 


64 


253 


63 


150 


134 


655 


321 


1058 


Chile 


31 


131 


60 


140 


150 


480 


241 


751 


California 


22 


72 


69 


137 


186 


459 


279 


668 


E Africa 


30 


159 


29 


118 


121 


366 


180 


643 


NW America 


51 


117 


66 


143 


161 


373 


273 


635 


Antarctica 




88 




118 




357 




563 


S Africa 
















547 


E Mediterranean 


30 


73 


49 


90 


131 


267 


210 


430 


Viet Nam 




115 




86 




223 




424 


Red Sea 


30 


92 


34 


118 


79 


173 


143 


383 


Tropical W Africa 


19 


59 


22 


42 


88 


198 


129 


299 


Angola 


8 


34 


18 


22 


71 


140 


97 


196 


Peru 




29 




20 




107 




156 


Colombia 


12 


23 


13 


21 


46 


79 


71 


123 


Macquarie 1 


12 


15 


25 


28 


46 


60 


81 


103 


St Helena 


10 


13 


9 


10 


34 


45 


53 


68 


Ascension 1 


9 


14 


11 


15 


16 


23 


35 


52 


S Australia 


39 


119 


104 


231 










Tropical/subtropical 



















Charophyta (Stoneworts) 

The charophytes or stoneworts are a very distinctive group 
of macrophytic green algae that occur from Spitzbergen in 
the north (80 °N) to the Kerguelen Islands in the south (c. 
50°S). A few are restricted to brackish water but the large 
majority are widely distributed in such freshwater habitats 
as ponds, lakes, ditches, temporary pools, streams, rivers 
and swamps. The six extant genera are placed in two tribes: 
the Chareae - Chara, Lamprothamnium, Nitellopsis and 
Lychnothamnus; and the Nitelleae - Nitella and Tolypella. 
It is difficult to undertake a biogeographic analysis based on 
charophyte species because of the current uncertainty 
surrounding taxonomic limits and the ranking of 



infrageneric taxa. In Wood's world monograph on the 
group (Wood, 1965) the infrageneric taxa were divided into 
sections, species, subspecies, varieties and forms. He 
considered morphologically similar monoecious and 
dioecious taxa to be 'species pairs' and combined them. 
Other charologists do not accept Wood's views on merging 
monoecious and dioecious taxa and continue to regard them 
as distinct. 

Unlike most other groups of freshwater algae sufficient 
regional information exists on the distribution of 
charophytes to allow for global analysis. In carrying out 
such an analysis Khan and Sarma (1985) used Wood's 
classification but did not recognise the merging of 



62 



Lower Plant Diversity 



monoecious and dioecious taxa. They included charophytes 
described after 1965 and taxa reduced by Wood to 
synonymy but subsequently shown to be distinct. Khan and 
Sarma recognised 440 taxa, of which 274 were known from 
only one region or continent ('endemics'). For assessing the 
geographical distribution of taxa eight broad zones 
(regions/continents) were recognised: North America, South 
America, Africa, Europe, Asia (including Japan but 
excluding India), India, Pacific Island region, and Australia. 
Antarctica was not included as it is the only continent for 
which charophytes have yet to be reported. 



Table 7.9 Stonewort diversity 



REGION 



North America 

Asia 

Africa 

Europe 

Australia 

South America 

India 

Pacific Region 

World 



GENERA 


SPECIES 


ENDEMIC 
SPECIES 


4 


114 


50 


5 


122 


48 


4 


116 


42 


6 


91 


41 


5 


62 


25 


5 


89 


25 


6 


125 


23 


4 


72 


19 



440 



274 



Source: Khan, M. and Sarma, Y.S.R.K. 1984. Cytogeography and 
Cytosystematics of Charophyta. In; Irvine, D.E.G. and John, D.M. 
(Eds), Sysiematics of Ike Green Algae. Academic Press, London and 
Orlando. 

Note: • Majority of the remainder (c. 166) have a restricted 
distribution (normally two or three regions/continents) and about seven 
are to be regarded as cosmopolitan. Fewer than a dozen taxa have been 
published since 1985 and most are from underworked regions (e.g. 
South America; Asia, especially China). 

It is impossible to determine to what extent tabulated 
estimates are significant or simply reflect collecting. Europe 
is one of the most intensively collected regions and so the 
lower numbers reported are likely to represent a real 
difference in diversity. The general unsatisfactory state of 
the taxonomy will continue to hamper biogeographical 
analysis. 

Charophytes form extensive and sometimes diverse 
associations in marl rich water bodies and are especially 
sensitive to nutrient enrichment or eutrophication. In some 
countries they have become dramatically less common and 
more restricted in distribution as a result of nutrient 
enrichment primarily from agricultural sources. This would 
seem to be the main threat to these algae along with the 
general loss of aquatic habitats through land reclamation. 
Brackish-water lagoons is an example of a habitat under 
threat in many countries and one the genus Lamprothamnion 
is almost wholly confined to it. In the British Isles this is 
the only charophyte protected by goverimient legislation 



although several freshwater species may also be under 
threat and have been recommended for protection. The 
conservation status of charophytes is difficult to determine 
without considerably more information on habitat 
requirements. 

Other groups of algae 

Comments on the diversity and global distribution of most 
groups of microalgae are not possible because of inadequate 
knowledge of the algal floras of the world. A reasonable 
coverage exists for a few regions but only for fairly well- 
defined algal groups such as the desmids (Division 
Chlorophyta, Order Desmidiales) and the diatoms (Division 
Bacillariophyta). Only a few attempts to analyse and 
interpret regional distribution patterns go so far as to 
consider the wider distribution of individual taxa. Doubt is 
often attached to the reliability of published lists so that the 
findings of regional comparisons need to be treated with 
caution. Frequently, 'regional endemics' have had to be 
reduced to synonymy because the describing authors failed 
to take adequate account of the taxonomic literature 
covering other regions. Sometimes the converse is true, and 
endemics are not recognised because they are incorrectly 
attributed to an extant taxon using identification guides 
written for another region. If progress is to be made it is 
essential to have sounder species concepts, more accurate 
identification, and considerably more information on the 
algal floras of under-collected parts of the world. 

References 

Dixon, P.S. 1982. Rhodophycota. In: Parker, S.P. (Ed.), 

Classification of Living Organisms. McGraw Hill, New York. 

Pp. 62-79. 
Galloway, D.J. 1992. A lichenological perspective. Biodiversity and 

Conservation; submitted September 1991. 
Hawskworth, D.L. and Ahti, T. 1990. A bibliographic guide to the 

lichen floras of the world, 2nd edn. Lichenologist 22:1-78. 
John, D.M. 1986. The algal flora; its analysis and biogeography. In: 

John, D.M., The Inland Wafers of Tropical West Africa. E. 

Schweizerbart'sche, Stuttgart. Pp. 133-160. 
Khan, M. and Sarma, Y.S.R.K. 1984. Cytogeography and 

Cytosyslematicsof Charophyta. In: Irvine, D.E.G. and John, D.M. 

(Eds), Sysamatics of the Green Algae. Academic Press, London 

and Orlando. Pp.303-330. 
Silva P.C. 1982. Chlorophycota. In: Parker, S.P. (Ed.), Classification 

of Living Organisms. McGraw Hill, New York. Pp. 133-161. 
Wood, R.D. 1965. In: Wood, R.D. and Imahori, K. (Eds), A Revision 

of the Characeae, Part I. Cramer, Weinheim. 
Wynne, M.J. 1982. Phaeophyceae. In; Parker, S.P. (Ed.), 

Classification of Living Organisms. McGraw Hill, New York. 

Pp. 115-125. 

Chapter abridgedfrom material contributed by the following 
staff of the Department of Botany, The Natural History 
Museum. (London): 

Alan Eddy (Bryophytes); D.J. Galloway (Lichens); David 
M. John (Algae); Ian Tittley (Green Algae). 



63 



1. Biological Diversity 

8. HIGHER PLANT DIVERSITY 



The higher plants, characterised by vascular tissue and 
reproducing either by spores, cones, or flowers, dominate 
the world's flora and vegetation. Along with the bryophytes 
(Chapter 7), they develop from an embryo resulting from 
the sexual fusion of cells. They consist of three groups: 

• the pteridophytes or ferns and fern allies, such as 
clubmosses, horsetails, quillworts and whiskferns 

• the gymnosperms, mainly the conifers and cycads 

• the angiosperms or flowering plants. 

THE GROUPS OF HIGHER PLANTS 

Pteridophytes 

Estimates of the total number of ferns and their allies vary 
between 10,000 and 13,000 species but is probably close to 
12,000, the majority of which are native to the moist 
tropics. 

The so-called 'fern allies' probably do not form a natural 
group but rather represent the end points of several distinct 
evolutionary lineages. Like the true ferns, they reproduce 
by spores. The earliest known vascular land plants belong 
to this group. These psilophytes (Psilophyta), which 
dominated the landscape during the Silurian and Devonian 
around 400 million years ago (Mya), are all but extinct; 
they are only represented by two relict genera - Psilotum 
(tropics) and Tmesipterus (Australia, New Zealand, South 
Pacific). Psilotum is extremely primitive, lacking both roots 
and leaves. 

Today, the lycopods (Lycopodiophyta) are represented by 
only five relict genera (/s-oerei^, Lycopodium, Phylloglossum, 
Selaginella, and Stilites), but their fossil record extends 
back to the Carboniferous (c. 300 Mya), when they formed 
the dominant vegetation. These extinct forms grew to 40m 
high and had a stem diameter of 2m; their remains form 
part of the coal reserves we rely on today. 

The horsetails and scouring rushes (Sphenophyta) are 
another ancient group, and are also all but extinct. They are 
represented by a single genus, Equisetum, containing some 
15 species found throughout the world, but especially well 
represented in North temperate bogs. 

The true ferns (Pteridophyta or Filicophyta) are much more 
diverse than are the fern allies. They show great range of 
form, from the tiny, delicate filmy ferns 
(Hymenophyllaceae) to tropical tree-ferns (Cyatheaceaeand 
Dicksoniaceae) more than 15m tall; leaves vary in length 
from 5mm to 10m. Ferns are cosmopolitan in distribution 
but are scarce in arid zones and occur in greatest numbers 
in the moist tropics, where they often grow epiphytically. 
It has been estimated that 12.5 % of the world's fern species 
are to be found in Papua New Guinea (Johns and Bellamy, 
1979), and 10% in India (Dixit 1984). Some species have 
a very wide distribution, notably Bracken Pteridium 
aquilinum, which is found throughout the temperate zones 
and over much of the tropics, while other species are 
extremely limited in their distribution. 



Gymnosperms 

The gymnosperms are trees (or occasionally shrubs) whose 
seeds lack the covering characteristic of the flowering 
plants. They include some 500 species of conifer, 100 
species of cycad, and a few other small but scientifically 
fascinating families. They first appear in the fossil record 
in the Carboniferous (c. 300 Mya) as the so-called 'seed 
ferns' (which were not true ferns at all, but intermediates 
between ferns and gymnosperms). Gymnosperms dominated 
the earth until the rise of the flowering plants. 

Conifers occur worldwide, but they reach their greatest 
diversity of species and genera in parts of Oceania and on 
the margins of the Pacific Ocean. They are the softwoods 
of commerce and are widely grown for timber and 
ornament. A conifer from the western USA, the Giant 
Sequoia Sequoia sempervirens is the tallest tree in the 
world, reaching a height of 110m; another conifer from 
western USA, the Bristlecone Pine Pinus aristata is thought 
to include the oldest living individual trees on earth, some 
being 4,900 years of age. The largest genera are the pines 
Pinus, firs Abies, and spruces Picea, which form extensive, 
economically important forests in the boreal zone of Eurasia 
and North America and in the mountains of the northern 
hemisphere. The podocarps Podocarpus are widespread in 
tropical and subtropical forests of the southern hemisphere. 
Locally, other genera are prominent, such as kauri pines 
Agathis (exploited for resin) in wet forests from Malesia to 
New Zealand, and Chinese Fir Cunninghamia lanceolata, 
the major timber tree of South and West China. 

Cycads, palm-like tropical trees, occur mostly in Central 
and South America, South Africa, and from Southeast Asia 
to Australasia. They include the Sago-palms Cycas, an 
ancient group which originated at least 240 Mya and are 
thus of considerable scientific interest. Many of them are 
highly restricted in their distribution and are of great 
conservation concern. 

Other gymnosperms include the famous maidenhair tree 
Ginkgo biloba, an isolated, ancient relict species native to 
China, the yews Taxus (source of the promising drug taxol) 
and their allies; joint-pines £/?/i?£yra, leafless 'switch plants' 
of scrub and semi-desert, Cnetum, mostly lianes of moist 
tropical forests, and the remarkable Welwiischia bainesii, 
which looks like a great woody turnip bearing only two 
huge, strap-shaped leaves and a cluster of either male or 
female cones, restricted to the coastal fog-belt of the Namib 
desert of Angola and Namibia. As a general rule, however, 
Africa has a very poor gymnosperm flora. 

Angiosperms 

The flowering plants, or Angiosperms, are an extremely 
diverse group of plants, containing some 250,000 species 
(see Table 8.2). From their first appearance in the fossil 
record around 135 million years ago, they evolved quickly 
and have come to dominate all other land plants, except in 
certain habitats (such as the boreal region, in which 
gymnosperms dominate). Most of our food comes from 



64 



Higher Plants 



angiosperms, as do many spices, drugs, poisons, fibres, 
building materials. Many angiosperms are much utilised for 
their valuable timber (see Part 2). 

Angiosperms are seed-producing plants that bear flowers 
that are often insect- or bird-pollinated. The plants range in 
size from 1mm {Wolffia spp.) to over 100m tall {Eucalyptus 
regans from Tasmania). The flowers can reach over Im 
across (Rafflesia arnoldii from Sumatra and Borneo). 

Estimates of the number of flowering plant species vary 
between 240,000 and 750,000, but most botanists accept 
250,000 species as the best figure. These species are 
grouped into some 17,000 genera. Despite an enormous 
diversity of growth form and floral structure, the number of 
flowering plant families recognised is relatively small. It 
has varied over the years from 200 to over 600, but there 
is now general agreement on a basic 300-400 'core' families 
of flowering plants. Many of these families, such as 
Compositae (daisy and dandelion family) and Cruciferae 
(cabbage family) are natural units, and can be recognised 
without too much difficulty by the non-botanist, while 
others are characterised by more technical features not 
easily discernible by the layman. 

Families vary greatly in the number of species they contain: 
on the one hand there are massive families like Orchidaceae 
(orchid family) with 25,000-35,000 species and 
Leguminosae (pea and bean family) with about 14,500 
species (see Table 8.2). In fact, only 31 families contain 
62% of known flowering plant species. At the other 
extreme are the 36 families with a single species, such as 
the Adoxaceae, the family of the well known North 
European woodland flower, Moschatel Adoxa 
moschatellina. 

The grouping of these families into higher taxonomic levels 
such as orders emd subclasses is somewhat more 
problematical, reflecting uncertainty about the fundamental 
evolutionary relationships between families. A commonly 
used scheme (after Cronquist, 1981) is presented in Table 
8.2. 

THE DISTRIBUTION OF fflGHER PLANTS 

Higher plants occur in virtually all ecosystems of the world, 
even in the sea, but their distribution is very uneven. Two- 
thirds of the world's flowering plants are tropical, 
emphasising the great importance of plant conservation in 
the tropics. Many large or economically important families 
such as Annonaceae (custard-apple family), Lauraceae 
(citmamonfamily), Moraceae (fig family), Dipterocarpaceae 
(dipterocarp family), Ebenaceae (ebony family) and 
Meliaceae (mahogany fsimily) are almost entirely restricted 
to the tropics. This contrasts with the distribution of those 
who study plants, for specialists in plant taxonomy work 
mostly in Europe or the USA. The richest continent for 
plants, and still the least explored botanically, is South 
America, home to perhaps as much as one-third of the 
world's higher plants. 

Table 8. 1 gives an assessment of the numbers of species of 
higher plants in various regions of the world. Some of the 
figures, however, are provisional estimates that need to be 



treated with caution. It must be emphasised also that the 
species concept used varies from one region to another, 
which means that any comparison of the numbers of plants 
between regions must be done with care. 

In particular, the differences in species richness between the 
regions of the world shown in Table 8.1 may be somewhat 
exaggerated. The species concept commonly used in Latin 
America, for example, tends to recognise more species, 
based on characters visible in the field, than the taxonomy 
of botanists working on the Malesian region. South America 
is still the continent with the most plants, but the 
differences between this region and tropical Asia or Africa 
may in time be found to be less than suggested. For 
example, estimates of the size of the flora of Colombia, a 
territory with high levels of species diversity and 
endemism, fell over a ten-year period firom 45,000 (Prance, 
1977) to 35,000 (Forero 1988). 

A degree of convergence is apparent. In 1985, lUCN cited 
figures of 20,000 species in North America and 11,300 in 
Europe (Davis et at., 1986). In Table 8.1 the estimate for 
North America has dropped to 17,000, following revised 
estimates by the Flora of North America workers, while 
that for Europe has risen to 12,500, following predictions 
based on the many species added to the recently revised 
first volume of Flora Europaea. It is fair to assume that 
North America does have more plants than Europe, but 
further convergence between the two figures is likely. 

These changes in numbers of species do not result strictly 
from extinctions or the evolution of new species, although 
both of these processes are happening. In most cases, they 
result from decisions of botanists as to the delimitation of 
individual species. Many species in a flora are not clearly 
defined entities, as is, for example, the Gingko tree Ginkgo 
biloba, but are members of a complex group of species 
between which differences may be small. This is 
particularly true of some tropical and Mediterranean floras, 
where many species are extremely difficult to identify in the 
field. At the same time, collaboration between botanists 
who study the floras of different continents (facilitated by 
modern information technology and electronic data retrieval 
systems) is helping to rationalise and standardise the 
classification of plants that have in the past been treated as 
distinct species in different regions. Opinions will naturally 
vary as to the u.se of the rank of species, subspecies or 
merely variety. 

Individual botanists tend to study either the plants of a 
particular country or the members of a particular family. 
Consequently, few data are available as to the numbers of 
species in individual habitats. Nevertheless, some general 
points can be made. Tropical forests, especially moist 
forests, are of enormous importance as habitats for plants. 
The species diversity of these forests, alongside fossil 
evidence, has led many botanists to argue that the flowering 
plants evolved in tropical forests, although it is more likely 
that they represent a 'museum' of evolution (Stebbins, 
1974). Probably half or slightly under half of all higher 
plant species are restricted in the wild to tropical forests, a 
proportion that may be a little lower than that of animals 
because of the exceptional plant richness of Mediterranean 
ecosystems, a richness that is not reflected in faunal 



65 



1. Biological Diversity 



Table 8.1 Distribution of higher plants 
by continents 

Latin America (Mexico through S America) 85,000 ' 

Tropical & Subtropical Africa 40,000 - 45,000 

North Africa 10,000 ' 

Tropical Africa 21,000 ' 

Southern Africa 21,000* 

Tropical & Subtropical Asia 50,000 ' 

India 15,000 ' 

Malesia 30,000 ' 

China 30,000 " 

Australia 15,000 ° 

Caribbean 

Pacific 

North America 17,000 ° 

Europe 12,500 '° 

Sources: ' Gentry, AH. 1982. Neolropical florislic diversity: 
phytogeographical connections between Central and South America, 
Pleistocene climatic fluctuations, or an accident of the Andean 
orogenyl Annals of the Missouri Botanical Garden 69:551-593.^ Based 
on figures for [he size of country floras given in Quezel, P. 1985. 
Definition of the Mediterranean region and the origin of its flora. In: 
Gomez-Campo, C. (Ed.), Plant Conservation in the Mediterranean 
Area. Junk. P. 17. ' Estimate by A.L. Stork, quoted by Peter Raven, 
pers. comm., 1991. ' Cowling, R.M. et al. 1989. Patterns of plant 
species diversity in southern Africa. In: Huntley, B.J. (Ed.), Biolic 
Diversity in Southern AJrica: concepts and conservation. Oxford, Cape 
Town. ' From Raven. P.H. 1987. The scope of the plant conservation 
problem woridwide. In: Bramwell, D. et al. (Eds), Botanic Gardens 
and the World Conservation Strategy. Academic Press. Pp. 19-29. ' 
From Davis, S. et al. 1986. Plants in Danger: What do we know? 
nJCN, Cambridge and Switzerland.' M.M.J, van Balgooy, Leiden, in 
lia. to J.R. Akeroyd, August 1991 . ' Prof Wang Siyu, Beijing, in litt. 
to J.R. Akeroyd, October 1991.' Nancy Morin. pers. comm. via Peter 
Raven, 1991 . '" Estimate by J.R. Akeroyd, based on Flora Europaea, 
1964-80, and the revision of Volume 1, in press. 

Note: 'Malesia' consists of the nations of Malaysia, Brunei, Indonesia, 
Philippines and Papua New Guinea. 

diversity. It is estimated that the Mediterranean basin has a 
flora of 25,000 species of higher plants (Quezel, 1985), a 
high proportion of which are endemic. The other regions of 
the world with a Mediterranean climate - the Cape Province 
of South Africa, SW Australia, California, and Central 
Chile - are also rich in endemics. 

Patterns of plant distribution 

Typical of most, but not all, groups of organisms, the 
diversity of higher plants increases as one moves from the 
poles to the equator. Plant species diversity, however, 
varies markedly on smaller scales. Between 40 and 100 tree 
species may occur on one hectare of tropical moist forest in 
Latin America, compared to 10-30 per hectare in forests in 
eastern North America. In a study done near Iquitos, Peru, 
Gentry found approximately 300 tree species per hectare 
with trunks greater than 10cm in diameter (Gentry, 1988). 

Myers (1990) has estimated that 18 places on earth (termed 
'Hot-Spots') support nearly 50,000 endemic plant species - 
about 20% of the world's total flora - but comprise only 
0.5% of the earth's surface. These 18 places, which range 



widely in scale, are as follows: Artantic coast of Brazil, 
California Floristic Province, Cape Floristic Province, 
Central Chile, Colombian Choco, Eastern Arc forests of 
Tanzania, Eastern Himalayas, Cote d'lvoire, Madagascar, 
New Caledonia, Northern Borneo, Peninsular Malaysia, 
Philippines, South Western Australia, Sri Lanka, Western 
Amazonia uplands. Western Ecuador, and the Western 
Ghats. This and other approaches to distinguishing areas of 
high diversity are discussed further in Chapter 15. 

Although the hot-spots sensu Myers are not deflned by 
habitat, they can be considered in such terms. Six units - 
the Atlantic coast of Brazil, the Colombian Choco, 
Northern Borneo, Peninsular Malaysia, the Philippines and 
the Western Amazonia uplands - are areas of which the 
natural vegetation cover (now severely degraded) is almost 
entirely tropical rain forest, a large proportion of it lowland 
forest. Two more units - the Eastern Arc forests of 
Tanzania and the Western Ghats in India - represent areas 
of tropical montane forest. The vegetation of Western 
Ecuador is essentially a mixture of both (Gentry, 1991). 
Madagascar, Cote d'lvoire and Sri Lanka each have a range 
of habitats but those with by far the richest floras are the 
tropical moist forests. The Eastern Himalayas are a region 
of subtropical to warm -temperate forests, and New 
Caledonia has a wide range of tropical habitats 
(Schneckenburger, 1991). The four other units - the 
California and Cape Floristic Provinces, Central Chile and 
SW Australia -are regions of predominantly Mediterranean 
vegetation. 

Geopolitical distribution of plant diversity 

Table 8.3 is a new compilation of higher plant richness and 
endemism assessed on a territorial basis. The associated 
figures are based on selected data from this table, and 
illustrate the approximate percentage of country floras 
composed of single-country endemic species (Fig. 8.1) and 
the relative species richness of different countries. The 25 
most species-rich countries are represented in Fig. 8.2 and 
countries grouped by continent in Figs. 8.3-8.8 (note that 
graph scales differ between continents). 

It should be noted that these data reflect the size and 
topographic complexity of the countries represented, in 
addition to diversity per unit area as a function of climatic 
and other factors. Nevertheless, the figures do confirm the 
great floristic richness of the regions of moist tropical 
forest. Territories that lie along the equatorial zone of moist 
trade winds can have enormous numbers of species, 
especially in South America: Venezuelahas 15,000-25,000, 
Colombia has 35,000, Brazil may have as many as 55,000 
flowering plant species. African countries show a similar 
high level of diversity, although numbers of species are not 
as great as in South America, perhaps because of 
prehistoric climatic fluctuation. Cameroon has an estimated 
8,000 flowering plant species, Gabon 6,000-7,000 and 
Tanzania 10,000. Floras in SW Asia are intermediate in 
size between those of Africa and South America: there are 
an estimated 20,000 flowering plant species in Indonesia 
and 12,000 in both Malaysia and Thailand. 

Amongst the richest floras are those of larger oceanic 
islands in tropical and warm-temperate latitudes. Cuba has 



66 



Higher Plants 



a flora of 5,499 higher plant species, 3,233 of them 
endemic; Japan has 5,372 species, some 2,000 of them 
endemic; New Caledonia has 3,094 species, 2,480 of them 
endemic; New Zealand has 2,371 species, 1,942 of them 
endemic. The richest island flora is probably that of 
Madagascar, estimated at up to 10,000 species, with 
perhaps as many as 8,000 endemics. These include eight 
endemic families of flowering plsmts, most notably the 
spiny, rather cactus-like Didiereaceae that are a major 
constituent of the vegetation in the drier parts of the island. 

Smaller oceanic islands, even in the tropics, have small 
floras due to the problems of long-distance dispersal for 
plants, but the low total number of species frequently 
includes a large endemic element. Mauritius, including 
Reunion, has a native flora of 878 higher plant species, of 
which 329 are endemic; Socotra has 788 flowering plants, 
268 of which are endemic; St Helena has a native flora of 
just 89 species, but 74 of these are endemic. Even some of 
the very tiny atoll territories in Oceania usually have one or 
a few endemic higher plants. 

Drier tropical and subtropical regions, on the other hand, 
have relatively poor levels of floral diversity when assessed 
purely on a numerical basis. Most of the arid sub-Saharan 
territories of the Sahel belt have smaller floras than have 
many countries in N. Europe: for example, Burkino Faso 
(1,100 higher plant species), Chad (1,600 species), Mali 
(1,741 species) and Niger (1,178 species). These territories 
have but a tiny number of endemics, perhaps no more than 
a dozen between them. That is not to say that the Sahel 
flora is not important, for it contains potentially valuable 
drought-resistant and economic plants. They certainly show 
a good deal less floristic diversity than the territories of the 
Mediterranean region (noted above). Several of the 
territories that border its shores have very high floral 
diversity: Greece has 4,900 flowering plants, 742 of them 
endemic; Spain about the same number, 941 of them 
endemic; and Turkey 8,472 with 2,651 endemics. These 
figure compare favourably with those from many tropical 
territories, although they also reflect more thorough levels 
of floristic exploration. 



References 

Airy Shaw, H.K. (ed.). A Dictionary of the Flowering 

Plants and Ferns. Eighth Edition. Cambridge Univ. 

Press. 1245 pp. 
Cowling, R.M. et al. 1989. Patterns of plant species 

diversity in southern Africa. In: Huntley, B.J. (Ed.), 

Biotic Diversity in Southern Africa: concepts and 

conservation. Oxford, Cape Town. 
Cronquist, A. 1981. y4n Iniegrated System of Classification of 

Flowering Plants. Columbia Univereity Press, NY. 
Davis, S. et al. 1986. Plants in Danger: What do we know? lUCN, 

Cambridge and Switzerland. 
Dixit, R.D. 1984. A Census of the Indian Puridophytes. BoUnical 

Survey of India, New Delhi. 
Forero, E. 1988. Botanical exploralion and phytogeography of 

Colombia: past, present and future. Taxon 37:561-566. 
Gentry, A.H. 1982. Neotropical floristic diversity: phytogeographical 

connections between Central and South America, Pleistocene 

climatic fluctuation, or an accident of the Andean orogGnyt Annals 

of the Missouri Botanical Garden 69:557-593. 
Gentry, A.H. 1988. Tree species richness of upper Amazonian forests. 

Proceedings of the National Academy of Sciences 85:156-159. 
Gentry, A.H. 1991 . Biological extinction in western Ecuador. Annals 

of the Missouri Botanical Garden 78:273-295. 
Johns, R.J. and Bellamy, A. 1979. The Ferns and Fern Allies of Papua 

New Guinea. Papua Nev Guinea Forestry College. 
Myers, N. 1990. The biodiversity challenge: expanded Hot-Spots 

analysis. The Environmentalist IO(4):243-255. 
Prance, G.T. 1977. Floristic inventory of the tropics: where do we 

stand? Annals of the Missouri Botanical Garden 64:659-684. 
Querel, P. 1985. Deflnitionof the Mediterranean region and the origin 

of its flora. In: Gomez-Campo, C. (Ed.), Plant Conservation in the 

Mediterranean Area. Junk. P. 17. 
Raven, P.H. 1987. The scope of the plant conservation problem 

worldwide. In: Bramwell, D. et al. (Eds), Botanic Gardens and the 

World Conservation Strategy. Academic Press. Pp. 19-29. 
Schneckenburger, S. 1991. Neukaledonien. Pflanzenwett einer 

Pazijildnsel. Palmengarten Sonderheft 16. Palmengarten, Frankfurt. 
Stebbins, G.L. 1974. Flowering Plants. Evolution above the species 

level. Edward Arnold. Pp. 165-170. 



Based on a document written by John Akeroyd and Hugh 
Synge. 



67 



1. Biological Diversity 



Table 8.2 



Vascular plants: a summary of systematic diversity 

MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 

FAMILY GENERA 



SPECIES 



Pt«ridophyte« 






Lycopodiaceae 


4 


587 


Selaginellaceae 


1 


725 


Isoetaceae 


1-2 


77-80 


Equisetaoeae 


1 


22 


Psilotaceae 


2 


3-10 


frue fems 






Ophioglossaceae 


3 


81 


Marattiaceae 


4 


204 


Osmundaceae 


3 


18 


Plagiogyriaceae 


1 


36 


Schizaeaceae 


5 


143 


Adiantaceae 


38 


712 


Parkeriaceae 


1 


4 


Vittariaceae 


9 


113 


Pteridaceae 


7 


259 


Marsileaceae 


3 


67 


Hymenophyllaceae 


5 


600 


Hymenophyllopsidacsae 


1 


8 


Stromatopteridaceae 


1 


1 


Matoniaceae 


2 


4 


Gleicheniaceae 


2 


140 


Cheiropleuriaceae 


1 


1 


Dipteridaceae 


1 


8 


Polypodiaceae 


40 


1,068 


Metaxyaceae 


1 


1 


Loxsomataceae 


2 


4 


Thyrsopteridaceae 


2 


6 


Dicksoniaceae 


3 


41 


Lophosoriaceae 


1 


1 


Cyatheaceae 


4 


623 


Thelypteridaceae 


30 


1.000 


Dennstaedtlaceae 


18 


486 


Aspleniaceae 


14 


711 


Woodsiaceae 


18 


70S 


Tectariaceae 


19 


431 


Oryopteridaceae 


20 


464 


Lomariopsidaceae 


8 


615 


Davalliaceae 


6 


218 


Blechnaceae 


8 


238 


Salviniaceae 


1 


10 


Azoltaceae 


1 


6 


Oymnosperms - Cycads 






Zamiaceae 


8 


80 


Cycadaceae 


1 


20 


Stangeriaceae 


1 


1 


Boweniaceae 






Qymnosperini - Conifers 







Pinaceae 

Taxaceae 

Taxodiaceae 

Cupressaceae 



10 



250 



5 


20 


10 


16 


19 


130 



DiSTRfBUTION 

cosmopolitan 

mainly tropical, with some temperate 

species 

temperate and tropical (aquatic) 

cosmopolitan, except Australasia 

tropical and subtropical 

temperate with some tropical 

mostly Old World tropical; some New World 

tropical 

temperate and tropical 

mostly Old World tropical; some New World 

tropical 

pantropical 

pantropicai; subtropical; warm temperate 

pantropical 

pantropical 

pantropical 

temperate and tropical 

pantropical 

northern South America 

New Caledonia 

Malesia 

pantropical 

tropical Asia and Malesia 

tropical Asia; l\/lalesia; Australia; Fiji 

pantropical; subtropical; some temperate 

pantropical 

New World tropical; New Zealand 

pantropical 

pantropical 

New World tropical 

pantropical 

pantropical; some in subtropical and 

temperate 

pantropical 

pantropical; subtropical; some temperate 

pantropical: some temperate 

pantropical 

temperate; tropical 

pantropical 

pantropical 

pantropical 

pantropical; subtropical; a few temperate 

pantropical; subtropical; some temperate 

tropical and subtropical 
Madagascar; eastern and Southeast Asia; 
Indomalaysia; Australia; Polynesia 
South Africa 



Northern Hemisphere, south to Sumatra, 
Java, Central America and West Indies 
Northern Hemisphere, south to Celebes and 
Mexico; one species in New Caledonia 
eastern Asia; Tasmania; North America 
cosmopolitan 



68 



Higher Plant Diversity 



Table 8.2 Vascular plants: a summary of systematic diversity 



MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 

FAMILY 

Araucariaceae 

Cephalotaxaceae 

Phyllocladaceae 



Podocarpaceae 
Gymnosperms - Ginkgo 

Ginkgoaceae 
Gymnosperms - Gnetophytes 

Ephedraceae 

Gnetaceae 

Welwitschiaceae 

Angiosperms - Dicots 

Magnoljidae 

Magnoliales 

Winteraceae 
Degeneriaceae 

Himantandraceae 
Eupomatiaceae 
Austrobaileyaceae 
Magnoliaceae 
Lactoridaceaa 
Annonaceae 
Myristicaceae 
Canellaceae 
Laurales 

Amborellaceae 

Trimeniaceae 

Monimiaceae 
Gomortegaceae 
Calyoanthaceae 
Idiospermaceae 
Lauraceae 
Hernandiaceae 
Piperales 

Chloranthaceae 

Saururaceae 

Piperaceae 
Aristolochiales 

Aristolochiaceae 
llliciales 

llliciaceae 

Schisandraceae 
Nymphaeales 

Nelumbonaceae 
Nymphaeaceae 
Barclayaceae 
Cabombaceae 
Ceratophyllaceae 
Ranunculales 



GENERA 

2 

1 
1 

6 

1 



8-10 

1 

2 



SPECIES 

38 

7 
7 

125 
1 

40 

30 
1 



9 


100 


1 


1 


1 


1-3 


1 


2 


1 


1 


12 

1 


220 

1 


1 

130 


1 

2,300 


15 


300 


6 


20 



600 



40 



50 



2 

50 

4 

8 



DISTRIBUTION 

Southern Hemisphere (excluding Africa) to 
Indochina and the Philippines 
eastern Himalayas to Japan 
Malaysia; Tasmania; New Zealand 
mostly Southern Hemisphere, extending 
north to Japan, Central America, and West 
Indies 

eastern China 

warm temperate North and South America; 
warm temperate Eurasia 
tropical (Indomalaya; Fiji; northern tropical 
South America; western tropical Africa) 
southwestern Africa 



primarily islands of southwestern Pacific 

Fiji 

New Guinea; Molucca Is.; northeastern 

Australia 

New Guinea and eastern Australia 

northeastern Australia 

widespread, especially Northern Hemisphere 

San Juan Islands (Chile) 

mainly tropical 

tropical 

tropical Africa; Madagascar; South America 

New Caledonia 

New Guinea; New Caledonia; Fiji; 

southeastern Australia 

tropical and subtropical, especially Southern 



30-35 


450 


Hemisphere 


1 


1 


central Chile 


3 


5 


China; North America 


1 


1 


northern Australia 


30-50 


2,000 


tropical and subtropical 


4 


60 


tropical 


5 


75 


tropical and subtropical 

eastern Asia; eastern and western North 


5 


7 


America 


10 


1,400-2,000 


tropical 



mainly tropical 

Southeast Asia; southeastern United States; 
Caribbean; Mexico 
tropical and temperate eastern Asia; 
southeastern United States 

warm Asia and Australia; eastern United 

States 

cosmopolitan distribution 

tropical Southeast Asia to New Guinea 

tropical and warm temperate 

cosmopolitan 



69 



1. Biological Diversity 



Table 8.2 Vascular plants: a summary of systematic diversity 

MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 

FAMILY GENERA SPECIES 



Ranunculaceae 
Circaeasteraceae 

Berberidaceae 

Sargentodoxaceae 

Lardlzabalaceae 

Menispermaceae 

Coriariaceae 

Sabiaceae 

Papaverales 

Papaveraceae 
Fumariaceae 
Hamamelidae 

Trochodandralas 

Tetracentraceae 
Trochodendraceae 
Hamamelidales 

Cercidiphyllacaae 
Eupteleaceae 

Platanaceae 

Hamamelidaceae 

Myrothamnaceae 

Daphniphyllales 

Daphniphyllaceae 

Didymelales 

Didymelaceae 

Eucommlales 

Eucommiaceae 

Urticales 

Ulmaceae 

Barbeyaceae 

Cannabaceae 

Moraceae 

Cecropiaceae 

Urticaceae 

Leitneriales 

Leitneriaceae 

Juglandales 

Juglandaceae 
Rhoipteleaceae 

Myrlcales 

Myricaceae 

Fagales 

Balanopaceae 
Fagaceae 

Betulaceae 
Casuarinates 

Casuarinaceae 
Caryophyllidae 

Caryophyllales 

Phytolaccaceae 

Achatocarpaceae 



SO 


2,000 


2 


2 


13 


650 


1 


1 


8 


30 


70 


400 


1 


5 


3 


60 


25 


200 


19 


400 





1 




1 




2 




2 




6-7 


26 


100 




2 




35 




2 




1 


18 


150 




1 


2 


3 


40 


1,000 


6 


276 


45 


700 



7-8 
1 



60 
1 



50 



1 


9 


6-8 


800 


6 


120 


1 


50 


IS 


125 


2 


8 



DISTRIBUTION 

widespread, especially North temperate and 

boreal 

Southeast Asia 

widespread, especially temperate Northern 

Hemisphere 

China, Laos, Vietnam 

Himalayas to Southeast Asia; Chile 

tropical and subtropical 

disjunct in tropical America, Europe, Asia 

Southeast Asia; tropical America 

temperate & tropical Northern Hemisphere 
mainly North temperate; also South Africa 



Nepal; central and southeastern China; 

Burma 

Korea, Japan to Taiwan 

China; Japan 

Japan, China, Assam 

eastern Mediterranean to Himalayas; 

Mexico to Canada 

widespread, especially eastern Asia 

Africa, Madagascar 

Asia and Malay Archipelago 

Madagascar 

montane forests of western China 

widespread, especially Northern Hemisphere 

northeastern Africa and adjacent Arabia 

North temperate 

tropical and subtropical 

tropical 

tropical and subtropical 

southeastern United States 

widespread in Northern Hemisphere and into 

South America 

southwestern China and North Vietnam 

mostly temperate and subtropical 

Southwest Pacific, especially New 

Caledonia 

cosmopolitan, except tropical and South 

Africa 

mainly temperate and cool Northern 

Hemisphere 

Australia, Pacific islands, Asia 



tropical and subtropical 

warm North America; Central America; 

South America 



70 



Higher Plant Diversity 



Table 8.2 Vascular plants: a summary of systematic diversity 



MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 

FAMILY 

Nyctaginaceae 
Aizoaceae 
Didiereaceae 
Cactaceae 

Chenopodiaceae 
Amaranthaceae 

Portulacaceae 
Basellaceae 
Molluginaceae 
Caryophyllaceae 

Polygonales 

Polygonaceae 

Plumbaginales 

Plumbaginaceae 
Dilleniidae 

Dilleniales 

Dilieniaceae 
Paeoniaceae 

Theales 

Ochnaceae 

Sphaerosepalaceae 

Sarcolaenaceae 

Dipterocarpaceae 

Caryocaraceae 

Theaceae 

Actinidiaceae 

Scytopetalaceae 

Pentaphylacaceae 

Tetrameristaceae 
Pellicieraceae 
Oncothecaceae 
Marcgraviaceae 
Quiinaceae 
Elatinaceae 
Paracryphiaceae 
Medusagynaceae 
Guttiferae 
(= Clusiaceae) 
Malvales 

Elaeocarpaceae 

Tiliaceae 

Sterculiaceae 

Bombacaceae 
Malvaceae 
Lecythidales 

Lecythidaceae 

Nepemhales 

Sarracenjaceae 

Nepenthaceae 
Droseraceae 
Violates 



GENERA 


SPECIES 


30 


300 


12 


2,500 


4 


11 


30-200 


1 ,000-2,000 


100 


1,500 


65 


900 


20 


500 


4 


15-20 


13 


100 


75 


2,000 


30 


1,000 


12 


400 


10 


350 


1 


30 


30 


400 


2 


14 


10 


30 


16 


600 


2 


23 


40 


600 


3 


300 


5 


20 



2 


2 


1 


1 


1 


1 


5 


100 


4 


40 


2 


40 


1 


1 


1 


1 



50 



20 



1,200 



10 


400 


50 


450 


65 


1,000 


20-30 


200 


75 


1,000-1,500 



400 



15 



75 
100 



DISTRIBUTION 

tropical and subtropical, especially New 

World 

South Africa; Australia 

Madagascar 

American deserts 

cosmopolitan, especially deserts and 

semideserts 

tropical and subtropical 

cosmopolitan, especially western North 

America and Andes 

tropical and subtropical, mostly New World 

tropical and subtropical, especially Africa 

widespread, especially North America 

mainly temperate Northern Hemisphere 

widespread, especially Mediterranean 



tropical and subtropical, especially Australia 
Eurasia, especially temperate eastern Asia 

tropical, especially Brazil 

Madagascar 

Madagascar 

tropical, especially rain forests of Malaysia 

tropical America, especially Amazon basin 

tropical and subtropical 

tropical and subtropical 

tropical western Africa 

southern China to Malay peninsula and 

Sumatra 

Malaysia; southern Venezuela {Guayana 

Highlands) 

Costa Rica, Panama, Columbia 

New Caledonia 

tropical America 

trooical America, especially Amazon basin 

tropical and subtropical 

New Caledonia 

Seychelles 

moist tropical and North temperate 

tropical and subtropical 

tropical and subtropical 

tropical and subtropical 

tropical, especially Central and South 

America 

cosmopolitan, especially tropical 

tropical, especially rain forests of South 
America 

easter and northwestern United States; 
northern South America 
East Indies to Madagascar; to northern 
Australia and Southeast Asia 
temperate and tropical 



71 



1. Biological Diversity 



Table 8.2 Vascular plants: a 


summary o 


MAJOR GROUP (CLASS) 






SUBCLASS 






ORDER 






FAMILY 


GENERA 


SPECIES 


Flacourtlaceae 


85 


800 


Bixaceae 


3 


IS 


Peridisceceae 


2 


2 


Cistaceae 


8 


200 


Huacaae 


2 


3 


Lacistemataceae 


2 


20 


Scyphostegiacoae 


1 


1 


Stachyuraceae 


1 


5-6 


Violaceae 


16 


800 


Tamaricaceae 


4-5 


100 


Frankeniaceae 


3 


80 


Dioncophyltaceae 


3 


3 


Ancistrocladaceae 


1 


15-20 


Turneraceae 


8 


120 


Malesherbiaceae 


1-2 


25 


Passifloraceae 


16 


650 


Caricaceae 


4 


30 


Achariaceae 


3 


3 


FouquierJaceae 


1 


11 


Hoplestigmataceae 


1 


2 


Cucurbitaceae 


90 


700 


Datiscaceae 


3 


4 


Begoniaceae 


3-5 


1,020 


Loasaceae 


14 


200 


Salicales 






Salicaceae 


2 


340 


Capparales 






Tovariaceae 


1 


2 


Capparaceae 


45 


800 


Cruciferae 






( = Brassicaceae) 


350 


3,000 


Moringaceae 


1 


10 


Resedaceae 


6 


70 


Batales 






Gyrostemonaceae 


5 


17 


Bataceae 


1 


2 


Ericales 







Cyrillaceae 

Clethraceae 
Grubbiaceae 

Empetraceae 

Epacridaceae 

Ericaceae 

Pyrolaceae 



14 



1 
1 


65 
3 


3 


5 


30 


400 


25 


3,500 


4 


45 



DISTRIBUTION 

tropical 

tropical 

tropical South America 

mostly ir^ temperate and warm temperate 

tropical Africa 

tropical America 

Borneo 

Himalayan region to Japan 

cosmopolitan 

Eurasia and Africa, especially Mediterranean 

region 

cosmopolitan, especially Mediterranean 

region 

rain forests of tropical Africa 

Southeast Asia; India; tropical Africa 

tropical and subtropical America and Africa; 

Madagascar 

Andes from Chile to Peru 

tropical and warm temperate, especially 

tropical America and Africa 

tropical and subtropical America; Africa 

South Africa 

arid parts of Mexico and southwestern 

United States 

western tropical Africa 

tropical and subtropical; rarely temperate or 

cool temperate 

Malesia; Asia; western North America 

tropical, especially northern South America 

temperate and tropical North and South 

America 

mostly North temperate; also Australia and 
Malay Archipelago 

tropical America 

tropical and subtropical 

cool temperate or warm temperate Northern 

and Southern Hemisphere 

xeric Africa; Madagascar; India 

Northern Hemisphere, mostly Old World, 

especially Mediterranean 

Australia 

tropical and subtropical America; 
Galapagos; Hawaii; New Guinea and 
northeastern Australia 

northern South America; Central America; 

West Indies; southeastern United States 

tropical America; southeastern United 

States; Southeast Asia; East Indies 

South Africa (Cape Province) 

cold Northern Hemisphere; southern South 

America; eastern United States; Europe 

mostly Australia, New Zealand, and East 

Indies 

temperate, cool and subtropical regions; 

montane tropical 

Northern Hemisphere, especially temperate 

and boreal 



72 



Higher Plant Diversity 



Table 8.2 Vascular plants: a summary of systematic diversity 

MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 

FAMILY GENERA SPECIES DISTRIBUTION 

Monotropaceae 10 12 

Diapensiales 



Diapensiaceae 
Ebenales 

Sapotaceae 
Ebenaceae 
Styracaceae 
Lissocarpaceaa 

Symplocaceae 
Primulales 

Theophrastaceae 

Myrsinaceae 

Primulaceae 
Rosidae 

Rosales 

Brunelliaceae 
Connaraceae 
Eucryphiaceae 



Cunoniaceae 

Davidsoniaceae 

Dialypetalanthaceae 

Pittosporaceae 
Byblidaceae 

Hydrangeaceae 

Columelliaceae 

Grossulariaceae 

Greyiaceae 

Bruniaceae 

Anisophylleaceae 
Alseuosmiaceaa 

Crassulaceae 
Cephalotaceae 

Saxifragaceae 

Rosaceae 

Neuradaceae 

Crossosomatacead 

Chrysobalanaceae 

Surianaceae 

Rhabdodendraceae 
Fabales 

Leguminosae 
(= Fabaceae) 
Proteales 



6 

70 
5 

10 
1 

1 
4 

30 
30 



16-24 
1 



25 
1 
1 

9 

2 

17 
1 

25 
1 

12 

4 
3 

25 
1 

40 

100 

3 

3 

17 

4 

1 



590 



18 

800 

450 

150 

2 

300-400 

100 

1,000 

1,000 



50 

300-400 

6 



350 
1 
1 

200 
4 

170 
4 

350 

3 

75 

40 
12 

900 
1 

700 

3,000 

10 

10 

450 

6 

3 

14,200 



Elaeagnaceae 



50 



arctic & North temperate; south to 
Himalayas 

tropical 

tropical and subtropical 

widely disjunct in both hemispheres 

tropical South America 

tropical and subtropical America; southern 

and eastern Asia; Australia; East Indies 

mostly New World tropical 

tropical and subtropical New and Old World; 

also temperate Old World 

mostly temperate and cold Northern 

Hemisphere; montane tropical 



tropical Amerca 

tropical, especially Old World 

eastern Australia; Tasmania; Chile 

Southern Hemisphere, especially Australia, 

New Guinea and New Caledonia; also 

Mexico and West Indies 

northeastern Australia 

Brazil 

tropical and warm temperate Old World, 

especially Australia 

Australia and South Africa 

temperate and subtropical Northern 

Hemisphere; southeastern Asia and Malesia 

Andes, from Colombia to Bolivia 

cosmopolitan 

South Africa 

South Africa and Natal 

tropical or subtropical forests, mostly Africa 

and Indomalaysia; South America 

Nbw Zealand and New Caledonia 

cosmopolitan, except Australia and 

Polynesia 

southwestern Australia 

cosmopolitan, especially temperate and cold 

Northern Hemisphere 

cosmopolitan, especially temperate and 

subtropical Northern Hemisphere 

deserts in Africa, across Middle East to 

India 

arid western United States and adjacent 

Mexico 

pantropical, especially New World 

Australia and tropical maritime 

tropical South America 

cosmoDolitan, especially tropical and 
subtropical 

temperate and subtropical Northern 
Hemisphere, to tropical Asia and northern 
Australia 



73 



1. Biological Diversity 



Table 8.2 Vascular 


plants: a 


summary o 


MAJOR GROUP (CLASS) 






SUBCLASS 






ORDER 






FAMILY 


GENERA 


SPECIES 


Proteaceae 


75 


1,000 


Podostemales 






Podostemaceae 


40 


200 


Haloragales 






Haloragaceae 


8 


100 


Gunneraceae 


1 


50 


Myrtalos 






Sonneratiaceae 


2 


10 


Lythraceae 


24 


500 


Penaeaceae 


7 


20 


Crypteroniaceae 


1 


4 


Thymelaeaceae 


50 


500 


Trapaceae 


1 


15 


Myrtaceae 


140 


3,000 


Punicaceae 


1 


2 


Onagraceae 


17 


675 


Oliniaceae 


1 


8 


Melastomataceae 


200 


4,000 


Combretaceae 


20 


400 


Rhizophorales 






Rhizophoraceae 


14 


100 


Cornales 






Alangiaceae 


1 


20 


Nyssaceae 


3 


7-8 


Cornaceae 


11 


100 


Garryaceae 


1 


13 


Santalales 






Medusandraceae 


1 


1 


Olacaceae 


24-30 


250 


Dipemodontaceae 


1 


1 


Opiliaceae , 


9 


50 


Santalaceae 


35 


400 


Misodendraceae 


1 


10 


Loranthaceae 


60-70 


700 


Viscaoeae 


7-8 


350 


Eremotepidaceae 


3 


12 


Balanophoraceae 


19 


45 


Rafflesiales 






Hydnoraceae 


2 


10 


Mitrastemonaceae 


1 


2 


Rafflesiaceae 


7 


50 


Celastrales 






Geissolomataceao 


1 


1 


Celastraceae 


50 


800 


Hippocrateaceae 


2-13 


300 


Salvadoraceae 


3 


12 


Stackhousiaceae 


3 


20-25 


Aquifoliaceae 


4 


320-420 


Icacinaceae 


50 


400 



DISTRIBUTION 

tropical and subtropical, especially warmer 
Southern Hemisphere 

mostly tropical, especially Asia and America 

cosmopolitan, especially Southern 

Hemisphere 

Southern Hemisphere to southern Mexico 

Old World tropical 

mainly tropical; also temperate 

Cape Province (South Africa) 

India, Philippines, Malay Archipelago 

cosmopolitan 

tropical and subtropical Africa and Eurasia 

tropical and subtropical; temperate Australia 

Balkans to northern India; Socotra 

temperate and subtropical, especially New 

World 

tropical and southern Africa; St Helena 

tropical and subtropical, especially South 

America 

tropical and subtropical, especially Africa 

tropical and subtropical 

eastern and tropical Asia; eastern Australia; 

Pacific islands; Madagascar; western Africa 

eastern North America; eastern Asia; Pacific 

islands; China 

North temperate; irregularly tropical and 

South temperate 

western North and Central America, from 

Washington to Panama 

rainforests of tropical western Africa 

tropical and subtropical 

southern China and Burma 

tropical and subtropical 

nearly cosmopolitan, especially arid climates 

temperate South America 

mostly tropical and subtropical 

cosmopolitan, especially tropical 

tropical America 

tropical and subtropical 

drier parts of Africa, Madagascar 
Borneo and Sumatra to Indochina and 
Japan; Mexico and Central America 
tropical and subtropical 

South Africa (Cape Province) 

pantroplcal, some In temperate regions 

tropical 

Africa; Madagascar; India; Sri Lanka; 

Southeast Asia 

Australia and New Zealand; southwestern 

Pacific 

more or less cosmopolitan 

pantroplcal 



74 



Higher Plant Diversity 



Table 8.2 Vascular plants: a summary of systematic diversity 

MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 

FAMILY GENERA SPECIES 

Aextoxicaceae 1 1 

Cardiopteridaceae 1 3 



Corynocarpaceae 


1 


5 


Dichapetalaceae 


3 


235 


Euphorbiales 






Buxaceaa 


5 


60 


Simmondsiaceae 


1 


1 


Pandaceae 


3 


26 


Euphorbiaceae 


300 


7,500 


Rhamnales 






Rhamnaceae 


55 


900 


Leeaceae 


1 


70 


Vitaceae 


11 


700 


Linales 






Erythroxyiaceae 


4 


200 


Humiriaceao 


8 


50 


Ixonanthaceae 


5 


30 


HugonJaceae 


7 


60 


Linaceaa 


6 


220 


Polygalales 






Malpighiaoeae 


60 


1,200 


Vochysiaceae 


7 


200 


Trigoniaceae 


3 


26 


Tremandraceae 


3 


28 


Polygalaceae 


12 


750 


Xanthophyllaceae 


1 


40 


Krameriaceae 


1 


15 


Sapindales 






Staphyleaoeae 


5 


50 


Melianthaceae 


2 


8-36 


Bretschneideraceae 


1 


1 


Akaniaceae 


1 


1 


Sapindaceae 


140 


1,500 


HIppocastanaceae 


2 


16 


Aceraceae 


2 


112 


Burseraceae 


16-20 


600 


Anacardiaceae 


60-80 


600 


Julianiaceae 


2 


5 


Simaroubaceae 


25 


150 


Cneoraceae 


1 


3 


Meliaceae 


51 


550 


Rutaceae 


150 


1,500 


Zygophyllaceae 


30 


250 


Geraniales 







DISTRIBUTION 

Chile 

Asia to New Guinea and Australia 

New Zealand; northeastern Australia; New 

Guinea 

pantropical, mainly Africa 

nearly cosmopolitan 

western United States and Mexico 

Africa, Asia, New Guinea 

cosmopolitan, especially tropical and 

subtropical 

cosmopolitan, especially tropical and 

subtropical 

pantropical 

tropical and subtropical; a few in temperate 

regions 

pantropical, especially New World 

mainly tropica! South America, with one 

species in Africa 

pantropical 

tropical 

widespread, especially temperate and 

subtropical 

tropical and subtropical, especially South 

America 

mostly tropical America, 1 in Africa 

subtropical in moist lowland forests 

Australia and Tasmania 

nearly cosmopolitan 

Indomalaysian region 

Argentina and Chile, mainly in dry regions 

Americas, Eurasia, Malay Archipelago 

Africa 

mountains of western and southwestern 

China 

eastern Australia 

tropical and subtropical; some in temperate 

regions 

North America to northern South America; 

Europe; Southeast Asia 

temperate and subtropical, especially 

Malesia; China 

pantropical, especially tropical America and 

Northeast Africa 

mainly pantropical, some in temperate 

regions 

tropical America (Central America, Peru) 

pantropical, some in warm temperate 

regions 

Mediterranean, Canary Is., Cuba 

tropical and subtropical; some in temperate 

regions 

nearly cosmopolitan, especially South Africa 

and Australia 

mostly arid tropical and subtropical, 

sometimes in saline habitats 



75 



/. Biological Diversity 



Table 8.2 Vascular plants: a summary of systematic diversity 

MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 

FAMILY GENERA 



Oxalidaceae 

Geraniaceae 

Limnanthaceae 

Tropaeolaceae 

Balsaminaceae 
Apiales 

Araliaceae 
Umbelliferae 
(= Apiaceae) 
Asteridae 

Gentianales 

Loganiaceae 
Retziaceae 

Gentianaceae 
Saccifoliaceae 

Apocynaceae 

Asclepiadaceae 
Solanales 

Nolanaceae 
Duckeodendraceae 

Solanaceae 

Convolvulaceae 

Cuscutaceae 
Menyanthaceae 

Polemoniaceae 

Hydrophyllaceae 

Lamiales 

Lennoaceae 

Boraginaceae 

Verbenaceae 
Labiatae 
(= Lamiaceae) 
Callitrichales 

Hippuridaceae 
Callitrichaceae 
Hydrostachyaoeae 

Plantaginales 

Plantaginaceae 

Scrophulariales 
Buddlejaceae 



7-8 

11 

2 
3 



70 

300 



20 
1 

75 

1 

200 



250 



SPECIES 

900 

700 
11 
92 

450 

700 

3,000 



500 
1 

1,000 

1 

2,000 
2,000 



2 

1 


66 
1 


85 


2,800 


50 


1,500 


1 
5 


150 
30-35 


18 


300 


20 


250 



4-5 



100 


2,000 


100 


2,600 


200 


3,200 


1 
1 

1 


1 
35 
20 


3 


254 


10 


150 



DISTRIBUTION 

tropical and subtropical; some in temperate 

regions 

temperate and warm temperate regions; 

some tropical 

temperate North America 

Mexico to Chile (in mountains), Patagonia 

tropical Asia and Africa, some in temperate 

regions; India to Java 

tropical and subtropical; some in temperate 

regions 

nearly cosmopolitan, especially North 

temperate regions and tropical mountains 



tropical and subtropical; relatively few 

species in temperate regions 

Cape Province of South Africa 

cosmopolitan, especially temperate and 

subtropical regions and tropical mountains 

southern Venezuela 

tropical and subtropical; relatively few 

species in temperate regions 

tropicals and subtropical, especially Africa, 

with relatively few species in temperate 

regions 

northern Chile and southern Peru, often 

along the seashore 

Amazon basin of Brazil 

nearly cosmopolitan, especially tropical 

South America 

nearly cosmopolitan, especially tropical and 

subtropical 

nearly cosmopolitan, especially warmer 

parts of New World 

cosmopolitan 

North temperate (Eurasia, Alaska to western 

South America), especially temperate North 

America 

wide-ranging, especially dry western United 

States 

New World from southwestern United 

States to Colombia and Venezuela 

cosmopolitan, especially western North 

America and Mediterranean region; east into 

Asia 

pantropical, with only a few species in 

temperate regions 

cosmopolitan, especially Mediterranean 

region and into central Asia 

temperate and boreal Northern Hemisphere; 
Australia; southern South America 
nearly cosmopolitan 
Madagascar; tropical and southern Africa 

cosmopolitan 

mainly tropical and subtropical 



76 



Higher Plant Diversity 



Table 8.2 Vascular plants: a summary of systematic diversity 

MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 



FAMILY 


GENERA 


SPECIES 


Oleaceae 


30 


600 


Scrophulariaceae 


190 


4,000 


Globulariaceae 


10 


300 


Myoporaceae 


3-4 


125 


Orobanchaceae 




17 


Gesneriaceae 


120 


2,500 


Acanthaceae 


250 


2,500 


Pedaliaceae 


20 


80 


Bignoniaceae 


100 


800 


Mendonciaceae 


2-4 


60 


Lentibulariaceae 


5 


200 


Campanulales 






Pentaphragmataceae 


1 


30 


Sphenocleaceae 


1 


2 


Campanulaceae 


70 


2,000 


Stylidiaceae 


5 


155 


Donatiaceae 


1 


2 


Brunoniaceae 


1 


1 


Goodeniaoeae 


14 


300 


Rubrales 






Rubiaceae 


450 


6,500 


Theligonaceae 


1 


3 


Dipsacales 






Caprifoliaceae 


15 


400 


Adoxaceae 


1 


1 


Valerianaceae 


13 


300 


Dipsacaceae 


10 


270 


Calycerales 






Calyceraceae 


6 


60 


Asterales 






Compositae 






(= Asteraceae) 


1,100 


20,000 


Angiosperms - Monocots 






Alismatidae 






Alismatales 






Butomaceae 


1 


1 


Limnocharitaceae 


3 


7-12 


Alismataceae 


12 


75 


Hydrooharitales 






Hydrocharitaceae 


15 


15 100 


Najadales 






Aponogetonaceae 


1 


40 


Scheuchzerjaceae 


1 


1 



DISTRIBUTION 

nearly cosmopolitan, especially Asia and 

Malesia 

cosmopolitan, especially temperate regions 

and tropical mountains 

Africa; Madagascar; Europe; western Asia 

Australia; Asia; Pacific islands; West Indies; 

northern South America 

150 

pantropical, with a few species in temperate 

regions 

tropical, with only a few species in 

temperate regions 

mostly tropical, especially along seacoast or 

in arid regions, with only a few species in 

temperate climates 

mainly tropical, especially tropical America 

South America; tropical Africa; Madagascar 

cosmopolitan 

Southeast Asia and nearby Pacific islands 

pantropical; western Africa 

cosmopolitan 

Australasia; south and Southeast Asia; 

southernmost South America 

southern South America; New Zealand; 

Tasmania 

Australia 

primarily Australia; also New Zealand, 

Japan, and tropical and subtropical Old and 

New World 

cosmopolitan, especially tropical and 

subtropical 

temperate eastern Asia to Mediterranean 

region and Canary Islands 

mostly North temperate and boreal regions; 

also tropical mountains 

circumboreal 

nearly cosmopolitan, especially North 

temperate regions and Andes 

Eurasia and Africa, especially Mediterranean 

region 

Central and South America 

cosmopolitan, especially temperate and 
subtropical regions 



temperate Eurasia 
tropical and subtropical 
cosmopolitan, especially Northern 
Hemisphere 

cosmopolitan 

Old World tropical to South Africa 
cool Northern Hemisphere 



77 



1. Biological Diversity 



fable 8.2 Vascular plants: a summary of systematic diversity 



MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 

FAMILY 

Juncaginaceae 
Potamogetonaceae 
Ruppiaceae 
Najadaceae 
Zannichelljaceae 
Posidoniaceae 
Cymodoceaceae 
Zosteraceae 
Triuridales 

Triuridaceae 

Petrosaviaceae 
Arecidae 

Arecales 
Palmae 

( = Arecaceae) 
Cyclanthales 

Cyolanthaceae 
Pandanales 

Pandanaceae 
Arales 

Araceae 
Lemnaceae 
Commelinidae 

Commelinales 

Rapateaceae 

Xyridaceae 

Mayacaceae 
Commelinaceae 
Eriocaulales 

Eriocautaceae 
Restionales 

Flagellariaceae 

Restionaceae 
Joinvilleaceae 



Centrolepidacoae 
Juncales 

Juncaceae 
Thurniaceae 
Cyperales 

Cyperaceae 

Gramineae 
(= Poaceae) 
Hydatellales 

Hydatellaceae 
Typhales 

Sparganiaceae 
Typhaceae 



GENERA 

5 
1 
1 
1 

4 
1 
5 
3 

7 
1 



70 



SPECIES 

20 

100 

1-2 

35 

7-8 

3 

18 

18 

70 

2 



200 


3,000 


11 


180 


3 


682-782 


110 
6 


1.800 
31 



16 


100 


4 


200 


1 
50 


4 
700 


13 


1,200 


1 


3 


30 

1 


400 

2 



35 



300 
3 



4,000 



500 


8,000 


2 


7 


1 


13 


1 


10 



DISTRIBUTION 

temperate and cold Northern and Southern 

Hemisphere 

cosmopolitan 

temperate and subtropical 

cosmopolitan 

cosmopolitan 

Mediterranean, Australia 

tropical and subtropical seacoasts 

subarctic, temperate, subtropical seacoasts 

tropical and subtropical 

southern China and southern Japan to 

Malay Peninsula and Borneo 



tropical and warm temperate 

tropical America 

Old World, especially tropical (Malesia) 

mostly tropical and subtropical 
cosmopolitan 



tropical South America, with one species in 

tropical western Africa 

tropical and subtropical; a few species In 

temperate region 

tropical western Africa; tropical and warm 

temperate America 

tropical and subtropical 

tropical and subtropical, with a few species 
in temperate regions 

Old World tropical 

widely distributed in Southern Hemisphere, 

especially Australia and South Africa 

Pacific Islands 

Australia; Southeast Asia; Pacific Islands; 

southernmost South America; mostly in 

nutrient-poor soils 

temperate or cold regions, or montane 

tropical 

Amazon basin and Guayana 

cosmopolitan, most abundant in temperate 

regions 

cosmopolitan, especially tropical and North 

temperate semi-arid regions with seasonal 

rainfall 

Australia, New Zealand, Tasmania 

chiefly North temperate regions, to Australia 

and New Zealand 

cosmopolitan 



78 



Higher Plant Diversity 



Table 8.2 Vascular plants: a summary of systematic diversity 



MAJOR GROUP (CLASS) 
SUBCLASS 
ORDER 

FAMILY 

Zingiberidae 
Bromaliales 

Bromeliaceae 
Zingiberales 

Strelitziaceae 



Heliconiaceae 
Musaceae 

Lowiaceae 

Zingiberaceae 
Costaceae 
Cannaceaa 
Marantaceae 

Liliales 

Philydraceae 

Pontedariaceae 

Haemodoraceae 
Cyanastraceae 

Llliaceae 
Irldaceae 

Velloziaceae 

Aloeaceae 

Agavaceae 



Liliida 



GENERA 



18 



SPECIES 



45 


2,000 


3 


7 


1 


100 


2 


42 



47 


1,000 


4 


150 


1 


50 


30 


400 



4 


5 


9 


30 


16 


100 


1 


7 


280 


4,000 


80 


1,500 


6 


250 


5 


700 



600 



Xanthorrhoaaceae 
Hanguanaceae 


9 

1 


55 
1-2 


Taccaceae 


1 


10 


Stemonaceae 


3 


30 


Smilacaceae 


12 


330 


Dioscoreaceae 
Orchidales 


6 


630 


Burmanniacaae 
Geosiridaceae 
Corsiaceae 
Orchidaceae 


20 

1 

2 

800-1,000 


130 

1 

9 

25,000-35,000 



DISTRIBUTION 



New World, except one species in western 
tropical Africa 

tropical 

tropical and subtropical South and Central 

America; one species widespread in 

southwestern Pacific islands 

tropical and subtropical Old World 

southern China; Malay Peninsula; Pacific 

islands 

tropical regions, especially southern and 

Southeast Asia 

pantropicai, especially New World 

tropical and subtropical New World 

pantropicai, especially New World 



Australia; western Pacific islands to Japan 

and mainland Southeast Asia 

tropical and subtropical; into North 

temperate regions 

mostly Southern Hemisphere, but reaching 

northern United States 

forests of tropical Africa 

widespread, especially dry, temperate to 

subtropical regions 

cosmopolitan, especially South Africa 

South America; Africa; Madagascar; 

southern Arabia 

Africa, Madagascar, Arabia, nearby islands; 

especially South Africa 

warm, mostly arid regions of New and Old 

Worlds; a few in distinctly temperate 

climates 

Australia; Tasmania; New Guinea; New 

Caledonia 

Malesia; Sri Lanka 

pantropicai, especially Southwest Asia and 

Polynesia 

eastern Asia; Malesia; northern Australia; 

southeastern United States 

tropical and subtropical, especially Southern 

Hemisphere; also in parts of North 

temperate region 

tropical and subtropical, with a few species 

in North temperate region 

pantropicai, with a few species in temperate 

regions 

Madagascar and other Indian Ocean islands 

New Guinea, Chile 

cosmopolitan 



Sources: Flowering plant information modified from Cronquisl, A. 1981. An Integrated System of Classification of Flowering Plants. Columbia 
Univ. Press. 1262 pp.; other information from Airy Shaw, H.K. (ed.). A Dictionary of the Flowering Plants and Ferns. Eighth Edition. Cambridge 
Univ. Press. 1245 pp.; and other sources. 



79 



1. Biological Diversity 



rable 8.3 


Species richness and endem 


ism: high 


er 


plants 










FLOWERING 


GYMNO- 


FERNS 


NUMBER OF 




K 


ESTIMATE/ 


COMPLETION 


DATE 






PLANTS 


SPERMS 




ENDEMICS ENDEMISM 


COUNT 






ASIA 






















Afghanistan 




3,500 


- 


- 


_ 


[30 


-35%] 


e2 


2 


1989-91 


Bahrain 




las 


1 


1 







0.0 


c 


1 


1991 


Bangladesh 




5,000 


- 


- 


- 






eZ 


2 


1972 


Bhutan 




5,448 


22 


— 


50-100 




1.4 


el 


3 


1991 


Bfitsh Indian Ocean 


Tefriofv 


100 


1 


— 







0.0 


el 


1 


1971 


Brunei 




3.000 


28 


_ 


7 




0.2 


e2 


5 


1990 


Cambodia 




_ 


_ 


_ 


_ 




_ 


_ 


_ 




China 




30,000 


200 


2.000 


18.000 




55.9 


a2 


3 


1991 


Cyprus 




1,650 


12 


20 


88 




5.2 


c 


1 


1977-85 


Hona Kong 




1.800 


4 


180 


25 




1.3 


e2 


2 


1978-91 


India 




15,000 


- 


1.000 


5.000 




31.3 


e2 


2 


1983-84 


Indonesia 




20,000 


- 


2.500 


15.000 




66.7 


e3 


4 


1991 


Iran. Islamic Rep 




6,500 


33 


— 


— 


130 


-35%1 


e2 


1 


1989-91 


Iraq 




2,914 


7 


16 


190 




6.5 


c 


1 


1966-86 


Israel 




2.294 


8 


15 


155 




6.7 


c 


1 


1982-84 


Japan 




4.700 


42 


630 


2.000 




37.2 


c 


1 


1987 


Jordan 




2,200 


6 


6 


- 




- 


c 


2 


1982-85 


Korea, Oem People's 


Rep 


{2.898 


- 


— 


107 




(14.0 


{c 




{1976-83 


Korea, Rep 




{2,898 


- 


- 


224 




(14.0 


(c 


_ 


{1976-83 


Kuwait 




234 


1 


1 







0.0 


e 


1 


1991 


Laos 






_ 


_ 






_ 


_ 


_ 




Letsanon 




2,000 


12 


40 


_ 




[10%] 


e3 


2 


1984-91 


Malaysia 




12,000 


— 


500 


— 






e3 


3 


1991 


Maldives 




260 


2 


15 


5 




1.8 


c 


1 


1983 


Mongolia 




2.272 


- 




229 




10.1 


c 


1 


1984 


Myanrrutf 




7.000 


- 


_ 


1.071 




15.3 


e2 


4 


1961 


Nepal 




6.500 


23 


450 


315 




4.5 


c 


2 


1978-82 


Oman 




1.018 


3 


14 


74 




7.1 


c 


1 


1991 


Pakistan 




4.917 


21 


— 


372 




7.5 


el 


2 


1986 


Philippines 




8.000 


31 


900 


3.500 




39.3 


e2 


3 


1982-91 


Qatar 




220 


1 










0.0 


c 


1 


1991 


Saudi Arabia 




1,729 


8 


22 


34 




1.9 


c 


2 


1991 


Singapore 




2,000 


2 


166 


1 




0.1 


el 


1 


1989-91 


Sri Lanka 




2.900 


- 


314 


900 




28.0 


c 


2 


1982-83 


Syria 




2.000 


12 


40 


_ 




f10%l 


e3 


2 


1984-91 


Taiwan 




2.983 


20 


565 


_ 




(25%) 


c 


1 


1982-91 


Thaibnd 




12,000 


25 


600 


— 






e2 


3 


1979-85 


Turkey 




8.472 


22 


85 


2.651 




30.9 


c 


1 


1988 


United Arab Emirates 




340 


2 


5 









c 


1 


1991 


Viet Nam 




- 


— 


_ 






_ 








Yemen. People's Dem Rep' 


1.373 


3 


41 


58 




4.1 


c 


2 


1991 


Yemen. Arab Rep' 




959 


1 


14 


77 




7.9 


c 


1 


1991 



USSR^ 



EUROPE 

Albania 

Andorra 

Austria 

Belgium 

Bulgaria 



22.000 



2.965 

980 

2.850-3.050 

1.250-1.550 

3.505 



74 



21 
6 

12 
2 

15 



45 
26 
66 
50 
52 



24 


35 

1 

320 



0.8 
0.0 
1.2 
0.1 
9.0 



el 
el 
a1 



1991 



1980-88 

1981 

1978-91 

1978-83 

1991 



Czechoslovakia 
Denmark 
Faeroe Islands 
Finland 
France 



2.507 

1.000-1.400 

236 

1.040 

4.500 



11 
2 
1 
4 

20 



72 
50 
25 
58 
110 



62 

1 

1 



133 



2.4 
0.1 
0.4 
0.0 
2.9 



1991 
1984-91 
1991 
1988 
1991 



Germany 

Greece 

Hungary 

Iceland 

Ireland 



2.600 

4.900 

2,148 

340 

892 



10 
21 
8 
1 
2 



72 
71 
58 
36 
56 



6 

742 

38 

1 





0.2 
14.9 
1.7 
0.3 
0.0 



el 
el 



1984-91 
1989 
1991 

1984-91 
1991 



Italy 

Liechtensteh 
Luxemtjourg 
Malta 
Mormco 



5.463 

1.400 

1.200 

900 



29 
10 

4 
3 

4 



42 
11 
18 



712 





5 





12.7 
0.0 
0.0 
0.5 
0.0 



e2 

el 
el 



1982 
1977 
1984-91 
1984 
1973 



Netherlands 

Norway 

Poland 

Portugal^ 

Ronnania 



1.170 
1.550-1.750 
2.200-2.400 
2.400-2.600 
3.000-3.350 



3 
4 

10 
8 

11 



48 
61 
62 
65 
62 





1 

3 

150 

41 



0.0 
0.1 
0.1 
5.8 
1.3 



el 
el 
el 
e2 



1991 
1078-91 
1978-91 
1978-91 
1977-78 



San Marino 
Spain' 
Sweden 
Switzerland 
United Kirwdom 



4,916 

1,550-1,750 

2,927 

1.550 



18 
4 

16 
3 



114 
60 
87 
70 




941 

1 

1 

16 



0.0 
18.6 
0.1 
0.1 
1.0 



el 
c 
el 



1991 

1984-91 

1978-91 

1989 

1991 



Vatican City 
Yugoslavia 



5,250 



23 



78 




137 



0.0 
2.6 



e2 



1991 
1978-91 



80 



Higher Plant Diversity 



Table 8.3 Sped 


es richness and 


endem 


ism: high 


er plants (continued) 






FLOWERING 
PLANTS 


GYMNO- 
SPERMS 


FERNS 


NUMBER OF % 
ENDEMICS ENOEMISM 


ESTIMATE/ 
COUNT 


COMPLETION 


DATE 


NORTM AND CEf^mAL AMERICA 


















Anguila 

Antigua and Barbuda 

Aruba 

Bahamas 

Barbados 




321 
766 
460 

1.172 
542 


1 
3 



33 

• 43 
30 


1 

25 

115 
5 


0.3 
,0.7%, 

9.4 
0.8 


c 
c 
c 
c 
c 


1 

1 
2 


1991 
1938-91 

1991 
1982-91 
1984-91 


Belize 
Bermuda 
Canada 

Cayman Islands 
Costa Rica 


2,50C 
10.000 


1-3.000 

147 

2.920 

518 

-12.000 


10 


33 
1 

9 


134 

20 

65 

20 

1.000 


150 
15 

147 

19 

1.800 


5.2 
9.0 
4.9 
3.4 
15.0 


e2 

c 
c 
c 
•2 


2 
1 
1 
1 
3 


1989-91 
1991 

1967-91 
1984 

1989-91 


Cuba 
Dominica 

Dominican Republic 
El Salvador 
Greenland (Denmark) 




5.996 
1,127 
{5.000 
2,500 
497 


23 
1 

{7 
8 

1 


495 

197 

{650 

400 

31 


3.229 

11 

{1.800 

17 




49.6 
0.8 

0.6 
0.0 


e 
c 
c 
e2 

c 


2 

1 

1 


1991 

1991 

1984-91 

1989-91 

1978 


Grenada 

Guadeloupe 

Guatemala 

Haiti 

Honduras 




919 
{1670 
8.000 
{5.000 
5.000 


1 

1 
29 

g 


148 
261 
{652 
{650 
325 


4 

26 

1,171 

{1.800 

148 


0.4 

1.6 

13.5 

31.8 

2.8 


•3 

c 

e2 

c 

e2 


2 
1 
3 

'1 


1979-91 
1991 
1989-91 
1984-91 
1978-91 


Jamaica 
Martinique 
Mexico 
Montserrat 
Netherlands Antiles 


20.000- 


2.746 

{1670 

-30,000 

554 


4 

1 

71 


558 

259 

1,000 

117 


906 

30 

3.624 

2 


27.4 
1.9 

13.9 
0.3 


c 
c 

e2 
c 


2 

1 
3 

1 


1991 
1979-91 
1984-91 

1991 


Nicaragua 
Panarrta 
Puerto Rico 
St Kitts and Nevis 
St Lucia 




7,000 

9,000 

2,128 

533 

909 


12 

1 


500 
577 
364 
122 
118 


57 

1,222 

235 

11 


0.8 

12.7 

9.4 

1.1 


e2 
e2 
e2 

c 
c 


3 
3 
2 

1 


1989-91 

1989-91 

1982-91 

1979 

1991 


St Vincent and the Grenadines 
Trinidad and Tot^ago 
Turks and Caicos Islands 
United States 
Virgin Islands (British) 




1,000 

2,132 

440 

18,956 


1 

1 
113 


165 
289 

7 
404 


226 

9 

4.036 


9.3 

2.0 

20.7 


e3 
e2 

c 
c 


3 

1 
1 
2 


1979-91 

1981-91 

1982 

1978-91 


Virgin Isbnds (US) 

SOUTH AMERICA 

Argentina 

Bolivia 

Brazil 

Chile 

Colombia 




- 


- 


- 


- 


- 


- 


- 


- 


15.000- 
4.750 


9,000 
-18,000 

55,000 
1-5,500 

35.000 


13 
17 


359 
150 


2,698 
1,500 


,25-30%, 

51.1 
4.3 


el 
e3 
a3 

el 
e2 


2 
5 

4 
2 
4 


1984-91 
1989 
1979 

1983-91 
1989 


Ecuador 
French Guiana 
Guyana 
Paraguay 
Peru 


16.500- 
7.000 


-20.000 
5.000 
6.000 

1-8.000 
13.000 


11 


1.100 
318 

1.000 


4,000 


20.7 


e2 
el 
e3 
e3 
e2 


4 
2 
2 

4 
4 


1986-91 
1991 
1991 
1985 

1984-91 


Suriname 

Uruguay 

Venezuela 


15.000- 


4.500 
-25.000 


2 

2 

14 


293 

81 

1.059 


8,000 


38.0 


el 
c 
e3 


2 

4 


1978-91 

1991 

1979-91 


OCEANIA 




















American Samoa 

Austraia 

Cook Islands 

Fiji 

French Polynesia 




328 

15,000 

184 

1,307 





11 


125 

100 
310 


10 

3 
812 


2.2 

,80%, 

1.1 

49.9 


e 
c 

c 
c 


1 
3 

1 
1 


1991 
1990 
1991 
1991 


Guam 

Kirbati 

Marshall Islands 

Miaonesia, Federated States of 

Nauru 




330 

60 

100 

50 



1 




10 

4 


2 
4 

1 


[69%, 
3.3 
3.6 

1.9 


•2 

82 

•2 


1 
1 
2 

2 


1970 
1873-74 
1960-82 

1982 


New Caledonia 

New Zealand 

Niue 

North Marianas Islands 

Palau 




2,750 

2,160 

150 

250 


44 

22 



1 


300 

189 

28 

64 


2,480 

1,942 

1 

81 


80.2 

81.9 

0.6 

25.7 


c 
c 
c 
e2 


2 

1 
1 
3 


1991 

1991 

1991 

1978-82 


Papua New Guinea 
Pitcairn Islands 
Solomon Islands 
Tokelau 
Tonga 




10,000 

56 

2,780 

26 

360 


44 


22 


1 


1,500 

20 

370 

6 

102 


14 

30 



25 


(55%, 

18.4 

0.9 

0.0 

5.4 


•2 

c 
•1 

c 
c 


4 
2 
3 

1 
1 


1979-81 

1860-83 

1991 

1991 

1991 


Tuvalu 

Vanuatu 

Wallis and Futuna Islands 

Western Samoa 




1,000 
250 
493 





200 


50 

5 
117 


5.0 

2.0 

16.9 


el 
el 

c 


1 
1 

1 


1978 
1983 
1991 



81 



/. Biological Diversity 

Table 8.3 Species richness and endemism: higher plants (continued) 





FLOWERING 


GYMNO- 


FERNS 


NUMBER OF 


% 


ESTIMATE/ 


COMPLEnON 


DATE 




PLANTS 


SPERMS 




ENDEMICS 


ENDEMISM 


COUNT 






AFrTARCTICA 


















Antarctica 


41 





11 


11 


21.2 


c 


1 


1SS0 


Falkland Islands (Malvinas) 
French Southern Territories 


148 





19 


14 


8.5 


c 


1 


1091 


30 





20 


11 


22.0 


c 


1 


leeo 


AFRICA 


















Algeria 


3,100 


18 


46 


250 


7.9 


el 


2 


1975-84 


Angola 


5,000 


- 


185 


1.260 


24.3 


e2 


3 


1991 


Benin 


{3050 


{1 


(200 





0.0 


c 


2 


1091 


BotsMina 


— 





15 


17 




c 


3 


1970-78 


Burkina Faso 


1.100 





— 





0.0 


e3 


3 


1954-85 


Burundi 


2,500 


- 


- 


_ 




e2 


2 


1901 


Cameroon 


8,000 


3 


257 


158 


1.9 


eZ 


3 


1984-83 


Cape Verde 


740 





34 


88 


11.1 


c 


1 


1985 


Central African Rep 


3,600 


2 


— 


100 


2.8 


e3 


3 


1958 


Chad 


1.600 


— 


_ 






el 


1 


1991 


Comoros 


660 


1 


60 


136 


18.9 


c 


2 


1917 


Congo 


4.350 


7 


- 


_ 


15-10%] 


e2 


2 


1988-91 


Cote d'lvoire 


3,517 





143 


62 


1.7 


c 


2 


1S85 


Djibouti 


835 


2 


4 


2 


0.3 


c 


1 


1989 


Egypt 


2.066 


4 


6 


70 


3.4 


c 


1 


1974-84 


Equatorial Guinea 


3,000 





250 


66 


2.0 


e3 


4 


1991 


Ethiopia 


6,000-7,000 


3 


100 


600-1400 


15.1 


e2 


4 


1980 


Gat>on 


6.000-7,000 


1 


150 


- 


15-10%) 


a2 


4 


1991 


Gambia 


966 





8 





0.0 


c 


1 


1001 


Ghana 


3.600 


1 


124 


43 


1.2 


e2 


2 


1991 


Guinea 


3,000 





_ 


88 


2.9 


e3 


3 


1001 


Guinea-Bissau 


1,000 





_ 


12 


1.2 


e2 


2 


1991 


Kenya 


6,000 


6 


500 


265 


4.1 


e2 


2 


1984 


Lesotho 


1,576 





15 


2 


0.1 


c 


1 


1971-75 


Liberia 


2,200 





— 


103 


4.7 


e3 


4 


1991 


Libya 


1.800 


10 


15 


134 


7.3 


c 


1 


1975-84 


Madagascar 


8.000-10.000 


5 


500 


5,000-8,000 


68.4 


e3 


4 


1987 


Malawi 


3.600 


4 


161 


49 


1.3 


e2 


2 


1970-75 


Mali 


1,741 





— 


11 


0.6 


c 


1 


1991 


Mauritania 


1.100 





— 


— 




e2 


1 


1976 


Mauritius 


700 





178 


329 


37.5 


el 


2 


1978-91 


Mayotte 


— 


— 


_ 


_ 










Morocco 


3,600 


19 


56 


600-650 


17.0 


el 


2 


1975-84 


Mozambique. People's Rep 


5.500 


9 


183 


219 


3.8 


el 


2 


1960-70 


Namibia 


3.128 


1 


45 


— 


_ 


c 


1 


1976 


Niger 


1,170 





8 





0.0 


c 


1 


1983 


Nigeria 


4,614 


1 


100 


205 


4.3 


e2 


2 


1991 


Reunion 


750 





240 


175 


17.7 


el 


1 


1991 


Rwanda 


2,288 


2 


— 


26 


1.1 


c 


2 


1978-88 


Saint Helena 


50 





24 


59 


79.7 


c 


1 


1991 


Sao Tome and Principe 


744 


1 


150 


134 


15.0 


c 


1 


1973 


Senegal 


2,062 





24 


26 


1.2 


c 


1 


1973 


Seychelles 


1,139 


1 


500 


250 


15.2 


c 


2 


1989-91 


Sierra Leone 


1,700-2,480 





— 


74 


3.5 


e2 


1 


1962-91 


Somalia 


3.000 


2 


26 


500 


16.5 


e2 


3 


1991 


South Africa 


2,300 


40 


380 




[70-80%] 


e2 


1 


1984 


Sudan 


3,132 


5 


— 


50 


1.6 


c 


2 


1952-56 


Swaziland 


2.636 


8 


71 


4 


0.1 


c 


1 


1983 


Tanzania 


10.000 


8 


- 


1,122 


11.2 


e2 


1 


1968 


Toqo 


<3050 


(1 


(200 





0.0 


c 


2 


1991 


Tunisia 


2,150 


10 


36 






el 


1 


1976-84 


Uganda 


5,000 


6 


400 


30 


0.6 


e2 


2 


1984 


Western Sahara 


330 


— 


— 






e2 


2 


1976 


Zaire 


11,000 


7 


- 


3.200 


29.1 


e2 


5 


1991 


Zambia 


4.600 


1 


146 


211 


4.4 


e2 


3 


1960-70 


Zimbabwe 


4,200 


6 


234 


95 


2.1 


e2 


2 


1970-75 



Note*: ( Indicates figure is a combiiied total with aDotber country. This applies to both Korean nations (flowering plants): Guadeloupe and Martuiique 
(flowering plants): Guatemala and Belize (ferns) Benin and Togo (all plants); Dominican Rep. and Haiti (data for Hispaniola only). % endemism: calculated 
from data unless in square brackets. Estimate/counI: c count; el approximate count; e2 extrapolation: e3 estimate on basis of any available information and 
comparabledoras. Completion: Percentage of flora slill to be described. 1: <5%(+/-known). 2:5-10%. 3:10-1.';%. 4:15-20%. 5: >20%. Date: date of 
mformalion. - no data available. ' no data available for the new combined Yemen RepubUc. ^ USSR: covers the former Union of Soviet Socialist Republics 
Portugal: data include the Azores. ' Spain: data do not include the Canary Islands 

TabJe compiled for WCMC by John Akeroyd. 



82 



Higher Plant Diversity 



Figure 8.1 Percent endemism of country floras 




E 
v> 

E 
<u 
■o 

c 
o 



0) 
A 



I 



05 2 



o o 

T- CVJ 






0) 
O) 



d 



(0 

13 
■a 

o 

c 



03 

N 



o 

Q. 
(0 
03 

c 



■H CO 



73 

C 
CO 



03 



83 



1. Biological Diversity 



'Figure 8.2 The 25 most plant-rich countries 




84 



Higher Plant Diversity 



Figure 8.3 Flowering plant richness: Asia and 'USSR' 

30,000 



25,000 



(0 20,000 

o 

0) 
Q. 
(0 

"5 15,000 

a> 

Si 

E 

z 10,000 



5,000 




■■■■Mill 



<^^/^^AA^A/M^AA</yyi^^^>yyy 



•«> 



>^°^ ^^-^^^^ ^^J'^A* 



<@ <J'» ,x? 



Country 



^'^^ 



Figure 8.4 Flowering plant richness: Europe 




85 



1. Biological Diversity 



Figure 8.5 Flowering plant richness: North and Central America 

25,000 




/^V 



/ 



mw/^^w^ 



Country ^ 



i«3Mi;e J.6 Jlowefpg |?l«int fjch^ and Ari|:|^q||lca 



50,000 




W/^V/^VAM 



Country 



86 



Higher Plant Diversity 



Figure 8.7 Flowering plant richness: Oceania including Australia 



14,000 




Country ^"?- .^ 

Figure 8.8 Flowering plant richness: Africa and Madagascar 



10,000 — 




W/^^^/^^/^-^^^"^'^^/^-^/^^ 



Country 



'4-vy 




87 



1. Biological Diversity 
9. NEMATODES 



The phylum Nematoda includes a very large number of 
very small worm-like animals which have a great impact on 
humans, often directly deleterious, as with many parasitic 
forms, but also with an important role in decomposition and 
nutrient cycling. The group contains a large number of 
described species, but the true proportion of the world's 
species that are nematodes is suspected of being very large 
indeed. This section is intended to introduce some features 
of nematodes important in the context of biological 
diversity. 

NEMATODE DrVERSITY 

More than 15,000 species have been described and the total 
number of species has been estimated at between 500,000 
species (Poinar, 1983) and around one million (J. 
Lambshead, pers comm.). Nematodes show a wide range of 
life histories, from the entirely free-living to almost totally 
parasitic in plants and many kinds of animals. The parasitic 
forms which afflict humans, domesticated animals and 
plants are among the best-studied species. Anderson (1984) 
showed that approximately a third of known nematode 
genera are parasitic on vertebrates (Table 9.1). 

Of the non-parasitic forms, those feeding on micro- 
organisms (especially bacteria) can be described as 
microbotrophic, and those that feed on multicellular 
metazoan organisms are described as />re<iaceou.j. All others 
are described as parasitic on plants and fungi, invertebrates 
or vertebrates (Poinar, 1983). 

Nematodes are usually long and cylindrical in shape (giving 
rise to the common name 'roundworms') and their cuticle 
is of a type of secreted collagen thought to be peculiar to 
nematodes. Uniquely, muscle-nerve links arise during 
development from the muscle not the nerve, as is usually 
the case (Barnes, 1980). Nematodes have a relatively 
complicated reproductive system and lack dispersive larvae. 
These features might be implicated in the high species 
richness of the group (J. Lambshead, pers. comm.). Body 
length varies enormously. One of the smallest known 
marine nematodes, Greeffiella minutum, is only 82/tm long; 
however, the largest nematode known, Placentonema 
gigannssima, which is parasitic in the placenta of the sperm 
whale has been recorded at over 8m (Poinar, 1983). 

Taxonomic procedures are difficult because of the small 
size of many nematode species. There have been several 
major taxonomic reviews over the last few decades. 



Classification is almost entirely based on morphological 
characteristics visible under a compound microscope 
(Poinar, 1983). Many species, especially those with 
parasitic relationships with other organisms, cannot be kept 
in culture and thus are not amenable to biochemical or 
genetic smdy. Scientists of different disciplines frequently 
work independently of each other, resulting in confusing 
taxonomic revisions. 

Estimates of the total number of nematode species vary 
greatly, current figures ranging from 500,000 to around one 
million. Recent work on species diversity in the meiofauna 
of deep-sea benthic samples has found very high diversity 
in each sample. However, taxonomic problems and the 
sheer number of organisms involved means that the species 
similarity between samples is still unresolved (J. 
Lambshead, pers. comm.). If many of these samples 
constitute separate species, nematodes may approach or 
even exceed the insects in species richness. 

Microbotrophic nematodes 

The microbotrophic nematodes, especially some marine 
forms, are generally thought to represent the most primitive 
organisms in the phylum, although there is an alternative 
hypothesis that extant microbotrophsare secondarily derived 
from parasitic forms (Poinar, 1983). It is difficult to 
elucidate the evolutionary history of a group which leaves 
few fossil remains but it is thought that microbotrophic 
nematodes were probably well represented in the Cambrian 
period, c. 600 million years ago. 

Microbotrophic nematodes are one of the most widespread 
and abundant animal groups known. Wherever a suitable 
food source exists they are found, even under extreme 
conditions such as hot sulphur springs or polar ice. Because 
of their relatively small size (although some grow to over 
10mm, most cannot be seen with the naked eye) they tend 
to go urmoticed even though present in great numbers. For 
example, about 90,000 nematodes of several different 
species have been found in a single rotting apple in an 
orchard and about 50,000 nematodes of at least eight 
different species have been reported from a single fig 
(Barnes, 1980). 

These nematodes can be divided into three groups - marine, 
freshwater and terrestrial - although even the so called 
terrestrial species are dependent upon the water film around 
soil particles and in interstitial spaces. Those species which 



Table 9.1 



HABITAT 



Approximate numbers of nematode families and genera known from 
different habitats 



Marine and freshwater 

Soil 

Plant (parasitic) 

Invertebrate (parasitic) 

Vertebrate (parasitic) 

TOTALS 



FAMILIES 

41 
64 
26 
42 
83 

256 



GENERA 

730 
429 
166 
187 
759 

2271 



Source: Anderson, R.V. 1984. The origins of zooparasilic nematodes. Canadian Journal of Zoology , 62:317-28. 



88 



Nematodes 



live in environments with only a periodic water supply, 
such as deserts, survive mostly as inactive larvae and only 
emerge when water is present. 

Marine species live in bottom sediments of many habitats 
from sandy shores and salt-marshes to ocean trenches and 
have been reported in numbers ranging from 100,000 to 10 
million individuals per m^ (Poinar, 1983). Thus they are the 
most important metazoan element of the meiofauna in all 
samples. Samples reported by Nicholas (1984) taken at 
various depths down to about 400m show a range in 
number of species from 3 to 125 per site and a range in 
densities of 110,000 to 5,261,000 animals per m^. These 
samples were derived from sediments, algae, shells and 
rocks, where bacteria and other micro-organisms flourish. 
In one study of deep-sea nematodes, examination of 216 
individuals yielded a total of 148 species (J. Lambshead, 
pers. comm.). 

Several groups of nematodes live in fresh and brackish 
waters, and transitional zones. Many of these species 
tolerate rapid fluctuations in salinity. As in marine habitats, 
the animals are usually present in the sediment, although 
they may occasionally swim freely. The most dense 
nematode faunas are associated with a reasonable oxygen 
supply and sediment with a high organic content. Lakes 
have a very variable fauna which probably depends upon 
their physical attributes, such as isolation and thermal 
stratification. Shallow marginal waters may be quite rich, 
probably sharing some species with wet terrestrial habitats. 
However, deeper waters seem to be species-poor unlike 
marine systems. A notable exception to this is Lake Baikal, 
where, as among other animal groups, considerable 
speciation has occurred and endemism appears to be high 
(Nicholas, 1984). 

In the soil the distinction between microbotrophic and 
parasitic nematodes becomes very blurred in certain taxa. 
All kinds of soils support large nematode communities (see 
Table 9.2 below) and the richest tend to be where there is 
plenty of organic matter, fine plant roots, etc. The 
interactions with plant roots and other organisms, such as 
fungi, are extremely complex and difficult to assess. 

It is thought that parasitism has arisen independently in 
several nematode taxa, and certainly the microbotrophic 
forms illustrate a great variety of interactions which could 



be considered as stages in the evolution of parasitism. For 
example, there are many examples of phoretic relationships 
with invertebrates. These range from larval stages attaching 
externally to mobile hosts who carry them to the next food 
source, to larval stages which live within a host apparently 
without harming it, but which cannot escape to continue 
their life cycle until the host dies of natural causes. Many 
of these relationships are very finely tuned to the life cycle 
of a specific carrier whilst others use a variety of suitable 
invertebrates. Not all relationships benefit the nematode 
alone: in some cases the carrier may also feed upon the 
nematodes. Relationships with plants may be equally 
complex, as nematodes may often feed upon the bacteria on 
and in decaying roots. However, some species are suspected 
of spreading disease to increase their food resource or of 
being able to feed upon living plant tissue as an alternative 
to bacteria. Even within one species, different forms may 
show different degrees of interaction, making rigid 
definitions impossible. 

Predaceous nematodes 

Predaceous nematodes are found in all habitats but are most 
abundant in terrestrial systems. All eat a few to many 
multicellular organisms in the course of their development, 
although bacteria, ciliates and organic particles may also be 
eaten. Little is known about prey-specificity in nature, as 
most studies, by necessity, have been carried out under 
laboratory conditions. However, some extremely common 
groups include other nematodes as prey items and may be 
potential biological control agents for nematode pests of 
plants. For instance, a single nematode of the family 
Mononchidae has been observed to kill over 1,000 
nematodes in a three-month period and estimates of density 
suggest that up to 300 million mononchid nematodes might 
be contained in an acre of soil (Poinar, 1983). However, 
observations also suggest that almost any in vertebrate of the 
correct size may be eaten and prey location is a chance 
affair. 

Little is known of the aquatic predaceous nematodes. 
However, observations which suggest that some marine 
forms may be able to penetrate foraminiferan tests to get at 
the body inside are of considerable interest as borings 
similar to those attributed to these nematodes have been 
seen in fossilized foraminiferan tests from the Holoceneand 
Cretaceous periods (Poinar, 1983). 



Table 9.2 Abundance and biomass of soil nematode fauna from different types of 
ecosystem 



ECOSYSTEM 



Tundra 

Coniferous forest 
Eucalyptus forest 
Deciduous forest 
Tennperate grassland 
Fen, bog, heathland 
Desert 
Tropical forest 



ABUNDANCE X lOOOm^ 
MEAN RANGE 



3,490 


800-10,000 


3,330 


1,125-15,000 


5,467 


4,040-7,449 


6,270 


255-29,800 


9,190 


2,432-30,000 


1,660 


330-3,900 


760 


423-1,100 


1,700 


1,500-1,900 





BIOMASS* 


MEAN 


RANGE 


1,350 


265-4,130 


510 


180-1,696 


1,423 


770-2,050 


2,760 


75-15,200 


3,800 


650-17,800 


660 


350-900 


410 


1 25-700 



Source: SohUnius, B. 1980. Abundance, biomass ana contribution to energy flow by soil nematodes in terrestrial ecosystems. Oikos 34:186-94. 
Note; * biomass is measured here in mg weight per m^. 



89 



1. Biological Diversity 



Table 9.3 Distribution of nematode genera among groups of vertebrates 



Rsh 

Amphibians 

Reptiles 

Birds 

Mammals 

TOTAL GENERA 



FISH 



62 



80 



AMPHIBIANS 


REPTILES 


BIRDS 


MAMMALS 


HOST SPECIES 

PER NEMATODE 

GENUS 


6 


7 


4 


1 


250 


20 


22 


2 


1 


50 




62 


4 


4 


60 






113 


17 
387 


60 
8 



51 



99 



140 



410 



Source: Modified from Inglis, W.G. 1965. Patterns of evolution in parasitic nematodes. In: Taylor, A.E.R. (Ed.), Evolution of Parasites. Blackwell 
Scientific Publishers, Oxford, UK and Poinar, GO. 1983. The Natural History of Nematodes. Prentice-Hall Inc., New Jersey, USA. 
Note; Numbers underlined indicate genera exclusive to each vertebrate group. 



Parasitic nematodes 

Plant parasitic nematodes have been found in most species 
of terrestrial plants, all over the world. Many are 
polyphagous and consequently a plant species may be 
attacked by a wide range of nematode species. For instance, 
Poinar (1983) lists 36 nematode species in 15 genera which 
have been identified parasitising potatoes and six species in 
four genera from wild chicory. Most fungi also suffer from 
nematode attacks, some species being serious pests in 
mushroom culturing operations. Plant parasites are 
apparently much less common in aquatic habitats, and 
relatively few species are known from seaweeds and marine 
fungi. 

Parasitic nematodes are similarly widespread in both 
invertebrate and vertebrate hosts and have evolved some 
remarkably complex life cycles. The greatest number of 
invertebrate parasites known are in the insects and some of 
these have been studied in great depth in the hope of 
developing successfiil biological control methods. As with 
the plant parasites many nematode species can attack a wide 
range of insect hosts. Others are highly specialised and 
adapted to the life cycle of one particular host. Of the 
former group, two nematode families include genera which 
have evolved mutualistic relationships with a single 
bacterium genus, which is unkown in a free living state. 
These nematodes introduce bacterial cells into a host insect 
which dies soon after becoming infected. The bacteria then 
grow on the body and the nematodes feed on the bacteria, 
ensuring some are carried to infect a new host. Insects of 



ten different orders are known to be attacked by these 
species (Poinar, 1983). 

Vertebrate parasites are equally widespread and, here again, 
some may utilise a whole range of hosts whilst others are 
extremely host specific. Many have developed complicated 
methods of dispersal which may involve invertebrates (or 
occasionally other vertebrates) as intermediate hosts. Some 
of the world's most debilitating diseases are spread by this 
method, such as onchocerciasis (river blindness). 

Nematode parasites tend to become more specialised in 
more developed vertebrate groups. The majority of 
nematode genera are confined to a single vertebrate genus. 
Of those that do have a wider host range a few can utUise 
different classes, but most are restricted to similar animals. 
Table 9.3 illustrates the higher diversification of nematode 
parasites in the higher vertebrate groups and the greater 
specifity associated with this. 



THE ECOLOGICAL IMPORTANCE OF 
NEMATODES 

Free living nematodes are vital components of ecosystems. 
Although not themselves decomposers, many feed on the 
primary decomposers, the bacteria and fiingi, which break 
down complex organic molecules and thus make these 
nutrients available in the food chain again. They are 
therefore elementary in the decomposition cycle. The 
predaceous species are also important consumers near the 



Table 9.4 


Estimated crop losses due to Meloidogyne species in 


tropical regions 


CENTRAL AMERICA 


SOUTH AMERICA 




BRAZIL 




WEST AFRICA 




SOUTHEAST ASIA 


AND CARIBBEAN 


















% 




% 




% 




% 




% 


Crop 


lOM 


Crop 


loas 


Crop 


lose 


Crop 


loss 


Crop lo«* 


Tomato 


38 


Cucumber 


33 


Tomato 


25 


Tomato 


46 


Tomato 24 


Chayote 


38 


Tomato 


27 


Coffee 


24 


Cowpea 


43 


Melon 18 


Guava 


35 


Bean (common) 


24 


Soybean 


23 


Okra 


42 


Bean (common) 18 


Pumpkin 


22 


Watermelon 


23 


Conon 


17 


Carrot 


38 


Eggplant 17 


Bean (common) 


16 


Pepper 


22 


Papaya 


15 


Pigeon pea 


35 


Black pepper 1 6 


Yam 


16 


Eggplant 


20 


Yam 


15 


Melon 


33 


Chinese Pechay 16 


Mean % loss 


















(all crops) 


15 




15 




13 




25 


11 



Source: Adapted from Sasser, J.N. 1979. Economic importance oi Meloidogyne in tropical countries. In: Lamberti, F. and Taylor, C.E. (Eds), 
Root-knot Nematodes (Meloidogyne species). Academic Press, London, UK. 
Note: Only the six worst-affected crops are shown in each case. 



90 



Nematodes 



base of food webs, feeding on unicellular algal primary 
producers and smaller metazoans. 

Nematodes are most often studied in their destructive 
capacity, as pests of agricultural crops and as parasites of 
livestock and humans. However, there is also potential for 
biological control applications, against a wide range of 
insect pests and against other nematode species. Free-living 
nematodes have been used as models for various 
experiments on the functioning of ecosystems and as 
indicators of environmental health, such as water pollution. 
Other potential and actual uses include nematodes as 
indicators of the quality of terrestrial soils, freshwater and 
marine sediments (van der Wal and de Goede, 1988), and 
in a whole range of biological research projects (see 
Nicholas, 1984, for examples). 

There are many aspects to the problems of nematode 
association with crops. For instance, nematode species 
which are useful in controlling pathogenic root fungi in one 
situation may in another destroy mycorrhizal fiingi, 
necessary for good plant growth. Similarly, some 
nematodes which feed harmlessly or even usefully on 
bacteria most of the time may also be able to move into 
plant roots, either to eat healthy plant tissue directly or to 
infect them to provide more food for their bacteria. This 
change may depend on environmental conditions, for 
instance the soil drying out, and may produce a sudden 
reaction in the crop which superficially resembles water 
stress. These cases are the cause of some debate and 
considerable research. However, other nematodes are 
without doubt serious crop destroyers. Poinar (1983) quotes 
estimates which suggest that 7-15% of the annual crop 
production of the USA is destroyed by nematodes. Table 
9.4 shows the estimated yield losses in several tropical 
regions due to species Meloidogyne, one of the most 
destructive nematode genera. Only the six worst-affected 
crops in each region are shown here in detail but in the 
original table Sasser (1979) gives figures for up to 21 crops 



in each region. The most destructive species in each case is 
M. incognita, followed by M. javanica, M. arenaria and M. 
hapla. 

Some of these problems have arisen as a result of crop 
monoculture which reduces natural control systems that 
normally keep such pests within acceptable limits. Various 
methods of control are possible, including timed planting to 
miss the most active cycle of the parasite, crop rotations 
which can include crops poisonous to the nematodes, and 
flooding. Another form of natural control which has 
received considerable attention in recent years entails use of 
fungi that are predaceous or parasitic upon nematodes. At 
least one of these former, a trap-forming deuteromycete in 
the genus Arthrobotrys, is commercially available (Poinar, 
1983) and is effective in tomato fields and greenhouses 
against Meloidogyne species. Various other fungi have been 
tested with varying results and other fungi which apparently 
produce nemotoxins are also being studied. 

On the other hand, control by nematodes of fiingal plant 
diseases and weeds have been investigated. For example, an 
encysting plant parasite Paranguina picridis has been used 
with some success in the USSR to control knapweed 
(Poinar, 1983). Predaceous nematodes have also been 
considered as control agents for ectotrophic root parasites, 
especially other nematodes, and microbotrophic nematodes 
for control against certain infective bacteria. 

In contrast to plant parasites, the invertebrate parasites are 
rarely a problem to man (except where plants or higher 
animals are also part of the life-cycle). In fact many have 
great potential for control of pest insects. In particular, 
certain nematodes have been intensively studied for possible 
mosquito control and others which parasitise water snails 
may be able to control schistosome-bearing snails. Insect 
pests of crops and livestock are also targeted by research 
programmes; several examples which have been tried are 
shown in Table 9.5, adapted from Poinar, 1983. 



Table 9.5 Examples of nematode species investigated as biological control agents 



FAMILY 



Mermithidae 
culicivorax 



Diplogasteridae 
uniformis 

Steinernematidae 
glaseri 

Heterorhabditidae 
bacteriophora 

Neotylenchidae 
iiricidicola 

Allantonematidae 
autumnalis 

Sphaerulariidaa 



SPECIES 

Romanomermis 



Pn'stionchus 



Neoaplectana 



Heterorhabditis 
(click beetles) 

Deladenus 
(wood wasp) 

Heterotylanchus 
(face fly) 

Tripius sciarae 



INSECT PEST 

mosquitoes 



Colorado beetle 



Agriotes spp. 



Sirex noctilio 



LOCATION 

North America, Taiwan, Europe, 
Africa, Oceania, Central 
America, Thailand 

Poland 



Japanese beetle Eastern USA 



HABITAT 

Ponds, 

ditches, 

lakes. 

Soil 



Soil 



Italy 



Australia 



Musca autumnalis North America 



Sciarid flies 



England (greenhouse) 



Soil 



Trees 



Dung 



Soil 



Source: Adapted from Poinar, G.O. 1983. The Natural History of Nematodes. Prentice-Hall Inc., New Jersey, USA. 

91 



1. Biological Diversity 



Tafele 9.6 Estimates of nematode infections in man {in millions) 



DISEASE 



NEMATODE/S 



AFRICA ASIA CENTRAL 

lexcl. & SOUTH 

'USSR'I AMERICA 



OCEANIA NORTH 
AMERICA (excl. 

■USSR) 



EUROPE 



•USSR- 



Ascariasis 


Ascaris lumbricoides 


159 


931 


Hookworms 


(various) 


132 


685 


Human 


Bnterobius vermicularis 


24 


136 


pinworm 








Trichuriasis 


Trichuris trichiura 


76 


433 


Trichinosis 


Trichinella spiralis 


1 




Others 




9 


49 


Elephantiasis 


Wuchereria bancrofti and 
Brugia malayi 


59 


300 


Other filariae 




178 


57 



104 
104 

40 

94 

3 

21 

22 
39 



<1 



5 

3 

29 

1 

35 

1 



39 

2 

75 

41 
5 
1 



30 

4 
48 

41 
2 



Source: Peters, W. 1978. Comments and discussion 11. In: Taylor, A.E.R. and Muller, R. (Eds), The Relevance of Parasitology to Human Welfare 
Today. Blackwell Scientific Publications, Oxford, UK. 



Nematode parasites of vertebrates are an enormous drain 
upon human resources, both in the effects on domestic 
animal species and on human life directly. The World 
Health Organization produces estimates for the numbers of 
people afflicted with the major parasitic diseases. Poinar 
(1983) gives figures for four of these for 1977-78: 
hookworm disease, onchocerciasis, ascariasis and 
trichuriasis in Africa, Asia and Latin America. Of these the 
first two cause the greatest number of deaths each year: 50- 
60 thousand deaths among 7 million to 900 million people 
with hookworm disease, and 20-50 thousand deaths out of 
30 million estimated cases of onchocerciasis. A different 
presentation of similar data is given in Table 9 6, adapted 
from Peters (1978). These estimates are apparently based on 
data collected in the 1940s although Peters suggests they 
adequately represent the current situation. 

The monetary costs caused by livestock disease are also 
immense, in terms of prevention, treatment, animals lost 
and human time. Where these parasites are also 
transmittable to humans, such as several of those affecting 
pigs, precautions against infection are also costly and time- 
consuming. Thus, unlike the possible benefits from free 
living and plant parasitic nematodes, and the considerable 
potential in invertebrate parasites, there are no obvious uses 



of vertebrate parasites with benefit to humans. 
References 

Anderson, R.V. 1984. The origins of zooparasitic nematodes. 

Canadian Journal of Zoology 62:317-28. 
Barnes, R.D. 1980. Invertebrate Zoology, 4th edn. Holt-Saunders 

Tokyo, Japan. l,089pp, 
Inglis, W.G. 1965. Patterns of evolution in parasitic nematodes. In: 

Taylor, A.E.R. (Ed.), Evolution of Parasites. Blackwell Scientific 

Publishers, Oxford, UK. Pp. 79-124. 
Nicholas, W.L. 1984. The Biology of Free-living Nematodes, 2nd edn. 

Clarendon Press, Oxford, UK. 251pp. 
Peters, W. 1978. Comments and discussion U. In: Taylor, A.E.R. and 

Muller, R. (Eds), The Relevance of Parasitology to Human Welfare 

Today. Blackwell Scientific Publications, Oxford, UK. Pp.25-40. 
Poinar, CO. 1983. The Natural History of Nematodes. Prentice-Hall 

Inc., New Jersey, USA. 323pp. 
Sasser, J.N. 1979. Economic importance of Ueloidogyne in tropical 

countries. In: Lambeni, F. and Taylor, C.E. (Eds), Root-knot 

Nematodes (Meloidogyne species). Academic Press, London, UK. 

Pp.359-374. 
Sohlenius, B. 1980. Abundance, biomass and contribution to energy 

flow by soil nematodes in terrestrial ecosystems. Oikos 34:186-94. 
Wal, A.F. van der and Goede, R.G.M. de (Eds) 1988. Nematodes in 

Natural Systems. Report of a workshop held at the Dept. of 

Nematology, Agricultural University, Wageningen, The 

Netherlands, 16-18 December 1987. Mededeling 199. 



92 



10. DEEP-SEA INVERTEBRATES 



Deep-Sea Invertebrates 



DEEP-SEA COMMUNITIES 

Until the mid-1960s it was believed that oceanic diversity 
was concentrated in shallow water around coasts and 
declined with both depth and distance from land as food 
resources became more remote. The first reports of 
unexpectedly high species diversity in bottom living 
communities arrived in 1967 with samples collected using 
a new technique: the epibenthic sled (Hessler and Sanders, 
1967). Although many were initially sceptical of the 
conclusions, the deep-sea envirotmient has been an active 
area of research and is now known to support communities 
rich in species, high in endemism and often ecologically 
unique. In terms of species numbers alone, the marine 
environment provides a relatively minor proportion of the 
global total. 

Approximately 71% of the Earth's surface is covered by 
sea, and about 51 % of its surface by ocean over 3,000ra in 
depth. Deep-sea communities are thus prevalent over a 
major proportion of the planet. All deep-sea habitat is in the 
aphotic zone, well below the distance sunlight can 
penetrate. Community structures and food webs are 
therefore very different from those found on land and in the 
shallower psirts of seas in that, except in the specialist case 
of hydrothermal vents (described below), there is no 
primary production and all life relies on organic material 
from other parts of the ocean. As deeper and deeper levels 
are reached biomass falls exponentially (Rowe, 1983). This 
was misinterpreted as being synonymous with falling 
species diversity (Grassle, 1991). Because, despite their 
enormous volume, the deep oceans appear to be relatively 
simple ecosystems, there was little reason to imagine that 
they should make any significant contribution to overall 
global species diversity. That species diversity in the 
benthic community should rise with increasing depth was 
therefore a major discovery. 

The benthic samples taken by Hessler and Sanders (1967) 
and later workers have revealed a hitherto unexpectedly 
high species richness. This discovery has prompted 
speculation that the deep sea is a site of prolific speciation 
and, as one of the most stable and ancient environments on 
Earth, perhaps the origin of certain higher-level taxa (Gage 
and Tyler, 1991). Several ideas have been postulated to 
explain this high diversity but it would appear that a 
combinationof factors is important. Grassle (1991) suggests 
four major influences: 

• the relative lack of environmental extremes such as those 
of temperature, salinity, low oxygen and major 
disturbances 

• patchy food resources 

• local disturbances and structures caused by animal 
activities 

• a large area with few barriers to dispersal. 

The first three of these are equivalent to the processes 
thought by some to be fundamental to the high species 
diversity in tropical terrestrial and shallow water 
ecosystems. Environmental stability allows the development 
of high species diversity with many highly specialised 



species. This is supported by observations in deep-sea areas 
that do not have long-term environmental stability, such as 
trenches and areas of strong bottom currents; these usually 
have a much reduced species diversity although their faunas 
may be of interest in other ways (Thome-Miller and 
Catena, 1991). 

The patchiness of food availability and local disturbance can 
be compared to the importance of gap appearances in the 
canopy of tropical forests, both involving small scale habitat 
diversity within a larger homogenous area and the 
maintenance of a mosaic of disequilibrium populations 
(Grassle, 1989). Most organisms which live in the deep sea 
are totally dependent on organic detritus falling from 
euphotic zones. This is largely of planktonic and faecal 
origin but larger masses such as pieces of wood, carcasses 
and algal mats are also of importance. Local disturbances 
such as feeding activities and burrowing and mound- 
building by polychaete worms also ensure local topographic 
variations which provide a variety of microhabitats. Weak 
bottom currents allow particulate organic matter to 
concentrate in hollows and lees. 

The large area of the deep ocean zone, coupled with the 
above factors, results in a very large species pool with wide 
dispersion potential. Grassle (1991) estimates that if the 
currently observed species-area relationship is extrapolated 
the total species pool may be in the order of 10 million. 
Although, as discussed below, there are many problems 
with predictions of this type, even this figure may be 
conservative. 

Faunal composition 

Studies of the benthic species assemblages of different 
regions are still in their infancy. The major difficulty is 
obtaining quantitative samples, since the depths involved are 
far greater than a diver can go. Much of the work which 
has been carried out has not been coordinated, leading to 
different sieve sizes for sampling, different collection 
techniques and different assessments of biomass (Rowe, 
1983). This makes comparisons between sites difficult. In 
addition, taxonomic problems in certain taxa have meant 
that, while it may be possible to have a species count from 
any one sample, it is not possible to say what the similarity 
is between samples. Nearly half the species in each new 
sample may be undescribed (Grassle, 1989), and there may 
be few taxonomists working on any one group, raising 
problems of species identification. Even in well sampled 
areas, sample sizes are small compared to the regions they 
are supposed to represent, and it is uncertain to what extent 
results can be extrapolated. However, the rate of discovery 
of new species and the proportion of species currently 
known from only one sample both indicate that a great 
number remain to be discovered (Grassle, 1991). 

Benthic fauna is usually classified into size classes, 
increasing from the nanobiota, through the meiofauna, the 
macrofauna and finally to the megafauna. A problem with 
this type of classification is it splits natural taxonomic 
groups and even age classes of the same species. Many 
workers prefer to classify all the members of certain taxa 



93 



1. Biological Diversity 



into the size class which best represents the group; for 
example, all nematodes are often considered as meiofauna. 

Small size and taxonomic problems mean that few 
comparative data are currently available on meiofaunal 
diversity. The major taxonomic groups in this size class are 
the nematodes and foraminiferans (protozoa). Other 
important taxa in this size class include the harpacticoid 
copepods and ostracods. 

More information is available for the macrofauna, which 
has been more extensively studied than other size classes. 
This is typically dominated by polychaetes (up to 75% 
numerically), peracarid crustaceans (including cumaceans, 
tanaids, isopods and amphipods) and a variety of smaller 
molluscs (Gage and Tyler, 1991), but most other phyla are 
also represented. Figures from Grassle (1991) (see Table 
10.1 and Fig. 10.1) demonstrate the species, family and 
phylum composition of a typical sample; (however, note 
these samples were taken at bathyal rather than abyssal 
depths - see below). Wolff (1977) also provides examples 
of the taxonomic composition of the macrofauna (and 
megafauna using the taxa listed here) in a number of 
regions (Table 10.2 and Fig. 10.2). However, the sampling 
methods are not the same in each area so these results may 
not be comparable. 



Table 10.1 


D 


iversity in 


benthic 




S8 


imples * 








NO. OF 


NO. OF 


GROUP 




FAMILIES 


SPECIES 


Annelida 




49 


385 


Arthropoda 




40 


185 


Mollusca 




43 


106 


Echinodernnata 




13 


39 


Nemertina 




1 


22 


Cnidaria 




10 


19 


Sipuncula 




3 


15 


Pogonophora 




5 


13 


Hemichordata 




1 


4 


Echiura 




2 


4 


Priapulida 




1 


2 


Brachiopoda 




1 


2 


Ectoprocta 




1 


1 


Chordata 




1 


1 


TOTAL 




171 


798 



Source: After Grassle, J.F. 1991. Deep-sea benthic biodiversity. 
Bioscience 4 1 (7) . 

Note: ♦ Sea-bed samples from 1,500m to 2,500m depth off New 
Jersey, north-east Atlantic. 



ifable 10.2 Composition of benthi 


ic macrofauna 


(percentage of total 


species present) 


LOCATION 


TRENCHES* 


CENT.N PACIFIC 


NW ATLANTIC 


NW ATLANTIC 


SAMPLE TYPE 


TRAWL 


A.D. 


AD. 


E.S. 


DEPTHS (ml 


6,000-10,000 


5,600 


4.400-5,000 


4,700 


Polychaetes 


7 


55 


55 


8 


Peracarid Crustacea (total) 


5 


24 


33 


32 


Tanaidacea 


<1 


18 


19 


1 


Isopoda 


4 


6 


12 


18 


Amphipoda 


<1 





2 


5 


Bivalvia 


19 


7 


4 


47 


Echinodermata (total) 


57 


1 


1 


2 


Ophiuroidea 


2 


<1 


<1 


2 


Holothuroidea 


54 


<1 








Others 


11 


11 


8 


11 


Number of individuals 


21,589 


287 


681 


3,737 



Source: After Wolff, T. 1977. Diversity and fauna! composition of the deep-sea benthos. Nature 267:780-785. 

Note: ♦ Trenches = Kurile-Kamchatka, Japan, Kermadec and Java A.D. = Anchor Dredge; E.S. = Epibenthic Sledge. 



In the megafauna, echinoderms of several classes are often 
the dominant mobile (or errant) life forms on or in 
association with the sea bottom. Their distribution may be 
very uneven, they may sometimes occur in great numbers 
on patches of detritus fallout and some scavenging forms 
may be found in large congregations at bait. Giant 
scavenging amphipods, growing up to about 18cm in length, 
are also characteristic in many areas. However, the high 
mobility of these animals means they are rarely caught in 
trawls and have been less well studied than less active 
animals. Other arthropods include a variety of sea spiders 
(Pycnogonida) and decapods of several families (both errant 
and sessile). Errant animals of several other taxa occur, 
including polychaetes, hemichordates, cephalopodsand fish. 
Sessile animals generally occur on any suitable surfaces. 
Sponges (Porifera), especially the glass sponges, are widely 
distributed and coelenterates (Cnidaria) are also well 



represented, dominated by anthozoans. Other taxa include 
bryozoa and brachyopoda. 

Distribution of deep ocean biodiversity 

There are general trends in species richness with respect to 
depth in benthic communities. The picture is very 
incomplete, however, so conclusions must be tentative. Rex 
(1983) examined data from four major taxonomic groups 
(polychaetes, gastropods, protobranchs and cumaceans) 
along a depth gradient down to 5,000m. All showed 
maximum diversity between 2,(X)0m and 3,000m. The three 
of these taxa which had been sampled with an epibenthic 
sled rather than an anchor dredge also showed a higher 
diversity between 4,000m and 5,000m than between Cm and 
1,000m (polychaetes were the exception). However, 
whether this is an artefact of the difference in sampling 



94 



Deep-Sea Invertebrates 



technique or a true difference between the taxa is unclear. 

The assemblages of different depth zones have differing 
patterns of geographical distributions. Abyssal species 
appear to have the most widespread distributions (Angel, 
1991), probably because there are fewest barriers to larval 
dispersal. For example, in the Polychaeta, which is one of 
the less cosmopolitan groups, 78% of all North Atlantic 
abyssal species are found in both the East and West 
Atlantic, compared to 58% of the bathyal species (Gage and 
Tyler 1991). Hadal, or ultra-abyssal, communities again 
have more disjointed distributions as only about 1 % of the 
Earth's surface is covered with water of such depth. Plain 
communities at these depths are poorly sampled but of 
particular interest are trench faunas (although not all 
trenches reach hadal depths). These are dealt with 
separately below. 

Latitudinal patterns are even less well studied. In pelagic 
communities there is a general trend for the number of 
species to increase from the polar to the tropical regions. 
Buzas and Culver (1991), also report a definite latitudinal 
gradient in the foraminiferans of open ocean sediments, 
typically ranging from 10-30 species in a few millimetres of 
sediment at high latitudes to 50-70 species in tropical 
latitudes. Whether this pattern is representative of the 
benthos as a whole is unclear. 

OCEAN TRENCHES 

Physical evolution and properties 

Ocean trenches are formed as a consequence of plate 
tectonic processes where sectors of expanding ocean floor 



pushes upon an unyielding continental mass or island arc, 
resulting in the crust buckling downwards (subducting) and 
being destroyed within the hot interior of the Earth. As 
oceanic crust ages and cools, it becomes denser and stiffer, 
resulting in a steeper angle of subduction and a deepening 
trench. Fig. 10.3 shows the locations of the principal 
known trenches, those occurring along the western edge of 
the Pacific being both the deepest, and geologically the 
oldest. Seismically, ocean trenches are highly active, as 
subduction is an erratic rather than a smooth process. This 
results in an unstable and unpredictable habitat compared to 
the relative environmental stability of the adjacent abyssal 
plains (Angel, 1982). 

Being generally close to land masses, ocean trenches tend 
to have relatively high rates of sedimentation, a significant 
amount of which is of organic origin and an important 
available food source for trench communities. Several 
trenches also underlie highly productive cold water 
upwelling zones, the organic fallout from which contributes 
greatly to their richness. The water within trenches 
generally originates from the surrounding bottom water, 
which is derived from cold surface water at high polar 
latitudes and is relatively well oxygenated (Angel, 1982). 

Endemism, diversity and biomass 

Trenches tend to be isolated linear systems. This, combined 

with their high seismic activity, would suggest that faunas 
low in species diversity but relatively high in numbers of 
endemic species should be found. These would be expected 
to show strong affinities at generic and family levels to 
other trenches in the same system, having all originated 
from the same parental species inhabiting the surrounding 



Table 10.3 Endemism among hadal species 



GROUP 



Cumacea 

Harpacticoida 

Ostracoda 

Crinoidea 

Gastropoda 

Pogonophora 

Amphipoda 

Tanaidacea 

Isopoda 

Porifera 

Coelenterata 

Pisces 

Bivalvia 

Holothurioidea 

Echiurida 

Ophiuroidea 

Asteroidea 

Others 

Polychaeta 

Cirripedia 

Pvcnogonida 

Foraminifera 

Sipunculida 

Total spp. 

Excl. Foraminifera 



TOTAL NO. OF 

HADAL SPECIES 

> 6000m 

3 

2 

2 

9 
16 
26 
17 
19 
49 
12 
12 

4 
26 
22 

8 

5 
12 

5 
32 

3 

3 
126 

4 

417 

291 



NO. OF SPP. 
EXCLUSIVELY AT 
DEPTHS > 6000m 

3 

2 

2 

8 
14 
22 
14 
15 
37 

9 

9 

3 
17 
14 

5 

3 

6 

2 
12 

1 

1 
35 



234 
199 



% ENDEMIC 


HADAL SPECIES 


100.0 


100.0 


100.0 


88.9 


87.5 


84.6 


82.4 


78.9 


75.5 


75.0 


75.0 


75.0 


65.4 


63.6 


62.5 


60.0 


50.0 


40.0 


37.5 


33.3 


33.3 


27.8 


0.0 


56.1 


68.4 



Source: Wolff, T. 1970. The concept of the hadal or ullra-ahyssal fauna. Deep-Sea Research 17:983-1003. 



95 



1. Biological Diversity 



Figure 10.1 Species and family diversity in sea-bottom samples 



^ 



spec i es 




Source: Grassle, J.F. 1991. Deep-sea benthic biodiversity. Bioscience 41(7). 
Note: Samples Uken at l,5OO-2,S0Om depth ofT New Jersey, USA. 



Figure 10.2 Composition of benthic macrofauna 



& 10 



1 



aiiiia 



Trenches CTr aw I ;] 
5 000- 10 000 n 



Cent.N Pacific C^ D 3 
5,600 m 



N *. At lisnt Ic CA . DO 
4,-100-5,000 m 



Peracor i d 
crustoceons 



Ech i noderms 



n 



N W At lant Ic CE 5D 
1, 700 m 



AD = Ancrnor dredge 



Epibentnic sledge 



Source: Wolff, T. 1977. Diversity and faunal con^osiUon of the deep-sea benthos. Nature 267:780-785. 



96 



Deep-Sea Invertebrates 



Figure 10.3 Distribution of the main ocean trenches 




r\ 



i 

•a 

c 



.55 



E 
5 



97 



1. Biological Diversity 



abyssal plains (Angel, 1982). In the few trenches studied, 
these hypotheses would appear to be true; however, as with 
other aspects of deep-sea diversity, generalisations remain 
tentative. 

Angel (1982) quotes Professor G.M. Belyaev (from which 
the following paragraph of information is taken). Between 
50% and 90% of the fauna of each ocean trench is endemic, 
compared to the overall endemism of hadal, or ultra-abyssal 
faunas, which is in the region of 57-60% (for example, see 
data given by Wolff, 1970, Table 10.3). There are some 25 
known endemic hadal genera, representing some 1 0-25 % of 
the total number of genera occurring in the hadal zone, and 
two known endemic hadal families; the Galatheanthemidae 
(Actinaria) and Gigantapseudidae (Crustacea). The latter 
family contains a single species: Gigantapseudes adactylus. 
The greatest number of endemic species known from a 
single trench is a sample of 200 from the Kurile-Kamchatka 
Trench; this may be compared with 10 endemic species 
known from the Ryukyu and Marianas Trenches. The 
Banda Trench has the lowest recorded proportion of species 
endemism (33%), and is probably the youngest trench 
geologically. In total, representatives of 33 classes, 150 
families and about 240 genera are known from hadal 
depths. 

As noted, high seismic activity may tend to produce low 
species diversity. Rapid sedimentation may have a similar 
effect. For example, the Aleutian Trench and the Japan 
Trench have relatively low macrofaunal diversities, 
attributable to frequent catastrophic slumping of canyon 
wall sediment (Grassle, 1989). 

In general, comparative data are sparse because of the 
variety of collection techniques employed. The composition 
of trench faunas is unusual (compared to abyssal faunas) in 
that they tend to be dominated by deposit-feeders (Angel, 
1982) and show a higher percentage of species of 
amphipods, polychaetes, bivalves, echiurids and 
holothurians, and a lower percentage of sea stars, 
echinoids, sipunculids and brittle-stars, and especially non- 
actinian and scyphozoan coelenterates, bryozoans, 
cumaceans and fishes, than in the surrounding abyss. 
Decapod crustaceans are completely absent (Gage and 
Tyler, 1991). 

Trenches appear to have a higher biomass than adjacent 
shallower areas, although within the trenches themselves the 
stocks of macrofauna decrease with depth at a rate similar 
to the general declining pattern. The higher biomass in 
trenches is probably a reflection of the net accumulation of 
sediment from the adjacent shallow continental margins 
(Rowe, 1983), as the amounts of available nutrients have a 
profound effect on trench faunas; 8.8g/m2 of living 
organisms have been assessed from the nutrient-rich South 
Sandwich Trench and 3.44g/m2 from the Kurile-Kamchatka 
Trench, compared to 0.008g/m^ from the nutrient-poor 
Marianas and Tonga Trenches (Angel, 1982). 

HYDROTHERMAL VENTS 

Hydrothermal vent communities were first discovered in 
1977, at a depth of 2,500m on the Galapagos Rift. They are 
now known to be associated with almost all known areas of 



tectonic activity at various depths (see Fig. 10.4). These 
include: along the East Pacific Rise off Mexico, in the 
Guaymas Basin in the Gulf of California, on the Juan de 
Fuca Ridge off Washington State, in subduction areas off 
Oregon and Japan, on the Mid-Atlantic Ridge at 26°N, in 
the Mariana Trough near the Mariana Trench, and in the 
Lau and North Fiji Basins to the west and east of Fiji (Gage 
and Tyler, 1991). These tectonic regions include ocean- 
floor spreading centres, subduction and fracture zones, and 
back-arc basins (Gage and Tyler, 1991). Cold bottom-water 
permeates through fissures in the ocean floor close to 
ocean-floor spreading centres, becomes heated at great 
depths in the Earth's crust and finds its way back to the 
surface through hydrothermal vents. The temperature of 
vent water varies greatly, from around 23 °C in the 
Galapagos vents, to around 350''C in the vents of the East 
Pacific Rise, and they may be rich in metalliferous brines 
and sulphide ions (Angel, 1982). Although the vent water 
may be at a high temperature, the majority of species live 
out of the main flow at temperatures of around 2°C, the 
ambient temperature of deep-sea water. 

Although vent communities are often separated from one 
another by gaps of a kilometre or so, they can be up to 
100km apart. They have yet to be found in certain areas of 
known hydrothermal activity, such as the Red Sea (Grassle, 
1 986). Hydrothermal vents and their associated communities 
are relatively short-lived at any particular site, probably 
only being active for between several years and several 
decades. This has been suggested by discoveries of 'dead' 
vents (visible from the remains of white shells which 
dissolve away completely in about 15 years) and by growth 
measurements of individual organisms (indicating very rapid 
growth to maturity at a large size) (Gage and Tyler, 1991). 
However, active hydrothermal centres appear to move 
relatively slowly, thus allowing dispersal of vent organisms. 

Areas of tectonic activity are connected over most of the 
earth's surface, and although this network is in a dynamic 
state, new areas are linked to old and so vent communities 
could be part of a unique ecosystem at least 200 million 
years old (Grassle, 1985). Studies on variation in vent 
species, comparing those in the main network and those 
isolated in remote parts of the system, provide important 
opportunities for evolutionary and genetic studies. Vent 
species are also of interest in that they flourish in the dark 
at high pressures and low temperatures (Grassle, 1986), 
which previously had been thought to inhibit productivity. 

Hydrothermal vent communities are unique in that they are 
supported by a non-photosynthetic source of organic carbon, 
i.e. chemosynthetic primary production. The enriched 
hydrothermal fluid supports large numbers of bacteria 
(predominantly Thiomicrospira species) which form dense 
bacterial 'mats', and are capable of deriving energy from 
reduced compounds such as hydrogen sulphide (Grassle, 
1986, Gage and Tyler, 1991). Many of the vent species 
filter-feed on these bacteria, whilst others rely on symbiotic 
sulphur bacteria for energy (Angel, 1982). 

Endemism, diversity and biomass 

The overall species diversity at vents is low compared with 
other deep-sea soft-sediment areas (Grassle, 1986), but 
endemism is high. More than 20 new families or sub- 



98 



Deep-Sea Invertebrates 



Figure 10.4 Hydrothermal vent and cold seep communities 




99 



1. Biological Diversity 



families, 50 new genera and nearly 160 new species have 
been recorded from vent environments, including brine and 
cold seep communities (discussed below) (Grassle, 1989; 
Gage and Tyler, 1991). Examples of these new taxa are 
given in Table 10.4. 

In biogeographic terms, vents can be regarded as 
ephemeral, biogeographic islands. With increasing spatial 
separation the species composition can vary considerably, 
with some species being replaced by closely related forms. 
Differences in subsurface flux of hydrothermal fluids and in 
vent configuration can result in large differences in faunal 
composition over short distances within or between vent 
fields. Geochemical differences between vent communities 
may also result in faunal dissimilarities, between the 
Galapagos and East Pacific Rise vents, for example 
(Grassle, 1986). However, the major features of the fauna 
at each vent site are consistent, whilst none of the species 
seems to be ubiquitous. The larvae of many vent species 
appear to have relatively poor dispersal abilities (Grassle, 
1986), and this could contribute to maintenance of high 
endemism. 

The biomass of vent communities is usually high compared 
to other areas of similar depth, and varies according to 
water temperatures and chemistry, reaching 8.5kg wet 
weight per m^ at lower temperature vents, and averaging 2- 
4kg wet weight per m^ at the hottest vents (200-360°C) 
(Gage and Tyler, 1991). Dense colonies of tube-worms, 
clams, mussels and limpets typically constitute the major 
proportions of biomass. Swarms of the probably vent- 
specific copepod species Isaacsicalanus paucisetus reached 
densities of 920 individuals m"^ and a dry weight biomass 
of 133 mg~^ at one site. Microbial production at low- 
temperature vents (10°C) is thought to be two or three 
times that of photosynthetic production at the surface in the 
same region (Gage and Tyler, 1991). 

Features of some major vent regions are noted below. 

Galapagos Spreading Centre 

This consists of 12 known active populated vents and three 
'dead' vents along a 30km section of ridge-crest. The two 
large bivalves Calyptogena magnifica and Bathymodiolus 
thermophilus, and vestimentiferan worms (especially the 
tube-dwelling Rifiia pachyptila) are the most distinctive 
species of these hydrothermal vents (Grassle, 1986). 

Eastern Pacific Rise 

These hydrothermal vents support a similar fauna to the 
Galapagos Spreading Centre, including the same two 
bivalve species (which can occur in enormous densities - the 
biomass of B. rhermophilus may exceed lOkg/m^), and 
Riftia pachyptila. More than 30 species of limpet-like 
gastropod have been recorded (mostly as yet undescribed), 
and mussels, shrimp, anemone and limpet species (Gage 
and Tyler, 1991). The spreading rate of ll-12cm/year is 
greater than that of the Galapagos spreading centre 
(Grassle, 1986). 

Mid-Atlantic Ridge 

The active hydrothermal vents discovered on this ridge are 
characterised by the presence of two species of caridean 
shrimp belonging to the new family Bresiliidae. These 



occur in great numbers, along with mats of bacteria. 
Compared to the eastern Pacific, the vent faunas are less 
varied; bivalve mussels appear to be uncommon, and 
tubeworms absent (Gage and Tyler, 1991). 

Mariana Trough 

This back-arc spreading centre borders the subduction zone 
of the Mariana Trench. It is isolated from the main mid- 
ocean ridge system. The vent-fauna is very different from 
those of the eastern Pacific, and is dominated by a sessile 
barnacle (the most primitive living barnacle species known), 
limpets and anemones. The giant bivalves of the eastern 
Pacific are replaced by a large, hairy-shelled gastropod 
(Gage and Tyler, 1991). 

Shallow-water hydrothermal vents 

Vents at depths of less than 20m have been described off 
the Palos Verdes Peninsula, California. They support a 
diverse assemblage of colourless chemosynthetic bacteria 
similar to those of deep-sea vent sites, which form mats 
around the vent openings. The mats provide nourishment 
for the mollusc Haliotis cracherodii (Kleinschmidt and 
Tschauder, 1985), commonly known as black abalone. 

COLD SEEPS 

Cold sulphide and methane-enriched groundwater seeps 
occur near the base of the porous limestone of the Florida 
Escarpment, as well as in the Gulf of Mexico (Fig. 10.4). 
The seeps support a dense faunal community associated 
with a covering or mat of bacteria on the sediment surface. 
These communities are strikingly similar in taxonomic 
composition to the hydrothermal vents of the east Pacific, 
a fact which points to a common origin and evolutionary 
history for both community types (Hecker, 1985). The 
community consists of large mussels and the vestimentiferan 
worm Escarpia laminata, as well as galatheid crabs, 
serpulid worms, anemones, soft corals, brittle stars, 
gastropods and shrimps. Mussel densities appear to be 
linked to methane levels in the water, whilst tubeworm 
density may be correlated with the hydrocarbon loading of 
the sediment (Gage and Tyler, 1991). 

Tectonic subduction zone seeps 

Subduction seeps are more diffuse and lower in temperature 
than hydrothermal vent seeps, and are rich in dissolved 
methane. They are known to occur off Oregon, where the 
fauna includes species of Lamellibrachia and large 
vesicomyid bivalves, and in the Guaymas Basin in the Gulf 
of California, where thick bacterial mats cover the sulphide 
and hydrocarbon-coated sediment. The cold Japanese 
subduction zone seeps occur at a depth of 1,000m in 
Sagami Bay near Tokyo and in the subduction zones of the 
trenches off the east coast of Japan. The communities vary, 
but include dense benthic assemblages dominated by 
Calyptogena clams associated with a stone crab Paralomis 
sp., sepulid worms, sea anemones, galatheid crabs, 
swimming holothurians and amphipods (Gage and Tyler, 
1991). 

Other colonised deep-sea seepage sites include a cold seep 
to the east of Barbados dominated by the mussel 
Bathymodiolus, vesicomyid bivalves and vestimentiferan 



100 



Deep-Sea Invertebrates 



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101 



1. Biological Diversity 



worms. Dense communities, probably of recent origin, have 
also been discovered on the Laurentian Fan on the south- 
east Canadian continental margin. These include vesicomyid 
and thyasirid bivalves, gastropods, pogonophorans, 
galatheid crabs and bacterial mats. There is evidence that, 
like hydrothermal vents, cold seeps are ephemeral and 
cyclic. However, many species are now known to occur in 
the deep sea in a variety of similar sulphur and other 
compound-reducing habitats, and have been found to occur 
around such temporary habitats as oil-rich whale carcasses, 
which may be important 'stepping-stones' for 
chemosynthetic-dependent deep-sea animals (Gage and 
Tyler, 1991). 

References 

Angel, M.V. 1982. Ocean trench conservation. Commission on 

Ecology Papers No. 1. lUCN. 
Angel, M.V. 1991. Biodiversity in the deep ocean. A working 

document for ODA. Unpublished MS. 
Buzas, M.A. and Culver, S.J. 1991 . Species diversity and dispersal of 

benthic foraminifera. Bioscience 41(7):483-489. 
Gage, J.G. and Tyler, P. A. 1991 . Deep-sea Biology: A natural history 

of organisms at the deep-sea Jloor. Cambridge University Press. 
Grassle, J.F. 1985. Hydrothermal vent animals: distribution and 

biology. Science Vol.229. 



Grassle, J.F. 1986. The ecology of deep-sea hydrolheraial vent 
communities. Advances in Marine Biology Vol. 23. Academic Press. 

Grassle, J.F. 1989. Species diversity in deep-sea communities. TREE 
4(1). 

Grassle. J.F. 1991. Deep-sea benthic biodiversity. Bioscience 41(7). 

Hecker, B. 1985. Fauna from a cold sulphur-seep in the Gulf of 
Mexico: comparison with hydrothermal vent communities and 
evolutionary in^lications. Biological Society ofWashinglon Bulletin 
6:465-473. 

Hessler, R.R. and Sanders, H.L. 1967. Faunal diversity in the deep- 
sea. Deep-Sea Research 14:65-78. 

Kleinschmidt, M. and Tschauder, R. 1985. Shallow-water 
hydrothermal venl systems off the Palos Verdes Peninsula, Los 
Angeles County, California. Biological Society of Washington 
Bulletin No.6. 

Rex, M.A. 1983. Geographic patterns of species diversity in the deep- 
sea benthos. In: Rowe, G.T. (Ed.), Deep-Sea Biology. Volume 8, 
The Sea. John Wiley and Sons, New York. Pp. 453-472. 

Rowe, G.T. 1983. Biomass and production of the deep-sea 
macrobenthos. In: Rowe, G.T. (Ed.), Deep-Sea Biology. Volume 8, 
The Sea. John Wiley and Sons, New York. Pp. 453-472. 

Thome-Miller, B. and Catena. J. 1991. The Living Ocean: 
understanding and protecting marine biodiversity. The Oceanic 
Society of Friends of the Earth, Washington DC. 

Wolff, T. 1970. The concept of the hadal or ultra-abyssal fauiM. Deep- 
Sea Research 17:983-1003. 

Wolff, T. 1977. Diversity and faunal composition of the deep-sea 
benthos. Nature 267:780-785. 



102 



11. SOIL MACROFAUNA 



Soil Macrofauna 



Compared to conspicuously diverse habitats such as tropical 
rain forest or coral reefs, the soil as a habitat in its own 
right, with its own rich fauna and flora, is often 
overlooked. It supports, however, a wide array of diverse 
animals, with representatives from every major phylum in 
the animal kingdom except the coelenterates and the 
echinoderms (Wallwork, 1976). 

SOIL AND SOIL FAUNA 

The soil habitat is not a uniform environment. Examination 
of a vertical section of the profile of a mature soil will often 
reveal several layers reflecting its past history and 
development. This sequence, from the organic litter layer 
on the soil surface to the parent materied below, can be 
divided into four main horizons (Eisenbeis and Wichard, 
1985): 

O-horizon: organic upper layer of plant debris lying on 
the surface of the mineral soil 

A-horizon: upper, fine mineral soil permeated by 
organic material 

B-horizon: weathered, rough mineral soil coloured by 
small deposits of humus 

C-horizon: original, unweathered material. 

The organic layer (O-horizon) can often be further 
subdivided into three sub-layers: the leaf litter layer, the 
fermentation layer and the humus layer, in a downward 
succession (Wallwork, 1976). The actual depth that the O- 
horizon attains is dependent on the rate of input from the 
covering vegetation and the rate of decomposition. 

The term 'soil fauna' can be used to encompass a large 
number of animal species, including any which spend a 
proportion of their life cycle in the soil, on the soil surface, 
or in the leaf litter. The soil fauna contains numerous life 
forms adapted to a great variety of microhabitats. In an 
attempt to clarify the distribution of organisms within the 
soil, Kevan (1962) proposed three categories, in terms of 
their respective adaptations to life in the soil: 

Euedaphon: inhabitants of the mineral soil, e.g. most 
earthworms, all Symphyla, many mites 
Hemiedaphon: inhabitants of the litter and fermentation 
layer, such as many woodlice and millipedes 
Epedaphon: inhabitants of the soil surface, such as most 
ground-beetles and scorpions. 

These categories are widely used, although some later 
authors (e.g. Eisenbeis and Wichard, 1985) have modified 
the definitions. Any given taxonomic group may include 
species in more than one of the above categories, as well as 
species which are not considered soil fauna. 

Table 11.1 shows all taxonomic groups to be considered in 
this context, with the term soil fauna being defined as 
narrowly as practicable. Taxonomic level varies from 
phylum to family. Taxonomic sequence follows Barnes 
(1984). 



Patterns of soil-fauna research 

Although research is being conducted on the key soil 
groups, much of it is limited to individual genera or species 
rather than whole orders; and it covers only a few of the 
major habitats. Thus, it is very difficult to build up a 
picture of the total fauna of a region using littrature 
primarily on soil research. 

The taxonomic precision of the primary literature also 
varies through time. The 1940s and 1950s saw a peak of 
species-level identifications by ecologists. Since the 1960s, 
ecological and taxonomic interests have developed, so few 
soil ecologists now provide species lists in their papers. 
Data are now more often presented at order level, with 
emphasis on biomass and productivity rather than on species 
assemblages. Very recently, there have been moves to 
revive taxonomic competence among ecologists 
(Erzinclioglu, 1989; Dempster, 1991). 

Other types of literature, such as general guides to animal 
groups, identification keys, and taxonomic monographs, 
provide useful information, but many are dated, thus 
reducing the accuracy of their assessment of species totals 
for a region. Many are also ordy the result of brief 
collecting expeditions and so can only be considered 
preliminary markers of the possible species richness. 

As our knowledge of the soil fauna and habitat expands, so 
our appreciation of its faunal diversity increases, sometimes 
ten-fold. The estimated world total of Pseudoscorpiones 
recently rose from 1,300 (Levi el al., 1968) to 3,000 
(Davies et al. , 1985), and of Collembola from 1,500-2,000 
(Wallace and Mackeras, 1970) to 10,000-20,000 
(Greenslade and Greenslade, 1983). 

This is in line with the trend shown by invertebrate 
diversity estimates in general. The degree to which current 
figures for soil biodiversity may be relied upon is 
geographically patchy: some areas have comprehensive and 
up-to-date lists for most groups, and these have been 
relatively stable for several decades despite an increasing 
pace of ecological and biogeographic research (e.g. 
Britain); a few others, such as Australia, are attempting to 
produce comprehensive overviews; but in most countries, 
the literature is becoming narrower and less easily used. 

Ecological functioning and importance of soil fauna 

The soil is basic to most terrestriad ecosystems, and the 
health and functioning of the soil rehes heavily on the 
activities of soil fauna. The initial formation of soil, for 
instance, at the end of a glaciation, depends greatly on 
detritivores to help in cycling of nutrients and humus 
formation. The accumulation of the latter is responsible for 
the development of the soil through time. The role of soil 
invertebrates in these pioneer phases must be considerable: 
several groups of invertebrates are known, from the fossil 
record, to have colonised newly exposed areas well in 
advance of the vascular flora (Buckland and Coope, 1991). 

The soil fauna is also a major vector of microorganism and 



103 



1. Biological Diversity 



Table 11.1 Taxonomic distribution of soil macrofauna 



PROPORTION OF GROUP 

WHICH ARE 

TERRESTRIAL 



PROPORTION OF 
TERRESTRIAL SPP. 
LIVING IN THE SOIL 



EXTENT TO WHICH 

SOIL SPP. UTILISE 

THE SOIL 



Platyhelminthes: 

Tricladida 
Nemertea 
Nematoda 
Annelida: 

Oligochaeta* 
Mollusca: 

Gastropoda 
Crustacea: 

Isopoda* 
Amphipoda 
Decapoda 
Chelicerata: Arachnida: 
Scorpiones" 
Pseudoscorpiones " 
Uropvgi 
Amblypygi 
Palprgradr 
Ricinulei 
Solifugae 
Opiliones" 
Araneae 
Acari*: 

Mesostigmata 
Prostigmata 
Astigmata 
Cryptostigmata 
Onychophora 
Unirannia: 

Diplopoda* 

Pauropoda 

Chilopoda* 

Symphyla 

Diplura 

Collembola* 

Protura 

Thysanura 

Embioptera" 

Orthoptera": 

Gryllotalpidae 
Tridactylidae 
Cylindrachetidae 
Tetrigidae 
Dermaptera" 
Isoptera" 
Blattaria' 
Psocoptera 
Thysanoptera 
Homoptera 
Coleoptera: 

Carabidae* 
Staphylinidae" 
Tenebrionidae 
Scarabaeoidea 
Elateroidea 
Cantharaoidea 
Hymenoptera: 

Formicidae' 
Megaloptera 
Diptera 



• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• •• 

• ••• 

• • 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• •• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• •• 

• •• 

• •• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 



• ••• 

• ••• 

• •• 



• ••• 

• • 

• ••• 

• •• 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• •• 

• • 

• •• 

• • 
• 

• •• 

• •• 

• •• 

• ••• 

• •• 

• ••• 

• ••• 

• •• 

• ••• 

• • 

• ••• 

• ••• 

• ••• 

• ••• 

• ••• 

• •• 

• •• 

• •• 

• • 



• •• 

• •• 

• •• 

• •• 

• • 

• •• 

• • 



• ••• 

• ••• 



• /••• 



• •• 

• •• 

• •• 

• •• 

• ••• 

• ••• 



• •• 

• •• 

• •• 

• •• 



• •• 

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• •• 

• •• 

• •• 

• •• 

• •• 

• •/••< 

• ••• 

• • 

• •• 



• •• 






Notes: • indicates taxa considered key soil groups for which adequate biogeographic and taxonomic information has been located and which are 
therefore considered in detail in this review. Nematodes are discussed in Chapter 9. Columns 2 and 3 are coded as follows: •••• all species; 
• •• most species; •• some species; • few species. Column 4 is coded as follows: •••• obligate soil-dwellers; ••• usually soil-dwelling, but 
may at times climb vegeution etc.; •• temporarily present, normally for a particular part of their life cycle (e.g. Diptera larvae); • regular users 
of the soil (i.e. for foraging) but able to spend much or all of their life in other microhabitats. 



104 



Soil Macrofauna 



cryptogam propagules (Gerson and Seaward, 1977; 
McCarthy and Healy, 1978). Many soil groups include 
decomposers which are important in the breakdown and 
recycling of nutrients throughout mature ecosystems. Most 
temperate soils differ from soils at lower latitudes in having 
a greater 'standing crop' of plant detritus, owing to the 
lower decomposition rates, and tend to be deeper and with 
a more elaborate profile, partly due to seasonality of 
precipitation and the effects of frosts. 

All of these processes, where soil invertebrates function as 
pioneers and as facilitators of cycling in later serai stages, 
are important in the rehabilitation of damaged ecosystems 
where, for example, the vegetation and/or top-soil has been 
lost. Earthworms have been shown to aid the development 
of vegetation in derelict industrial sites; monitoring of their 
population levels can therefore be used as an indicator of 
the recovery of the habitat (Davis, 1986). 

In most terrestrial habitats, the soil fauna is also important 
for niche creation: that is, the activities of some groups 
provide niches for other soil animals. Most importantly, the 
actions of earthworms are largely responsible for the 
structure of many soils, and their burrows allow access to 
deeper parts of the soil not normally penetrable by other 
groups; they thus provide retreats in the face of predation 
or desiccation. 

The soil macrofauna, in synergy with microorganisms, also 
acts as a major link between the soil and non-soil habitats. 
The role of these groups, and in catalysing the processes of 
nutrient cycles, releasing minerals for uptake by vascular 
plants, as well as providing a physical soil structure which 
strongly influences the development of plant communities, 
is crucial to the final appearance of the vegetation. 

Many non-soil animals such as birds and mammals feed on 
soil fauna regularly. For some groups, such as shrews 
(Soricidae), hedgehogs (Erinaceidae), some wading birds 
(Charadriiformes) and many reptiles and amphibians, soil 
fauna may make up the bulk of their diet, at least during 
part of the year. 

PATTERNS OF SPECIES RICHNESS 

This section contains a systematic account of the 
biogeographic patterns of the key soil groups prefaced by 
notes on their biology. The higher level classification of 
groups is not necessarily the same as followed elsewhere in 
this volume. The reference list for data cited in the tables 
below is available on request from WCMC. 

Phylum Annelida 

Sub-class Oligochaeta 

The Oligochaeta is divided into two main soil-dwelling 
groups, the earthworms (Lumbricina) and the potworms 
(family Enchytraeidae). Oligochaetes are soft-bodied 
segmented worms adapted to burrowing in the soil; they 
include the only truly terrestrial annelids and are 
ecologically a very important group. 

Oligochaeta: Lumbricina 

Earthworms are largely absent in highly acidic soils, such 



as peatlands and heathlands: few species can tolerate a pH 
lower than 4.0 (Wallwork, 1976). In base-rich soils, 
however, they often constitute a high proportion of the total 
animal biomass. Members of the family Lumbricidae 
dominate the fauna in north temperate regions, and range in 
size from less than 1cm to 35cm. Several other families 
occur in warm temperate and tropical countries, the best 
known being the Megascolecidae, some species of which 
can exceed 3m. 

Populations of 2.4-7.2 million earthworms per hectare have 
been reported from rich permanent grassland habitats in 
Britain (Cloudsley-Thompson and Sankey, 1968). They are 
of considerable importance in soil processes (Sims and 
Gerard, 1985). In addition to the benefits in agricultural 
soils, earthworms are ftindamental to the production of the 
soil structure within which many other soil invertebrates can 
live (Lavelle, 1983). Several important groups of soil fauna 
are able to penetrate deep into the soil, and thereby survive 
during dry weather, solely because of the network of fine 
passages created by earthworms. 

Oligochaeta: Enchytraeidae 

The potworms comprise the terrestrial members of a family 
many of whose members are freshwater or marine. They 
are rarely more than 25mm in length and can tolerate acid 
conditions much better than lumbricids; large populations, 
of the order of thousands per m^, may be found in more 
acid soils of oak woodlands and moorland peats (Wallwork, 
1976). Few other groups are as successful in colonising the 
rather sterile and water-logged soils of bogs; only 
nematodes and Diplura (Eversham, unpublished) thrive 
equally well in these conditions. 

Areas which were covered by ice during the last glaciation 
or which supported only tundra vegetation for several 
millennia lost almost all their earthworms; post-glacial 
recolonisation appears to have been restricted to a few 
highly mobile, eurytopic species. Thus, Britain and north- 
west Europe support a small fauna of only 10-30 species 
and the earthworms of natural habitats are only slightly 
more diverse than those of improved agricultural soils. 
Countries bordering the Mediterranean have many more 
species, with particular concentrations in the Iberian 
Peninsula and Italy; even the French fauna reaches 97 
species (Lavelle, 1983). In such areas, agricultural 
improvement displaces the more stenotopic species. A 
similar pattern is found in North America. Of nearly 400 
lumbricid species recognised, only 5% occur in the northern 
areas which were overlain by ice sheets. A whole 
superfamily, the Crilodriloidea, is now confined to a small 
area of the southern USA (Sims and Gerard, 1985). 

There is limited evidence that the centres of species richness 
in the southern hemisphere are now being threatened by the 
introduction of north temperate species, which are 
associated with agricultural soils but may be able to out- 
compete the indigenous fauna (Ljungstrom, 1972). 

Other aspects of family level distribution throw light on 
much more ancient geomorphological history. A 
consequence of the two effects (relict Gondwana 
distributions and Pleistocene glacial defaunation) is seen, 
for instance, in the much richer earthworm faunas of 



105 



1. Biological Diversity 



southern hemisphere islands like New Zealand (192 species; 
Lee, 1959) compared with that of a similar-sized landmass 
such as Britain (28 species), which should for reasons of 
island biogeographic theory be expected to acquire species 
much more readily from its nearby continent. The 
impoverished fauna of Iceland (8 species; Lavelle, 1983) is 
an even more extreme example of this; it is likely that the 
whole of this fauna is recently introduced by man. The 
position of Japan in relation to the Eurasian landmass is 
reflected in its relatively rich fauna (75 species; Easton, 
1981). 



discovered. In well-worked regions, there is clear evidence 
of this niche specialisation, as well as landscape-scale 
differentiation (Harding et at. , 1991). 

Some species associated with ancient natural habitats are 
now threatened by agricultural change and other human 
modifications of the landscape, such as the clearance or 
replanting of ancient woodland, the drainage of wetlands 
(e.g. Ligidium hypnorum in England), and general 
disturbance of coastal habitats (e.g. Armadillidium album 
throughout its range). 



Table 11.2 Soil species: Oligochaeta 



Table 11.3 Soil species: Isopoda 



TOTAL SPECIES 

Lumbricina 

New Zealand 

France 

Japan 

Oregon (USA) 

UK 

Little Carpathians (East Europe) 

Denmark 

Sweden 

Washington (USA) 

Iceland 

Enchytraeidae 
North America 
Europe 
Little Carpathians (East Europe) 



1,200 



192 
97 
75 

267 

25 
22 

19 

13 

137 

S 



143 

in 

24 



Phylum Crustacea 

Almost all the terrestrial Crustacea belong to the order 
Isopoda, the familiar woodlice, slaters or sowbugs. A very 
few members of the mainly aquatic Amphipoda and land 
crabs have also adopted a terrestrial existence. 

Class Malacostraca: Isopoda 

Some genera rarely venture up to the soil surface, whereas 
others spend most of their existence among leaf litter and 
grass roots, and a few forage regularly among herbaceous 
vegetation or even in the lower branches of trees (Sutton, 
1980). In all these cases, the major part of woodlouse diet 
is probably dead plant matter, though some species have 
been observed browsing on the living foliage of trees. 
Isopods have developed a wide range of behavioural 
adaptations to avoid desiccation. 

Eurasian Isopoda appear to have a strong centre of diversity 
around the Mediterranean - especially in Spain, Italy and 
North Africa; it has been suggested that the fauna in these 
areas is even more diverse than that of tropical sub-Saharan 
Africa (P.T. Harding, pers. comm.). A few north-west 
European species have been widely spread by man, and 
make up a large proportion of the common synanthropic 
woodlice of North America and other temperate regions, 
and a few species are now almost cosmopolitan, e.g. 
Cylisticus convexus (Harding and Sutton, 1985). Although 
superficially amongst the better-known soil macrofauna, 
some woodlice are very small and cryptic, and occupy 
narrow and obscure niches: for example, the coastal 
shingle-bank fauna of northern Europe is only just being 



France 

North America 

Germany 

UK 

Holland 

Little Carpathians (East Europe) 



156 
100 
60 
42 
35 
28 



Phylum Chelicerata 

Class Arachnida 

Second only to the insects among the arthropods in terms of 
species numbers, the arachnids are an ancient and mainly 
terrestrial group. 

Arachnida: Scorpiones 

A morphologically rather uniform group of nocturnal 
predators with modern species ranging from 1.3cm to 18cm 
in length, but some Carboniferous species attained a length 
of 86cm (Barnes, 1980). Although usually thought of as 
typical of arid regions, there are many species which 
require a humid environment and occur in tropical moist 
forests. Most species occur in warm regions, but a few 
occur near the snow-line in mountains, and a single species 
occurs as far north as Canada (Levi et at., 1968). 



Table 1 1 .4 


Soil 


species: 


Scorpi 


iones 


TOTAL SPECIES 


' 


1,000 + 


Africa (S) 








159 


Iran 








36 


USA 








20-30 


Kenya (N) 








26 


Arabia 








23 


Tanzania/Kenya 








23 


Africa (W) 








17 


Iraq 








15 


Israel ^ 








15 


Australia (W) 








11 


Syria 








11 


Turkey 








11 


Egypt 








9 


Israel (N) 








8 


Trinidad 








7 


Libya 








6 


Madagascar 








6 


Kenya (S) 








6 


Jordan 








5 


Tobago 








3 



It is possible that the ranges of some temperate species are 



106 



Soil Macrofauna 



currently not entirely climatically determined, but reflect 
incomplete recolonisation after the glaciation. From the 
literature it appears that scorpions have a surprisingly even 
distribution of species richness in the warmer regions of the 
world. There is no evidence of any areas of marked 
radiation, which may be characteristic of an ancient and 
morphologically conservative group. The only exception is 
the apparent radiation of the rich southern African fauna, 
which parallels the high diversity of certain plant groups, 
especially Erica and Protea (Good, 1964). An additional 
factor in producing the even distribution of species, with 
few areas of very high diversity, may be their mode of life: 
they are bare-ground active hunters of large invertebrates 
and small vertebrates, and consequently occupy a broad 
niche space which cannot easily be partitioned between 
species, even if individual population density is high. In this 
respect, they provide an interesting contrast with the 
Carabidae, another group of surface-active generalist 
predators as discussed below. 

Arachnida: Pseudoscorpiones 

These small arachnids, the largest being only 8mm long and 
most only 2-3mm, superficially resemble scorpions. Most 
species live in leaf litter, and require a high humidity; in 
suitable woodlands, very high densities may be attained, 
with over 500 per m' commonly recorded, and peaks of 
over 900 per m^ reported (Gabbutt, 1967). The efficient 
dispersal of species, particularly those with narrow 
microsite requirements (nests, barns, decomposing 
vegetation), is enhanced by phoresy - attaching themselves 
to other arthropods, especially Diptera and occasionally 
Coleoptera, and remaining attached until the host reaches 
another patch of suitable habitat. The maximum diversity of 
pseudoscorpions is widely believed to be in the tropics 
(Wallwork, 1976), but the available data are very patchy, 
with no comprehensive regional reviews, even in generally 
well documented areas such as Europe and North America; 
almost all the literature focuses on individual genera or 
species. The classification at species and family level is still 
in a state of flux. There is some evidence of microsite 
specialisation at the landscape scale (Legg and Jones, 1988), 
but few sites support a particularly rich range of 
pseudoscorpions. 



Table 11.5 


Soil 


species: 






Pseudoscorpiones 




TOTAL SPECIES 






3,000 


North America 






200 


South Africa 






109 


Australia 






99 


Brazil 






40 


UK 






26 



Arachnida: Opiliones 

The harvestmen or harvest-spiders have an average body 
length of 5-lOmm, but the largest tropical species reach 
20mm with a leg length of 160mm (Barnes, 1980). 
Harvestmen are abundant in leaf-litter and low vegetation in 
most habitats. In some tropical forests, the predatory force 
of harvestmen is thought to exceed that of the spiders 
(Dalingwater, 1983), although they will also scavenge on 



dead animals, and will eat a very wide range of organic 
matter, including fruit. Many species forage on the trunks 
and branches of trees when adult, but even these species 
tend to spend most of their juvenile life in litter or grass 
roots. Many species are nocturnal, as an adaptation to 
avoiding desiccation; the more resistant species are able to 
be active by day (Todd, 1949). 

There are two ecological/systematic divisions in the 
harvestmen which show contradictory distribution trends, 
although the overall pattern is of higher diversity in the 
tropics. The actively predatory Laniatores are almost 
exclusively tropical and can be regionally diverse, e.g. 581 
species in South America (Lawrence, 1931). The other 
main group, the scavenging Palpatores, show the reverse 
trend, with high diversity in the temperate regions: the 
known South American fauna contains a mere 29 
Palpatores, while Europe possesses 215 species, compared 
to the meagre 14 native south-European Laniatores, of 
which only eight occur in central/northern Europe 
(Lawrence, 1931; Martens, 1978). 

Harvestmen are more sensitive to desiccation than most 
arachnids, so are ill-adapted to a desert enviroimient. This 
may explain the low diversity in Australia, for instance 
(where there is a rich spider fauna), compared with the rich 
Opiliones fauna in moist tropical forests, where they may 
be able to out-compete the spiders (Dalingwater, 1983). 



Table 11.6 Soil species: Opiliones 



TOTAL SPECIES 

South America 

Europe 

Africa (excluding S Africa) 

New Zealand 

Europe (N of Mediterranean) 

North America 

South Africa 

Madagascar 

China 

Australia 

UK 

Holland 



3,500 

581 

232 

201 

170 

110 

104 

90 

69 

60 

38 

23 

21 



Arachnida: Acari (Oribatei) 

There are seven major groups of mites and ticks in this 
huge order, but only mites of three suborders occur 
predominantly in soil. They have a worldwide distribution. 
The Cryptostigmataor Oribatei are generally saprophagous, 
some feeding directly on decomposing litter fragments while 
others eat the fiingi and bacteria which coat the litter. The 
Mesostigmata also include some saprophages, but many 
species are predatory. Prostigmatid mites are very varied in 
form and habit and include many non-soil-dwelling species. 
Of these three suborders the Cryptostigmata or Oribatei are 
by far the best known, in terms both of taxonomy and 
ecology; the prostigmatid and mesostigmatid soil-mites have 
received less attention and are less confined to the soil. 

Most Oribatei are less than 1mm long, some very much 
smaller. High population densities can occur, with figures 
of 130,000 per m^ being unexceptional. They occur in a 
wide range of soil and litter microhabitats the world over 



107 



1. Biological Diversity 



(Luxton, in prep.) and play an important part in litter 
decomposition, both directly (those which feed directly on 
litter will consume about 20% of their body weight in litter 
each day), and indirectly (they stimulate microbial action in 
the litter). As the single most important fungivorous group 
in the soil, up to 50% of microfungal grazing and spore 
dispersal is attributable to oribatids (Eisenbeis and Wichard, 
1985). 

The available numerical data suggest that temperate soils 
support a more diverse cryptostigmatic mite fauna than the 
tropics, but this is almost certainly an artefact of sampling. 
The British Isles, with 300 species, would appear to have 
the richest concentration of any area, but also has the only 
up-to-date checklist (Luxton, in prep.). The available world 
literature concentrates almost entirely on generic and 
species taxonomy, or the fauna of very small sampling 
areas within atypical habitats. Oribatids are such an 
important group within the soil, being geographically and 
biotopically ubiquitous, that their overall biodiversity 
pattern will be of great interest when sufficient comparable 
data have accumulated. 



Table 11.8 Soil species: Chilopoda 



Table 11.7 



TOTAL SPECIES 



Soil species: 
(Oribatei) 



UK 

USSR (European) 

Bulgaria 

Japan 

Arctic 

Little Carpathians (East Europe) 

Canada (N) 

Peru 

Ghana 

Alaska 

India 



Acari 



7.000 

300 

278 + 

250 

170 

144 

129 

106 

91 

52 

10 
(8 ) 



Phylum Uniramia 

Class Chilopoda 

This class comprises the centipedes, an important group of 
elongate, swift and agile predators which play a 
considerable part in most soil ecosystems. The class may be 
divided into four orders, representing the four main lines of 
morphological adaptation: the Geophilomorpha, the most 
subterranean group of centipedes, rarely seen on the 
surface; Lithobiomorpha;Scolopendromorpha, including the 
largest of all centipedes, some reaching almost 30cm in 
length; Scutigeromorpha, the majority of which live in dry, 
rocky habitats, hunting among rocks and scree. Several 
families of centipede are better represented at lower 
latitudes, the Scutigeromorpha in particular being confined 
to warm-temperate and tropical regions, though a few 
species occur inside human habitations further north. The 
trend in family distribution appears, from the very limited 
data, to be reflected in species richness too; but the 
accessible literature on centipedes is fragmentary, and even 
the most thoroughly researched areas such as northern 
Europe still have many areas of taxonomic confiision. 



TOTAL SPECIES 

Peru 

Germany 

Transvaal 

Natal- Zululand 

UK 

Holland 

Canada (N) 

Africa (SW) 

Congo 

Bermuda 

Tunisia 

Cyprus 

Peru (NE) 

Arctic 



3,000 

74 
60 
47 
42 

41 

35 

29-31 

27 

10 

7 
7 
6 

(6) 
3 



Class Diplopoda 

The millipedes live in litter, under bark, and in the soil, 
being active in the open only after dark. Some are cave- 
dwelling, and several species live commensally in the nests 
of ants. All millipedes are predominantly saprophages, 
feeding on dead leaves, fallen logs and branches of trees, 
though some may also occasionally browse on mosses, 
lichens, algae or even living vascular plants. They often 
occur at high densities, and can be the main shredders of 
leaf litter in woodland soils that are too acid to support a 
rich earthworm population (Blower, 1985). 

Documented diversity is rather low in most areas, including 
tropical Africa, but there is a high figure for North 
America. This suggests a Nearctic warm-temperate peak of 
diversity, enhanced by the absence of east-west 
geographical barriers in the Americas (where the main 
mountain ranges run north-south). This may have permitted 
much greater northward spread of taxa than in Eurasia 
(where there are major physical barriers - Pyrenees, Alps, 
Himalayas etc. - running east-west, and restricted post- 
glacial recolonisation of the region). 



Table 1 1 .9 Soil species: Diplopoda 



TOTAL SPECIES 

Central America and Mexico 

North America 

France 

Natal-Zululand 

Germany 

Peru (NE) 

Transvaal 

Congo 

Madeira 

UK (1958) 

Holland 

Denmark 

Little Carpathians (East Europe) 

Africa (SW) 

Bermuda 

Cyprus 

Tunisia 



7,000 

750f 
749 
250 
188 

160 
78 
69 
67 
53 
52 
45 
39 
31 
17 
8 
6 
(1) 



108 



Soil Macrofauna 



The four-fold difference in recorded diversity between 
Britain (41 species) and Natal-Zululand (188 species) may 
be partly owing to the glacial effect; but millipedes are 
considered to be largely woodland/forest animals. Southern 
Africa has supported much more extensive woodlands with 
a stable history, throughout the Quaternary. The very low 
diversity in the Arctic probably reflects the low primary 
productivity, and thus the limited vegetable detritus for 
millipedes to consume. An extreme example of island 
speciation in soil fauna because of natural barriers may be 
found on Madeira, where 25 of the 53 species are now 
considered endemic. Ecological segregation in those regions 
which have been adequately studied tends to be on a 
macrohabitat scale, with grassland, woodland or sand-dune 
species, for instance, rather than intensive multispecies 
resource partitioning within a single habitat (Blower, 1985). 

Class Oligoentomata: Collembola 

The collembolans or springtails are small apterygotes 
(primitive insect-like hexapods; Dohle, 1988), seldom 
greater than 5mm long. 

Like the mites, they have a cosmopolitan distribution, 
ranging from the seashore to high mountain-tops, and from 
the equator to the poles. Similarly, they can occur in very 
high densities, the smaller species reaching hundreds per 
cm^ in ideal conditions. Species vary in their desiccation 
tolerance, so that different microsites in a habitat will 
support different species. The majority of Collembola are 
saprophages, feeding on decomposing plant and animal 
debris, although a few are predators, and others are small- 
scale pests of crops, notably the Lucerne Flea Sminthurus 
viridis. Because of their enormous densities and ubiquity, 
springtails are a crucial food-source for many small soil 
predators, including pseudoscorpions, and some staphylinid 
and carabid beetles. 

Like the Oribatei, the Collembola appear to show a trend to 
higher diversity in temperate regions than in the tropics. 
Again, data quality may be suspect, but appears to be 
considerably higher and more uniform for Collembola than 
for Oribatei. A possible explanation of this trend proposed 
by Rapoport (1982) is that temperate soils are richer in 
nutrients and organic matter, as well as being more 
elaborately structured. 



are endemics, with that of managed grassland, where only 
1-2% of species are endemic and the majority are 
cosmopolitan (Greenslade and New, 1991). This clearly 
suggests that the Collembola will be highly sensitive to 
human impacts on natural and semi-natural vegetation; 
unfortunately, little research has been done elsewhere in the 
world. 



Table 11.10 Soil species: Collembola 

TOTAL SPECIES 10,000-20,000 



Australia 

UK 

USSR 

California (USA) 

Little Carpathians 

(East Europe) 

Peru 

Arctic 

Iceland 

Philippines 

Sudan 



1 ,000-2,000 
300 
300 
150 
143 

97 
91 
58 
37 
24 



Class Pterygota: Dermaptera 

The earwigs are a distinctive order of medium-sized insects 
allied to the Orthoptera. Although often hiding among litter 
or in the soil during the day, many species forage 
nocturnally among vegetation, flying readily and climbing 
trees (Imms, 1957). They are included here as soil fauna 
because almost all return to the soil to breed. Most species 
are thought to be omnivorous (Marshall and Haes, 1988). 

Earwigs are essentially tropical and subtropical in 
distribution. Most species are sedentary, so individual 
species tend to have rather small geographic ranges, and 
consequently the fauna of each region contains a high 
proportion of endemics. The African fauna has been more 
intensively studied than others. Central Africa appears to be 
an important centre of diversity, particularly for the more 
primitive families of earwigs; it contains about 30% of the 
known world species of the ancient Carcinophoridae, for 
example, but only 18% of the more advanced Labiidae 
(Brindle, 1973). Literature on other tropical regions is 
sparse, although the Indian subcontinent appears, like 
Africa, to hold important concentrations of species. 



Comparing similarly-sized land masses with broadly similar 
climate reveals a constancy of coUembolan fauna: Britain 
(3(X) species), Japan (241 species) and New Zealand (293 
species) (Chinery, 1973; Rapoport, 1982). However, it is 
almost certain that the majority of species have yet to be 
found: for instance, Wallace and Mackeras (1970) could 
.refer to only 215 described species, whereas Greenslade and 
Greenslade (1983) estimated there were 1,000-2,000 
Australian species. The figures for mainland North 
America, lower than for Britain, are likely to be a sampling 
artefact. 

Little has been published on patterns of collembolan 
endemism, but many species and genera have wide 
geographic ranges, implying some effective mechanism for 
long-distance dispersal, possibly wind-blown or rain-blown 
eggs. The available figures for the Tasmanian fauna 
contrast the native forest fauna, where up to 40% of species 



Table 11.11 Soil species: Dermaptera 



TOTAL SPECIES 

Africa 

India 

Australia 

USSR 

USSR (European) 

California (USA) 

UK 

Iceland 



1,200 

298 

185 
60 
26 
17 
10 
5 
1 



Only a very few earwig species are truly cosmopolitan, 
although their lifestyle makes them susceptible to accidental 
transport through commerce. Many such casual 
translocations lead only to temporary establishment, but if 
the climate is suitable a species may become more 



109 



1. Biological Diversity 



widespread. For example, the Indo-Australian species 
Marava arachidis is now well established in Africa and the 
Americas, but occurs only sporadically in Britain and 
northern Europe, usually in warehouses of imported organic 
materials (Brindle, 1973; Marshall and Haes, 1988). The 
sole cosmopolitan temperate species, the European Forficula 
auricularia is the common garden earwig in North America 
and elsewhere, though in the tropics it occurs mainly in 
montane areas. It has been implicated in the demise of three 
endemic earwigs of the genus Anisolabis in Hawaii 
(Howarth and Ramsey, 1991). 

Pterygota: Embioptera 

This primitive order comprises small to medium-sized soft- 
bodied cylindrical insects, commonly known as web- 
spinners. The females of most species are believed to be 
predominantly herbivores, while the males' diet may 
include other insects and soil arthropods. 

Web-spiimers are essentially tropical animals. The small 
numbers of European species are confined to the south, 
their northern limits being the Crimea, Bulgaria and the 
shores of the Mediterranean, although a few species occur 
fiirther inland in Spain. The American fauna totals over 70 
species, of which three are introduced and the rest are 
endemic (Ross, 1944). The highest concentration of species 
is probably in Australia (65 species (Ross, 1970)). 

Overall, web-spiimer species occur in widely-scattered, 
isolated areas, the group distribution being highly 
discontinuous. 



Table 11.12 Soil species: Embioptera 



TOTAL SPECIES 

Australia 

South America 

Europe and Mediterranean 

Central America 

USA 

Europe (S) 

USSR 

California (USA) 

USSR (European) 



100 

65 

44 

24 

15 

12 

5 

2 

3 

1 



Pterygota: Orthoptera 

Four families of Orthoptera are largely soil-dwelling: the 
Gryllotalpidae, Tridactylidae, Cylindrachetidae and 
Tetrigidae. Many other species of grasshoppers and crickets 
spend some of their time among leaf litter and/or lay their 
eggs in the soil but are not included here because a 
significant part of their life-cycle takes place away from the 
soil. 

The literature on the three soil-dwelling groups of 
orthopteroids is partial and ft'agmented. It is thus difficult 
to draw global conclusions at this stage. 

Orthoptera: Gryllotalpidae 

The mole-crickets are a small and specialised family of 
large, bulky insects which construct burrows mainly for 
feeding. Although found mostly in natural grasslands, they 
occasionally reach pest status by attacking root crops. 



especially (in temperate areas) potatoes (E.C.M. Haes, 
pers. comm.). Most species can fly, and can therefore 
colonise new areas. They are rare in cool-temperate regions 
and more diverse in warm-temperate ones. 

Many species are phenotypically very similar, but there 
may be genetically-isolated cryptospecies awaiting 
recognition. Those species already described are fairly 
uniformly distributed between the main biogeographic 
regions, with no marked concentrations apparent from the 
literature. A few species are occasionally transported by 
man, mainly among root-crops; and the commonest 
Eurasian species, Gryllotalpa gryllotalpa has been 
introduced into North America. 



Table 11.13 Soil species: Gryllotalpidae 

TOTAL SPECIES 50 



Australia 

USSR 

USSR (European) 

UK 



Orthoptera: Tridactylidae and Cylindrachetidae 

The pigmy mole-crickets are not closely related to 
Gryllotalpidae, but have converged on the same lifestyle 
and acquired the same modifications of body form. They 
are relatively small - less than 10mm long - and live in 
damp sandy soils usually close to water. 

The Tridactylidae are widely scattered in warm-temperate 
and subtropical regions, whereas the Cylindrachetidae are 
confined to Australia, New Guinea and Patagonia (Imms, 
1957); the latter probably indicative of the family's early 
evolutionary origins on Gondwanaland. 



Table 11.14 Soil species: Tridactylidae 
and Cylindrachetidae 



TOTAL SPECIES 

Australia 

USSR 

USSR (European) 



50 

4 
4 
3 



Orthoptera: Tetrigidae 

The groundhoppers or grouse-locusts are relatively small, 
usually less than 20mm. Most are found in damp 
microsites, such as river or pond margins. The eggs are 
often drought-resistant, enabling species to occupy 
seasonally-wet habitats (Hartley, 1962). Most species are 
unable to fly. 

The Tetrigidae is a large group, with many described 
species. They appear, from the limited figures available, to 
be best represented in warmer regions, the Australian fauna 
being among the largest, though quite high concentrations 
have been described in some cool temperate areas. 
However, their taxonomy is still being clarified, and the 
ecological distinctions between closely-related species are 



tlO 



Soil Macrofauna 



only just beginning to be determined, even in western 
Europe (Devriese, 1990). 

Table 11.15 Soil species: Tetrigidae 

TOTAL SPECIES 700 



Australia 

Europe, Asia and N Africa 

USSR 

USSR (European) 

UK 



70 

50 

14 

9 

3 



Class Pterygota: Blattaria 

Small (e.g. temperate Ectobius, 5-7mm) to large (e.g. 
tropical Blaberidae, up to 15cm) insects. Most of the world 
fauna lives in low vegetation or on the ground, probably as 
scavengers; dense populations can occur in the litter layer 
of wjirm forests, and some species occur in caves. A 
handful of cosmopolitan species are pests and can be very 
abundant in domestic situations. 

Cockroaches are characteristic of tropical moist forests, 
which support the largest diversity. Australia, for instance, 
has 439 species, most found in the native forests. 
Comparing two areas of roughly equal size, the British Isles 
support only three species, all in the genus Ectobius, 
whereas the West Indies are home to 156 species, including 
representatives of all the major families. There are several 
cosmopolitan species spread by man and now established in 
most countries. For this reason, published checklists, 
particularly in colder regions, often overestimate the 
indigenous fauna by including aliens which are restricted to 
heated domestic premises, e.g. Britain has three native and 
23 casual or introduced species, of which five are well 
established (Marshall and Haes, 1988); the whole of the 
USSR has 41 native and 12 alien species. 



Table 11.16 Soil species: Blattaria 



TOTAL SPECIES 

Australia 

Africa (Wl 

West Indies 

USA 

USSR 

California (USA) 

UK 



3,500 

439 

300 

156 

55 

50 + 

5-6 

3 



Pterygota: Isoptera 

The termites or 'white ants' are one of two main groups of 
soil-dwelling social insects (the others being the ants, 
Hymenoptera: Formicidae) whose colonies consist of a 
complex caste system, in which four main types can be 
recognised: the queen(s), workers, soldiers, and alate 
sexuals. The most primitive types are wood-boring and 
feeding, making no external modification to the decaying 
timber in which they live; such forms generally lack the 
worker caste. Certain genera may become pests by boring 
in domestic timbers. The remaining families are more 
exclusively soil-dwelling, some simply excavating galleries 
underground with little surface protrusion, while others 
construct large termite-mounds or termitaria which extend 



the nest many metres above the soil surface and form a 
conspicuous feature of the landscape in African and 
Australian scrub-grasslands. Many species feed in the same 
maimer as earthworms, ingesting the soil detritus, 
microfiingi and bacteria, or upon the roots of grasses and 
other plants. Others cultivate elaborate 'fungus gardens' on 
compost pre-prepared from vegetable matter. The majority 
of these more advanced species do not forage beyond the 
confines of the nest, unlike social Hymenoptera. The actual 
impact of termites on tropical ecosystems is still being 
evaluated (e.g. Collins, 1980, 1983, 1989). 

In addition to their direct contribution to biodiversity, 
termites are important in providing niches for an extensive 
cohabiting fauna in their nests, ranging from commensals to 
symbionts, parasites and specialist predators. 

Termites occur widely outside the polar and cold-temperate 
regions, except in the Palaearctic. The Ethiopian region 
appears to possess the richest diversity of genera as well as 
species, and is thus probably the most important centre of 
termite evolution (Bouillon, 1970). It contains the largest 
proportions of endemics. High numbers of species are also 
found in South America and the oriental region. 

Broad patterns of temperature explain much of the variation 
in termite diversity. In the northern hemisphere, a strong 
correlation between diversity and latitude has been found 
(Sutton and Collins, 1991), though this may be a slight 
over-simplification: the correlation would be iax less clear 
using southern-hemisphere data, because of the rich termite 
fauna of Australia, which extends beyond the Tropic of 
Capricorn. 



Table 11.17 Soil species: Isoptera 



TOTAL SPECIES 

Ethiopian Region 

South America 

Oriental Region 

Australia 

Congo and Cameroon 

Thailand 

Palaearctic Region 

Myanmar 

Pakistan IW) 

California (USA) 

Mexico(W} 

New Zealand 

USSR 

Europe 



2,000 

570 

499 

434 

182 

78 

74 

41 

39 

30 

15 

15 

11 

4+ 

2 



Pterygota: Hymenoptera (Formicidae) 

The ants are morphologically conservative but behaviourally 
diverse social insects with an elaborate caste system. Their 
nests vary from a few individuals in a space of less than 
1cm' contained insidt a dead twig (e.g. Leptothorax) to 
huge soil-based mounds with hundreds of thousands of 
foraging workers, which may be the dominant predatory 
force in whole forests (Brian, 1977). The diversity of 
individual size and feeding ecology allows many species to 
coexist in an area, and to partition resources, thereby 
avoiding competition (Davidson, 1978). The majority of ant 
nests are situated either within the mineral soil, or in the 



111 



/. Biological Diversity 



litter layer; although with deserved reputations as predators, 
many species also consume large volumes of plant material, 
especially seeds. Quite a high proportion of ant species have 
complex interactions with other ants. Like termites, Jints 
also interact elaborately with other invertebrates, thereby 
increasing invertebrate diversity, through providing a range 
of additional niches within their nests; the range of 
symbiotic, inquiline, commensal, scavenging, parasitic and 
predatory lifestyles closely parallels those found within 
termite nests. 

The ants are a large and diverse group, with most species 
in tropical regions, and a sharp decline toward the cool- 
temperate. Even on a small scale, in Europe and North 
America, there is a clearly marked latitudinal decline in 
diversity (Cushman and Lawton, in press); for instance, 
France has 180 species, whereas Britain has only 46 
including introductions. The Palaearctic and Nearctic faunas 
are roughly equal in total diversity and pattern of species 
richness, their post-glacial colonisation apparently being 
unaffected by the topographic differences between the 
continents described under Diplopoda. This may be because 
the winged queens of ants are highly mobile, and so could 
travel long distances and recolonise virgin habitats as they 
became available with the retreat of the ice-sheet. This 
could also be the reason why Britain (46 species) has twice 
as many species as New Zealand (23) despite the fact that 
the total fauna of Oceania is much richer than that of 
Europe: the isolation of New Zealand is too great for 
uncontrolled flight to convey large numbers of species. 

Ants have been the focus of much ecological research and 
speculation over the past 40 years. It has recently been 
observed that in Europe and temperate North America there 
is a latitudinal cline in individual mean size, with larger ant 
species in the boreal forest and many more tiny species 
around the Mediterranean/southern USA (Cushman and 
Lawton, in press). Further explanations of regional 
biodiversity have been related to vegetation patterns 
(Greenslade and New, 1991), and Australian work has also 
shown a high species turnover (beta diversity) across the 
continent. 



Table 11.18 



TOTAL SPECIES 



Soil species: 
(Formicidae) 



Hymenoptera 



10,000 



very wide-ranging, in diet varying from obligate herbivore 
and detritivore to highly specialised predator. Their size 
ranges from less than 2mm to several centimetres, and they 
occupy almost all habitats from permanently waterlogged 
soils to the driest deserts. Although a proportion of forest 
species forage in the canopy, and rest under bark, the great 
majority are closely linked to soil and litter. Ground-beetles 
can reach high diversity in small habitat patches because of 
the variety of ways in which they can divide up the food 
resource, microsites, and time (different species being 
diurnal, nocturnal or crepuscular) (Greenslade, 1963). 

With over 40,000 described species, the Carabidae are 
potentially valuable in analysing patterns of soil fauna 
distribution. Unfortunately, many areas still lack 
comprehensive reviews of their fauna, so the available 
literature remains patchy. However, the high diversity 
reported from the main tropical landmasses is probably a 
genuine effect; these areas did not suffer the extremes of 
recent glaciations, and the long periods of stability may 
have allowed local speciation to occur. 

One of the most striking examples of intensive local 
speciation is provided by the tiger-beetles (sub-family 
Cicindelinae) in India, where there are 150 species in the 
genus Cicindela. The explanation of this high diversity is 
probably a complex of past dispersal, ecological isolation 
(largely through local climatic effects) and habitat 
specialisation (Pearson and Ghorpade, 1989). This contrasts 
with the low diversity of other surface-dwelling generalist 
predators such as scorpions. 

There is a rich boreo-montane fauna in the northern 
hemisphere: carabids make up a large proportion of most 
European early post-glacial fossil deposits (Atkinson, Briffa 
and Coope, 1986), and this highly mobile element is equally 
important in North America - hence the rich 
Canadian/ Alaskan fauna (850 species, Lindroth, 1969). The 
comparison of Britain (350 species) with New Zealand (538 
species, Hudson, 1934) probably reflects local speciation on 
the oceanic island: over 90% of New Zealand's terrestrial 
arthropods are endemic (Howarth and Ramsey, 1991). In 
contrast, Britain has in effect only been partially recolonised 
from mainland Europe because of the breach of the land 
bridge to Europe by the English Chaimel, and has only a 
single 'endemic' carabid, Tachys edmondsi (Lindroth, 
1974). 



Neotropical Region 

Australia 

North America ( + USA) 

USA 

California (USA) 

France 

Sweden 

Denmark 

Finland 

Norway 

UK 

New Zealand 



Pterygota: Coleoptera (Carabidae) 

The ground-beetles and tiger-beetles may be the largest of 
all families in terms of total species; over 40,000 species 
are described (Erwin et ai, 1979). They are ecologically 



2,233 


Table 11.19 


Soli 


species: 


Coleoptera 


1 ,100 
585 




(Carabidae) 




400-I- 










200+ 


TOTAL SPECIES 






40,000 


180 










61 


Neotropical Region 






5,000 


49 


North America 






2,500 


47 


Australia 






1,613 


46 


California (USA) 






800 


46 


New Zealand 






538 


23 


UK 






350 

176 




Iraq 







Although tropical forests support a very rich carabid fauna, 
arid grasslands are less rich; this is in part because of their 



112 



Soil Macrofauna 



replacement by the more drought-adapted Tenebrionidae. 
For example, whereas Britain has a mere 44 tenebrionids in 
a beetle fauna of over 3,000 species, Morocco has 711 
species, which amounts to 15% of the total fauna (Kocher, 
1958). 

Pterygota: Coleoptera (Staphylinidae) 

The rove-beetles range in size from less than 1mm to 
several centimetres. Many species are predatory, but others 
feed on decaying organic matter - vegetation, dung or 
animal corpses. A number of species occur in ants nests, 
some commensally or scavenging, others partially predatory 
on the ant brood, but oflen providing the ants with a sweet 
secretion in return. As a group, the Staphylinidae are an 
important predatory force in moist temperate habitats 
(Hammond, in prep.), perhaps rather less so in the tropics. 
Many species are difficult to identify, and they are therefore 
often excluded from surveys. 

The rove-beetles are less well-known than the carabids, but 
the existing numerical data reveal several patterns among 
the temperate fauna. Most noticeably, the staphylinids 
outnumber the carabids in each documented area in the 
northern hemisphere, whereas in the southern, the reverse 
is true. One possible explanation for this is that rove-beetles 
are more prone to flying and were thus able to continue 
colonising new areas despite rising sea-level after the last 
Ice Age. The lower diversity in the southern hemisphere is 
harder to explain, and data are too few to evaluate with 
confidence; in some cases (e.g. Australia, with only 650 
species) the generally more arid climate may limit the 
Staphylinidae. 



Table 11.20 



TOTAL SPECIES 

North America 

California (USA) 

UK 

Australia 

West Indies 

Morocco 

New Zealand 



Soil species: 
(Staphylinidae) 



Coleoptera 



27,000 

2,800 
1,000 
1,000 
650 
468 
423 
216 



GENERAL PATTERNS OF DIVERSITY 

This preliminary study has shown that the different groups 
of soil macrofauna function ecologically in very different 
ways and that most trends in distribution will be group- 
specific. The soil fauna is such a diverse group that the 
distributional trends within, for example, scorpions may run 
counter to those of the CoUembola. In a more detailed 
study, it may thus be better to consider the major groups 
separately: the differences between soil groups may be 
greater than those between soil and non-soil members of the 
same group. 

It would thus be an over-simplification to look for a single 
pattern of soil faunal biodiversity. That said, there are some 
indications of global pattern which hint at concentrations of 
species very different from those found in most plant and 
animal groups. 



The usual trend towards higher diversity in the tropics 
compared with temperate regions is certainly apparent in 
some soil groups such as the scorpions, soliftigids and 
Orthoptera. However, the limited information available for 
others, such as the CoUembola, appears to show the 
reverse: temperate faunas may be more diverse than tropical 
ones. A possible explanation lies in the difference between 
the profiles of the two soils; tropical soils do not possess 
the depth or varied horizons seen in temperate ones. This 
is because of efficient re-cycling processes producing a low 
organic content, and lack of thermal seasonality (Rapoport, 
1982). Both of these factors reduce the niche space and 
habitat quality of the soil, and consequently the soil-fauna 
diversity that it can support. A more fundamental difference 
is revealed when the respective ages of the soils are 
considered. The older tropical soils, such as those in 
Australia and Africa, are strongly leached and weathered, 
while the temperate soils, such as those in northern Europe, 
possess large areas of unweathered rock left by the 
retreating ice-caps of the last glaciation. The latter therefore 
have a higher mineral content, and a steady release of 
inorganic nutrients, which enhances the fertility of the soil. 

It is premature to identify centres of diversity and 
endemism with any co.nfidence although a few areas on 
present evidence stand out. The faunas of South Africa, 
Australia, and the Mediterranean Basin are richer than the 
average in most groups. That of New Zealand shows a 
higher degree of endemism than other similar-sized areas, 
and is species-rich in some groups such as the Carabidae. 
In many, the South American fauna is too poorly described 
in the literature to allow detailed comparison, but the few 
available figures suggest it is very rich in many groups. 

Explanations of patterns of diversity depend on several 
different effects, which may be contradictory. For example, 
post-glacial history may have led to an impoverished fauna 
in large parts of the northern hemisphere, yet it is also 
responsible for the elaborate soil structure and landscape 
mosaic seen in many areas of Europe and North America, 
which enhance diversity. These two effects are jointly 
responsible for the Mediterranean species concentrations in 
several groups: during the glaciation, large numbers of 
species appear to have survived in Mediterranean refugia, 
and failed to recolonise the rest of northern Europe during 
the post-glacial. At the same time, the seasonality of the 
climate round the Mediterranean helps to diversify the soil 
habitat, enabling many more species to co-exist. 

One factor underlying patterns of diversity which is more 
theoretical and harder to verify derives from the ecology of 
the groups. Some generalist predators such as scorpions and 
soliftigids may have such broad niches that rather few 
species can coexist in an area, although the regional 
diversity in such groups can be high if the individual 
species have small ranges, and species complementing 
occurs on a smaller scale than usual. 

Several recent estimates have suggested that the true 
diversity of soil fauna, in common with most invertebrates, 
may be ten times or more than the number of described 
species (Erwin, 1982; May, 1988). 



113 



/. Biological Diversity 



References 

Atkinson, T.C.. Briffa, K.R. and Coope, G.R. 1986. Reconstruction 

of late glacial climates from Coleoptera using the mutual climate 

range method. In: Berger. W.H. and Labeyrie. L.D.. The Book of 

Abstracts and Reports from the Conference on: abrupt climate 

change (NATO/NSF). University of California, Los Angeles. 

Pp .56-59. 
Bames, R.D. 1980. Invertebrate Zoology. Saunders, Hiitadelphia. 
Bames, R.S.K. (Ed.) 1984. A Synoptic Classification of Living 

Organisms. Blaclcwell, Oxford. 
Blower, J.G. 1985. Millipedes. Synopses of the British Fauna New 

Series 35. Brill/Backhuys, London. 
Bouillon, A. 1970. Termites of the Ethiopian region. In: Krishna, K. 

and Weesner, F.M. (Eds). Biology of Termites, Vol. 11. Academic 

Press, New York. Pp. 153-280. 
Brian, M.V. 1977. Ants. Collins, London. 
Brindle, A. 1973. The Dermaptera of Africa. Part 1. Annales du 

Musee Royal de I'Afrique Centrale Ser. 8 (Zoologie) 205:1-335. 
Buckland, P.C. and Coope, G.R. 1991 . A Bibliography of Quaternary 

Entomology. CoUis, ShefTield. 
Chinery, M. 1973. A Field Guide to the Insects of Britain and 

Northern Europe. Collins, London. 
Cloudsley-Thompson, J.L. and Sankey, J.H.P. 1968. Land 

Invertebrates. Methuen, London. 
Collins, N.M. 1980. The effects of logging on termites (Isoptera) 

diversity and decomposition processes in lowland dipterocarp 

forests. Tropical Ecology and Development :\ 13-121. 
Collins, N.M. 1983. Termite populations and their role in litter 

removal in Malaysian forests. In: Sutton. S.L.. Whilmore, S.C. 

and Chadwick, A.C. (Eds). Tropical Rain Forest: ecology and 

management. Blackwell, Oxford. Pp.31 1-325. 
Collins, N.M. 1989. Termites. In: Lieth, H. and Werger, M.J. A. 

(Eds), Tropical Rain Forest Ecosystems. Ecosystems of the world, 

vol. 14b. Elsevier, Amsterdam. 
Cushman, J.H. and Lawton. J.H. (in press). Latitudinal variation in 

body size and species richness: patterns in the structure of 

European ant assemblages. American Naturalist. 
Dalingwater, J. 1983. EX International Congress of Arachnology, 

Panama, August 1983. Newsletter of the British Arachnological 

Society 38:2-4. 
Davidson, D.W. 1978. Size variability in the worker caste of a soil 

insect (Veromessor pergandei Mayr) as a function of the 

competitive environment. y4mencan Naturalist 112:523-532. 
Davies, V.T.. Harvey. M.S. and Main, B.Y. 1985. Volume S: 

Arachnida; Mygalomorphae , Araneomorphae in part, 

Pseudoscorpionida , Amblypygi and Palpigradi . Bureau of Flora and 

Fauna, Canberra. Zoological Catalogue of Australia. Australian 

Government Publishing Service. Canberra. 
Davis. B.N.K. 1986. Colonization of newly created habitats by plants 

and animals. Journal of Environmental Management 22:361-371 . 
Dempster, J. P. 1991. Opening remarks. In: Collins, N.M. and 

Thomas, J. A. (Eds), The Conservation of Insects and their 

Habitats. Academic Press, London. Pp. 143-153. 
Devriese, H. 1990. Herziene Telrigidae-label. Saltabel 3:29-30. 
Dohle, W. 1988. Myriapoda and the Ancestry of Insects. Manchester 

Polytechnic/British Myriapod Group. Manchester. 
Easton, E.G. 1981 . Japanese earthworms: a synopsis of the Megadrile 

species (Oligochaela) . Bulletin of the British Museum (Natural 

History) Zoology 40:33-65. 
Eisenbeis, G. and Wichard. W. 1985. Atlas on the Biology of Soil 

Arthropods. Springer-Verlag, London. 
Erwin, T.L. 1982. Tropical forests: their richness in Coleoptera and 

other arthropod species. Coleopterists' Bulletin 36(l):74-75. 
Erwin, T.L., Ball, G.E., Whitehead. D.R. and Halpem, A.L. 1979. 

Carabid Beetles: their evolution, natural history and classification. 

Junk, The Hague. 
Erzinclioglu, Y.Z. 1989. Campaign for real zoology. New Scientist 

123(1 676) :62-63. 
Eversham, B.C. 1982. A conspectus of European Diplura. (privately 

circulated). 
Eversham. B.C. and Arnold, H.R. (in press). Introductions and their 

place in British wildlife. In: Harding, P.T. (Ed.), Biological 

Recording of Changes in British Wildlife. 



Gabbutt, P.D. 1967. C^anlitative sampling of the pseudoscorpion 

Chihonius ischnosceles (Hermann) from beech litter. Journal of 

Zoology, London 151:469-478. 
Gerson, U. and Seaward, M.R.D. 1977. Lichen-invertebrate 

interactions. In: Seaward, M.R.D. , Lichen Ecology. Academic 

Press, London. 
Good, R. 1964. The Geography of the Flowering Plants. Longman, 

London. 
Greenslade, P. and New. T.R. 1991. Australia: conservation of a 

continental insect fauna. In: Collins, N.M. and Thomas, J. A. 

(Eds), The Conservation of Insects and their Habitats. Academic 

Press, London. Pp.33-70. 
Greenslade, P.J.M. 1963. Daily rhythms of locomotor activity in some 

Carabidae (Coleoptera). Entomologia ExperimentaUs et Applicata 

6:171-180. 
Greenslade, P.J.M. and Greenslade, P. 1983. Ecology of soil 

invertebrates. In: Soils: an Australian viewpoint. Division of Soils. 

CSIRO. Melbourne/Academic Press, London. Ch.40:645-669. 
Hammond, P.M. (in prep.). Provisional Atlas of the Rove Beetles 

(Coleoptera: Staphylinidae . Omaliinae) of the British Isles. 

Biological Records Centre, Huntingdon. 
Harding, P.T., Rushton, S.P., Eyre, M.D. and Sutton, S.L. 1991. 

Multivariate analysis of British data on the distribution and ecology 

of terrestrial Isopoda. In: Anon., The Biology of Terrestrial Isopods 

in. Universite de Poitiers, Poitiers. Pp. 65-72. 
Harding. P.T. and Sutton, S.L. 1985. Woodlice in Britain and Ireland: 

distribution and habitat. Institute of Terrestrial Ecology, Abbots 

Ripton. 
Hartley, J.C. 1962. The egg of Tetrix (Tetrigidae, Orthoplera), with a 

discussion of the probable significance of the anterior horn. 

Quarterly Journal of Microscopical Science 103:253-259. 
Howarth, F.G. and Ramsey, G.W. 1991. The conservation of island 

insects and their habitats. In: Collins, N.M. and Thomas, J. A. 

(Eds), The Conservation of Insects and their Habitats. Academic 

Press, London. Pp. 71-107. 
Imms, A.D. 1957. A General Textbook of Entomology^ 9th edn. 

Methuen. London 
Kevan. D.K. McE. 1962. Soil Animals. Witheiby, London. 
Kocher, L. 1958. Catalogue commente des Coleopteres du Maroc. 

Fascicule 2: Hydrocanthares , Palpicomes, Brachelytres. Fascicule 

6: Tenebrionides. Ministere de I'Instnictionpublique et des Beaux- 
arts, Rabat. 
Lavelle, P. 1 983 . The structure of earthworm communities. In: 

Salchell, J.E. (Ed.), Earthworm Ecology: from Darwin to 

vermiculture . Chapman and Hall, London. Pp. 449-466. 
Lawrence. R.F. 1931. The harvest-spiders(Opiliones)of South Africa. 

Annals of the South African Museum 29(2):342-508. 
Lee. K.E. 1959. The earthworm fauna of New Zealand. Bulletin New 

Zealand DSIR 130:1-486. 
Legg, G. and Jones, R.B. 1988. Pseudoscorpions. Synt^ses of the 

British Fauna New Series 40. Brill, London. 
Levi, H.W., Levi, L.R. and Zim, H.S. 1968. Spiders and their Kin. 

Golden Press. New York. 160pp. 
Lindrolh, C.H. 1961-1969. The ground beetles (Carabidae excl. 

Cicindelidae) of Canada and Alaska. Parts 1-6. Opusc. Entomol. 

Suppl. 20:1-200. Part 2 (1961): 24:201^08. Part 3 (1963): 

29:409-648. Part 4 (1966): 33:649-944, Part 5 (1969): 

34:945-1192. Part 6 (1969): 35:i-xviii, Part 1 (1969). 
Lindroth, C.H. 1974. Coleoptera Carabidae. Handbook for the 

Identification of British Insects 4(2): 1-148. 
Ljungslrom. P.O. 1972. Taxonomical and ecological notes on the 

earthworm genus Vdeina and a requiem for the South African 

acanthodrilines. Pedobiologia 12:100-110. 
Luxton, M. (in prep.). Provisional Atlas of the Moss Mites of the 

British Isles (Arachnida, Oribatida). Biological Records Centre, 

Huntingdon. 
McCarthy, P.M. and Healy, J.A. 1978. Dispersal of lichen propagules 

by slugs. Lichenologist 10:131-134. 
Marshall, J.E. and Haes, E.C.M. 1988. Grasshoppers and Allied 

Insects of Great Britain and Ireland. Harley Books, Colchester. 
Martens, J. 1978. Weberknechte,Opiliones.Dt> Ti^rwelt Deutschlands 

64. 464pp. 
May, R.M. 1988. How many species are there on earth? Science 

241:1441-1449. 



114 



Soil Macrofauna 



Pearson, D.L. and Ghorpade, K. 1989. Geographical dislribulion and 

ecological history of liger beetles (Coleoplera: Cicindeldae) of the 

Indian subcontinent. Journal of Biogeography 16(4);333-344. 
Rapoport, E.H. \9%2. Areography. Geographical Strategies of Species. 

Pergamon Press, Oxford. 
Ross. E.S. 1944. A revision of the Embioptera or Web-Spinners of the 

New World. Proceedings of the United States National Museum 

94:401-504. 
Ross, E.S. 1970. Embioptera. In: The Insects of Australia. A textbook 
for students and research workers. CSIRO. Carlton, Victoria 

(Melbourne University Press). 
Sims, R.W. and Gerard, B.M. 1985. Earthworms. Synopses of the 

British Fauna New Series 31. Brill/Backhuys, London. 
Sutton, S.L. 1980. Invertebrate Types: woodlice. Pergamon Press, 

Oxford. 144pp. 
Sutton, S.L. and Collins, N.M. 1991. Insects and tropical forest 

conservation. In: Collins, N.M. and Thomas, J. A. (Eds), The 

Conservation oflnsecfs and their Habitats. Academic Press, 



London. Pp. 71-107. 
Todd, V. 1949. The habits and ecology of the British harvestmen 

(Arachnida:Opiliones) with special reference to those of the Oxford 

district. Journal of Animal Ecology 18:204-229. 
Wallace, M.M.H. and Mackeras, I.M. 1970. The Entognathous 

hexapods. In: The Insects of Australia. A textbook for research 

workers. CSIRO. Carlton, Victoria (Melbourne University Press). 
Wallwork, J. A. 1976. The Distribution and Diversity of Soil Fauna. 

Academic Press, London. 

This is a condensed version of a consultancy report 
prepared by B.C. Eversham, A.S. Jotliffe and B.N.K. Davis 
of Monks Wood Experimental Station, a unit of the Institute 
of Terrestrial Ecology (Natural Environment Research 
Council). The full unpublished report is entitled: Soil fauna 
biodiversity: a preliminary global review. Project 
T13061AL 



115 



1. Biological Diversity 
12. FISHES 



THE DIVERSITY OF FISHES 

Fishes make up the most abundant class of vertebrates, both 
in terms of numbers of species smd of individuals. They 
exhibit enormous diversity in size, shape, biology, and in 
the habitats they occupy. They are also the least known of 
vertebrates. It is clear, however, that the group of animals 
popularly termed fishes is defined by the retention of 
primitive vertebrate features (aquatic, gills, fins, 'cold- 
blooded') and the extant groups include several rather 
distantly-related evolutionary lineages. The first jawed 
vertebrates, around 500 million years ago, were fishes, and 
the first tetrapod land vertebrates arose fi'om among the 
fishes around 400 million years ago. 

There are in excess of 22,000 described species of fish. 
Vertebrates as a whole comprise around 43,000 species; 
thus, approximately half of all described vertebrates are 
fishes. Given that some 200 new species of fish have been 
described annually in recent years, probably well over half 
of all vertebrate species are fishes. 

The great majority is comprised of bony fishes, mainly 
teleosts (advanced jawed fishes); in addition, there are 
around 800 species of cartilaginous fish (sharks, rays, 
chimaeras) and 70 jawless fish (lampreys and hagfishes). 

Fishes range in size from around 1cm (as shown by a 
Philippines Goby Pandaka pygmaea, which is about 1.2cm 
in adult length, and another in the Indian Ocean, about 
1cm) to the Whale Shark Rhincodon typus, which attains 
15m. Some fish, typified by eels, are long and slender, 
others are globular; some are almost colourless, others are 
brilliantly coloured; some are fast and graceful, others 
sedentary. 

They occupy almost every kind of aquatic habitat, ranging 
from sub-zero waters under the Antarctic icecap to near- 
boiling hot springs, and in water that is almost pure or 
highly saline. Many occupy the lightless ocean depths, a 
few dozen inhabit lightless cave systems (and some have 
lost both eyes and skin pigment). 

Liquid water in lakes and rivers totals around 126,000km', 
equivalent to 0.0093 % of the total volume of liquid water 
in the world. The oceans comprise about 
l,320,000,0001an', or 97% of the total. More than 8,400 
fish species, or about 40% of all fishes, live in freshwater. 
There is thus around 1(X),000 km' of water for each marine 
species but a mere 15km' for each freshwater species: a 
difference of several orders of magnitude. 

It has been calculated that some pelagic marine species may 
attain population levels of 10'' individuals, although a more 
typical value might be 10'. The mean value for freshwater 
species has been estimated to range down to lO*. Given the 
different water volume available per species, this represents 
a possible ten-fold decrease in water volume per individual 
in freshwater over marine species. This is not inconsistent 
with the greater net primary productivity per unit area, and 
greater plant biomass, in freshwater as compared with 
marine habitats. 



Fishes provide the major world source of food derived firom 
wild animals. Whether assessed in terms of tonnage traded 
or proportion of total dietary protein, fishes are a global 
resource of the first magnitude. Although the tropics 
generally have far higher species richness and endemism 
than temperate or arctic regions, and include 50% and 30% 
of the world's open water and continental shelf water, 
respectively, tropical fisheries contribute only about 16 % of 
world fish production (Longhurst and Pauly, 1987). 

Table 12.2, modified from Nelson (1984), lists the orders 
of extant fishes. Most orders are geographically very 
widespread, with representatives in the Atlantic, Indian and 
Pacific Oceans and/or on most continents: those with less 
wide distributions are noted in the table. Also listed are the 
numbers of families, genera and species in each order, with 
estimates of the number of species in marine and freshwater 
habitats. 

We have made no attempt to deal comprehensively with the 
biodiversity of fishes, but have concentrated on aspects of 
species diversity, and include below material dealing with 
species richness and endemism in freshwaters, and notes on 
subterranean and coral reef fishes. 



FRESHWATER FISHES: 
ENDEMISM 



SPECIES RICHNESS AND 



Estimates have been made of species richness on major 
landmasses (Table 12.1), and detailed information is now 
available for a few families, but Tables 12.6 to 12.10 below 
are a first preliminary attempt to collate data on species 
richness and endemism of indigenous freshwater fishes on 
a global scale. Summary data on rivers and lakes are 
represented graphically in Figs 12.2 and 12.3. 



Table 12.1 



South America 

Africa 

Asia 

North America 

Central America 

Europe 

Australia 

New Zealand 



Freshwater fishes: species 
richness by continents 



2200 

1800 

1500 

950 

354 

250 

170 

27 • 



Sources: Estimates cited in Nelson, J.S. 1984. Fishes of the World, 
2nd edn. John Wiley and Son, New York. 

Notes: ' Estimate probably should be much higher, (Nelson, 1984). 
^ Mostly diadromous. 

In contrast to practice in other parts of this book, data on 
species diversity are presented in terms of water bodies 
rather than country units. River systems, for example, 
frequently cross several country boundaries or themselves 
constitute the boundary, making a country approach to data 
compilation more difficult and biologically less meaningful. 

Introduced species are excluded from the counts wherever 
possible, as are subspecies (although some information 
sources are too imprecise to allow this in all cases; these 



116 



Fishes 



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Fishes 



exceptions are recorded in the notes). In general, river 
systems or lakes were included only when estimates of both 
the total and the endemic fish fauna were available. Several 
very important rivers for which no useful data could be 
traced (e.g. the Ganges, Irrawaddy, Sikiang, etc.) have 
been excluded. For some of these, information does exist, 
but is too outdated or incomplete to use. 

Faunal knowledge 

The quality and extent of faunal studies vary widely from 
country to country. The geography of countries, which are 
artificial constructs, often bears little relationship to the 
geography of water bodies, which are natural. Because the 
great majority of faunal inventories are on a sub-national 
basis, substantial gaps in the coverage of a multinational 
river system frequently result. The probability of such 
incompleteness should be borne in mind when using the 
figures given below. In general, data quality is highest in 
developed countries, where species richness is lowest, and 
faunal inventory will probably remain least satisfactory in 
systems that cross several developing country boundaries 
(e.g. the Mekong), wl^ere species richness is undoubtedly 
high. It is of some concern that ichthyologists do not know 
with precision how many species of fish exist in 
multinational rivers, and often have but sparse knowledge 
of the fauna of rivers where fishes are an important human 
food resource. The ability to provide appropriate 
management remains correspondingly impoverished. 

Taxonomic knowledge 

Difficulties concerned with the taxonomic status of fishes 
arise from scientific disagreement or ignorance. Freshwater 
fish species vary in morphology throughout their range as 
a result of genetic, dietary and other factors. A specimen 
from one region may therefore have received a different 
taxonomic name from specimens from another population 
of the same species in another region. This result of 
parochial taxonomic research can be corrected when a 
taxonomist has access to a suitably large sample on which 
to work. A similar problem occurs when different 
taxonomic status is given to the same species by different 
authors so that the same biological species can appear under 
different names in different faunal lists. When uncritical 
overviews have been undertaken the same species can 
appeeu' as two or more nominal species in the same list, 
thereby artificially inflating the number of species. Without 
the time to compare specimens and refer to the original 
descriptions, the number of species (both widespread and 
endemic) quoted in this document is based on a reasonable 
interpretation of the published literature and reference to 
people actively working in particular fields. 

What are 'freshwater fishes'? 

Freshwater fishes Jire customarily categorised as primary or 
secondary. This categorisation is essentially ecological not 
taxonomic, although based on families. Primary freshwater 
fishes, in this usage, are those families with little salt 
tolerance (stenohaline) and therefore confined to fresh 
waters. This has meant that the sea is a barrier and their 
current distribution is a result of physiographical events. 
The families Cyprinidae, Characidae and Cobitidae are 



examples of this group. Secondary freshwater fish families 
contain species which mostly live in fresh water but have 
some degree of salt tolerance and can cross salt waters. The 
Cichlidae, for example, are in this category. There is an 
accepted third category, the peripheral fishes, containing 
families that do not conform to either of the other two 
categories. Some may spend most of their life in fresh 
waters; others live in brackish waters. Marine families with 
representatives in fresh waters are also grouped here along 
with some anadromous or catadromous fish. The usefulness 
of categorising fish on the basis of salt tolerance had been 
challenged by Rosen (1974) who thought that fish should be 
regarded as continental or oceanic. 

A pragmatic approach has been taken to determining which 
species to include in these estimates. In general, if most 
members of the species live in the sea, isolated freshwater 
populations are not included below. Some arbitrary 
decisions have been made. Anguillid eels have been 
excluded on the grounds that they breed in the sea, can 
move overland, and no populations isolated in fresh water 
are known. 

Endemism 

In normal biological usage, an endemic species is one 
confined to some given area, which may be defined as a 
site, a country, a continent or, in this compilation, a 
discrete river system or lake. If, however, a list of fish is 
constructed on the basis of river systems the full picture of 
very localised species will not emerge. For example, most 
riverine endemic fish species live in head-waters and often 
in very short stretches of river. The geophysiccd process of 
head-water capture has frequently resulted in one highly 
localised species living in two or more much larger river 
systems yet, in reality, being confined to a world 
distribution of just a few square miles. It has not been 
possible for the present document to compile adequate data 
on species which are local or regional endemics but are not 
endemic to one particular river system. They are not 
included below and it should be borne in mind that there 
are many more species of fishes with extremely localised 
distributions than is apparent here. 

Species richness in rivers and lakes 

The number of fish species present in subtropical and 
tropical rivers is highly correlated with the area of the river 
basin; temperate rivers show a similar pattern although the 
number of species rises more steeply with increasing basin 
area in tropical systems than in higher latitudes 
(Welcomme, 1979). The relationship appears to break down 
at high latitudes, where some tundra rivers are very 
extensive but have few fish species. Data gathered by 
Welcomme (1990) and Daget and Economidis (1975) are 
tabulated (Table 12.3) and shown graphically (Fig. 12.1). 

Lake area is in general positively correlated with species 
richness, but a variety of additional factors may be 
involved. On a global scale, surface area and latitude 
together account for about one-third of the overall variation 
in species number (Barbour and Brown, 1974). For a 
sample of 14 lakes in North America, these factors 
accounted for most of the variation in species number, the 



119 



1. Biological Diversity 

figure 12.1 Number of fish species and river basin area 



TU 


, uuu 


= 












- 


^ 


Latin America 




in 




- 


o 


Afr i ca 


)K 




,000 


^ 


X 


Ba i kans 


o 


0) 




_ 








a 

U) 




- 




5(« ^ 


)K 


0) 

4- 


100 


- 













■_ 




oO>S,°>? 




L 




L 




* ox 




n 

£ 


10 

1 


- 




xXx x^ 

XX 

1 1 1 1 1 


1 



both axes 



0,1 1 10 100 1000 

lie River basin area C1000 l^i^ square]) 



10,000 



Source: Dau in Welcomme, R.L. 1990. Sutus of fisheries in South American rivers. Interciencia 15(6):337-345; and Daget, J. and Economidis, 
P.S. 1975. Richesse spicifique de I'ichtyofaune de Mac&loine orienule et de Thrace occidentale (Grice). Bulletin du Museum National d'Histoire 
Saturelle, 3e s^rie, no 346, icologie ginirale 27:81-84. 



Table 12.3 


Numbers of fish species and river basin area 






RIVER 


IVUMBER OF 


BASIN AREA 


RIVER 


NUMBER OF 


BASIN AREA 




SPECIES' 


(Icm') 




SPECIES' 


(km») 


Latin America 






Sassandra 


71 


84,140 


Sucio 


11 


794 


Bandama 


75 


100,000 


Paz 


21 


1,884 


Cunene 


59 


169,824 


San Tiguel 


14 


2,985 


White Nile 


136 


229,087 


Paraguay 


178 


181,970 


Senegal 


86 


342,768 


Uruguay 


115 


223,872 


Kasai 


129 


357,273 


Magdalena 


166 


256,622 


Volta 


107 


378,443 


Negro 


254 


331,131 


Chart 


195 


575,440 


Parnaiba 


90 


362,000 


Ubangui 


263 


668,344 


Madeira 


398 


691,831 


Niger 


166 


1,100,000 


Orinoco 


318 


950,000 


Zambezi 


178 


1,280,000 


Parane, La Plata 


355 


3,100,000 


Zaire 


790 


3,968,000 


Amazon 


2000 


5,711,000 


Ballians 






Africa 






Aspropotamos 


8 


129 


Me 


20 


3,981 


Laspopotamos 


9 


180 


Bouda 


27 


5,012 


Loutos 


5 


211 


Bia 


33 


9,441 


Marmaras 


7 


235 


Shire 


40 


19,953 


Potamos 


5 


265 


Cavaily 


30 


22,387 


Bospos 


12 


376 


Soi(oto 


47 


35,481 


Kossithnos 


13 


435 


Oueme 


75 


39,811 


Kompsatos 


8 


600 


Kafue 


61 


44,668 


Filiouris 


13 


1,490 


Ruaha 


42 


59,566 


Nestos 


19 


6,178 


Tana 


84 


66,834 


Strymon 


30 


17,035 


Comoe 


63 


70,795 


Evros 


31 


52,788 


Gambia 


93 


83,176 









Source: DaU in Welcomme, R.L. 1990. Sutus of fisheries in South American riven. Interciencia 1S(6):337-34S; and Daget, J. and Economidis, 
P.S. 1975. Richesse sp&ifique de I'ichtyofaune de Macidoine orientale et de Thrace occidentale (Gr^e). Bulletin du Musium National d'Histoire 
Naturelle, 3e s^rie, no 346, icologie g^n^rale 27:81-84. 

Note: ' Total fish number given above will differ in some instances fix>m numbera given in the main set of tables (12.6-12. 10) because of different 
original data sources. 



120 



Fishes 



Table 12.4 


Numbe 


sr of fish 


species, iak( 


} area and lati 


tude 






LAKE 


NUMBER OF 


SURFACE 


LATITUDE 


LAKE 


NUMBER OF 


SURFACE 


LATITUDE 




SPECIES' 


AREA (km^l 






SPECIES' 


AREA (km^l 




Africa 








Philippines 








Albert 


46 


5346 


1.7''N 


Lanao 


20 


357 


7.9°N 


Bangweulu 


68 


2072 


ILI'S 


USSR 








Chad 


93 


17500 


13.0°N 


Aral Sea 


17 


64500 


45.0"'N 


Chilwa 


13 


673 


15.3°S 


Baikal 


50 


31500 


54.0'>N 


Edward 


53 


2150 


0.5"'S 


Balkhash 


5 


18500 


46.0 °N 


Kivu 


17 


2370 


2.0 °S 


Beloe 


22 


1125 


60.2">N 


Malawi 


245 


28490 


12.0''S 


Black Sea 


156 


423488 


43.0''N 


Mwer^ 


88 


4413 


9.0<'S 


Caspian Sea 


74 


436 


42.0''N 


Nabugabo 


24 


30 


0.6°S 


Gusinoo 


13 


165 


51.2°N 


Rudolf 


37 


9065 


3.5°N 


Issyk Kul 


11 


6206 


42.0°N 


Rul<wa 


22 


3302 


8.0°S 


Ladoga 


48 


18400 


ei.QON 


Tana 


18 


3626 


12.0°N 


Leprindo 


14 


24 


56.5°N 


Tanganyika 


214 


32893 


6.0° S 


Onega 


28 


10340 


61. SON 


Victoria 


177 


69484 


LO'S 


Pestovo 


17 


2 


58.3«N 


Canada 








Sea of Azov 


17 


38000 


46.0''N 


Athabasca 


21 


7154 


59.2''N 


Seliger 


21 


221 


57.2"'N 


Big Trout 


24 


616 


53.8°N 


Taimyr 


13 


4650 


74.5'>N 


Great Bear 


12 


31153 


ee.CN 


Teletskoe 


14 


231 


51.6»N 


Groat Slave 


26 


27195 


61.4"'N 


USA 








Keller 


13 


406 


es.g'N 


Black 


10 


5 


34.7''N 


Kootenay 


19 


399 


49.5°N 


Canandaigua 


37 


41 


42.8<'N 


La Ronge 


19 


1425 


55.0°N 


Cayuga 


60 


171 


42.7''N 


Opeongo 


22 


60 


45.7''N 


Erie 


113 


25719 


42.2''N 


Great Britain 








Huron 


99 


59596 


44.5°N 


Loch Lomond 


15 


71 


56.1 "N 


Jones 


13 


1 


34.7''N 


Windermere 


9 


15 


54.3°N 


Keuka 


30 


44 


42.5''N 


Guatemala 








Michigan 


114 


58016 


44.0">N 


Peten 


23 


98 


17.0°N 


Ontario 


112 


19477 


43.5°N 


Yzabal 


48 


684 


15.5»N 


Otisco 


17 


10 


42.8''N 


Italy 








Owasco 


10 


85 


42.8°N 


Maggiore 


21 


212 


46.0''N 


Salters 


14 


1 


34.7'>N 


Japan 








Seneca 


39 


174 


42.6°N 


Biwa 


46 


676 


35.2''N 


Singlotary 


14 


3 


34.6°N 


Mexico 








Skaneateles 


14 


54 


42.8°N 


Chapala 


14 


1080 


20.2"'N 


Superior 


67 


82414 


47.5''N 


Pfitzcuaro 


7 


111 


19.6°N 


Waccamaw 


36 


36 


34.3''N 


Zirahudn 


5 


8 


19.4''N 


Walnut 


30 


1 


42.6"'N 


Nicaragua-Costa Rica 






White 


19 


5 


34.6''N 


Nicaragua 


40 


8264 


11.5''N 


Yugoslavia-Albania 






Peru-Bolivia 








Ohrid 


17 


347 


41.0''N 


Titicaca 


18 


9065 


16.0°S 











Source: Data in Barbour, CD. and Brown, J.H. 1974. Fish species diversity in lakes. The American Naturalist 108 (962):473-489. 

Note: ' Total fish number given above differs in some instances from numbers given in the main set of tables (12.6-12. 10) because of different 

original data sources. 



very strong effect of latitude probably a reflection of 
climatic severity and isolation from colonisation sources. In 
contrast, in a sample of 14 lakes in tropical Africa, surface 
area, depth and conductivity were the primary factors 
involved (increasing depth in a sense represents an 
increased area available to non-pelagic fishes). Select data 
used by Barbour and Brown are given in Table 12.4. 

SUBTERRANEAN FISHES 

At least 47 species of fishes are either cave-adapted or have 
cave-adapted populations. These highly localised 
populations are widely distributed across the globe, from 
about 38°N southward to the Tropic of Capricorn. 
Information on these fishes is given here in order to 
illustrate a facet of vertebrate biodiversity that is little- 



known although of great intrinsic interest and of scientific 
value in illustrating aspects of the evolutionary process. 

Taxonomic and distributional data are summarised in Table 
12.11 and site localities mapped in Fig. 12.4. 

These 47 cave species represent seven orders and 13 
families. Although frequently called cave fishes, this is not 
wholly accurate as some live in honeycombed rocks 
(aquafers) in which there are not necessarily any caves that 
can be entered by humans. Indeed, some species are only 
known from artesian wells that have penetrated these 
aquafers. It is therefore better to refer to these fishes as 
'subterranean', 'cave-adapted' or troglobionts. 

Characteristic of such species is a marked trend toward 



121 



1. Biological Diversity 



eyelessness, lack of pigment and low metabolic rate. It is 
interesting to note that similar physical characteristics have 
evolved in some freshwater species confined to rapids and 
torrents in Africa and South America. These torrenticolous 
species have presumably lost their eyes and body pigment 
as a result of a lack of light in their habitat under stones 
and rocks in turbid rapids. 

Of the 13 families which include cave-adapted fishes, nine 
are among the primary freshwater group. Indeed, the 
Homalopteridae, Ictaluridae, Pimelodidae, 
Trichomycteridae,Cyprinidae,CobitidaeandAmblyopsidae 
have particularly narrow salinity requirements. The families 
Ophidiidae, Synbranchidae and Eleotridae are primarily 
marine. The subterranean members of these families live 
near the coast in caves where they have been trapped in 
some cases, by land uplift. In all cases, cave species form 
a very small minority of the species in their respective 
families. 

Population sizes are generally unknown. Nemacheilus 
smithi, for example, is known from just one specimen. Only 
two cave-adapted forms have been bred in captivity. An 
eyeless population of Astyanax fasciatus is on widespread 
sale as the 'blind cave tetra'. The blind form of this species 
breeds true, yet if mated with the above ground (epigean) 
form, as happens in nature, a complete range between 
eyeless and fully-eyed, and depigmented and fiilly 
pigmented, forms will result. Most laboratory based 
behavioural studies have been conducted on this species 
(e.g. Wilkens, 1971). Some observations on Phreatichthys 
were made by Ercolini and Berti (1975). 

Studies on subterranean fishes in the wild are lacking. 
There is some evidence that breeding is seasonal and related 
to the influx of water into the subterranean environment. 
The young of Caecobarbus geertsi are only found after the 
rainy season (M. Poll, pers. comm.). 

Because of the conspicuous superficial differences between 
a subterranean (hypogean) species and its epigean relatives 
it had been considered normal practice to allocate a 
hypogean species to a different genus. This action is now 
considered to be phylogenetically unjustified (Roberts and 
Stewart, 1976; Banister, 1984) and published nomenclatural 
changes are used in the species list below. 

Not all cave fishes show the same degree of non- 
development of eyes or pigment. Some have very small 
eyes (are microphthalmic) or have eyes covered with skin, 
some are lightly pigmented. Such species can be regarded 
as not yet fully cave-adapted. The acquisition of extreme 
cave morphology implies the passage of time and this notion 
has been used by some authors (e.g. Wilkens, 1982) to 
argue that the fiilly cave-adapted species have been in their 
environment longer than those that are partially adapted. 
This argument involves the questionable assumption that 
evolutionary rates are the same in all species. These 
arguments also do not take account of the evidence for 
neoteny in cave fishes (Gould, 1977; Banister, 1984). 

The subterranean fishes are of particular scientific value in 
exemplifying dramatic evolutionary phenomena. Within 
seven orders and 12 families of fishes there are 46 
examples of parallel evolution occurring in similar 



environments. These evolutionary microcosms are often 
now under threat. The waters in which these species live 
and have evolved are a final sump for water soluble 
chemicals used on land. In the regions where subterranean 
fish live, water is often at a premium for human 
consumption and tapped for that purpose (the only habitat 
of Satan eurystomus is also the water supply for San 
Antonio, Texas). 

CORAL REEF FISHES 

Coral reef fishes are those associated with coralline 
structures. Many of these species can also occur in habitats 
other than coral reefs and in regions outside the geographic 
range of reef-building corals (Sale, 1980). Coral reefs are 
tropical, shallow water ecosystems, largely restricted to the 
area between the latitudes 30°N and 30°S (see Chapter 23). 
These complex systems are highly productive, a result of 
efficient recycling, high nutrient retention, and a structure 
which provides habitat for a great range of organisms 
(UNEP/IUCN 1988a,b,c). 

Central parts of the Indo-West Pacific contain the highest 
number of reef fish species (Ehrlich, 1975), and richness 
decreases with increasing distance from this core area. Sale 
(1980) considers that this general pattern cannot be 
accounted for entirely by ecological hypotheses based upon 
latitudinal gradients in diversity, but may be due to 
historical factors. The origin and maintenance of high 
diversity is subject to debate. One view is that high 
diversity is sustained on reefs because of resource 
partitioning between species, fish assemblages being 
equilibrium communities (Dale, 1978; Robertson and 
Lassig, 1980; Smith and Tyler, 1972). An opposing view 
is that these communities are non-equilibrium unstable 
systems, and that species abundance is determined through 
independent differential responses to unpredictable 
environmental changes (Sale, 1977, 1978, 1980;, 1978; 
Sale and Williams, 1982). 

Most reef fish species are relatively rare in terms of 
individuals in the community. Thus, at Toliara (south-west 
Madagascar) only about 25% (136) of the total number of 
fish species present were ranked as abundant (Harmelin- 
Vivien, 1989). Many families of coral reef fishes have a 
circum-tropical distribution, although there are pronounced 
differences at species level; the number of reef fish species 
within a single zoogeographic region varies between 100s 
and 1,000s. Most families in tropical seas include species 
that occur in the coral reef fauna, and some families are 
almost entirely restricted to reefs, such as Chaetodontidae, 
Scaridae, and Labridae. Within the demersal component 
(feeding on benthic organisms), the families Acanthuridae, 
Balistidae, Belennidae, Holocentridae, Ostraciodontidae, 
Pomacentridae (damselfish) and Serranidae tend to 
dominate. Principal pelagic families associated with reefs, 
other than the top predators such as Carangidae, Sphyraena 
and sharks, include Atherinidae (silversides), Pomacentridae 
and small lutjanids such as Caesio and its relatives 
(Longhurst and Pauly, 1987). 

Small-sized species tend to predominate, although the range 
is from 2-3cm for some Eviota species to over 5m for some 
sharks. Fish distribution is highly heterogeneous within a 



122 



Fishes 



particular geomorphological reef zone because of stochastic 
processes involved in fish larvae settlement (Gladfelter et 
al., 1980). Complexity in reef structure contributes to 
species richness among reef fish by providing a wider 
variety of niches. On a local scale, fish community 
structure varies markedly between reef flat and outer reef 
slope; these zones are subject to different environmental 
factors affecting egg type, size-class categories, and feeding 
ecology. Other zones, including boulder tract, seagrass beds 
and deep outer flagstone all harbour characteristic fish 
assemblages. 

There is a strong positive correlation between coral and fish 
species richness at given sites, although this is less evident 
on a small scale within reef zones (Table 12.5). It has also 
been suggested that there is a positive correlation between 
the degree of live coral cover and species richness and 
abundance of reef fishes (Bell and Galzin, 1984). In 
addition, the presence of dietary specialist fish species is 
oflen related to specific coral growth forms; for example, 
the exclusive coral feeders in the Chaetodontidae are 
positively correlated with the abundance of tall-branched 
coral colonies (Bouchon-Navarro et al. , 1985). 

Table 12.5 Numbers of reef fishes and 
coral species 



CORAL REEF SITE NUMBER OF 


NUMBER OF 


FISH SPECIES 


CORAL SPECIES 


Great Barrier Reef (Australia) 


2,000 


500 


New Caledonia 


1.000 


300 


French Polynesia 


800 


168 


Heron Island (Great Barrier) 


750 


139 


Society Islands 


633 


120 


Toliara (Madagascar) 


552 


147 


Aqaba 


400 


150 


Moorea (Society Is) 


280 


48 


St Gllles (Reunion) 


258 


120 


Tutia Reef (Tanzania) 


192 


52 


Tadjoura (Djibouti) 


180 


65 


Bale Possession (Reunion) 


109 


54 


Kuwait 


85 


23 


Hermitage (Reunion) 


81 


30 



Source: Data from Harmelin-Vivien, ML. 1989. Reef fish 
conununity stnicture: an Indo-Pacific comparison. In: Harmelin-Vivien, 
M.L. and Bourlibre, F. (Eds), Vertebrates in Complex Tropical 
Systems. Springer-Verlag, New York. 

References 

Banister, K.E. 1984. A subterranean population of Garra bareimiae 
CTeleostei: Cyprinidae) from Oman, with comments on the concept 
of regressive evolution. Jounxal of Natural History 18:927-938. 

Baihour, CD. and Brown, I.H. 1974. Fish species diversity in lakes. 
The American Naturalist 108 (962):473-489. 

Bell, J.D. and Galzin, R. 1984. The influence of live coral cover on 
coral reef fishes communities. Marine Ecology 
Progress Series 15(3):265-274. 

Bouchon-Navarro, Y., Bouchon, C, and Harmelin-Vivien, M.L. 
1985. Impact of coral degradation on a chaetodontid fish 
assemblage (Moorea, French Polynesia). Proceedings of 5th 
International Coral Reef Symposium S-.m-Ail. 

Daget, J. and Economidis, P.S. 1975. Richesse sp^cifique de 
I'ichlyofaune de Mac^doine orientale et de Thrace occidentale 
(Grice). Bulletin du Museum National d'Histoire Naturelle. 3e 
s^rie, no 346, ^cologie g^n^rale 27:81-84. 



Dale, G. 1978. Money-in-the bank: a model for coral reef fiah 

coexistence. Environmental Biology of Fishes 3(l):103-108. 
Ehrlich, PR. 1975. The population ecology of coral reef fishes. 

Annual Review of Ecology and Systematics 6:21 1-247. 
Ercolinl, A. and Berti, B. 1975. Light sensitivity experiments and 

morphological studies on the blind phreatic fish Phreatichlhys 

andruzzi Vinciguerra from Somalia. Monitore Zoologico ItaUano 

(NS) Suppl. 6:29^3. 
Gladfelter, W.B., Ogden, J.C. and Gladfelter, E.H. 1980. Similarity 

and diversity among patch reef fish communities: a comparison 

between tropical western Atlantic (Virgin Islands) and tropical 

central Pacific (Marshall Islands) patch reefs. Ecology 61(5):1156- 

1168. 
Gould, S.J. 1977. Ontogeny and Phytogeny. Belknap Press of Harvard 

University Press, ix -t- 501pp. 
Harmelin-Vivien, M.L. 1989. Reef fish community structure: an Indo- 

Pacific comparison. In: Harmelin-Vivien, M.L. and Bourlibre, F. 

(Eds), Vertebrates in Complex Tropical Systems. Springer-Verlag, 

New York. Pp.21-60. 
Longhurst, A.R. and Pauly, D. 1987. Ecology of Tropical Oceans. 

Academic Press Inc., San Diego, London. 
Nelson,J.S. \9i4. Fishes of the WorW, 2nd edn. John Wiley and Son, 

New York. 
Roberts, T.R. and Stewart, D J. 1976. An ecological and systematic 

survey of fishes in the rapids of the lower Zaire or Congo river. 

Bulletin of the Museum of Comparative Zoology 147(6):239-3I7. 
Robertson, D.R. and Lassig, B. 1980. Spatial distribution patterns and 

coexistence of a group of territorial damselfishes from the Great 

Barrier Reef Bulletin of Marine Science 30:187-203. 
Rosen, D.E. 1974. Phylogeny and zoogeography of salmoniform fishes 

and relationships of Lepidogalaxias salmondroides . Bulletin of the 

American Mttseum of Natural History 153 2:265-326. 
Sale, P.P. 1977. Maintenance of high diversity in coral reef fish 

communities, ^mtfnco/i Naturalist 111:337-359. 
Sale, P.F. 1978. Coexistence of coral reef fishes: a lottery for living 

space. Environmental Biology of Fishes 3(1): 85-102. 
Sale, P.F. 1980. The ecology of fishes on coral reefs. Oceanography 

arul Marine Biology Annual Review 18:367-421 . 
Sale, P.F. and Williams, D.Mc.B. 1982. Community structure of coral 

reef fishes: are the patterns more than those expected by chance? 

American Naturalist 120:121-127. 
Smith, C.L. and Tyler, J.C. 1972. Space resource sharing in a coral 

reef fish community. Bulletin of the Natural History Mi4seum Los 

Angeles Science Bulletin 14:125-170. 
UNEP/IUCN 1988a. Coral Reefs of the World. Volume 1: Atlantic and 

Eastern Pacific. UNEP Regional Seas Directories and 

Bibliographies. lUCN, Gland, Switzerland and Cambridge, 

UK/UNEP, Nairobi, Kenya. 373pp., 38 maps. 
UNEP/IUCN 1988b. Coral Reefs of the World. Volume 2: Indian 

Ocean, Red Sea and Gulf. UNEP Regional Seas Directories and 

Bibliographies. lUCN, Gland, Switzerland and Cambridge, 

UK/UNEP, Nairobi, Kenya. 389pp., 36 maps. 
UNEP/IUCN 1988c. Coral Reefs of the World. Volume 3: Central and 

Western Pacific. UNEP Regional Seas Directories and 

Bibliographies. lUCN, Gland, Switzerland and Cambridge, 

UK/UNEP, Nairobi, Kenya. 329pp., 30 maps. 
Welcomme, R.L. 1979. Fisheries ecology of floodplain rivers. 

Longman, London and New York. 
Welcomme, R.L. 1990. Status of fisheries in South American rivers. 

Interciencia l5(6):337-345. 
Wilkens, H. 1971. Genetic interpretation of regressive evolutionary 

processes: studies on hybrid eyes of two Astyanax cave populations 

(Characidae, Pisces). Evolution 25:530-544. 
Wilkens, H. 1982. Regressive evolution and phylogenetic age: the 

history of the colonization of freshwater of Yucatan by fish and 

Crustacea. Bulletin of the Association of Mexican Cave Studies 

8 :237-244 and Bulletin of the Texas Memorial Museum 28:237-244. 



Chapter abridged from a consultancy report by Keith 
Banister, with additional material by WCMC staff (general 
introduction, reef fishes). 



123 



1. Biological Diversity 



Table 12.6 Freshwater Fishes: Eurasia 



No of No of 

•pocies endemics 
Baltic Sea basin 

Neva 40 

Dvina 43 

Vistula 43 
Black Sea basin 

Danube 67 5 

Dniepr 58 

Dniestr 58 

Kuban 46 

Don 56 

Crimea 14 

Sakayra basin (Turkey) 40 
Caspian Saa basin 

Volga 61 

Ural 48 

Terek 37 

Kura & Araxes 47 Q 

Sefid & Atrek c 22 c 6 
Aral Sea basin 

Amu-Darya 44 17 

Syr Darya 46 3 

Issy-Kul Lake basin 1 1 3 

Lake Balkash basin 12 3 

Tarim basin ' 14 1 
White Sea drainage 

N Dvina 25 

Pechora 22 
Arctic Ocean basin 

Ob 43 

Yenisei (excl. Lake Baikal) 42 2 

Lake Baikal 50 23 

Lena 43 

Kolmya 29 
Bering Sea drainage 

Anadyr 20 1 

Kamchatka 15 
Pacific Ocean drainage 

Amur c 90 67 

Yalu 74 c 4 

Hong Ha (Red River may c 180 77 
include brackish water species) 

North Vietnam rivers 203 c 7 

South Vietnam rivers ^ 255 very few 

Mekong c 500 7 

Malayan Peninsula ^ 183 3-83 

Tasek Bera swamp (Malaysia) 95 

Gombak (Malaysia) 28 
Japan 

Overall ' c 1 20 c 53 



Lake Biwa (Japan) ' 
Philippines 

Lake Lanao (Mindanao) ' 
Indonesia 

Kapuas (Kalimantan) ' 

Java 

Lake Poso (Sulawesi) ° 

Papua New Guinea 

Fly river ' 
Northern rivers 
Sri Lanka 



Indian Ocean drainages 



No of 

species 
< 63 



c24 



c250 

c 100 

10 



103 
c84 



No of 

sndemics 
8 



c 18 



54 



Mae Khong '" 


215 


Lake Indawgyi 


43 


Lake Lortak 


13 


Lake \n\6 


28 


Nepal (rivers Arun, Trisuti 


101 


Mardi-Kola, all Ganges head-waters) 




Indus 


147 


(Kabul, Chamkani-Kurram, 


45 


Zhob Gowmal, all Indus 




head-waters) 




Tigris & Euphrates 


62 


Endorheic basins: Mongolia 




Ugiy Nuur 


7 


Biger Nuur 


8 


Boon Tsagaan Nuur 


2 


Endorheic basins: China 





Upland lakes of Yunnan " 65 

Er-Hai (Yunnan) " 6 
Endorheic basins: Afghanistan-Iran 

Helmand-Sistan basin 27 

Hari-Tedzhen 12 

Murgals 15 

Lake Reza lyeh (Urmin) '^ 14 
Arabian Peninsula and Levant 

Oman mountains 3 

Red Sea, Gulf of Aden 8 
and Wadi Hadramut systems 

Rub al Khali drainage 3 

Jordan river drainage 24 

Azraq Oasis " 1 
Western and southern Europe 

(excluding the river basins considered elsewhere) 

Lake Ohrid " 1 7 

Europe '° 76 



c35 

c6 

8 



17 
c36 



<77 



15 

2 



7-8 





22 
107 



57 



44 

5 



1 -57 


5 



2 
7 

3 
12 

1 



3 
10 



The rivers are arranged roughly clockwise from the Baltic Sea 
drainage. Major lakes are included along with their tributaries, as most 
literature treats the ichthyofauna on a regional or basin basis. Within 
an Eurasian context this treatment is biologically rational, as many of 
the lake fishes are anadromous. 



Regrettably, no reliable data could be found for several major river 
systems in this region; these include the Hwang Ho, Sikiang, 
Iirawaddy, Ganges, and rivers of peninsular India (notably the 
Godaveri, Cauvery and Narmada). 



124 



Fishes 



Notes 



' In tola there are 16 species endemic to the Aral Sea basin. 

^ Of these species, about 80 are brackish water inhabitants or largely marine. 

^ The freshwater fishes of Peninsular Malaysia are divided into 3 faunal zones: the northwest, the northeast and central, and the south zone. The 
numbers of freshwater fishes in each division are given respectively as 47, 98 and 58. The number of species listed in various articles as endemic 
varies extremely widely. Some reliance can be placed on the total number of primary freshwater fish, at least as to the order of magnitude, but 
very little on the number of endemic species. 

* This figure probably includes some euryhaline species. 
^ The total figure includes introductions and subspecies. 

* The number of endemic species will be higher if the immediately adjacent rivers were included (Roberts 1989). 

' The endemic tally would be 47 if one or more other rivers from central-southern New Guinea were included (Roberts 1978). 

' This lake is famed for a reported endemic species-flock of cyprinids. However, since 1962 when alien species were introduced the indigenous 
fauna has become extinct (see Komfield & Carpenter 1984; Reid 1980). Furthermore, many of the original specimens collected by Herre that 
led to the idea of the Lanao species flock were destroyed during the Japanese invasion in World War II. The number of species on other islands 
varies widely but has not been the subject of detailed listings. 

' It is not known if 2 of these species still survive. Introductions are likely to be responsible for their possible extirpation (Kottelat 1990). 

'° This figure apparently includes about 40 brackish water and introduced species. The endemics are loaches and homalopterids from head-water 
streams. 

" These figures include subspecies as well as 2 endemic genera. It also seems that endemic In this context means very limited distribution but in 
more than one water body (Li 1982). 

" All these species are cyprinids. 

" The fauna of this region, especially of Lake Urmin, is very badly in need of re-examination. 

** There have been very many Instances in historical times of translocation of fishes within and into this area that well over half the fishes now 
living in the system are not indigenous. These have not been included above. 

'^ One of the 'endemics' occurs in immediately adjacent lakes. 

'^ The European fish fauna is richest In the west and becomes Increasingly depauperate towards the Mediterranean, Atlantic and North Sea coasts. 
This trend Is even more marked in the off-shore islands which were separated from continental Europe at the end of last ice age, before the full 
complement of the refLigla fauna had moved westwards. Only the most widespread or euryhaline forms live In Ireland, for example. The endemic 
species live in Dalmatia (1), Greece (3), Spain (3), North Italy south of the Alps (1), Italian rivers draining into the northwest Adriatic (1) and 
the Rhone (1). The European fishes have been much studied but rarely in a global context, and the significance of minute differences has been 
given greater importance than is probably justified. Only recently has a trend started to look at European fishes in an Eurasian context, which 
probably will affect the classification of the fishes quite considerably. 

Table 12,7 Freshwater Fishes: North America 



Total 
species 



Endemic 
species 



Total 
species 



Endenrtic 
species 



Far north 

Hudson Bay drainage ' 



Central Appalachian western drainages 



101 









(Ohio system headwaters) 






Ungava Bay watershed ^ 


18 





Allegheney 


92 





Arctic archipelago ^ 


8 





Muskingum 


111 





(no primary freshwater fish) 






Monongahela 


89 





St Lawrence River 


98 


1 


Little Kanawha 


72 





Newfoundland rivers 


20 





Kanawha: below falls 


90 





(no primary freshwater fish) 






Kanawha: above falls 


49 


6 


Labrador rivers 


26 





Guyandotte 


67 





(2 primary freshwater fish) 






Big Sandy 


94 






Northern Appalachian rivers 

Delaware to Nova Scotia " 

(about 85 primary fresh-water fish) 

Central Appalachian Atlantic drainages 

Edisto 

Santee 

Peedee 

Waccamaw 

Cape Fear 

Neuse 

Tar 

Roanoke 

James 

York 

Rappahanock 

Potomac 

Susquehanna 



Southeastern USA 



150 



55 





90 


5 


76 


1 


51 


2 


71 


1 


70 





66 





87 


7 


70 


3 


49 





50 





65 


1 


61 


1 



Ogeechee 


58 


'^^ 


Savannah 


75 





Apalaohicota drainage 


86 


7 


Choctawhatchee 


74 





Perdido 


57-64 





Mobile Bay drainage 


157 


c40 


Kissimmee river (and Lake 


37 





Okeechobee) 






Suwannee (and 


43 





Withlacoochee) 






Mississippi-Missouri ^ 


c260 


ell 


Rio Grande Basin 


121 


69 


California Coastal to Oregon 






(and internal basins) 






Colorado ' 


30 


18 


Sacramento system ' 


38 


6 



125 



1. Biological Diversity 







Total 


Endemic 




Total 


Endemic 






species 


species 




species 


species 


Far north 








Yukon and Mackenzie^^asine 
Peace 

Mackenzie river 
Yukon river ' 






Death Valley system 
North central basins 
Lahontan basin 




8 

4 

13 


6 

2 
5 


24 
34 
33 







Bonneville basin 




19 


8 


Lakes 






Oregon lakes 

Klamath river 

N California - Oregon 

Catcadia 


rivers 


15 
28 
29 


3 
6 
3 


Superior 

Erie' 

Ontario 

Michigan'" 


44 
99 
95 

78-130 









(the Columbia system north to Stikine! 
Columbia 


1 

45 


13 


Huron 
Pontachartrain 


86 
76 




1 


Fraser 




39 





Lahontan - see I ^hontan basin 






Skeena 

Nass 

Stikine 




32 
27 
27 







Tahoe - see Oregon lakes 
Great Slave lake 
and tributaries 


36 






Notes 



The many recent introductions are excluded here. The drainage covers a wide range of climate zones and most of the species are in the south 

of the region and are probably recent (post-glacial) migrants. 

This figure includes freshwater species with some degree of euryhalinity. 

Fish have only occupied this area for 14,(XX) years. Much of it is ice-covered in winter. 

The unique endemic is a rare anadromous coregonid found oiJy in the fresh waters of the southern tip of Nova Scotia. 

Of these endemics 56 come from the Cumberland, Tennessee and Arkansas drainages, ie, a very small part of the system. 

The number of species and endemic species could change substantially at any time as there is disagreement about the specific or subspecific status 

of some forms, as well as known problems with hybridization. 

One of the Sacramento endemics has been widely introduced elsewhere and the number of endemics would have been much higher if smalt, 

adjacent, but quite separate rivers had been included here. 

Migratory forms are included in the Yukon figures. 

One endemic subspecies now -extinct. 

Larger figure includes tributaries. 



Table 12.8 Freshwater Fishes: Central and South America 



Total 
species 



Endemic 
species 



Total 

species 



Endemic 
species 



Mexico 



Nicaragua 



Santiago 

Lerma 

Morella 

Patzcuaro 

Zirahuin 

San Juanico 

Valle de Mexico ' 

Puebia plateau 

Atoniico 

Ameca 

Magdalena 

Armeria 

Coahuayana 

Balsas 

Papagayo 

Varde Atoyac 

Panuco 

Gulf coast 

Papaloapan 



17 
35 
14 


2 

15 
1 


Pacific slopes 
Atlantic slopes 


10 


2 



Lake Xiloa 


8 


Lake Managua 


6 
5 


2 
1 


South America 


4 


2 


Trinidad 


7 





Magdalena 


20 


7 


Maracaibo 


8 


1 


Caribe 


11 


3 


Lago de Valencia 


9 


3 


Orinoco ^ 


27 


8 


Amazon * 


4 





Rio Negro (Amazon) 


9 


1 


Lake Titicaca 


75 


22 


Trans-Andean region 


21 


1 


La Plata ' 


57 


9 


Uruguay 



c39 





12 





32 





12 





26 


1 


36 


5 


166 


? 


108 


31 


48 


6 


35 


4 


318 


88 


C2000 


c 1800 


436 


35 


20 


14 


390 


c 100 


c550 


c 110 


c 160 


c35 



Notes 

' In this region 3 additional former endemic species have recently become extinct. 

The zero for die number of endemic species in the lake does not reflect the fact that it contains species of extremely limited distribution which 

variously occur in associated water bodies. 

So far as can be ascertained, these figures include subspecies and probably also include some not strictly freshwater fish. 
' This figure is extremely imprecise. Most published figures vary widely, and the relevance of deuiled studies at one locality to the fauna of the 

appropriate part of the subsystem is in doubt. 
' The total number of species in this river includes an unknown number of euryhaline species. The Parana, above the Guayra falls, has a high 

proportion of endemics in its fauna which is depauperate when compared to the rest of the system. 
The entities listed in the table include riven, lakes, and one island (Trinidad). 



126 



Table 12.9 Freshwater Fishes: Australia and New Zealand 



Fishes 



Auclralia ' 



Total 
species 



3 
c 110 



Endemic 
species 



5 
c 105 



Total Endemic 

species species 



New Zealand ' 



c30 



27 



Notes 

' It is very difficult to categorize the Australian fishes in the same way as in other parts of the world. Strictly speaking, primary freshwater fish 
number just 3, of which 2 are endemic. The total number of species living all or the major part of their lives in fresh water is about 150. Of 
these, about 1 10 seem to be confined to fresh waters, even if they are capable of living in sea water. A further difficulty is that many of the 
'fresh' waters are remarkably saline, especially in the desert regions. The great majority of fishes are confined to the short, peripheral, coastal 
rivers. All the 1 10 or so species had marine ancestors and many have marine close relatives; they are either physically confined to non-marine 
waters or are supposed to inhabit and breed in the freshwater parts of rivers. However, this figure could easily vary by 15 % either way. 

' Similar problems occur in evaluating the status of New Zealand fishes, except that there are no primary freshwater fishes there. 

Table 12.10 Freshwater Fishes: Africa 



Atlantic drainane 

Senegal ^ 

Gambia 

Tomin6 

Koukour^ 

Great Scarcie (Kolentd) 

Sassandra 

Bandama 

Komod 

Volta ' 

Mono 

Ouem§ 

Niger 

Mungo-Meme 

Rio Muni 

Zaire ^ 

Cunene * 

Orange-Vaal 

Cape drainage 

Rivers of the great 

escarpment and eastern plateau ^ 

Indian Ocean Drainage 

Olifants river 
Limpopo 
Zambezi 
Great Ruaha ° 
Tana 

Mediterranean drainage 

Nile 

Tunisian rivers 



Total 


Endemic 


species 


species 


83 


3 


79 





36 


1 


>44 


5 


23 





65 


2 


77 


1-2 


74 


1 


132 


8 


39 





62 


1 


149 


13 


27 


5 


81 


>6 


c700 


c500 


55 


2? 


16 


5 



13 



10 



10 


5 


49 


2 


122 


c25 


>36 


3 




>2 



115 
6 



26 
1 



Internal drainage rivers 

Omo (Lake Turkana 
Chari (Chad) ' 
Malagarazi (Tanganyika) ' 
Ruzizi (Tanganyika) ® 
Cubango (Okavango) '° 

Natural lakes 

Afrera (Guilietti) 
Albert 

Bangwelu " 
Barombi-Mbo " 
Chad " 
Chilwa '* 
Edward-George 
Eyasi complex '* 
Jipe 
Kivu '* 
Malawi " 



Mweru '^ 
Nabugabo '" 
Natron and MagadI 
Rukwa 

Tanganyika " 
Tsana (Tana) " 
Tumba ^ 

Turkana (Rudolf) " 
Upemba lakes '^ 
Victoria (including 
Kyoga) '' 
Zwai " 
Madagascar ^ 



Total 


Endemic 


species 


species 


20 


1 


c 162 


c257 


>14 


1 


92 


29 


2 


1 


46 


9 


86 





17 


12 


93 


1-30 


13-18 


1 


c55 


c35 


1 


1 


4? 


2 


17-33 


6-7 


>250 


>230 




c338 




c 1000 


85 





24 


5 


1 


1 


<17 


1 


>250 


>230 


c20 


1? 


>100 


1 


48 


10 


c 130 


1 


>250 


>225 



<20 



c40 



38 



Notes 

' The 3 endemic species are on]y found in small headwater streams. 

^ There is a large number of small rivers draining south from the Guinea highlands which hold many species restricted to several rivers in that 

region. In the original species descriptions the localities are given but cannot be put into context as the total fauna of these rivers has not been 

described. The high level of regional endemicity is not reflected in this table. Only the larger rivers (Tomine to Volta) have been studied in 

sufficient detail to make an adequately reliable entry. 
' The Zaire flgures are a consensus of the most recent estimates. Over the last few years reduction in the number of nominal ^ecies by 

synonymisationhas roughly equalled the descriptions of new taxa. The given figure has been based on the collections made at relatively few sites 

within the vast river network. (See, in particular, Banister, 1986: 215-216.) 
* Comments made in Note ^ apply equally lo the small rivers of Angola between the Quanza and the Cunene. For exan^le, Ansorge, made a 

collection of fish in the early years of this century close to Lucalla railway station on the Lucalla river. His collection contained 25 species, of 

which 1 1 were unique to thai site. No more recent records of fish collections from that region have been located. 



127 



1. Biological Diversity 

' There is a very high level of endemicity in this localized Cape fauna. The nuin named rivers are the Berg, Breder and Buffalo riven. The 

indigenous fauna is not speciose but now there are many introductions, to the detriment of the local fauna. 
* This figure is based on a pre-impoundmenl survey in just one part of the Rufigi system. 
' Although 25 is the most commonly cited number of endemics in the Chari-Logone system, it seems likely that, at best, many are sub-species. 

The basin fauna consists largely of widespread Nilotic fishes with a contribution of Niger-Benue faunal elements. The Chari-Benue watershed 

is extremely low and the systems connect during periods of heavy rain. 
' The Malagarazi is a swampy river flowing sluggishly westward across a plain to Lake Tanganyika. Its poorly known fauna is Zairean in origin 

as the present Malagarazi is a now isolated former part of the Zaire system. 
' The Ruzizi is the main inflow to Lake Tanganyika, yet it is only about 12,500 years old. At that time the water level in Lake Kivu rose lo such 

an extent that it overflowed southwards and the Ruzizi was formed . The upper and lower reaches of the river have different faunas and different 

hydrological conditions: Upper reach - Total 27. Endemic 7; Lower reach - Total 65, Endemic 20; Common to both - Total 13, Endemic 6. 

There are difficulties in evaluating the fauna of the lower reaches because of fish movemenu between the Ruzizi and the lake. The lake cichlids, 

however, rarely penetrate far up the river. In addition to the species enumerated above, there are 3 endemic species in streams flowing from 

the west into Lake Tanganyika. The streams are not meaningfijlly named. 
'° The fauna of this endoiheic river is essentially that of the Zambezi (q. v. ) . However, its upper reaches and headwaters are very poorly known. 
" The 86 species include those that live in the surrounding interconnecting small lakes, creeks and marshes. Lake Bangweulu does not have clearly 

deflned limits. Poll (1957) stated that 17 species live in the main lake. 
" The total number includes the species that inhabit the feeder streams and may occur in the lake itself at the feeder inflows. Of the 12 endemics, 

1 1 are cichlids. 
" Chad is a rapidly dissociating lake in a shallow basin. Formerly it was much more extensive. The total number of species is that of the entire 

basin. Only one species is endemic to the nucleus of the lake, but 25-30 are endemic to the entire basin. 
" This lake periodically dries up. The fish take refiige in residual pools or in feeder streams when this happens or when the conductivity gets too 

high. The higher figure for the total number of species includes those that normally live in the feeder streams, but all must live together at times 

of desiccation. 
" This is a series of 4 small lakes on the Tanzanian shield, Eyasi, Kitangiri, Manyara and Singida, that are the remnants of a former, much larger 

shallow lake. 
" In the earlier literature, no distinction was made between an occurrence in a feeder stream and in the lake itself. The figures given above are, 

respectively, for the lake basin and the lake, but at least one of the basin species occurs in the lake but only at the mouth of feeder streams. 
" Lake Malawi illustrates the uncertainties involved in compilation of this list. The three lines of species numbers above demonstrate the difference 

between published figures, current knowledge, and a probable future number when the lake fauna is well known. The top line is the published 

estimate. The second line is the current number of species described or known to be in press and to be published within the next year or so. The 

third estimate is based on information from Prof J. Slauffer (Pennsylvania State University); "Additionally, there are at least 200 entities which 

most authorities working in the lake recognize as valid species, but for which no species descriptions exist. Many of these are known by common 

names in the aquarium trade. Based on the numberofundescribed species which occur in the trawl samples and the fact that little is known about 

the fishes inhabiting the Mozambique coast, I estimate that there are at least 1000 species which inhabit Lake Malawi. Approximately 95% of 

the loul fish fauna is endemic to the lake." (m /in. to K. Banister 25 June 1991 .) Whichever number is most correct, only 38 species are not 

cichlids. 
" This lake lies on a shallow watershed between the Zambezi and Zaire systems and contains fish from both systems. 
" The formation of this lake, an offshoot of Lake Victoria, has been dated at 4,000 years BP. All the endemics ate cichlids. 
^ These are relict, highly alkaline lakes, formerly parts of a larger lake. 
" There is a much higher percentage of non-cichlid endemics than in the other rift valley lakes and a much higher number of families with endemic 

representatives. 
" The alleged one endemic is the loach Nemacheilus abyssinicus. There is considerable suspicion that the unique specimen was accidentally 

translocated from a collection of middle eastern fishes into the Degen collection of fish from Lake Tsana and inadvertently described by 

Boulenger (1902) as indigenous to that lake. 
" Although definable as a lake, it is a zone of permanent inundation up to 10 metres deep. 
" Of the 48 species, 36 are exclusively in the lake. The other 12 occur only in the Omo River inflow. 
" The Upemba lakes lie in the Kamalondo depression and are a shifting series of permanent, shallow, eutrophic lakes that are in varying contact 

with the Lualaba river. Of necessity, the number of the species has to include those also present in the Lualaba. 
" Giving a reliable number of Lake Victoria species is very difficult as two contradictory factors are involved. First, there are an unknown number 

of yet undescribed cichlid species in museum collections. Second, the recent introduction of the predatory Nile perch {Laus niloticus) into the 

lake has apparently caused the extirpation of some species. The fauna of Lake Victoria is in a sute of flux and the figures must be treated 

correspondingly. 
^ Unusually, none of the endemics are cichlids. They are cyprinids and probably spend some time in the lake as well as in the Maki river. The 

lake is drying out and there is no recent information on the fish fauna. 
" All are 'secondary' freshwater fishes; see Introduction. 



References 

Banister, K.E. 1986. Fish of the Zaire system. In: Davies, B.R. and 
Walker, K.F. (Eds), The Ecology oj River Systems. Dr W. Junk, 
Dordrecht, Netherlands. Pp.215-224. 

Boulenger, G.A. 1902. Descriptions of new fishes from the collection 
made by Degen, E. in Abyssinia. Annals and Magazine of Natural 
History (Series 7) IO(60):42l-439. 

Komfield, I. and Carpenter, K.E. 1984. Cyprinids of Lake Lanao, 
Philippines: taxonomic validity, evolutionary rates and speciation 
scenarios. In: Echelle, A. A. and Komfield, 1. (Eds), Evolution of 
Species Flocks. University of Maine at Orono Press, Orono. 
Pp.69-84. 

Kottelat, M. 1990. Synopsis of the endangered Buntingi (Osteichthyes: 
Adrianichthyidae and Oryziidae) of Lake Poso, Central Sulawesi, 
Indonesia, with a new reproductive guild and descriptions of three 
new species. Ichikyological Exploration in Fresh Waters 1(1):49- 



67. 
Li Shusen 1982. Fishftuna and its differentiation in the upland lakes 

of Yunnan. Acta Zoologica Sinica 28(2):169-176 (In Chinese with 

English summary]. 
Poll, M. 1957. Les genres des poissons d'eau douce de I'Afrique. 

Annates du Musee Royal du Congo Beige. Tervuren, Sciences 

zoologiques 54:1-191. 
Reid, G.Mc.G. 1980. "Explosive speciation' of carps in Lake Lanao 

(Philippines) - fact or fancy? Systematic Zoology 29:314-316. 
Roberts, T.R. 1978. Anichthyologicalsurvey of theFly river in Papua 

New Guinea with descriptions of new species. Smithsonian 

Contributions to Zoology 281:1-72. 
Roberts, T.R. 1989. The freshwater fishes of western Borneo 

(Kalimantan Barat, Indonesia). California Academy of Sciences 

14:1-120. 

Tables prepared for VfCMC by Keith Banister. 



128 



Fishes 



Figure 12.2 Freshwater river fishes: species richness and endemism 




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o 
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i 



129 



1. Biological Diversity 



figure 1 2.3 Freshwater lakie fishes: species richness and endemism 




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135 



1. Biological Diversity 

13. HIGHER VERTEBRATES 



The vertebrates, with around 43 ,000 known species, make 
up a very minor proportion of the global total of some 1 .7 
million described species but, by virtue of their size, 
adaptions and ecological role, often exert a major effect on 
the structure of communities and habitats. 

Vertebrates (Craniata or Vertebrata) make up the principal 
sub-phylum of the three included in the phylum Chordata. 
The vertebrates share the common characteristic of a hard 
endoskeleton (interior skeleton) with a backbone. There are 
seven classes (Parker, 1982), of which three, namely the 
Cephalaspidomorphi or Agnatha (lampreys and hagfishes), 
the Chondrichythes (sharks, rays, and skates) and 
Osteichthyes or Teleostomi (the bony fishes) are commonly 
referred to collectively as fishes. They are the extant 
members of diverse early vertebrate lineages, no longer 
recognised as a monophyletic taxonomic group. Fishes 
comprise nearly half of all extant vertebrate species. Data 
on species richness and endemism in freshwater fishes are 
presented in Chapter 12. The remaining four classes - 
Amphibia (amphibians), Reptilia (reptiles), Aves (birds) and 
Mammalia (mammals) - are often referred to as the higher 
vertebrates or tetrapods. 

THE GROUPS OF HIGHER VERTEBRATES 

Amphibians 

No single characteristic uniquely defines the amphibians. 
All are ectotherms, using external environmental sources of 
energy to regulate body temperature, and have highly 
permeable skin and pedicellate teeth. Most, but not all, 
have a dual life-cycle, being aquatic as larvae and terrestrial 
or semi-terrestrial as adults. Amphibians are the only four- 
limbed animals in which metamorphosis, the abrupt 
transformation from larvae to adult, occurs. 

There are currently in excess of 4,000 described species of 
amphibian (Frost 1983), divided into approximately 400 
genera, 34 families and three orders (Halliday et al., 1986). 
The three living orders are the Urodela or Caudata 
(salamanders, newts and their allies); the Anura (frogs and 
toads); and the Gymnophiona (the caecilians). Amphibians 
are ecologically less versatile than other higher vertebrate 
groups, in general being dependent on adequately high 
temperatures, moist conditions, and the availability of water 
for breeding and larval development. 

Reptiles 

The most obvious feature of reptiles is their covering of 
dry, horny scales, formed by localised thickenings of the 
keratin layer of the epidermis. Other characteristics include 
air-breathing, ectothermy - the dependence on external 
sources of heat to maintain a rather variable blood 
temperature - simple unspecialised 'homodont' teeth, and 
reproduction (normally on land) via the production of 
shelled eggs or live young. 

Approximately 6,550 species of living reptile have been 
described, classified into about 905 genera, 48 families and 



four orders (Halliday el al., 1986). These comprise the 
Chelonia (tortoises, turtles and terrapins), the Crocodylia 
(crocodiles and alligators), the Rhynchocephalia (which 
contains two species of tuatara Sphenodon), and the 
Squamata. This last group is divided into three suborders: 
Sauria (lizards); Serpentes (snakes) and Amphisbaenia 
(worm lizards) (many taxonomists recognise each of these 
as an order, rather than suborder). Unlike most amphibians, 
most reptiles are truly terrestrial and do not require 
environments rich in water; a number of species have also 
been able to adapt to marine habitats. The most species- 
rich, abundant and widely distributed reptile groups are the 
lizards and snakes. 

Birds 

All birds are, like mammals, endotherms, but their 
distinctive characteristic is that they possess feathers. 
Feathers are an evolutionary modification of reptilian scales 
which initially probably simply served a thermoregulatory 
function but now, in conjunction with the development of 
the forelimbs into wings, allow most birds the power of 
flight. Birds have lost all teeth from their bills, and 
reproduce by laying hard-shelled eggs. 

Sibley and Monroe (1990) recognise 9,672 species of bird, 
organised into 2,057 genera, 144 families, and 23 orders. 
Birds are therefore the most diverse terrestrial vertebrate 
group. They have adapted to all the major habitats of the 
world, including equatorial forests, hot deserts, and the 
high Arctic and Antarctic. 

Mammals 

Mammals are animals whose bodies are insulated by hair 
(often in the form of a thick pelt or ftir), which nurse their 
infants with milk produced from mammary glands, and 
which share a unique jaw articulation between the dentary 
(the main bone of the lower jaw) and the squamosal bone of 
the skull. Present-day mammals are 'heterodont', i.e. their 
teeth are specialised to fulfil different functions, and 
endothermic, i.e. their internal body temperatures are 
maintained by energy generated from metabolic processes 
within the body. 

Corbet and Hill (1991) list 4,327 recognised mammal 
species, arranged into approximately 1,(X)0 genera, 135 
families, 18 orders and two subclasses (Macdonald, 1984). 
The division into subclasses reflects a separation which 
occurred almost 200 million years ago between the egg- 
laying Prototheria (the only survivors of which are three 
Monotremes: the platypus and two echidnas) and the Theria 
which bear live young. The live-bearing mammals diverged 
around 90 million years ago into the groups now recognised 
as marsupials (infraclass Metatheria) and the placental 
mammals (infraclass Eutheria). As a class, mammals are 
extremely versatile and have adapted to almost all terrestrial 
and aquatic habitats. Monotremes are only found in 
Australasia and marsupials are confined mainly to 
Australasia and the Neotropics, but placental mammals have 
spread throughout the globe, including the polar regions. 



136 



Higher Vertebrates 



THE DISTRIBUTION OF HIGHER VERTEBRATES 

Patterns of higher vertebrate distribution 

As with many other organisms, species richness of land 
vertebrates tends to increase at lower latitudes. Amphibians, 
for example, are generally absent at very high latitudes 
(although one salamander species, Hynobius keyserlingii, 
ranges as far north as the Arctic circle 66.5°N) and species 
richness in most groups increases progressively towards the 
equator. Trends along moisture and altitudinal gradients are 
superimposed upon the latitudinal trend. For example, in 
North America, the greatest numbers of species are found 
in sireas of high rainfall, principally in the south-eastern 
USA and secondarily in the north-west. Amphibian species 
diversity generally declines with altitude, so that a transect 
along the Equator from the Amazon basin to the crest of the 
Andes reveals a gradual reduction from 81 species at 340m 
to only four species above 3,500m (Duellman and Trueb, 
1985). Reptiles are extremely sensitive to cold conditions 
and species diversity is very low in very high latitudes. 
Reptile species diversity increases towards the subtropics 
and tropics, to which some groups, such as the Crocodylia, 
are completely confined. Similarly, the diversity of birds 
and mammals increases towards the Equator. 

The geopolitical distribution of higher vertebrates 

Table 13.1 is a new compilation of data on species richness 
and endemism in vertebrates other than fishes, assessed on 
a geopolitical basis. This table is intended to complement 
the parallel compendium of flowering plant data (Table 8.3) 
earlier in this book. 

Figs 13. 1-13.8 show select data from Table 13.1 in graphic 
form. In this set of figures we have focused on single- 
country endemic species of mammals, birds and 
amphibians; the data are less complete for reptiles. We do 
not yet have a full data set for total country numbers, and 
here show (Fig. 13.2) the countries with most mammal 
species. Figs 13.3-13.8 represent the same countries shown 
in the higher plant graphs (Chapter 8). 

Content and format 

The table attempts to give realistic estimates of: 

• the total number of species of mammals, birds, reptiles 
and amphibians present in each country of the world 

• the number of species in each group that is endemic to 
each country. 

'Endemic' in this context means that the species distribution 
is entirely within the political boundaries of a given 
country; they are single-country endemics, as opposed to 
site or area endemics. 

It is important to note that for the purposes of this table, 
islands are included with their parent country (unless 
separately listed). Thus, the Galapagos are included with 
Ecuador, Hawaii with USA, the Canary Islands with Spain, 
and so on. Some apparent anomalies in the estimates are a 
result of this political aggregation; for example, the UK has 
13 endemic birds listed, but 12 of these are from overseas 
territories (Henderson, Inaccessible, St Helena, S Georgia 



and S Sandwich Is, Tristan da Cunha). This affects the bird 
data in particular for a small number of countries. 

Criteria for inclusion 

Certain conventions have been followed wherever possible. 

• Marine cetaceans, sea turtles and sea snakes are 
excluded. However, in a very few cases, especially 
where data have been taken from non-primary sources, 
we have been unable to establish whether cetaceans, for 
example, have been included or not. 

• Data for birds include regular breeding species and 
exclude non-breeding migrants, occasional visitors and 
vagrants. It was felt that this would give a more 
consistent basis for comparison, and would avoid, for 
example, the problems involved in enumerating vagrants. 
Data available for some countries have not allowed us to 
make these exclusions and the figures will be 
correspondingly inflated - for example, an estimate of 
the birds of a Sahara-Sahel country will be low if only 
regular breeding species are counted, but more than 
twice as large if winter migrants and vagrants are 
included. 

• Species known to be recently extirpated from or recently 
introduced to a country have been excluded. 

Data quality 

The estimates will become increasingly accurate as more 
and better data become available. Errors arise principally 
because of inadequate species inventory within countries 
and continual flux in the taxonomic status given to different 
population groups. 

Species inventory based on field survey work is to varying 
degrees incomplete. Knowledge of the fauna of many 
developing countries is based largely on old and 
taxonomically outdated literature, often from colonial times. 
Taxonomic work results in continuing changes in 
nomenclature and the delimitation of species boundaries; 
populations recognised by one authority as belonging to one 
species will often be assigned to one or more other species 
by another taxonomist. 

A further complication arises from the fact that animal 
distribution is dynamic not static; the geographical limits of 
species change over time, either as a slow advance or 
retreat of populations at the edge of a species range or as a 
more rapid population collapse or colonisation event (the 
latter perhaps most evident with bird populations). 

We have made no systematic attempt to survey the primary 
literature for taxonomic changes that post-date the published 
works consulted. In general, the number of species reported 
in older literature to occur in any given country will have 
been both reduced by synonymy and enlarged by the 
description of new species. 

These factors mean that a substantial margin of error is 
associated with all these data. It has not been possible to 
make a rigorous assessment of the extent to which estimates 
from several sources for a given parameter differ, but 
informal comparisons suggest a margin of plus or minus 



137 



1. Biological Diversity 



10% is quite common and greater variation is not 
uncommon. 

In the 'endemic species' columns we have attempted to 
minimise problems arising from taxonomic differences by 
deriving estimates for each group for almost all countries 
from a single consistent source. These sources are marked 
with an asterisk in the list below. In a few cases, later 
estimates based on new fieldwork have been incorporated. 

The 'total species' columns include data from a variety of 
sources. These include published country or regional faunal 
monographs and the WCMC species database (itself based 
upon the former category of sources, but not complete for 
all vertebrate classes for all countries of the world). The 
extent of variety among these data sources, in terms of data 
quality, publication date and place of origin, will have led 
to a corresponding variety in data quality among the figures 
provided. 

References 

• Corbet, G.B. and Hill, J.E. 1991. A World Ust of Mammalian 
Species, 3rd edn. Natural History Museum Publications and Oxford 
University Press. 



Duellman, W.E. and Trueb, L. 1985. Biology of Amphibians. 

McGraw-Hill, London, New York. 
Frosl, D.R. 1983. Amphibian Species of the World. A taxonomic and 

geographical reference. Allen Press Inc. and the Association of 

Systematics Collections, Lawrence, USA. 
Halliday, T., Adier, K. and O'Toole, C. 1986 (Eds). The 

Encyclopaedia of Reptiles and Insects. Unwin, London, UK. 
Macdonald, D. 1984 (Ed.). The Encyclopaedia of Mammals. Unwin, 

London, UK. 
Parker, S.P. 1982. Synopsis and Classification of Living Organisms. 

McGraw-Hill, London, New York. 

• Peters, J. A., Donoso-Barros, R. and Orejas-Miranda, B. 1986. 

Catalogue of the Neotropical Squamata. (Part 1 Snakes, Part n 
Lizards and Amphisbaenians). Smithsonian Institution. 
Porter, K.R. 1972. Herpetology. Saunders Company, Philadelphia, 
London and Toronto. 

• Schwartz, A. and Henderson, R.W. 1991. Amphibians and Reptiles 

of the West Indies: descriptions, distributions, and natural history. 
University of Florida Press. 

* Sibley, C.G. and Monroe, B.L. 1990. Distribution and Taxonomy of 

Birds of the World. Yale University Press, New Haven and 
London. 

* Welch, K.R.G. 1982. Herpetology of Africa: a checklist and 

bibliography of the orders Amphisbaenia, Sauria and Serpentes. 
Robert E. Krieger Publishing. Malabar, Florida. 



138 



Higher Vertebrates 



iable 13.1 Species richness and endemism: higher vertebrates 





MAMMALS 


BIRDS 


REPTILES 


AMPHIBIANS 




Specie. 


Endemic 


Species 


Endemic 


Species 


Endemic 


Species 


Endemic 




kiKHni 


speciem 


known 


epacies 


known 


species 


known 


species 


ASIA 


















Afghanistan 


123 





456 





103 


- 


6 


1 


Bahrain 


— 





— 





25 





— 





Bangladesh 


10S 





354 





119 


— 


19 





Bhutan 


109 





448 





19 


— 


24 





Bf rtish Indian Ocean Terrlorv 


- 










— 


- 







Brunei 


155 





359 





44 


_ 


76 





Cambodia 


117 





305 





82 


- 


28 





China 


394 


62 


1100 


63 


282 


— 


190 


131 


Cyptus 


21 





80 


2 


23 


1 


4 





Hona Kona 


38 





107 





61 





23 


2 


India 


317 


38 


969 


69 


389 


156 


206 


110 


Indonesia 


515 


165 


1519 


258 


511 


150 


270 


100 


Iran, Islamic Rep 


140 


4 


- 


1 


164 


3 


11 


5 


Iraq 


81 


1 


145 


1 


81 


— 


6 





Israel 


— 


2 


169 





— 


— 


— 





Japan 


90 


29 


>250 


20 


63 


28 


52 


35 


Jordan 


— 





132 





- 


- 


- 





Korea. Dem People's Rep 


— 





— 





19 


1 


13 





Korea, Rep 


49 





— 





18 


— 


13 


1 


Kuviait 


- 





27 





29 





2 





Laos 


173 





461 


1 


66 


_ 


37 


1 


Lebanon 


52 





124 





- 


- 


_ 





Malaysia 


264 


14 


501 


4 


268 


- 


158 


39 


Maldives 


— 





24 





— 


— 


— 





Mongolia 


— 


6 


_ 





— 


_ 


_ 





Myanrrtar 


300 


8 


?867 


4 


203 


29 


75 


9 


Nepal 


167 


1 


629 


1 


80 


- 


36 


7 


Oman 


46 


3 


- 





64 


11 


— 





Pakistan 


151 


3 


476 





143 


22 


17 


2 


Philippines 


166 


90 


395 


172 


193 


131 


63 


44 


Qatar 


_ 










17 





_ 





Saudi Arabia 


_ 


1 


59 





84 


5 


_ 





Singapore 


57 


1 


118 





— 




— 





Sri Lanka 


86 


12 


221 


20 


144 


75 


39 


19 


Svria 


— 





165 





— 


— 


— 





Taiwan 


62 


13 


160 


15 


67 


20 


26 


6 


Thailand 


251 


5 


616 


2 


298 


39 


107 


13 


Turkey 


116 





284 





102 


5 


18 


2 


United Arab Emirates 


— 





— 





37 


1 


_ 





Viet Nam 


273 


5 


638 


12 


180 


— 


80 


26 


Yemen 


- 


1 


- 


8 


77 


25 


_ 


1 



USSR* 



EUROPE 

Albania 

Andorra 

Austria 

Belgium 

Bulgaria 



276 



68 

83 
58 
81 



55 



215 
104 
227 
180 
242 



14 

8 

33 



13 

20 
17 
17 



Czechoslovakia 
Denmark 
Faeroe Islands 
Finland 

France 

Germany 
Greece 
Hungary 
Iceland 

IrelarKi 

Italy 

Liechtenstein 
Luxemtjourg 
Malta 

Mormco 

Netherlands 
Norway 
Poland 
Portugal 

Romania 

San Marino 

Spain 

Sweden 

Switzerland 

United KirKldom 

Vatican City 

Yugoslavia 



81 
43 

60 
93 
76 
95 
72 
11 
25 
90 
64 
55 
22 

55 
54 
85 
63 
84 

82 
60 
75 
50 



227 
185 

75 
230 
267 
237 
244 
203 

80 
141 
254 
134 
130 

28 

187 
235 
224 
214 
249 

275 
249 
201 
219 







9 













2 


6 


13 





12 

5 



5 

32 

12 

51 

15 



1 

40 

7 

7 

8 

6 

7 

5 

9 

29 

25 

53 
6 

14 
6 









4 




1 




1 






1 



13 




2 



19 
14 



5 
32 
20 
15 
17 



3_ 

34 
10 
14 

1 

3 
16 

5 
18 
17 
19 

25 

13 
18 

7 







3 

1 



10 










2 








139 



1. Biological Diversity 



Table 13.1 Species richness and endemism: higher vertebrates (continued) 



NORTH AND CENTHAL AMERICA 

Anguila 

Antigua and Barbuda 

Aruba 

Bahamas 

Barbados 



MAMMALS 
Species Endemic 

known species 



12 
6 



BIRDS 
Species Endemic 

loiown species 



REPTILES 
Species Endemic 

known species 



AMPHIBIANS 
Species Endemic 

known species 



88 
24 



9 
10 
24 



1 

4 

2 

16 

3 












34 



Belize 
Bermuda 
Canada 

Cayman Islands 
Costa Rica 



125 

136 

8 

205 



528 

426 

45 
848 



107 

41 

214 




6 

17 



40 
162 



Cuba 
Dominica 

Dominican Republic 
El Salvador 
Greenland fPenmark) 



31 
12 
20 

135 



15 
1 


1 




159 
59 

125 
7450 



22 
2 






100 
13 



79 

2 

22 

4 





41 

2 



23 



3« 



15 



0_ 



Z 

25 

17 

?_ 

18 



169 



0_ 

2 

22 

14 

1 

g_ 



2 



122 

1_ 

1 



Greruda 

Guadeloupe 

Guatemala 

Haiti 

Honduras 



14 
10 

184 
20 

173 



50 
480 



12 
231 
152 



1 

2 

10 

29 

11 



3 
88 
56 



Jamaica 
Martinique 
Mexico 
Montserrat 
Netherlands Antiles 



22 

9 

439 



3 



136 







159 
53 

961 
43 



25 

1 

88 

1 




717 



25 

3 

368 

2 

4 



284 



Nicaragua 

Panama 

Puerto Rico 

St KItts and Nevis 

St Lucia 



?218 
13 

7 
8 



2 
11 






7922 
94 
40 
51 





6 

11 



4 



161 

7226 

46 

9 

15 



6 

18 

20 



5 



59 

164 

22 

3 

4 



St Vincent and the Grenadines 

Trinidad and Tobago 

Turks and Caicos Islands 

United States 

Virgin Islands (British) 



9 
100 



346 




1 

93 




108 
258 
184 
650 



2 
1 

69 




16 



Virgin Isbnds (US) 

SOimi AMERICA 

Argentina 

Bolivia 

Brazil 

Chile 

Colombia 



258 
280 
394 
91 
359 



47 

7 
68 
11 
22 



1257 

1573 

432 

1721 



21 

IS 

191 

15 

73 



250 

468 

78 

383 



63 

11 
172 

33 
104 



123 
110 
502 
39 
407 



37 

14 

294 

25 

141 

136 

2 

10 

4 

86 

7 

2 

76 





169 



2 

0_ 






0_ 


3 



1_ 

100 

2 


0_ 








Ecuador 
French Guiaru 
Guyar^ 
Paraguay 
Peru 



271 
152 
193 
156 
344 



21 
1 

3 

46 



1435 



7650 
1705 



37 

1 





106 



120 
298 



100 

1 

2 

4 

96 



343 



85 
241 



Surlname 
Uruguay 
Venezuela 

OCEANIA 

American Samoa 

Austraia 

Cook IslarKis 

Fiji 

French Polynesia 



187 

81 

288 



3 
282 



2 



11 





210 



1 




38 

571 

28 

87 
67 







45 




351 

7 
25 
25 



11 
700 



25 





1 

55 



616 

9 




180 


2 





Guam 

Kirbab 

Marshall Islands 

Micronesia, Federated States of 

Nauru 



23 
15 
18 

47 
9 



3 
1 


18 
1 



10 

7 



New Caledonia 

New Zealand 

Niue 

North Marianas Islands 

Palau 



116 

285 

16 

31 
48 



20 

74 



3 

10 



32 
40 

4 



23 

40 





Papua New Guinea 

PItcaIrn Islarxls 

Solomon Islands 

Tokelau 

Tonga 



242 



47 



1 



49 


18 





578 
19 

163 
65 
39 



54 


7Z 

2 



57 

7 
6 



183 



IS 



0_ 



Tuvalu 

Vanuatu 

Waltis and Futuna Islands 

Western Samoa 



12 



9 
84 
14 





10 



8 



22 
8 



140 



Higher Vertebrates 

Table 13.1 Species richness and endemism: higher vertebrates (continued) 



ANTARCTICA 

Antarctica 

Falkland Islands ^Malvinas) 

French Southern Territories 

AFRICA 

Algeria 

Angola 

Benin 

Botswana 

Burkina Paso 



MAMMALS 
Species Endemic 
known species 



BIRDS 
Species Endemic 

known species 



REPTILES AMPHIBIANS 

Species Endemic Species Endemic 
known species known species 



92 
276 
188 

154 
147 



192 
872 

630 
569 
497 



1 
12 






3 
IS 
1 
2 
3 




23 

1 




Burundi 
Cameroon 
Cape Verde 
Central African Rep 
Chad 



107 
297 



209 
134 




10 

2 




633 

848 

36 

668 

496 




11 
4 





19 
10 



2 
65 






Comoros 
Congo 
Cote d'lvoire 
Djitjouti 
Egypt 



12 
200 
230 



99 
500 
683 
311 
132 



Equatorial Guinea 

Ethiopia 

Gabon 

Gambia 

Gharm 



184 
255 
190 
108 
222 



1 
26 
3 





392 
836 
617 
489 
721 



3 
26 


1 



2 

30 
4 


4 



Guinea 

Guinea-Bissau 
Kenya 
Lesotho 
Liberia 



190 
108 
309 
33 
193 



1 



10 



1 



529 
376 
1067 
288 
590 



187 
62 



3 
2 

15 
2 
2 



88 
38 



4 
1 
10 
1 
4 



Libya 

Madagascar 

Malawi 

Mali 

Mauritania 



76 
105 
195 
137 

61 



4 

67 





1 



80 
250 
630 
647 

49 




97 






252 

124 

16 



1 

231 

6 

2 

1 



144 
69 





142 

1 

1 





Mauritius 

Mayotte 

Morocco 

Mozambique, People's Rep 

Namibia 



105 
179 
154 



102 

209 
666 
640 



10 



1 



2 
1 
8 
5 
25 



62 
32 



Niger 
Nigeria 
Reunion 
Rwanda 
Saint Helena 



131 

274 

2 

151 



473 

831 

33 

669 



Sao Tome and Principe 

Senegal 

Seychelles 

Sierra Leone 

Somalia 



8 
155 



147 
171 



124 
625 
126 
614 
639 



24 

9 


11 



16 

15 

193 



6 
1 

13 
1 

66 



12 

27 



9 
1 
11 
2 
3 



South Africa 
Sudan 
Swaziland 
Tanzania 
Togo 



247 
267 
47 
306 
196 



27 
7 


12 
1 



774 
938 
381 
1016 
630 



7 


13 




106 
245 



76 
6 


48 
1 



39 
121 



36 
2 


40 
3 



Tunisia 

Uganda 

Western Sahara 

Zaire 

Zambia 



78 
315 

15 
415 
229 



1 
4 
1 
25 
3 



173 

989 

60 

1086 

732 




3 

23 




33 
2 



44 
83 






53 
1 



Zimbabwe 



196 



635 



153 



120 



Notes: See text for geoerBl conventioDS adopted and sources for eDdemics data. Depeodent islands are iiKluded with the parent territory. ? may include 
marine species where data refers to mamnuLs or reptiles, or may include non— breeding species where data refers to birds. - no data. USSR*: covers the 
former Union of Soviet Socialist Republics. 



141 



1. Biological Diversity 

Figure 13.1 Higher vertebrates: the 25 most endemic-rich countries 




S8|oeds p JsqiunN 



142 



Figure 13.2 Mammal richness and endemism: major countries 



Higher Vertebrates 







^ 



\ 






N>> 



2. 



V 
\ 



.\ 






% 



\ 



S8|03ds 10 jaqoinN 



143 



1. Biological Diversity 



Figure 13.3 Higher vertebrate endemism: Asia 




' " Country ^ V** 



Figure 13.4 Higher vertebrate endemism: Europe 

25 FTTl 




Mammals ^ Birds [3 Amphibians O Reptiles 



J I I I I I I I L 



y^^^^^ry^^y^y^y^^^ 



tf' Country 



144 



Higher Vertebrates 



Figure 13.5 Higher vertebrate endemism: North and Central America 

400 



300 



•5 

V) 

O 200 

a> 

13 

E 

3 
Z 



100 



Mammals ■ Birds ||| Amphibians 




Figure 13.6 Higher vertebrate endemism: South America and Antarctica 




Mammals 



Birds 



Amphibians : ; Reptiles 



'— ~^ <=<=> '—-^ -•■■- • I I I I I I I I I I I L_ 



l/<^/ 



'^5^^/^> 






6,.- Country 



145 



1. Biological Diversity 



Figure 13.7 Higher vertebrate endemism: Oceania including Australia 




I Mammals H Birds j ] Amphibians 



■^1 = K- ^t-1 .^h. I. ■^^ . ..pa ^^ _1_ 



_l I I I I I I L. 



pgure 13.8 Higher vertebrate endemism: Africa and Madagascar 



300 — 



(0 
V 

o 

0) 

Q.200 

CO 



0) 

n 
E 

z 



100 



Mammals ■ Birds Amphibians 







Country 



146 



14. ISLAND SPECIES 



Island Species 



Islands frequently have distinctive and often unique 
assemblages of species. In general they have lower species 
diversity than equivalent continental areas, but tend to have 
elevated numbers of endemic species. The number of 
species in a particular taxonomic group on a given island 
and the proportion of these which are endemic appears to 
depend on a wide variety of factors, both historical and 
ecological. Among these are the degree of isolation, age, 
size, topography and climate of the island and the biological 
characteristics of the taxonomic groups concerned, in 
particular their vagility (the ease with which they disperse). 
Historical accident also appears to play a large part in 
patterns of species occurrence on islands. 

Island endemics tend to be of two types: relict species 
which appear to have been more widespread in the past and 
species which have evolved in isolation on the island 
concerned. Relict species are generally confined to islands 
which were previously part of larger land masses but which 
have been isolated through processes of continental drift or 
changes in sea level. Madagascar and New Caledonia are 
examples of this, although, because of its size and long 
period of isolation, Madagascar is perhaps more accurately 
regarded as an island continent than an oceanic island. In 
contrast, many island species are believed to represent the 
results of adapative radiation in situ following accidental 
colonisation by individuals. The biotic composition of 
isolated, oceanic islands which have never been part of 
larger land-masses (and are generally volcanic in origin) is 
largely a result of this process. The taxa represented on 
these islands are those which have (or whose ancestors had) 
the capacity for long-range dispersal. Thus, at a very 
general level, oceanic islands may have good representation 
of, and high levels of endemism in, plants, birds and some 
invertebrate groups, such as land snails and some insects, 
while having low diversity of groups such as non-volant 
mammals and amphibians. 

Once islands have been colonised, other factors play an 
important role in determining subsequent patterns of 
evolution and speciation. Species which are highly vagile 
tend not to speciate and diversify - this applies to, for 
example, most groups of sea-birds and to strandline 
vegetation. Species in these groups tend to have very wide 
distributions, so that, for example, most tropical and sub- 
tropical Pacific islands have essentially the same, small 
number of species forming their shoreline vegetation. In 
contrast, groups such as the rails (Rallidae), pigeons 
(Columbiformes) euid tortoises (Testudinidae) which are 
essentially terrestrial but which have the capacity for long- 
range dispersal will tend to form separate species on islands 
or island groups which they successfully colonise. The 
degree of speciation which occurs on islands subsequent to 
colonization appears to be highly dependent on habitat 
diversity, which is itself dependant on the size, topography 
and climate of the island. Thus, low-lying oceanic islands, 
such as coral atolls, tend to have low diversity and low 
rates of endemism for most groups, while montane 
(generally volcanic) islands tend to have much higher 
species diversity and rates of endemism. As with continental 
ecosystems, other factors being equal, species diversity 
increases with decreasing latitude. 



Island - especially oceanic island - biotas tend to share 
similar features, such as gigantism in plants and reptiles, 
dwarfism in large mammals (although most examples of this 
are extinct) and flightlessness in birds. These may arise 
from the disharmonic colonisation of islands and the 
subsequent evolution of plants and animals in isolation 
(Bramwell, 1979). Of particular importance to conservation 
are those factors which appear to lead to an increasing 
extinction-proneness amongst island species (discussed more 
fully in Chapter 16). These are largely related to the 
evolution of island species generally in the absence of large 
terrestrial 'predators' - for plants these being grazing 
mammals, for animals these being carnivores. This helps 
explain the often catastrophic effect of the introduction of 
animals such as rats, rabbits, goats, pigs and cats on native 
island biotas. 

This report discusses two important island groups - plants 
and land snails - in some detail. Available data on these two 
groups has been collated in Tables 14.1 and 14.3. 

It is impractical, in a global approach, to treat each island 
individually, but appropriate to consider them in groups. In 
this report, we have mainly followed the classification of 
islands into 147 units made by the International Working 
Group on Taxonomic Databases for Plant Sciences (TDWG) 
(HoUis and Brummitt, in press). 

For plants, coverage of true oceanic islands is reasonably 
complete. Most important continental shelf islands other 
than those of the Sunda Shelf and New Guinea have also 
been included. 

Where complete datasets are available for particular islands, 
regression analysis shows a moderately close relationship 
between numbers of endemic plants and snails (see 
Fig. 14. 1) but no clear relationship between snails and birds 
or between plants and birds (bird data not shown). 



Figure 14.1 Islands: relationship between 
plant and snail endemism 




001 003 



O.DI 0.03 1 I 

EncMnic pianis (;iOaa < 



147 



1. Biological Diversity 



PLANTS ON OCEANIC ISLANDS 

The number of endemic species and the proportion of the 
flora that is endemic varies considerably from island to 
island and appears to depend on a number of the factors 
outlined above. On some island groups, like the Hawaiian 
Islands, the flora can be described as consisting mainly of 
'endemics and aliens'; here the endemic species form 89% 
of the native flora (Wagner et al., 1990). However, on 
other islands, such as those of the Caribbean, the endemics 
form only a small element in a diverse flora of 
predominantly widespread continental species. 

The extent to which island endemic floras consist of relict 
species tends to be a matter of speculation. Greuter (1979) 
suggests that about half the flora of Crete, for example, is 
of the relict element. Palaeontologists have found fossils of 
some Canarian endemics in southern Europe and south 
Russia; these species include the famous Dragon Tree 
{Dracaena draco), and the dominant species of the Canarian 
laurel forests, at present a vegetation type now only found 
in parts of the Canaries, Madeira and to a lesser extent the 
Azores. The implication is that this remarkable type of 
forest, now endangered in much of its range, once covered 
much of the Mediterranean Basin in the Miocene Period, up 
to 20 million years ago (Bramwell and Bramwell, 1974). 

The relict species include an extraordinary array of endemic 
monotypic genera and even families. Monotypic families 
(i.e. families with only one species each) on islands include 
Lactoridaceae (Lactoris fernandeziana) on Juan Fernandez, 
Dirachmaceae (Dirachma socorrana) on Socotra, and 
Degeneriaceae (De generic vitiensis) on Fiji. All are 
threatened species and, in consequence, threatened families. 

In contrast, many of the endemics have evolved in isolation 
on islands. In the Canary Islands, for example, adaptive 
radiation of colonists has led to over 30 endemic species in 
each of the genera £c/ii«m (Vipers Bugloss), Limonium (Sea 
Lavender) and Aeonium. The most outstanding example of 
diversification and adaptive radiation in the plant world is 
the Hawaiian Islands, where some genera, such as Cyanea 
and Cynandra, have over 50 endemic species. Wagner et 
al. (1990) propose that 469 Hawaiian species, in 20 large 
genera, evolved from only 26-32 different colonists, clearly 
showing the scope of the evolutionary capacity of isolated 
islands. The species that result from adaptive radiation tend 
to be difficult to classify, often with much hybridisation 
between the various species. As with the Galapagos finches, 
which helped Darwin develop the theory of evolution and 
natural selection, these series of evolving and evolved island 
endemics are of great importance to science. 

One of the most extraordinary features of island plants is 
the phenomenon of gigantism. A group of plants that is 
otherwise herbaceous and often weedy is represented on 
some islands as tall shrubs or trees. For example, the 
endemic species of Vipers Bugloss (Echium) and the Sea 
Lavenders (Limonium) in the Canary Islands include woody 
shrubs with stems several metres high. Some of the most 
remarkable examples are the tree daisies (Compositae) on 
St Helena in the Atlantic Ocean and on the Juan Fernandez 
islands off Chile. 



In assessing the importance of islands for conservation of 
the world's plants, the best single measure is simply the 
number of species endemic to the island or island group. In 
virtually all cases, for plants, estimates of some kind are 
available, varying from counts made from detailed floristic 
analyses to estimates by knowledgeable botanists. This is 
one of the few datasets on biodiversity, at least for plants, 
that is complete to a reasonable standard of accuracy 
worldwide. 

Table 14.1 lists the islands and island groups of the world 
of less than 120,000km^ in size in declining order of 
endemic plant species (covering flowering plants, 
gymnosperms and ferns). This gives a rough guide to the 
importance of each for botanical conservation. Of the 
greatest importance are those three islands with over 1 ,(X)0 
endemic plant species each - Cuba with 3,233, New 
Caledonia with 2,480 and Hispaniola (the Dominican 
Republic and Haiti) with 1,800. The Hawaiian Islands were 
previously included but the first comprehensive and 
complete account of the plants has reduced the number of 
endemics to below the thousand. 

The number of endemics is an effective measure of the 
importance of individual islands or island groups for plant 
conservation worldwide. However, this very simple 
approach is less appropriate where a significant part of the 
endemic flora is shared between two or more of the island 
groups used. For isolated islands or island groups like St 
Helena, Juan Fernandez and the Hawaiian Islands, the 
number of endemics shared with other island groups is very 
small. But in the Lesser Antilles (the Leeward and 
Windward Islands) in the Caribbean the shared endemics 
form a considerable proportion of the endemic flora as a 
whole. This is partly a consequence of the geographical 
classification used; because many of the islands are 
individual nation states, the classification tends to treat each 
individual island as a single unit, rather than to cluster them 
together, as with, for example, the Galapagos Islands or 
Canary Islands. It is partly a consequence of the geography 
and biology of the islands; the islands tend to be close 
together, and have similar climates and land forms. Also, 
because of their proximity to the Greater Antilles (Puerto 
Rico, Cuba, Hispaniola and Jamaica), and to Central and 
South America, there are numerous shared species both 
within the Lesser Antillean chain and between various 
islands of the chain and neighbouring areas. 

The completion of the Flora of the Lesser Antilles (Howard, 
1989) has permitted an analysis of the endemics of this 
region. The results are given in Table 14.2, below, and in 
the accompanying map (Figure 14.2). The table shows the 
number of plant endemics with different patterns of 
distribution recorded in the Flora. As can be seen, only 107 
of the 327 species endemic to the Lesser Antilles as a whole 
are endemic to single TDWG units (and so are included in 
Table 14.2). The highest number of endemics for any island 
is 25 on Guadeloupe, which is also home to a further HI 
Lesser Antillean endemics. 

The map shows the distributions of 190 of the 327 
endemics. Most of the combinations of islands that had only 
one or two endemics were omitted from the map, as were 
all combinations of over five islands, as being too complex 



14S 



J 



Island Species 



Table 14.1 Oceanic islands in declining order of endemic plant species 

ISLAND 



NO. OF ENDEMIC DATE OF ISLAND 

PLANTS INFORMATION 



NO. OF ENDEMIC DATE OF 

PLANTS INFORMATION 



Cuba 

New Caledonia 

Hispaniola 

Jamaica 

Taiwan 

Hawaii 

Fiji 

Canary Is 

Caroline Is 

Socotra 

Mauritius 

Puerto Rico 

Trinidad-Tobago 

Ogasawara-Shoto 

Vanuatu 

Galapagos Is 

Andaman Is 

Tubuai Is 

Comoros 

Juan Fernandez 

Reunion 

Madeira 

Bahamas 

Sao Tome 

Marquesas Is 

Cape Verde 

Cyprus 

Lord Howe I 

Northern Marianas 

Nicobar Is 

Balearic Is 

Seychelles 

Western Samoa 

Azores 

Bioko 

St Helena 

Corsica 

Rodrlgues 

Aldabra 

Sicily 

Tristan da Cunha 

Chatham Is 

Norfolk I 

Principe 

Solomon Is 



3233 

2480 

1800 ', ■ 
894 
892 * 
850 ' 
700 •• 
593 ' 
293 " 
267 
246 "■ 
234 
215 ' 
152 
150 
148 
144 
140 '■* 
136 
123 
120«, 

lis 

112 
108 
105 

92 

90 

84 

81 « 

72 = 

70 

63" 

57' 

49 

49 

46 

45 

45 

43* 

41 

40 

36 

36 

35 

30 



1991 

1991 

1984 

1988 

1982-91 

1990 

1984 

1990 

1979, 82 

1991 

1991 

1982 

1981 

1978 

1975 

1980s 

1989 

1984 

1917 

1991 

1991 

1980s 

1982 

1944 

1931-35 

1974-79 

1977-91 

1991 

1979, 82 

1989 

1991 

1991 

7 

1980s 
1978 
1991 
1991 
1991 
1980 
1991 
1965, 81 
1991 
1991 
1944 
1991 



American Samoa 


27 


Virgin Is (US) 


27 ' 


Sardinia 


26 


Guadeloupe 


25 


Tonga 


25 


Martinique 


24 


Tuamotu Is 


20" 


Pitcairn Is 


19 = 


St Vincent 


19 


Netherlands Antilles 


7-19 


Cayman Is 


18 ' 


Annobon 


17 


Christmas 1 


17 


Coco, Isia del 


15' 


Bermuda 


14 


Guam 


14 


Dominica 


12 


Falkland Is 


12 


Gambler 


11 ' 


St Lucia 


11 


Ascension 1 


10 


Kazan Retto 


9 


Turks and Caicos Is 


9 


Auckland Is 


6' 


Easter 1 


6 


Antigua-Barbuda 


5''= 


Maldives 


5 


Malta 


5 


Wallis and Futuna 


5' 


Antipodean Is 


4 


Grenada 


4 


Selvagens 


4 


Barbados 


3 


Campbell Is 


3 ' 


Cook Is 


3 


Macquarie 1 


3' 


Montserrat 


2 


St Kitts-Nevis 


2 


St Martin-St Barthelemy 


2 


Marion and Prince Edward Is 


1-2 


Anguilla 




Antigua-Barbuda 




Kerguelen Is 


1 1 


Nauru 




Netherlands Leeward Is 





1982 
1974 

1991 

1974-89 
1991 . 

1974-89 

1931-5 

1983 

1974-89 
? 
1984 
1973 
1980s 
1966 
1991 
1991 

1974-89 
1991 
1974 

1974-89 
1991 
1991 
1982 
1985 
1990 
1938 
1961 
1991 
1977 
1981 

1974-89 
1980s 

1974-89 
1961 
1991 
1960 

1974-89 

1974-89 

1974-89 
1989 

1974-89 

1974-89 

1975 

? 

1974-89 



Sources; Compiled from numerous sources. See Davis, S. et at. 1986. Plants in Danger: what do we know? for many pre-1986 references. 
Notes: ' Omits ferns; ^ Omits ferns and gymnosperms; ' Omits monocotyledons; * Includes subspecies and varieties; * Estimated from a given 
percentage of endemism; ^ A slight underestimate as omits endemic species treated as infraspecific level in the WCMC plants database; ' Certainly 
an underestimate; * Covers Haiti and Dominican Republic; ^ An underestimate as omits full treatment for families not yet covered in the Flore des 
Mascareignes; '^ Probably an underestimate as only for Great Nicobar Island; ^ Omits tile coralline islands, which are listed under Aldabra. 



to display graphically. However, the map does show the 
broad pattern of plant endemism in the region, and provides 
a convincing argument for a regional approach. 

LAND SNAILS 

'If we take the whole globe, more species of land shells are 
found on the islands than on the continents. " 



Alfred Russel Wallace 1892. Island Life, 2nd edn. 
Macmillan, London. 563pp. 

Global distribution of snail diversity 

Recent estimates of world land snail species richness 
suggest a total of between 30,000 and 35,000 species 
(Solem, 1984). 



149 



1. Biological Diversity 



Table 14.2 Plant endemism in the Lesser Antilles 



NO OF SPECIES 

107 occur in 
55 occur in 
47 occur in 
40 occur in 
18 occur in 
60 occur in 
TOTAL ENDEMICS 327 



NO. OF TDWG UNITS 

1 unit 

2 units 

3 units 

4 units 

5 units 
> 5 units 



NO. OF SPECIES MAPPED 

107 

48 

20 

15 

8 


190 



Source; Howard, R.A. 1974-89. Flora of the Lesser Antilles . 6 vols. Endemics counted by Hugh Synge, 1991. 

Notes: Geographical units used: (from north to south) Anguilla, St Martin-St Barthelemy, Netherlands Leewards (Saba and St Eustatius), St Kitts- 
Nevis, Barbuda-Antigua, Montseirat, Guadeloupe (including Marie Galante, Les Saintes and Le Desirade), Dominica, Martinique, St Lucia, St 
Vincent, Barbados, Grenada. The TDWG classification divides the Grenadine islands between St Vincent and Grenada, and so records for 'The 
Grenadines' in the Flora have been disregarded. 



Figure 14.2 Plant endemism in the 
Lesser Antilles 



ANGUajJk 




Species richness and endemism in land snails tend to be 
closely correlated; areas with high diversity generally have 
high endemism. This close relationship is shown graphically 
in Fig. 14.3 (the named islands below the line have fewer 
endemics than expected). On several islands with high snail 
diversity all the native species are endemic and the only 
non-endemics are those introduced by man. Land snail 
richness and endemism are distributed very unevenly around 
the world, and tend to be highest on islands and in 
mountains. 



1969), and on the Greek islands in the Aegean Sea, 
suggests that there is a direct correlation between island size 
and snail species richness. Other work in the Pacific 
suggests that this relationship is not always a simple one, 
and Solem (1973) (also Peake, 1981) concluded that highest 
diversities are found on islands about 15-40km' in area and 
with an elevation of over 400m. Altitude is thus an 
important factor, and atolls, for example, do not have high 
snail richness or endemism. 

There is some indication that isolation is also an important 
factor. The island with the greatest number of species is 
Rapa, one of the smallest and most remote islands in 
French Polynesia. The location with the highest known snail 
species richness (i.e. greatest number of species per unit 
area) is Manukau Peninsula in North Island, New Zealand, 
where 82 species have been found in a small area. 

There is some evidence that although islands often have 
remarkably high diversity and abundance (in the absence of 
human impact), their snail faunas are often not 'saturated' 
and additional snail species could survive. Evidence for this 
is seen from work in Madeira and on the Greek Islands, 
where humans have introduced species but the numbers of 
endemic species have stayed the same (Solem, 1984). 

Correlation of land snail diversity with other species 

Patterns of land sneiil diversity and endemism are generally 
considered not to correlate strongly with those for other 
groups of animals, particularly higher vertebrates. Available 
data for islands show a marked positive correlation between 
numbers of endemic plant species and endemic molluscs 
(Fig. 14.1), but not between molluscs and birds. There is 
a lack of data on mollusc faunas of tropical continental 
areas, and it is thus difficult to make more general 
statements. 



A major problem in discussing mollusc richness and 
endemism is the lack of information for several regions of 
the world, notably Asia, the Neotropics and the Nearctic; 
some continental tropical areas are particularly under- 
recorded and new data could significantly change the 
current picture of land snstil diversity patterns. 

Although islands often have highly diverse habitats, not all 
islands have rich snail faunas. Work in Melanesia (Peake, 



Solem (1984) draws attention to the following islands as 
known or believed to be important for snails: 

• Reasonably well studied large snail faunas on the small 
high islands of Micronesia, Melanesia, Polynesia, 
Indonesia, Philippines, Mascarenes, Antilles, Madeira. 

• Surveys or studies under way suggest important snail 
faunas in Japan, Oahu, Tahiti, New Caledonia, New 



ISO 



Island Species 



Table 14.3 Land snails: species richness and endemism on islands 



TOTAL SPECIES 



ENDEMIC SPECIES 



% ENDEMICS 



ATLANTIC 

Atlantic (Macaronesian) telands 

Azores 

Canary Is 

Cape Verde Is 

Madeira 

Selvagens 
Mid-AUantic Islands 

Annobon (Pagalu) 

Bioko (Fernando Po) 

Principe 

Sao Torn* 

St Helena 
South Atlantic 

Falkland Is 
Northern Eixopean Islcinds 

Faeroe Is 

Iceland 

Svalbard 

MEDITERRANEAN 

Corsica 
Cyclades 
Malta 
Pityuse Is 

Sardinia 

INDIAN OCEAN 

Aldabra 

Adamans and Nicobars 

Anjouan 

Comoros (inc. Mayotte) 

Grand Comore 

lie Europa 

Mascarene Is 

Mayotte 

MauritJLS 

Moheli 

Reunion 

Rodrigues 

Seychelles 

Socotra 

Sri Lanka 

Madagascar 

CARIBBEAN 

Barbuda 

Barbados 

Cuba 

Guadeloupe 

Jamaica 

Martinique 

St Bethelemy 

St Martin 

Saba 

Puerto Rico 

Mona 

PACIFIC 
Eastern 

Japan 
Southwestern 

Fiji 

Viti Levu 

Laltemba 

Karoni 

Mothe 

New Caledonia 

Tutuib 

Upolu 

Solomon Is 

Tikapia 

Vanuatu 

Wallis 

Futuna 
South-Central 

Henderson 

Tahiti 

Rapa 
North and Nofth-Cenlral 

Hawaiian Is 

Oahu 

Kauai 

Maui 

Lanai 

Molokai 

Hawaii 
Pacific islands off Central & South America 

Galapagos 

Juan Fefn&ndezis 
Australia and New Zealand 

New Zealand 

Kermadec Is 

Lord Howe I 
Norfolk I 



98 

181 

37 

237 

1 

9 
6 

ze 

26 
c. 31 



20 

35 



. 100 
88 

C.46 
36 



C.9 

81 

58 

136 

37 

6 

145 

90-95 

109 

18 

40 

25 

C.57 

49 

c. 265 

380 



10 
37 

:. 600 
53 

-450 
37 

C.36 
14 

>85 
12 



492 

60 
58 
22 
20 
13 
300 

44 

200-270 

16 

58 

15 
21 

c. 18 

80 

>105 

C.1000 
395 

70-80 

167 

54 

126 

128 

C.90 
23 



c. 1000 

c. 20 

C.85 

84 



41 


41.8 


141 


77.9 


18 


43.2 


171 


88 


1 


100 


7 


77.7 


C.4 


c.66.6 


15 


57.7 


19 


73 


C.25 


C.80 


























c. 10 


C.10 


>20 


C.23 


C.7 


c. 15 


4 


11 


21 


- 


c.4 


C.44 


75 


93 


0-3 


0-50 


127 


87.6 


32-41 


29-39 


77 


70.6 


16 


40 


15 


60 


24-26 


c.44 


46 


94 


— 


C.95 


361 


95 


'""""""" 





C.5 


c.7 


9 


17 


— 


80-95 


IS 


c. 40 





- 















e.487 



c. 299 
8 



7 

57 



c. 2 

3 
C.72 
>105 

:. 1000 

c. 387 

71 



>66 
23 



C.20 
c. 50 
c. 84 



44 

98 



e. 5 

C. 16 

90 

100? 

c. 99.9 
98 
99 



c. 73 
100 



c. 60 
100 



Source: table provided by Susan M. Wells (lUCN/SSC Mollusc Specialist Group) 
Notes: c. approximated figure. > figure is minimum estimate. 



151 



1. Biological Diversity 



Figure 14.3 Island snails: relationship between species richness and endemism 



3,000 



1,000 



300 



(U 

u 
a 



E 
(U 
•D 

c 

LU 



100 



30 



10 



1 * 




)K BAHBADOS 
^ W' y^ PITYUSE 

-51^ ^ 

HENDERSON GIBRALTAR 

FUTUNA 



_L 



J 



10 



30 100 

Tola I spec i es 



300 



1,000 



3,000 



Zealand, Madagascar, Madeira. 
• Poor information available but almost certainly important 
islands: Hispaniola, Cuba, Jamaica, New Guinea. 

Some of these areas, particularly the small high islands, do 
not have particularly high diversities of vertebrates. 

Ecology of snails and diversity patterns 

Snails that have colonised islands and subsequently 
speciated tend to be those that are good at dispersal and 
thus tolerant of stress: the key factors are the presence of a 
shell to resist desiccation (few slugs are found on islands), 
and ovoviviparity. On most islands which have high snail 
diversity, snails are largely confined to the interiors and 
more mountainous regions and are often forest species 
restricted to primary forest. 

Viable populations of certain snail species appear to be able 
to exist in very small areas over very long periods of time; 
this must contribute to maintenance of high species 
richness. Factors favourable to land snail speciation and the 
persistence of diverse faunas are: (1) a stable and moderate 
water supply providing a moist habitat (without either 
torrential downpours or arid periods), (2) deep litter, (3) a 
topography of gullies along streams sheltered from 
prevailing winds, (4) lack of dismrbance by man, (5) small- 
scale vegetation changes e.g. as a result of climatic 
variation, (6) little predation. Such criteria are found on 
many volcanic islands and in mountains. 



Environmental conditions that are not optimal for snails 
include: (1) certain types of forest such as rain and 
monsoon, which may have little litter, an overabundance of 
rain, acidic soils and seasonal climates; (2) grassland (which 
may however provide local conditions leading to high 
abundance); (3) deserts (except where there are mountain 
refugia). 

Hireats and extinctions 

Known extinctions of island land snails are listed in Chapter 
16. Solem's work in the Pacific (Solem, 1976, 1983) gives 
some idea of the rates of extinction that may be taking 
place. The endodontoid snails (Families Endodontidae, 
Charopidae, Punctidae) are tiny tropical snails, only a few 
millimetres in diameter and are the most diverse group in 
the Pacific where over 600 species have been described. 
Over 100 may have become extinct this century; they are 
mainly ground dwellers in primary forest and are threatened 
by habitat loss and introduced ants (that prey on the eggs). 

Other important island families are entirely or largely 
arboreal, such as the Partulidae. This family is restricted to 
the Pacific and comprises about 120 species, most of which 
are probably threatened. Most is known about the Partula 
of the Society Islands, where they are threatened 
particularly by the introduced carnivorous snail Euglandina 
rosea. Many populations of achatinelline snails in Hawaii 
have been lost because of over-collecting and habitat 
modification; these species are rendered highly vulnerable 



152 



Island Species 



to extinction because of very low lifetime fecundity (6-24) 
(Hadfield, 1986). Tillier (in litt., 10 Sept. 1991) says that 
from his experience (Caribbean, New Caledonia) the island 
land snails most at risk are those in dry lowland forests 
which may be lost to cattle grazing or development more 
rapidly than upland forest. 

In New Zealand at least, and probably elsewhere, the native 
snails are totally dependent on native plant associations for 
survival. In this country the rate of extinction is apparently 
fast outstripping the rate of description of undescribed 
species, many of which are 'spot' endemics, restricted to 
tiny alpine localities or areas of limestone outcrop (Climo 
etal., 1986). 



References 

Bramwell, D. 1979. Inlroduction. In: Bramwell, D. (Ed.), Plants and 

Islands. Academic Press. Pp. 1-10. 
Bramwell, D. and Bramwell, Z. 1974. Wild Flowers of the Canary 

Islands. Stanley Thomes (Publishers), London. 
Climo, P.M., Roscoe, D.J. and Walker, K.J. 1986. Research on land 

snails in New Zealand. WRLG Research Review No. 9. Wildlife 

Research Liaison Group, Wellington, NZ. 2gpp. 
Greater, W. 1979. The origin and evolution of island floras as 

exemplified by the Aegean Archipelago. In: Bramwell, D. (Ed.), 

Plants and Islands. Academic Press. Pp. 87-106. 
Hadfield, M.G. 1986. Extinction in Hawaiian achatinelline snails. 

Wa/aco/og/a 27(1):67-81. 



Hollis, S. and Brummitt, R.K. (in press). World Geographical Scheme 

for Recording Plant Distributions. International Working Group on 

Taxonomic Databases for Plant Sciences (TDWG) and Hunt 

Botanical Library, Pittsburg. 
Howard, R.A. 1974-89. Flora of the Lesser Antilles. 6 vols. Endemics 

counted by Hugh Synge, 1991 . 
Peake, J.F. 1969. Patterns in the distribution of Melanesian land 

MoUusca. Philosophical Transactions of the Royal Society B 

255:285-306. 
Peake, J.F. 1981. The land snails of islands - a dispersalist's view 

point. In: Forey, P.L (Ed.), The Evolving Biosphere. British 

Museum (Natural History), Cambridge University Press. Chapter 

19. 
Solem, A. 1973. Island size and species diversity in Pacific island land 

snails. Malacologia 14:307-400. 
Solem, A. 1976. Endodontoid land snails from Pacific Islands 

(MoUusca: Pulmonata: Sigmurelhra). Part I. Family Endodontidae. 

Field Museum of Natural History, Chicago. 508pp. 
Solem, A. 1983. Endodontoid land snails from Pacific Islands 

(MoUusca: Pulmonata: Sigmurethra). Part II. Families Punctidae 

and Charopidae, zoogeography. Field Museum of Natural History, 

Chicago. 336pp. 
Solem, A. 1984. A world model of land snail diversity and abundance. 

In: Solem, A. and Bniggen, A.C. van (Eds), Worldwide Snails. 

E.J. BrillAV. Backhuys, Leiden. Chapter 1, pp.6-22. 
Wagner, W.L. el al. 1990. Manual of the Flowering Plants of 

Hawai'i. 2 vols. University of Hawaii Press, Bishop Museum 

Press. 

Chapter based on plant account provided by Hugh Synge 
and snail account supplied by Susan M. Wells (and the 
lUCN/SSC Mollusc Specialist Group.) 



153 



1. Biological Diversity 

15. CENTRES OF SPECIES DIVERSITY 



INTRODUCTION 

A principal goal of conservation activity is to ensure the 
long-term survival of as many species as possible. 
Traditionally, most resources available have been allocated 
to single 'flagship' species, either through in situ measures 
or through ex situ captive breeding efforts. Often these are 
large, charismatic species which generate considerable 
public interest. Habitat destruction and modification are the 
most important factors now affecting species survival and 
although conservation initiatives focused on single species 
may protect a particular organism's habitat, and by 
extension a host of other associated species, they do not 
necessarily conserve those habitats which contain the most 
species. 

Biodiversity is not distributed uniformly across the globe: 
some habitats, particularly tropical forests among terrestrial 
systems, possess a greater number or density of species 
than others. Thus a 13.7km^ area of the La Selva Forest 
Reserve in Costa Rica contains almost 1,500 plant species, 
more than the total found in the 243,500km^ of Great 
Britain, while Ecuador harbours more than 1,300 bird 
species, or almost twice as many as the USA and Canada 
combined (Myers, 1988). Given the budgetary constraints 
on conservation and the competing demands of other forms 
of land-use, some system is necessary for identifying the 
areas in which a certain allocation of effort will maximise 
species survival. It is widely accepted that the identification 
and prioritisation of important centres of biodiversity are 
necessary at both the national and the global scale. A 
number of methods by which such areas could be 
determined have been suggested. 

METHODS OF DETERMINING AREAS OF 
CONSERVATION PRIORITY 

Overall species diversity 

The simplest method of suggesting target areas for 
conservation action is to identify countries with the highest 
number of species (greatest species richness). For example, 
Mittermeier (1988) and Mittermeier and Werner (1990) 
recognised that a very small number of countries situated 
mainly in the tropics possess a large fraction of the world's 
species diversity, and introduced the concept of 
'Megadiversity Countries' which, they suggested, merit 
special international attention. McNeely et al. (1990) used 
country species lists of vertebrates, swallowtail butterflies, 
and higher plants to identify 12 such megadiversity 
countries: Mexico, Colombia, Ecuador, Peru, Brazil, Zaire, 
Madagascar, China, India, Malaysia, Indonesia and 
Australia. Together these countries hold up to 70% of the 
world's species diversity in these groups. This approach is 
relatively simple in that it involves species inventory within 
a given geopolitical boundary; it also recognises that 
conservation action is managed at the country level. One 
drawback to this approach, however, is that it fails to take 
into account the uniqueness of the fauna and flora of a 
country or region. There may be considerable overlap in 
species composition between different regions with high 
species numbers, particularly if they are situated close to 



one another geographically. Taking mammal species in two 
of the megadiversity countries listed above as an example, 
271 species of mammal (excluding Cetacea) have been 
recorded from Ecuador and 344 from neighbouring Peru, 
but 208 of these are common to both countries. In addition, 
high diversity regions may contain large numbers of very 
widely distributed species which are currently neither 
threatened nor otherwise of special conservation concern. 

Endemic species diversity 

An alternative approach is to identify areas with the greatest 
numbers of 'endemic' or 'restricted-range' species. An 
endemic species is one restricted to some given area, which 
might be a mountain top, a river, a country or continent. In 
this context, the assessment is often based on single-country 
endemics, or on some small identifiable region within a 
country. At the global level these are areas of high 
conservation priority because if unique species are lost they 
can never be replaced. Although not biologically 
meaningful, the choice of country boundaries for assessing 
endemicity is of great practical significance because 
conservation action is usually administered at the national 
level. 

An important study that attempted to use endemic plant 
species to identify areas of global conservation concern was 
that of Myers (1988). Focusing on tropical forests, Myers 
identified 10 regions or 'Hot Spots' that are characterised 
by high concentrations of endemic species and are 
experiencing unusually rapid rates of habitat modification or 
loss (Table 15.1). These 10 areas cover only 292,000km^, 
or 0.2% of the Earth's land surface, and comprise 3.5% of 
the remaining primary forest. Together, however, they 
harbour 34,400 endemic plant species (27% of all tropical 
forest species and 13 % of all plant species worldwide). 

In a subsequent publication, Myers (1990) identified a 
further eight terrestrial hot spots, four in tropical forest 
areas and four in Mediterranean-type areas (Table 15.1). 
Together these contain 15,555 endemic plant species, or 6 % 
of the world's total, in 454,400km^ or 0.3% of the world's 
land area. This second selection of eight areas are therefore 
not nearly as rich in endemic species as the first 10, 
containing only 45% as many plant species in an area one 
and a half times as large. In total these 18 sites contain 
approximately 49,955 endemic plant species, or 20% of the 
world's plant species, in just 746,400knf, or 0.5% of the 
Earth's land surface. 

Despite its limitations (e.g. the difficulty of quantifying 
threats to the existing habitat, and the paucity of 
distributional information available for many of the world's 
plant species), Myers' work is jm important step towards 
determining areas where conservation requirements are 
greatest and where the potential benefits from conservation 
measures would be maximised. 

From the wider conservation perspective, the question of 
interest is whether levels of endemism in one taxon are 
correlated with those in others. If endemism follows similar 
patterns for different taxa, then conservation measures 



1 



154 



Centres of Species Diversity 



Table 15.1 Numbers of endemic species present in 18 'Hot Spots' 



REGION 


HIGHER PLANTS 


MAMMALS 


REPTILES 


AMPHIBIANS 


SWALLOWTAIL 
BUTTERFLIES 


Cape Region (South Africa) 


6,000' 


15 


43 


23 





Upland western Annazonia 


5,000' 


- 


- 


c. 70 


- 


Atlantic coastal Brazil 


5,000' 


40 


92 


168 


7 


Madagascar 


4,900' 


86 


234 


142 


11 


Philippines 


3,700' 


98 


120 


41 


23 


Borneo (north) 


3,500' 


42 


69 


47 


4 


Eastern Himalaya 


3,500' 


- 


20 


25 


- 


SW Australia 


2,830' 


10 


25 


22 





Western Ecuador 


2,500' 


9 


- 




2 


Colombian Choc(5 


2,500' 


8 


137 


111 





Peninsular Malaysia 


2,400' 


4 


25 


7 





Californian floristio province 


2,140' 


15 


15 


16 





Western Ghats (India) 


1,600' 


7 


91 


84 


5 


Central Chfle 


1,450' 


- 


- 


- 


- 


New Caledonia 


1,400' 


2 


21 





2 


Eastern Arc Mts (Tanzania) 


535' 


20 


- 


49 


3 


SW Sri Lanka 


500' 


4 


- 


- 


2 


SW Cote d'lvoire 


200' 


3 


- 


2 





TOTAL 


49,955 


375 


892 


737 


59 



Sources: For plants, Myers (1988', 1990'); for animals, miscellaneous sources (WCMC). 

Notes: - indicates no data yet available. All regions are classed floristically as tropical forest, with the exceptions 

of four legions which have Mediterranean-type floras, i.e. Cape Region South Africa, SW Australia, Californian floristic province and Central Chile. 



focused in areas of high endemism will generate enhanced 
returns in terms of overall biodiversity conservation. 
Myers' botanical hot spots are undoubtedly good sites to 
conserve endemic plants, and they often contain high 
numbers of endemics among other groups. There are 
exceptions, however, and the strength of such relationships 
remains to be investigated. Area, size, scale, and the 
biogeography of different taxa will be among the important 
variables. 

Bibby et al. (1992) examined available data for other 
groups to compare with bird data, and showed that 
endemism at least among larger vertebrates is often, though 
not always, related. Countries with high numbers of 
endemics in one vertebrate group often also have high 
numbers of endemics among other vertebrates (see Table 
15.2). Statistically, numbers of mammals and birds, and of 
mammals and reptiles, correlate quite closely. Country size 
is probably an important factor underlying these 
correlations: larger countries tend to have larger numbers 
of species and also larger numbers of endemic species of 
each taxon. 

Even if associations do exist between levels of endemicity 
in different taxa, care must be exercised in their 
interpretation and application since correlations are merely 
generalisations. For example. Table 15.1 shows that while 
there may be some broad similarities amongst endemic 
species numbers in different vertebrate and plant taxa, there 
are significant discrepancies. Thus, although the Colombian 
Choco has high numbers of endemic reptiles juid 
amphibians (137 and 111 respectively) it has relatively few 



endemic mammals (8); and the Cape Region of South 
Africa, which has the highest number of endemic plant 
species (6,300) has only 15 endemic mammals. Overall 
conservation priorities should therefore be based on a 
synthesis of detailed analyses of different taxonomic groups, 
not an analysis of the pattern of endemicity in just one 
taxon. 



Critical faunas analysis 

Whether simple species richness or levels of endemism are 
initially used to assess the biological importance of sites, 
the concept of 'complementarity' and its application in 
'critical faunas analysis', first introduced by Ackery and 
Vane-Wright (1984), is increasingly used to determine 
conservation priorities objectively. In this approach the 
entire set of taxa within the group under consideration, e.g. 
single-country endemic amphibians, constitutes the 
'complement'. The single most important site for 
conservation is that at which the greatest proportion of the 
complement is represented. The portion of the complement 
not included is called the 'residual complement'. The 
priority for second site selection can be determined by 
identifying the site that adds the greatest proportion of the 
residual complement to the initial choice. The process can 
be continued in a step-wise sequence until all sites have 
been considered and allocated a priority. The advantage of 
this process is that it produces an objective and optimised 
selection sequence, against which the performance of any 
other (sub-optimal) sequence can be judged for its relative 
efficiency in representing total biodiversity. 



155 



1. Biological Diversity 



fable 15.2 Countries rich in endemic land vertebrates 



COUNTRY 






ENDEMIC TAXON 








RANK 


















ORDER 


MAMMALS 




BIRDS 




REPTILES 


AMPHIBIANS 


1 


Australia 


210 


Indonesia 


356 


Australia 


605 


Brazil 


293 


2 


Indonesia 


165 


Australia 


349 


Mexico 


368 


Mexico 


169 


3 


Mexico 


136 


Brazil 


176 


Madagascar 


231 


Australia 


160 


4 


USA 


93 


Philippines 


172 


Brazil 


178 


Madagascar 


142 


S 


Philippines 


90 


Peru 


106 


India 


156 


Ecuador 


136 


6 


Brazil 


70 


Madagascar 


97 


Indonesia 


150 


Colombia 


130 


7 


Madagascar 


67 


Mexico 


88 


Philippines 


131 


India 


110 


8 


China 


62 


New Zealand 


74 


Colombia 


106 


Indonesia 


100 


9 


USSR 


55 


Solomon Islands 


72 


Ecuador 


100 


Peru 


87 


10 


PNG 


49 


India 


69 


Peru 


95 


Venezuela 


76 


11 


Argentina 


47 


Colombia 


58 


Cuba 


79 


Cameroon 


65 


12 


Peru 


46 


Venezuela 


45 


South Africa 


76 


Zaire 


53 



Source: WCMC database. 



Collins and Morris (1985) performed a critical faunas 
analysis at the country level, examining endemicity in 
swallowtail butterflies. They found that if the five countries 
with the highest numbers of endemic swallowtail species 
enacted conservation plans to protect swallowtails, then 
54% of the world's total number of swallowtail species 
would be conserved. If the next five countries were 
included, the total protected would rise to 68%. Increments 
decreased as further blocks of five countries were added, 
with 15, 20, 25, 30, 35, 40 and 45 countries respectively 
including 77, 90, 93, 95, 96, 97 and 99% of the world's 
swallowtails. 

This type of analysis can be used to direct international and 
national attention to faunistically important countries, states 
or provinces. Local knowledge must however remain the 
basis for more detailed conservation plaiming, in order to 
identify precise centres of species richness and importance 
within a country, and to plan a system of protection around 
those centres. 

Whilst earlier studies were based on species numbers alone, 
more sophisticated studies of this kind are now being 
developed which attempt to take into account species 
turnover between sites, not otdy in a simple numerical sense 
but by use of some taxic diversity index. Taxonomic 
dispersion is the most complex but perhaps intuitively most 
attractive of these, in that, given a hypothesis of the 
evolutionary relationships among members of a group, it 
attempts to select an even spread of taxa across the 
hierarchy (see Chapter 2). 

Table 15.3 shows one application of this procedure, to 
determine the priority sequence of African protected areas 
for the conservation of antelopes. Serengeti National Park 
(Tanzania) is the richest single site, holding breeding 
populations of 24% of all African antelope species. The 
highest incremental change occurs with the addition of 
Kafue National Park (Zambia): together the two parks hold 
38%. The addition of two further reserves, Haut Dodo 
Faunal Reserve (C6te d'lvoire) and Ouadi Rim6-Ouadi 



Achim Faunal Reserve (Chad) brings the representation of 
African antelope species diversity to over 56% in just four 
protected areas. 

In critical faunas analysis, if all the species in the world in 
the taxon under consideration are to be conserved, and if all 
species are treated as taxonomically equal, then a priori 
endemics are accorded a high value in the prioritisation 
sequence. Thus Ackery and Vane-Wright (1984) found that 
in order to conserve all 158 species of milkweed butterflies 
(Lepidoptera: Danainae) a total of 31 sites or 'critical 
faunas' needed protection. Site selection was made starting 
with the site that contained the highest number of endemics 
- in this case Sulawesi. Of these 31 sites, 24 were sufficient 
to protect all the narrow endemics, and a ftirther seven 
were sufficient to complete the list. In practice, even if the 
conservation of 1(X)% of the Earth's biodiversity is the 
goal, some species will of necessity be neglected. The 
critical faunas approach may not always offer a sufficiently 
flexible strategy for plaiming conservation at the global 
level (Vane-Wright et al., 1991). 

Conclusion 

Although species are normally used as the basis for critical 
faunas evaluation or distributional analysis, other taxonomic 
groupings such as genus or family can be used instead. 
Different forms of weighting system can also be introduced, 
so that for instance a species in a monotypic genus, such as 
the Giant Panda Ailuropoda melanoleuca might be allotted 
a higher conservation priority than a species with many 
congeners. New measures of biodiversity are now being 
developed which can take into account the genetic 
distinctiveness of species based on the relative position of 
species and other taxa in the classification hierarchy. For 
example, Vane-Wright el al. (1991) suggest using a 'taxic 
diversity measure' based on the information content of 
cladistic hypotheses (indicating the branching pattern of 
evolution), which would provide a measure of taxonomic 
distinctiveness. Bibby et al. (1992) apply a simple method 
of assigning taxonomic uniqueness to endemic species based 



156 



Centres of Species Diversity 



Table 15.3 Biodiversity scores for Afrotropical antelopes 



STEP 


DIVERSITY 


DIVERSITY 


CONSERVATION 


NO. 


INCREMENT % 


CUMULATIVE % 


AREA NAME 


1 


23.95 


23.95 


Serengeti NP 


2 


13.70 


37.65 


Kafue NP 


3 


9.99 


47.64 


Haul Dodo FR 


4 


9.32 


56.96 


0. Rime-0. Achim FR 


5 


4.85 


61.81 


Yangudi Rassa NP 


6 


4.71 


66.52 


Odzala NP 


7 


5.27 


71.79 


W. Pretorius GR 


8 


3.50 


75.29 


Manovo-G-St Floris NP 


9 


2.81 


78.10 


De Hoop NR 


10 


2.82 


80.91 


Gorongosa NP 



COUNTRY 



Tanzania 

Zambia 

Cdte d'ivoire 

Chad 

Ethiopia 

Congo 

S Africa 

C African Rep 

S Africa 

Mozambique 



Note: Part of Ihe optimised priority area sequence of protected areas in terms of their potential for conservation of African antelopes, based on the 
taxonomic dispersion measure and complementarity. Serengeti National Park (Tanzania) is the richest single site, holding breeding populations of 
species accounting for 24% of African antelope diversity. The highest incremental addition occurs in Kafue National Park (Zambia); in combirution 
Ihe two total 38 % . The addition of two further reserves (one in Cote d'ivoire; one in Chad) brings the representation of African antelope taxonomic 
diversity lo over 56%. (Based on data from East (1988, 1989, 1990) and Gentry fm press) and analysis of Williams (unpublished report).) 



on the diversity of the genus and family to which the 
species belongs. 

The kinds of technique outlined above are useful tools 
which enable conservation biologists to prioritise sites and 
allocate scarce resources. Care must be taken to base 
overall global conservation priorities on a number of taxa, 
which ideally should be well-represented throughout the 
world. It should, however, be remembered that the 
identification of areas of high diversity is but the first step 
in determining effective conservation plans. The size and 
heterogeneity of the sites under consideration also have 
serious implications for conservation biology through their 
effects on minimum viable population sizes, stochastic 
ecological effects, etc. Planners must seek to conserve 
multiple populations whenever possible, to allow for chance 
local extinctions. Progress in designing the protection of a 
fitnctional ecological system or set of systems has recently 
been made in Australia (e.g. Margules, 1989), where 
wildlife services are developing step-wise analyses intended 
to take these kinds of factors into account. 

Two major projects have developed and refined approaches 
to the systematic identification of centres of species 
endemism or diversity at the global level. The lUCN Plant 
Conservation office is identifying centres of plant diversity, 
and the International Countil for Bird Preservation (ICBP) 
has identified centres of endemism among restricted-range 
birds. The approaches and major findings of these two 
projects are detailed below. Simple visual comparison of the 
two world maps relating to these projects (Figs 15.1 and 
15.2) shows much broad correspondence between the sites, 
although there are differences in detail (e.g. more 
botanically diverse areas identified in Mediterranean 
regions). The sites concerned are noted in Tables 15.6 
(plants) and 15.7 (birds). 

CENTRES OF PLANT DrVERSFFY 

The rUCN Plant Conservation Programme is at present 
carrying out a project to identify the several hundred major 
Centres of Plant Diversity (CPD). These are defined as 
places particularly rich in plant life which would if 
protected safeguard the majority of wild plants in the world. 
The book lUCN is preparing with the help of collaborators 



worldwide will provide detailed data sheets on some 250 
selected areas. It will also document the many benefits, 
economic and scientific, that conservation of these areas 
would bring and will outline the potential value of each for 
sustainable development. 

lUCN has defined the CPD 'sites' as of three types: 

• botanically rich sites that can be defined geographically 
(e.g. Mt Kinabalu in Borneo) 

• geographically defined regions with high species 
diversity and/or endemism (such as the Atlas Mountains, 
or the Cordillera Betica in Spain) 

• vegetation types and floristic provinces that are 
exceptionally rich in plant species (such as the Amazon 
rain forests and the South-West Botanical Province of 
Western Australia). 

The formal criteria for inclusion of sites in the Centres of 
Plant Diversity project specify that each must have one or 
both of the following two characteristics: 

• the area is evidently species-rich, even though the 
number of species present may not be accurately known 

• the area is known to contain a large number of species 
endemic tc it. 

The following characteristics are also considered in the 
selection: a) the site contains an important gene pool of 
plants of value to man or plants that are potentially useful; 
b) the site contains a diverse range of habitat types; c) the 
site contains a significant proportion of species adapted to 
special edaphic conditions; d) the site is threatened or under 
imminent threat of large-scale devastation. 

The selection is therefore based on botanical importance 
rather than on degree of threat. A site that could be 
considered safe one year could be severely endangered the 
next. This is particularly likely in the tropics where 
pressures on land continue to increase. 

The site selection process involved extensive consultations 
with experts in all major regions. In Africa, China, India, 
North and South America, this has resulted in Workshops 
at which data on lists of proposed CPD sites have been 
reviewed, and the final site selection made. For the Central 
Asian region, the final selection has not yet been made. 



157 



1. Biological Diversity 

i=igure 15.1 Centres of plant diversity: the world 




158 



Centres of Species Diversity 



Figure 15.2 Endemic bird areas: the world 




E 



o 
o 
o 

ID 

O 
O 
O 
■+ 

O 
O 
O 



159 



/. Biological Diversity 



The difficulty in selecting sites varies greatly ft-om one part 
of the world to another. In some regions the selection is 
easy. In West Africa, for example, it has long been known 
that the famous Tai Forest National Park is the only large 
portion of rain forest in Cote d'lvoire still intact; with over 
150 plants endemic to the park, the Tai is an obvious 
candidate for inclusion. Often, especially in Africa, the 
Centres of Plant Diversity are mountains, like Mt Nimba 
where the borders of Guinea, Liberia and Ivory Coast meet, 
Mt Mulanje in Malawi, and the Air Mountains in the 
Sahara. Such mountains have a wide range of diverse plant 
communities but are often delimited by low-diversity habitat 
making identification of sites relatively easy. 

In other areas the selection is much more difficult. The 
islands of Borneo and New Guinea, for example, contain 
the largest floras in Asia. Virtually all the habitats are rich 
in plants, but floral diversity varies from place to place in 
very complex ways. As a result, it is very hard to specify 
which parts of Kalimantan, if protected, would include the 
most plant species. In Irian Jaya, botanical knowledge is not 
yet sufficient to say with any degree of confidence which 
areas are richest in plant species. 

In some regions, the selection of the sites that need to be 
protected cannot be made on botanical criteria alone. For 
example, the Atlantic forests of Brazil are reduced to 2-5 % 
of their original extent, and they have a quite different 
complement of species to the much larger Amazonian 
forests. To save their flora, as many as possible of the 
surviving remnants should be protected. Where such 
remnants provide two similar sites, with similar 
complements of species, socio-economic considerations 
rather than botanical ones will influence the decision as to 
which sites might be protected. In such cases the CPD 
project will identity the whole vegetation type - in this case 
the Atlantic forests of Brazil - and not recommend detailed 
protection strategies for the various sites within that region. 

In addition to data sheets on the selected sites, the CPD 
publication will contain Regional Overviews which will 
describe the general patterns of vegetation and plant 
distribution. Opinions will naturally vary as to the exact 
choice of sites for coverage at international level, and in 
order to avoid implications that only the 250 or so sites 
outlined should be protected, the Regional Overviews will 
also contain lists of other sites for botanical conservation, 
many of a lesser priority but important nonetheless. 

The 'Centres' concept is particularly appropriate for plant 
conservation because it focuses on the plant-rich tropics. As 
the map of sites (Fig. 15.1) shows, most of the 241 sites 
selected so far are in the tropics, where it is not usually 
possible to identify threatened plant species individually. 
Botanists can, however, say which areas are rich in plants 
and which are not without knowing the status of every 
single species. Thus, while identifying threatened species 
provides a practical approach to planning plant conservation 
in most temperate countries, and on most islands, 
identifying Centres of Plant Diversity is the best approach 
in most of the tropics. 

It is as yet unknown to what extent the sites identified as 
Centres of Plant Diversity can also be described as centres 



of diversity for animals; it is intended to investigate this 
during later stages of the project. 

All the 241 Centres of Plant Diversity selected so far are 
listed in Table 15.6. As the data on degree of protection 
show, many are already protected areas, such as Bwindi 
(Impenetrable) Forest (Uganda), the wet tropics of 
Queensland (Australia) and the Sinharaja Forest (Sri 
Lanka). In virtually all cases, however, more conservation 
work is needed to ensure the full complement of plants 
survives intact. Below we show the areas selected for 
Africa and Peninsular Malaysia, showing the application of 
the approach in regions of very different size. 

Centres of Plant Diversity: Africa 

White (1983) recognises 17 major phytogeographic 
divisions (phytochoria) for mainland Africa. Of these, 
seven are classed as Regional Centres of Endemism, each 
having more than 50% of its species confined to it and a 
total of more than 1 ,000 species endemic to it. Two more 
phytochoria (Afromontane and Afroalpine) are patchily 
distributed on mountains. The remainder are termed 
transition zones, having low species endemism and, in some 
cases, very impoverished floras. These main divisions, 
which cover vast areas, were used as the starting point for 
selecting sites for the CPD project. In general, floristically- 
rich phytochoria have been allocated more Data Sheet sites 
than those with impoverished floras; however, some regions 
with very high endemism, such as the Cape, will be treated 
as one 'super-site'. 

Salient features of White's phytochoria are outlined below, 
and indicated in Fig. 15.3. The CPD sites are shown in the 
same map, superimposed on these regional divisions and 
details presented in Table 15.4. For comparison, areas of 
bird endemism identified by ICBP are mapped in Fig. 15.4 
and detailed in Table 15.5. 

Guineo-Congolian (A) 

8,000-12,(K)0 vascular plant species; endemism very high, 
80%. The tropical rain forest in west and central Africa. 
Western block (Guinea) floristically distinct from central 
block, mostly cleared or threatened. Gulf of Guinea 
islands, especially Sao Tome, also have high endemism. 
Central block (Congo) has two main centres of plant 
diversity: west (especially Gabon - the most species-rich 
rain forest in Africa, and Cameroon), and east (especially 
Zaire). In Cameroon, forests nearer coast richer (e.g. 
Korup), extending into south-east Nigeria (e.g. Oban). In 
Zaire, forests near coast (e.g. Mayombe) reported to be 
floristically distinct, threatened; forests on east side (e.g. 
Maiko, Kahuzi-Biega, Ituri, probably Itombwe) appear to 
be richer than those in centre. 

Zambezian (B) 

8,500 vascular plant species; high endemism, 54%. 
Miombo, mopane and chipya woodland. Most diverse area 
is Haut Shaba, Zaire (including Kundelungu). Zambia: 
richest miombo is in wetter area near Zaire border 
(extension of Haut Shaba). Angola: Huila Plateau rich in 
endemics, Itigi thicket near TanzaniayZambia border also 
rich. Local endemics in Zaire on metalliferous soils and on 
serpentine in Zimbabwe (e.g. Great Dyke) need protection. 



160 



Centres of Species Diversity 



Sudanian (C) 

2,750 vascular plant species, most widely distributed; 
regional endemism low, 35%. Woodland (mainly 
hoberlinia, Khaya). 

Somalia-Masai (D) 

2,500 vascular plant species; 50% regional endemism. 
Acacia, Commiphora woodland. Rather homogenous; 
Somalia the richest country. 

Cape(E) 

Fynbos, with S,600 vascular plant species; high endemism, 
60-68%. Extraordinarily rich in species and endemics. 
Many important Jireas. Invasive species a major problem. 

Karoo-Namib (F) 

6,000 vascular plant species; 35-40% regional endemism. 
Dwarf succulent shrubland. Unparalleled diversity of 
succulents. Important centres in north (Gariep centre, 
including the Richtersveld) and south (southern Namibia and 
western Cape Province, South Africa). 

Mediterranean (G) 

4,000 vascular plant species; endemism low, 20%. 
Evergreen oak forest, macchia, maquis. High Atlas the 
most outstanding area botanically, many species and 
endemics. 

Afromontane (H) 

4,(X)0 vascular plant species; endemism very high, 75%. 
Forests, afroalpine vegetation. Afroalpine vegetation 
(above forest limit) especially rich in local endemics. 
Eastern Arc mountains in Tanzania and south-east Kenya 
have many species absent from central Africa, especially in 
submontane forest. Richest mountains in central Africa 
uncertain, but possibly East Kivu (e.g. Itombwe) and 
Bwindi. All African mountain forests especially important 
for watershed protection. 

Indian Ocean coastal (M & O) 

Comprising Zanzibar-Inhambane regional mosaic in north, 
and Tongaland-Pondoland in south. Both with 3,000 
vascular plant species and low endemism, 15-20%. Most 
important are the coastal forest remnants, floristically 
similar to the Guineo-Congolian, but with c. 40% of species 
endemic to coastal belt, many with very restricted 
distributions. In Kenya, c. 50 forest patches, most very 
small. In Tanzania, number of sites uncertain, need more 
fieldwork to determine which areas are key; includes Rondo 
Plateau. 



CENTRES OF AVIAN ENDEMISM 

The International Council for Bird Preservation, in its 
Biodiversity Project, has undertaken a major data collation 
and analysis project to identify areas supporting 
aggregations of restricted range endemic birds. This project 
has served two functions: first, it applies rigorous scientific 



criteria for identifying areas of high conservation value for 
birds; and second, it reviews the information on patterns of 
endemism in other taxonomic groups so that the value of 
birds as biodiversity indicators can be assessed. The major 
results of the project are now published in Bibby et al. 
(1992). 

Locality records were gathered for species with breeding 
ranges below 50,000km^ (about the size of Sri Lanka, Costa 
Rica or Denmark). Remarkably, there are 2,608 species or 
27% of the world's birds with such small ranges. In all, 
some 55,000 separate locality records of birds were 
accurately geo-referenced and mapped with the aid of a 
Geographic Information System. 

Species of restricted range tend to occur together, for 
instance on islands or in isolated areas of a particular 
habitat, such as tropical montane forest. Boundaries of these 
natural groupings of species have been identified 
(designated as Endemic Bird Areas or EBAs). They number 
221 and embrace 2,480 species, which is the vast majority 
of all restricted range birds. Both the numbers of species 
involved and the number of EBAs divide roughly equally 
between continental areas and islands. 

The tropics, with 76% of all Endemic Bird Areas, are the 
most important zone and there are very few at north 
temperate latitudes (Fig. 15.2). Indonesia is by far the most 
important country, with 411 restricted range species of 
which 339 are confined to the country. Peru, Brazil, 
Colombia, Papua New Guinea, Ecuador, Venezuela, the 
Philippines, Mexico and the Solomon Islands all have more 
than 100. 

Table 15.7 shows the political affiliation, altitudinal range 
and habitats, and richness in restricted range birds of each 
EBA. The size of EBAs varies considerably, from the 
Northwestern Hawaiian Islands (5km^) to the Guianas 
(170,000km^). However, over 30% of EBAs have areas of 
less than lO.OOOkm^ and are therefore considerably smaller 
than the maximum range size allowed for any one species. 
Island EBAs are generally smaller than continental EBAs. 
For instance, 29% of island EBAs are smaller than 
1 ,000km", whereas no continental EBAs are this small. The 
extent of EBAs in Africa, Middle East and Europe are 
shown in Fig. 15.4 and sites are detailed in Table 15.5. 

The number of restricted range bird species contained 
within EBAs also varies, from the minimum of two used to 
define an EBA to 67 in the Solomon Islands EBA. A large 
number, 757 (29%), of these birds are threatened, and they 
constitute 77% of all threatened birds. Most EBAs (85%) 
have one or more threatened restricted range bird species 
(see Table 15.5 for Africa and adjacent areas). The 
principal habitat used by birds in the EBAs is forest (69% 
of restricted range species) with smaller numbers using 
scrub (12%). Other habitats such as grasslands are poorly 
represented, largely because species in these habitats are 
generally more widespread. 



161 



1. Biological Diversity 



Figure 15.3 Centres of plant diversity: Africa 




Notes: D>ta Sheet sites are shown superimposed on the main phytochoria (after White, 1983). Letter codes denote the following: (A) Guineo- 
Congolian regional centre of endemism. (B) Zambezian regional centre of endemism. (C) Sudanian regional centre of endemism. (D) Somalia-Masai 
regional centre of endemism. (E) Cape regional centre of endemism. (F) Karoo-Namib regional centre of endemism. (G) Mediurranean centre of 
endemism. (H) Afromontane archipelago-like regional centre of endemism. (I) Guinea-Congolia/Zambezia regional transition zone. (K) Guinea- 
Congolia/Sudania regional transition zone . (L) Lake Victoria regional mosaic . (M) Zanzibar-Inhambane regional mosaic . (P) Sahel regional transition 
zone. (O) Tongaland-Pondoland regional mosaic. (Q) Sahara regional transition zone. (R) Mediterranean/Sahara regional transition zone. 



162 



Centres of Species Diversity 



Figure 15.4 Endemic bird areas: Africa, IVIiddle East, Europe 




E 



(Source: ICBP) 
Robinson projection 



163 



1. Biological Diversity 



Table 15.4 Centres of Plant Diversity: sites in continental Africa 



SITE 


SITE NAME 


COUNTRY 


NO. 






1 


Sapo Forest 


Liberia 


2 


TaT Forest 


Ivory Coast 


3 


Mt Nimba 


Guinea, Ivory Coast, Liberia 


4 


Salonga National Park 


Zaire 


5 


Mayombe-Cabinda 


Congo, Cabinda, Zaire 


6 


Korup-Oban 


Cameroon, Nigeria 


7 


Dja 


Cameroon 


8 


Crystal Mountains 


Gabon 


9 


Massif du Chaillu 


Gabon 


10 


Massif de Doudou 


Gabon 


11 


Maiko 


Zaire 


12 


Bwindi (Impenetrable) Forest 


Uganda 


13 


Kundelungu/Upembe 


Zaire 


14 


Huila Plateau 


Angola 


15 


Zambesi Source Area 


Zambia 


16 


Okavango-Kwando 


Angola, Namibia, Botswana 


17 


Mbali-Mahali Hills 


Tanzania 


18 


Cape Floristic Province 


South Africa 


19 


Mt Kenya 


Kenya 


20 


Eastern Arc Mts: Usambaras 


Tanzania 


21 


High Drakensberg 


South Africa 


22 


Mt Mulanje 


Malawi 


23 


Bale Mts 


Ethiopia 


24 


Mt Cameroon 


Cameroon 


25a 


Karoo-Namib region 


South Africa 


25b 


Gariep Centre 


South Africa, Namibia 


25c 


Brandberg-Kaokoveld 


Angola, Namibia 


26 


Cal Madow 


Somalia 


27 


Hobyo 


Somalia 


28 


Limestone bush/woodland, Ogaden 


Ethiopia, Kenya, Somalia 


29 


Garamba 


Zaire 


30 


High Atlas mts 


Morocco 


31 


Pondoland Plateau 


South Africa 


32 


Rondo Plateau 


Tanzania 



NO. OF PLANT 
SPECIES 



> 2,000 



3,500 
2,000 

> 3,000 

> 3,000 

> 1 ,000 

1 ,000 taxa 



8,600 


800 


1,921 taxa' 


>800 


> 1 ,000 


1,200 


5,000 taxa 


> 1 ,000 


< 1 ,000 



Of known) estimated to occur in the area. * denotes number of vascular planta so far 



Note: Figures refer to the number of vascular plant species 
recorded. 

Importance for other taxonomic groups 



The review of other taxoDomic groups suggests that the 
EBAs are also of great importance for mammals, reptiles, 
amphibians, molluscs, insects and plants. However, there 
are gaps in data on these other groups, and additional data 
on these could significantly change the conservation 
evaluation of some EBAs. It seems likely, also, that in 
other groups different scales of endemism may occur (more 
fine-grained for various invertebrate groups and some plant 
taxa, for instance), and it is worth noting that entirely 
different approaches are needed to deal with non-terrestrial 
endemism. 

Evaluation for importance and threats 

EBAs were evaluated on biological importance and threat. 
The biological importance index reflects richness in 
restricted range species per unit area, modified to allow for 
taxonomic uniqueness of the species involved. On this 
basis, ICBP assigns EBAs to three categories. EBAs which 
are also significant centres of endemism for at least two 



other taxonomic groups are upgraded by one category. This 
has the overall effect of increasing the priority of EBAs 
which are important for other groups: uniform quantitative 
data on other groups are urgently needed to refine these 
priorities. Threats to EBAs are evaluated on the proportions 
of restricted-range species threatened, and the extent of 
coverage by the protected areas system (see Table 15.5). 

Conclusions 

Bibby et al. (1992) conclude that 20% of all bird species 
are confined to just 2% of the world's land surface. The 
total area of all 221 EBAs accounts for 4.5% of the land 
surface. Since more widely ranging species also occur in 
these EBAs, the proportion of the world's birds that could 
be conserved if EBAs were secured would greatly exceed 
the 27% whose ranges are highly restricted. 

Further work and follow-up 

ICBP aims to promote the conservation of all 221 EBAs, in 
collaboration with other international and national 



164 



Centres of Species Diversity 



Table 15.5 Endemic bird areas of Africa, the Middle East and Europe 



AREA NAME 


SIZE 


SPP. 


CONFINED 


SPP. 


OCCURRING 


SPP. R 


PA 




(km'l 


T 


N 


Tot. 


T 


N 


Tot. 




l%l 


Sites in continental Africa 




















Upper Guinea forests 


113,000 


4 


1 


5 


5 


1 


6 


5.5 


7 


Cameroon mountains 


7,300 


8 


4 


26 


9 


4 


28 


27.0 


7 


Cameroon and Gabon lowlands 


40,000 


4 




5 


5 


- 


6 


5.5 


22 


Angola 


14,000 


5 


4 


14 


6 


4 


15 


14.5 


4 


North-east Somalia 


41,000 


2 


- 


5 


2 


- 


5 


5.0 





Central Ethiopian highlands 


37,000 


2 


1 


4 


2 


1 


4 


4.0 





South Ethiopian highlands 


15,000 


4 


- 


4 


4 


- 


4 


4.0 





Central Somalian coast 


1,200 


1 


1 


2 


1 


1 


2 


2.0 





East Zairean lowlands 


49,000 


4 


1 


5 


4 


1 


5 


5.0 


3 


Albertine Rift Mountains 


44,000 


8 


4 


37 


10 


4 


40 


38.5 


12 


Kenyan mountains 


46.000 


2 




6 


2 




7 


6.5 


6 


Serengeti 


47,000 


- 


1 


3 




1 


3 


3.0 


43 


Kenyan and Tanzanian coastal 


8,800 


5 


- 


7 


6 




8 


7.5 


7 


forests 




















Eastern Arc Mountains 


39,000 


11 


2 


26 


13 


2 


30 


28.0 


11 


South Zambia 


47,000 


1 


1 


2 


1 


1 


2 


2.0 


14 


East Zimbabwean mountains 


4,900 


- 


2 


2 


1 


2 


4 


3.0 


7 


South-east African coast 


43,000 


- 


2 


2 




3 


3 


2.5 


3 


South-east African grasslands 


60,000 


2 


- 


2 


2 




2 


2.0 





Cape region 


24,000 
8,100 


- 


1 


3 




1 


4 
10 


3.5 
8.5 


50 


Sites outside continental Africa 










Canary Islands and Madeira 


6 


- 


9 


6 


30 


Cape Verde Islands 


4,000 


1 


- 


4 


1 


- 


4 


4.0 


9 


Principe 


140 




- 


6 


3 




12 


8.8 





Sao Tome 


860 


6 


1 


15 


9 


1 


21 


16.8 





Tristan da Cunha Islands 


200 


5 


- 


6 


5 


- 


6 


6.0 





Caucasus 


64,000 




1 


2 




1 


2 


2.0 


9 


Cyprus 


9,300 




- 


2 


- 


- 


2 


2.0 





Iraq marshes 


40,000 




- 


2 


- 


- 


2 


2.0 





Arabian mountains 


59,000 


1 


- 


7 


1 


- 


7 


7.0 


1 


Socotra 


3,500 


1 


- 


6 


1 


- 


6 


6.0 





Granite Seychelles 


240 


6 


- 


10 


6 


- 


10 


10.0 


3 


Aldabra 


160 


1 


1 


2 


1 


1 


4 


2.7 


4 


Comoro Islands 


1,900 


4 




10 


4 


- 


13 


11.2 





Mayotte 


360 


1 


- 


3 


1 


- 


6 


4.2 





West Madagascan dry forest 


30,000 


1 




3 


2 


- 


4 


3.5 


3 


East Madagascan humid forests 


1 1 2,000 


13 


1 


17 


14 


1 


18 


17.5 


5 


Central Madagascan lakes 


2,000 


2 


- 


2 


2 




2 


2.0 





West Madagascan coastal 


5,000 


2 


- 


2 


2 


- 


2 


2.0 


11 


wetlands 




















South Madagascan Dldiera scrub 


30,000 


2 


1 


8 


2 


1 


8 


8.0 


3 


Reunion 


2,500 


1 


- 


3 


1 


- 


7 


5.0 


2 


Mauritius 


1,900 


6 


- 


6 


6 




10 


8.0 


2 


Rodrigues 


100 


2 


- 


2 


2 




2 


2.0 






Key: T=threatened; N = near threatened; SPP. R=species richness; PA = coverage by protected areas. 



organisations. The list of priority areas should enable a 
wide range of organisations to develop both regional and 
local programmes to help implement measures to prevent 
mass species extinctions. These measures will range from 
establishment and management of protected areas to the 
sustainable use of natural resources in the centres of 
endemism, and will require political and economic 
collaboration at all levels. There is a need to strengthen 
local data on birds and other taxa, and within EBAs, to 
study habitats which are vital for the survival of restricted 



range species. Key sites must be identified within EBAs for 
the targeting of conservation resources. 

References 

Ackery, P.R. and Vane-Wright, R.I. 1984. Milkweed Butterflies. 
British Museum (Natural History), London. 

Collins, N.M. and Morris, M.G. 1985. Threatened Swallowtail 
Butterflies of the World. The WCN Red Data Book. RICN, 
Cambridge, UK and Gland, Switzerland. vii-(-401pp.-t-8pls. 



165 



1. Biological Diversity 



Bibby, C.J., Crosby, M.J., Heath, M.F., Johnson, T.H., Long, A.J., 

Slanersfield, A.J. and Thirgood, S.J. 1992. Putting Biodiversity 

on ihe Map: global priorities for conservation. ICBP, 

Cambridge, UK. 
East, R. (Ed.) 1988. Antelopes. Global survey and regional actions 

plans. Pan 1. East and northeast Africa. lUCN, Gland. 
East, R. (Ed.) 1989. Antelopes. Global survey and regional actions 

plans. Part 2. South and south-central Africa. lUCN, Gland. 
East, R. (Ed.) 1990. Antelopes. Global survey and regional actions 

plans. Pan 3. West and central Africa. lUCN, Gland. 
Gentry, A. On press). The subfamilies and tribes of the family 

Bovidae. 
Margules, C.R. 1989. Introduction to some Australian developments 

in conservation evaluation. Biological Conservation 50:1-11. 
McNeely, J. A., Miller, K.R., Reid, W.V., Mittermeier, R.A. and 

Werner, T.B. 1990. Conserving the World's Biological 

Diversity. lUCN, Gland, Switzerland. 
Mittermeier, R.A. 1988. Primate diversity and the tropical forest: case 

studies from Brazil and Madagascar and the importance of the 

megadiversity countries, [n: Wilson, E.O. and Peter, P.M. 

(Eds), Biodiversity. National Academic Press, Washington, DC. 

Pp. 145-154. 



MiUermeier, R.A. and Werner, T.B. 1990. Wealth of planU and 

animals unites 'megadiversity* countries. Tropicus:4(l):l ,^5 . 
Myers, N. 1988. Threatened biotas: 'hot spots' in tropical forests. The 

Environmentalist 8(3): 187-208. 
Myers, N. 1990. The biodiversity challenge: expanded hot-spota 

analysis. The Environmentalist 10:243-256. 
Vane-Wright, R.I., Humphries, C.J. and Williams, P.H. 1991. What 

to protect? - systematics and the agonies of choice. BiologictU 

Conservation 55:235-254. 
White, F. 1983. The Vegetation Map of Africa. A descriptive memoir 

lo accompany the Unesco/AETFATfVNSO Vegetation Map of 

Africa. 
Williams, P.H. (unpublished). Afrotropical antelopes - priority areas 

for biodiversity. Progress report to The Natural History 

Museum, London, WCMC and lUCN-SSC. 

Text, table ami maps on plant diversity supplied by lUCN 
Centres of Plant Diversity Project. Text, table and maps on 
bird diversity provided by ICBP Biodiversity Project. 
Additional material from R.l. Vane-Wright, Biodiversity 
Programme, The Natural History Museum (London). 



166 



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Table 15.7 Endemic bird areas of the world 



Centres of Species Diversity 



NAME 



POLITICAL UNIT(S) 



AFRICA, THE MIDDLE EAST AND EUROPE 



Canary Islands and Madeira 
Cape Verde Islands 
Upper Guinea forests 

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Cameroon and Gabon lowlands 

Principe 

Sao Tome 
Angola 

Tristan da Cunha Islands 

Caucasus 

Cyprus 

Iraq marshes 

Arabian mountains 
Socotra 

North-east Somalia 
Central Ethiopian highlands 
South Ethiopian highlands 
Central Somalian coast 

East Zairean lowlands 
Albertine Rift Mountains 

Kenyan mountains 

Serengeti 

Kenyan and Tanzanian coastal 

forests 

Eastern Arc Mountains 

South Zambia 

East Zimbabwean mountains 
South-east African coast 
South-east African grasslands 
Cape region 

Granite Seychelles 

Aldabra 

Comoro Islands 

Mayotte 

West Madagascan dry forest 

East Madagascan humid forests 

Central Madagascan lakes 

West Madagascan coastal wetlands 

South Madagascan Didiera scrub 

Reunion 

Mauritius 

Rodrlgues 



Spain, Portugal 

Cape Verde 

Cote D'lvoire, Ghana. 

Guinea, Liberia, Sierra 

Leone 

Cameroon, Equatorial 

Guinea, Nigeria 

Cameroon, Gabon, 

Equatorial Guinea, Nigeria 

Sao Tome and Principe 

Sao Tome and Principe 
Angola 

St Helena 

USSR, Turkey 
Cyprus 
Iraq, Iran 

Saudi Arabia, Yemen 
Yemen 

Somalia 
Ethiopia 
Ethiopia 
Somalia 

Uganda, Zaire 

Burundi, Rwanda, Uganda, 

Zaire 

Kenya, Tanzania 

Kenya, Tanzania 
Kenya, Tanzania 

Malawi, Mozambique, 
Tanzania 

Botswana, Zambia, 
Zimbabwe 

Mozambique, Zimbabwe 
Mozambique, South Africa 
Lesotho, South Africa 
South Africa 

Seychelles 

Seychelles 

Comoros 

Comoros 

Madagascar 

Madagascar 

Madagascar 

Madagascar 

Madagascar 
Reunion 
Mauritania 
Reunion 



ALTITUDE (ml 


HABIT AT(S) 


SIZE (km^) 


SPP. R. 


250-2,000 


forest. 


rocky 


8,100 


8.5 


0-160 


rocky. 


mixed 


4,000 


4.0 


100-1,400 


forest 




113,000 


5.5 


700-2,900 


forest 




7,300 


27.0 


0-800 


forest 




40,000 


5.5 





0-1,000 


forest, 
mixed 


140 


8.8 




0-2,000 


forest 


860 


16.8 




0-1,500 


forest, 
mixed 


14,000 


14.5 




0-300 


grassland, 
mixed 


200 


6.0 


1 


,500-4,000 


rocky, mixed 


64,000 


2.0 




0-1,900 


forest, scrub 


9,300 


2.0 




0-100 


wetland, 
mixed 


40,000 


2.0 


1 


,800-3,200 


scrub, mixed 


59,000 


7.0 




0-1,400 


scrub, 
grassland 


3,500 


6.0 




300-2,100 


rocky, mixed 


41,000 


5.0 


1 


,300-3,100 


rocky, scrub 


37,000 


4.0 


1 


,275-2,300 


scrub, mixed 


1 5,000 


4.0 




0-100 


desert, 
grassland 


1,200 


2.0 




700-1,500 


forest 


49,000 


5.0 


1 


,000-3,200 


forest 


44,000 


38.5 



1,100-3,700 forest, 
mixed 



46,000 



6.5 



1,100-2,100 


savanna 


47,000 


3.0 


0-500 


forest 


8,800 


7.5 


750-3,000 


forest 


39,000 


28.0 


600-1,000 


forest, 
savanna 


47,000 


2.0 


1,200-2,400 


forest 


4,900 


3.0 


0-100 


forest, scrub 


43,000 


2.5 


1,700-2,200 


grassland 


60,000 


2.0 


0-1,000 


forest, 
mixed 


24,000 


3.5 


0-900 


forest 


240 


10.0 


0-8 


forest 


160 


2.7 


400-2,600 


forest 


1,900 


11.2 


0-1,700 


forest 


360 


4.2 


0-800 


forest 


30,000 


3.5 


0-2,300 


forest 


1 1 2,000 


17.5 


750-1,500 


wetland 


2,000 


2.0 


0-100 


wetland, 
forest 


5,000 


2.0 


0-200 


scrub, forest 


30,000 


8.0 


200-2,300 


forest 


2,500 


5.0 


300-800 


forest, scrub 


1,900 


8.0 


0-390 


forest, scrub 


100 


2.0 



187 



1. Biological Diversity 



Table 15.7 Endemic bird areas of the world 



West China 


China 


900-1,300 


desert, 


, scrub 


15,000 


2.0 


Western Himalayas 


Afghanistan, India, 
Nepal, Pakistan 


1,600-3,600 


forest 




33,000 


9.0 


Indus valley 


India, Pakistan 


0-200 


wetland. 


37,000 


2.0 








scrub 








Western Ghats 


India 


0-2,450 


forest 




28,000 


16.0 


Sri Lanka 


Sri Lanka 


0-2,260 


forest 




36,000 


23.0 


Tibetan valleys 


China 


3,600-4,600 


scrub. 


rocky 


7,900 


2.0 


South Tibet 


China 


2,700-5,000 


scrub. 


forest 


18,000 


2.0 


Eastern Himalayas 


Bhutan, China, India, 
Myanmar, Nepal 


900-4,000 


forest 




70,000 


22.8 


Assam plains 


Bangladesh,lndia 


0-1,000 


wetland. 


43,000 


3.8 








grassU 


ind 






Tirap Frontier 


India, Myanmar 


500-1,800 


scrub, 


mixed 


14,000 


2.0 


Qinghai mountains 


China 


1,800-5,100 


rocky. 


mixed 


22,000 


3.0 


Central Sichuan mountains 


China 


1,500-3,600 


forest 




30,000 


9.8 


West Sichuan mountains 


China 


2,700-4,900 


forest. 


mixed 


24,000 


3.0 


South Chinese forests 


China 


300-1,900 


forest 




1 1 ,000 


4.0 


Yunnan mountains 


China, Myanmar 


1,500-3,650 


forest 




26,000 


3.3 


Burmese plains 


Myanmar 


0-1,000 


scrub. 




16,000 


2.0 








agricultural 






Andaman Islands 


India 


0-700 


forest 




8,200 


10.0 


Nicobar Islands 


India 


0-600 


forest 




2,000 


7.0 


Annamese lowlands 


Laos, Viet Nam 


0-1,500 


forest 




1 2,000 


5.3 


Hainan 


China 


500-1,800 


forest 




1 2,000 


2.8 


Da Lat Plateau 


Viet Nam 


900-2,300 


forest 




7,400 


5.1 


Cochinchina 


Viet Nam 


0-1,200 


forest 




1 5,000 


2.5 


Shanxi mountains 


China 


2,000-2,800 


forest 




14,000 


2.0 


Fujian mountains 


China 


200-2,000 


forest 




45,000 


3.8 


Taiwan 


Taiwan 


300-3,300 


forest 




36,000 


15.3 


Nansei Shoto Islands 


Japan 


0-500 


forest, 


mixed 


4,500 


9.3 


Ogasawara Islands 


Japan 


100-400 


forest. 


mixed 


100 


1.5 


SOUTH-EAST ASIAN ISLANDS AND i 


AUSTRALIA 

Philippines 


350-2,800 


forest 














Luzon mountains 




36,000 


11.8 


Luzon lowlands and foothills 


Philippines 


0-1,300 


forest 




1 2,000 


14.8 


Mindoro 


Philippines 


0-1,500 


forest 




10,000 


7.3 


Negros and Panay 


Philippines 


0-1,300 


forest 




26,000 


10.6 


Cebu 


Philippines 


0-1,300 


forest 




5,100 


1.0 


Palawan 


Philippines 


0-1,000 


forest 




1 4,000 


17.8 


Samar, Leyte, Bohol and Mindanao 


Philippines 


0-1,500 


forest 




66,000 


15.6 


lowlands 














Mindanao mountains 


Philippines 


700-3,000 


forest 




32,000 


21.6 


Sulu Archipelago, excluding Basilan 


Philippines 


0-790 


forest 




1,700 


4.5 


Bornean mountains 


Indonesia, Malaysia 


0-3,000 


forest 




27,000 


27.8 


Sumatra and Peninsular Malaysia 


Indonesia 


600-3,000 


forest 




53,000 


25.2 


Enggano 


Indonesia 


0-150 


forest, 


mixed 


370 


2.0 


Javan and Balinese mountains 


Indonesia 


800-3,000 


forest 




18,000 


23.9 


Javan and Balinese lowlands 


Indonesia 


200-800 


forest, 


scrub 


16,000 


4.0 


Flores and associated islands 


Indonesia 


0-2,300 


forest 




36,000 


23.2 


Sumba 


Indonesia 


0-1,400 


forest 




1 1 ,000 


11.2 


Timor and associated islands 


Indonesia 


0-2,600 


forest 




26,000 


26.7 


Tanimbar and associated islands 


Indonesia 


0-1,750 


forest 




5,600 


31.1 


Talaud and Sangir Islands 


Indonesia 


0-1,700 


forest 




1,600 


7.1 


Sulawesi mountains 


Indonesia 


500-3,000 


forest 




24,000 


30.8 


Sulawesi lowlands 


Indonesia 


0-2,000 


forest 




24,000 


16.9 


Banggai and Sula Islands 


Indonesia 


0-2,300 


forest 




6,900 


11.9 


Buru 


Indonesia 


0-1,750 


forest 




8,000 


18.4 



188 



Centres of Species Diversity 



Table 15.7 Endemic bird areas of the world 

NAME POLITICAL UNIT(S) ALTITUDE (m) HABITAT(S| 

SOUTH-EAST ASIAN ISLANDS AND AUSTRALIA (continued) 



Seram 

Halmahera 

West Papuan Islands and Vogelkop 

lowlands 

Vogelkop mountains 

Geelvink Bay Islands 

North New Guinean mountains 

North New Guinean lowlands 

Adalbert and Huon mountains 
Central New Guinean high mountains 

Central New Guinean mid mountains 

Trans-Fly and Upper Fly 

Christmas Island 

Kimberley and the Top End 

Cape York 

Atherton region 

South-west Australia 

Murray-Darling region and adjoining 

coast 

South-east Australia 

Tasmania 

NORTH AND CENTRAL AMERICA 

California 
Guadalupe Island 
Baja California 
Sierra Madre Occidental 
North-west Mexican Pacific slope 
Sierra Madre Oriental 
North-east Mexican Gulf slope 
Central Mexican marshes 
Yucatan Peninsula 

Revillagigedo Islands 
Central Mexican highlands 
Sierra Madre del Sur 
Isthmus de Tehuantepec 
North Mesoamerican highlands 

North Mesoamerican Pacific slope 



South Central American Caribbean 

slope 

South Central American Pacific slope 

Costa Rican and Panamanian 

highlands 

North Choco and Darien lowlands 

Oarien highlands 

Cocos Isles 

Cuba and the Bahamas 

Jamaica 



Indonesia 
Indonesia 
Indonesia 

Indonesia 

Indonesia 

Indonesia, Papua New 

Guinea 

Indonesia, Papua New 

Guinea 

Papua New Guinea 

Indonesia, Papua New 

Guinea 

Indonesia, Papua New 

Guinea 

Indonesia, Papua New 

Guinea 

Christmas Island 

Australia 

Australia 

Australia 

Australia 

Australia 

Australia 
Australia 

USA 

Mexico 

Mexico 

Mexico, USA 

Mexico, USA 

Mexico, USA 

Mexico, USA 

Mexico 

Belize, Guatemala, 

Honduras, Mexico 

Mexico 

Mexico 

Mexico 

Mexico 

Belize, El Salvador, 

Guatemala, Honduras, 

Mexico, Nicaragua 

Mexico, Guatemala, El 

Salvador, Nicaragua, 

Honduras 

Costa Rica, Guatemala, 

Nicaragua, Panama 

Costa Rica, Panama 

Costa Rica, Nicaragua, 

Panama 

Colombia, Costa Rica, 

Panama 

Colombia, Panama 

Costa Rica 

Bahamas, Cuba, Turks 

and Caicos Is 

Jamaica 



0-1,750 


forest 




0-1,750 


forest 




0-900 


forest 




600-3,000 


forest 




0-700 


forest. 


mixed 


600-2,200 


forest 





0-900 forest 



SIZE (km^) 



1 4,000 
29,000 
1 4,000 

26,000 

3,200 

1 1 ,000 

32,000 



500-3,500 


forest 


19,000 


2,700-4,600 


forest, mixed 


6,800 


500-3,800 


forest 


98,000 


0-1,000 


forest, wetland 


64,000 


0-350 


forest 


140 


0-1,700 


rocky, mixed 


105,000 


0-500 


mixed 


43,000 


0-1,700 


forest 


28,000 


0-500 


mixed 


1 1 5,000 


0-500 


scrub, mixed 


98,000 


0-1,200 


forest 


85,000 


0-1,600 


forest, mixed 


68,000 


0-550 


forest, scrub 


30,000 


0-1,300 


mixed 


280 


0-1,000 


mixed 


17,000 


1,200-3,050 


forest 


36,000 


0-1,000 


forest, scrub 


1 4,000 


1,800-3,500 


forest 


1 6,000 


0-1,000 


mixed 


77,000 


1,500-2,500 


wetland 


10,000 


0-300 


forest, scrub 


138,000 


0-3C0 


scrub, forest 


280 


900-3,500 


scrub, forest 


41,000 


300-2,000 


forest, scrub 


18,000 


0-1,000 


scrub, forest 


7,700 


600-3,000 


forest 


68,000 



0-1,050 forest, scrub 15,000 

0-1,200 forest 25,000 

0-1,500 forest 24,000 

600-3,350 forest 27,000 

0-1,000 forest 14,000 

600-1,600 forest 

0-700 forest, scrub 

0-2,000 forest, scrub 

0-2,200 forest, scrub 11,000 



SPP.R 



19.3 
32.5 
11.6 

13.3 
9.6 
4.5 

7.1 

8.3 
13.5 

32.8 

6.6 

2.0 
13.0 

4.3 
14.8 
13.5 

5.5 

9.5 
15.0 

3.0 
2.0 
3.0 
3.5 
9.0 
2.0 
4.0 
2.0 
15.1 

5.0 

15.8 

6.3 

2.3 

21.0 



3.0 

8.0 

13.0 
52.5 

10.0 



4.200 


13.5 


47 


3.0 


93,000 


21.3 



30.3 



189 



1. Biological Diversity 



Table 15.7 Endemic bird areas of the world 

NAME POLITICAL UNITIS) 

NORTH AND CENTRAL AMERICA (continued) 



Hispaniola 

Puerto Rico 
East Caribbean 



SOUTH AMERICA 

North Choco and Darien lowlands 

Darien highlands 
Gulanas 

Tepuis 

Cordillera de Caripe and Paria 

Peninsula 

North Venezuelan mountains 

Venezuelan llanos 

Merida mountains 

Guajiran lowlands 

Santa Marta Mountains 

Nechi lowlands 

Eastern Andes of Colombia 

Upper Rio Negro white sand forests 

Cauca valley 

Magdalena valley 

Choco 

Western Andes of Colombia and 

Ecuador 

Galapagos Islands 

Central Andes of Colombia and 

Ecuador 

Eastern Andes of Ecuador 

Napo lowlands 

Ecuadorian dry forests 

North Peruvian cloudforests 

Maranon valley 

North-east Peruvian riverine forests 

East cordilleran ridgetop forests 

East Peruvian Cordilleras 

North Peruvian coast 

Western Andes of Peru 

Junin grasslands 

Eastern Andes of Peru 
South-east Peruvian lowlands 
South-east Peruvian Andes 
South Peruvian Pacific slope 
Upper Bolivian yungas 
Lower Bolivian yungas 
Bolivian Andes 
East Bolivian lowlands 
North Argentinian Andes 



Dominican Republic, 
Haiti 

Puerto Rico 
Antigua and Barbuda, 
Anguilla, Netherlands 
Antilles, Barbados, 
Dominica, Grenada, 
Guadeloupe, St Kitts- 
Nevis, St Lucia, 
Martinique, Montserrat, 
St Vincent and 
Grenadines, British 
Virgin Is, Virgin Is (US) 



Colombia, Costa Rica, 
Panama 



ALTITUDE (m) HABITAT(S) 



0-3,000 forest, scrub 

0-1,200 forest, mixed 
0-1,500 forest, scrub 



SIZE (km") 



76,000 

9,000 
6,600 



0-1,000 forest 



14,000 



SPP.R. 



26.1 



17.9 
30.3 



10.0 



Colombia, Panama 


600-1,600 


forest 


4,200 


13.5 


Brazil, French Guiana, 


0-1,100 


forest 


174,000 


11.5 


Guyana, Suriname 










Brazil, Guyana, 


500-2,800 


forest 


35,000 


39.0 


Venezuela 










Venezuela 


700-2,500 


forest 


4,000 


8.6 


Venezuela 


750-2,400 


forest 


7,100 


11.3 


Colombia, Venezuela 


0-1,100 


savanna, mixed 


57,000 


2.0 


Venezuela 


750-4,000 


forest 


18,000 


18.0 


Colombia, Venezuela 


0-600 


scrub, forest 


36,000 


10.5 


Colombia 


750-4,600 


forest 


5,400 


17.6 


Colombia 


0-1,500 


forest 


28,000 


8.5 


Colombia, Venezuela 


900-5,200 


forest, wetland 


67,000 


22.2 


Colombia, Venezuela 


100-500 


forest 


10,000 


11.5 


Colombia 


600-2,700 


forest 


19,000 


7.5 


Colombia 


200-2,700 


forest 


29,000 


8.0 


Colombia, Ecuador 


0-1,200 


forest 


59,000 


17.0 


Colombia, Ecuador 


500-3,300 


forest 


27,000 


37.7 


Ecuador 


0-1,300 


scrub, forest 


8,000 


23.0 


Colombia, Ecuador 


2,100-5,200 


forest, mixed 


37,000 


15.8 


Colombia, Ecuador, Peru 


400-2,000 


forest 


24,000 


13.0 


Brazil, Ecuador, Peru 


100-600 


forest 


1 29,000 


8.0 


Ecuador, Peru 


0-2,000 


forest, scrub 


57,000 


47.5 


Ecuador, Peru 


1,500-3,200 


forest 


9,200 


6.0 


Peru 


200-2,400 


forest, scrub 


1 1 ,000 


11.0 


Peru, Ecuador 


100-450 


forest 


1 1 ,000 


2.0 


Ecuador, Peru 


1,000-2,400 


forest 


8,900 


6.5 


Peru 


1,900-3,700 


forest 


44,000 


22.0 


Ecuador, Peru 


0-500 


scrub, mixed 


31,000 


5.5 


Peru 


1,800-4,300 


scrub, forest 


59,000 


20.0 


Peru 


3,700-5,000 


wetland, 
grassland 


17,000 


4.0 


Peru 


700-1,600 


forest 


1 1 ,000 


6.5 


Brazil, Peru 


1 00-400 


forest 


155,000 


14.0 


Peru 


2,500-4,300 


forest, scrub 


13,000 


11.0 


Chile, Peru 


0-3,000 


scrub, mixed 


76,000 


8.0 


Bolivia, Peru 


1,800-3,700 


forest 


19,000 


15.0 


Bolivia, Peru 


700-2,400 


forest 


38,000 


20.5 


Argentina, Bolivia, Peru 


1,400-4,600 


scrub, forest 


32,000 


13.0 


Bolivia, Brazil 


200-750 


forest, grassland 


93,000 


7.0 


Argentina 


2,000-4,000 


scrub, mixed 


17,000 


6.0 



190 



Centres of Species Diversity 



SIZE (km') SPP.R. 



Table 15.7 Endemic bird areas of the world 

NAME POLITICAL UNIT(S) ALTITUDE (m) HABITAT(S) 

SOUTH AMERICA (continued) 

Argentinian grasslands 

Argentinian Cordilleras 

Juan Fernandez Islands 

Central Chile 

Tierra del Fuego and the Falklands 

Central Amazonian Brazil 

West Amazonian Brazil 

Fernando de Noronha 

North-east Brazilian caatinga 

Alagoan Atlantic slope 

Bahian deciduous forests 

Mines Gerais deciduous forests 

Serra do Espinaco 

Bahian and Espirito Santo Atlantic 

slope 

South-east Brazilian lowland to 

foothills 

South-east Brazilian mountains 

South-east Brazilian Araucaria forest 

Entre Rios wet grasslands 
PACIFIC ISLANDS 

Mariana Islands 

Yap 

Palau Islands 

MIcronesian Islands 

Admiralty islands 

St Matthias Islands 

New Britain and New Ireland 

D'Entrecasteaux and Solomon Sea 

Islands 

Loulsiade Archipelago 

Solomon Islands 

San Cristobal 

Rennell Island 

Vanuatu and the Santa Cruz Islands 

New Caledonia and the Loyalty Islands 

Samoan Islands 

Fijian Islands 

Norfolk Island 

Lord Howe Island 

New Caledonia North Island 

South Island 

Auckland Islands 

New Caledonia Islands 

Northwestern Hawaiian Islands 

Hawaiian Islands 

Hawaii 

Marquesas Islands 

Society Islands 

Tuamotu Archipelago 

Lower New Caledonia Islands 

PItcairn Islands 

Note: Spp. R. is an index of the numbers of restricted-range species occurring in each EBA taking into account (he sharing of qjecies between 

EBAs. 

Table supplied by ICBP 



Argentina 


100-500 


scrub, wetland 


34,000 


3.0 


Argentina 


1,600-2,900 


grassland, mixed 


10,000 


3.0 


Chile 


0-1,300 


forest, scrub 


180 


3.0 


Argentina, Chile 


0-1,600 


forest, scrub 


137,000 


10.0 


Argentina, Chile, 


0-1,200 


grassland. 


119,000 


9.0 


Falklands 




wetland 






Brazil 


0-300 


forest 


35,000 


16.0 


Brazil 


0-400 


forest 


30,000 


2.0 


Brazil 





forest, scrub 


26 


2.0 


Brazil 


0-900 


forest, scrub 


100,000 


9.5 


Brazil 


0-1,000 


forest 


30,000 


13.7 


Brazil 


250-900 


forest 


8,000 


2.5 


Brazil 


300-500 


forest 


10,000 


2.0 


Brazil 


700-1,600 


grassland, scrub 


30,000 


5.5 


Brazil 


0-600 


forest 


40,000 


10.7 


Argentina, Brazil, 


0-1,500 


forest 


50,000 


44.2 


Paraguay 










Brazil 


500-2,200 


forest 


65,000 


22.5 


Argentina, Brazil, 


0-1,000 


forest 


30,000 


4.0 


Paraguay 










Argentina, Uruguay 


0-200 


wetland 


25,000 


3.0 


Guam, N Marianas 


0-950 


forest, mixed 


1,000 


10.8 


Micronesia 


0-180 


mixed, forest 


56 


4.2 


Palau 


0-240 


forest, mixed 


500 


12.0 


Micronesia 


0-800 


forest, mixed 


580 


13.1 


Papua New Guinea 


0-700 


forest, mixed 


1,900 


8.6 


Papua New Guinea 


0-650 


forest, mixed 


300 


4.5 


Papua New Guinea 


0-2,200 


forest, mixed 


46,000 


41.4 


Papua New Guinea 


0-2,200 


forest, mixed 


3,400 


2.9 


Papua New Guinea 


0-800 


forest 


1,300 


5.7 


Papua New Guinea, Solomon 
Is 


0-2,500 


forest 


32,000 


51.3 


Solomon Is 


0-2,000 


forest 


3 300 


19.0 


Solomon Is 


0-110 


forest, mixed 


840 


7.3 


Solomon Is, Vanuatu 


0-1,800 


forest, mixed 


16,000 


20.4 


New Caledonia 


0-1,600 


forest, mixed 


19,000 


23.3 


American Samoa, Samoa 


0-1,200 


forest, mixed 


3,000 


11.7 


Fiji 


0-1,200 


forest, mixed 


18,000 


27.8 


Australia 


0-320 


forest, mixed 


35 


4.0 


Australia 


0-760 + 


forest, scrub 


17 


2.0 


New Zealand 


0-2,000 


forest 


41,000 


1.5 


New Zealand 


0-2,500 


forest, mixed 


43,000 


8.5 


New Zealand 


0-600-1- 


grassland 


570 


1.0 


New Zealand 


0-270 + 


mixed 


960 


5.0 


USA 


0-300 


scrub, mixed 


5 


4.0 


USA 


0-3,100 


forest 


6,200 


20.5 


USA 


0-3,100 


forest 


10,000 


11.5 


French Polynesia 


0-1,200 


forest 


1,000 


10.5 


French Polynesia 


0-1,700 


forest, mixed 


400 


5.3 


French Polynesia 


0-110 


forest, plantation 


690 


7.3 


French Polynesia 


0-700 


forest, mixed 


190 


6.6 


Pitcairn 


0-33 


forest 


36 


3.5 



191 



1. Biological Diversity 

16. SPECIES EXTINCTION 



Species extinction is a natural process. The fossil record 
suggests that all species have a finite lifespan and that the 
vast majority of species that have ever existed are now 
extinct, with extinct species outnumbering living species by 
a factor of perhaps a thousand to one. 

Species become extinct when all individuals die without 
producing progeny. They disappear in a different sense 
when a species lineage is transformed over evolutionary 
time, or divides into two or more separate lineages (so- 
called pseudo-extinction). The relative frequency of true 
extinction and pseudo-extinction in evolutionary history is 
unknown, although the former's great importance is 
demonstrated by the disappearance of entire, and once 
highly diverse, lineages such as trilobites and ammonites. 

HOW SPECIES BECOME VULNERABLE TO 
EXTINCTION 

Two broad categories of process are believed to affect the 
dynamics of populations, and provide the fundamental 
mechanisms of species extinction: 

• deterministic processes (or cause and effect relationships) 
e.g. glaciation or direct human interventions such as 
deforestation 

• stochastic processes (chance or random events), which 
may act independently or influence variation in 
deterministic processes. 

The magnitude of the effects of these processes depends on 
the size and degree of genetic connectedness of populations. 
Four types of stochastic processes can be distinguished 
(Shaffer, 1987): demographic uncertainty (resulting from 
random events in the survival and reproduction of 
individuals); environmental uncertainty (due to 
unpredictable changes in weather, food supply, disease, and 
the populations of competitors, predators, or parasites); 
natural catastrophes (floods, fires or droughts); and genetic 
uncertainty (random changes in genetic make-up, to which 
several factors contribute). 

Models of the effects of stochastic processes suggest that: 

• demographic uncertainty is only a hazard for relatively 
small populations (numbering tens or hundreds of 
individuals) 

• there is no critical population size that once reached 
guarantees a high level of long-term security from 
environmental uncertainty 

• progressively larger increases in population size yield 
diminishing returns in persistence times for a given 
catastrophic event. 

When demographic and environmental uncertainty interact, 
their effects compound each other, so that in a variable 
environment any loss in population size proportionally 
increases the chance of population extinction. Thus, to be 
reasonably certain of conserving a species for a significant 
length of time, one must preserve either very large 
population sizes (hundreds to millions of individuals or 
more, depending on the biology of the species) or numerous 
populations (Schaffer, 1987). 



The isolation of populations 

The 'equilibrium theory' of island biogeography developed 
by MacArthur and Wilson (1963 and 1967) is an extension 
of the species-area relationship (see Chapter 5). Whilst 
originally used to model species richness and turnover on 
real islands, it has subsequently been used to predict 
changes in species number in isolated habitat islands. 

The area of an island sets an upper limit to the maximum 
population size of each species. Since small populations are 
inherently more prone to extinction than large (for reasons 
discussed above), extinction rates tend to be inversely 
proportional to island area. Successfiil colonisation by new 
species is not affected so much by area as by the degree of 
isolation of the island: islands near to the mainland or to 
other islands are colonised at higher rates than those farther 
away. Increased isolation of populations not only reduces 
the incidence of colonisation by new species, but decreases 
the probability that immigrants of an existing species will 
arrive. Over time, an equilibrium is eventually reached on 
any island at which the loss of species through extinction is 
balanced by the arrival and colonisation of new species. 

A later modification of the theory incorporates the 'rescue 
effect' (Brown and Kodric-Brown, 1977). The immigration 
of new, unrelated individuals can play an important role in 
maintaining an isolated population, because their 
demographic and genetic contributions tend to increase its 
size and genetic fitness, thereby reducing the possibility that 
it will become extinct. The significance of the rescue effect 
is that fewer immigrants are needed to rescue an existing 
population than to successfully found a new one. 

Island biogeographic theory has far-reaching implications 
for conservation biology. Rates of habitat modification are 
currently so high that virtually all natural terrestrial habitats 
and protected areas are destined to become ecological 
'islands' in surrounding 'oceans' of habitat much altered by 
human activity. Not only is the total area of many natural 
habitats rapidly decreasing, but those large natural habitat 
islands that now exist are being fragmented into 
archipelagos of habitat islands. This process of 
fragmentation and isolation is predicted to lead directly and 
indirectly to accelerated species extinctions at both the local 
and global scales. 

Consequences of insularisation 

The combination of short- and long-term insulsu'isation 
effects is predicted to reduce the number of species to a 
lower equilibrium. A study of understorey birds in 
fragments of tropical forest ranging from 0.1 to 571ha in 
the Usarabara Mountains, Tanzania, found just this result 
(Newmark, 1991). Since separation, smaller forest 
fragments have lost more bird species than larger areas, and 
more isolated fragments have lost more species than those 
close to a source of potential colonists. Similarly, Klein 
(1989) observed communities of dung and carrion beetles 
(subfamily Scarabaeinae) in fragmented habitat patches of 
different sizes in the Amazon rain forest of Brazil. He 
found that forest fragments had lower species richness, an 



192 



Species Extinction 



(1989) observed communities of dung and carrion beetles 
(subfamily Scarabaeinae) in fragmented habitat patches of 
different sizes in the Amazon rain forest of Brazil. He 
found that forest fragments had lower species richness, an 
increased proportion of rare species, and sparser 
populations in comparison with continuous undisturbed 
forest. These differences were more pronounced in small 
fragments (< Iha) than large. 

Many researchers, however, are now convinced that 
calculation of rates of species loss in habitat islands or 
reserves using the species-area relationship is unjustified as 
a basis for detailed conservation recommendations. 
Boeckeln and Gotelli (1984) argue that the models 
developed ignore species identity, habitat heterogeneity and 
population sizes, and have such wide margins of error that 
they have low explanatory power and give uru'eliable 
estimates. For example, Soule et al. (1979) predicted on the 
basis of a simple species-area model that the Serengeti 
National Park will lose 50% of its large msunmals (some 15 
ungulate species) in the first 250 years of isolation, while 
Western and Ssemakula (1981) attempted to incorporate 
habitat diversity data and predicted that only one species 
will be lost. Zimmerman and Bierregard (1986) argue that 
beyond the ecological truism that species richness increases 
with area, the equilibrium theory of biogeography has 
revealed little that is of "real value for planning real 
reserves in real places". In designing reserves to protect 
Central Amazonian forest frogs, Zimmerman and 
Bierregard consider that critical breeding habitat and places 
that contain quality habitat at high density must be found 
before the reserve size question is addressed. In general, 
biologists need empirical studies that directly measure the 
effects of habitat fragmentation on specific groups (Klein, 
1989). 

Ecological correlates of vulnerability to extinction 

There is considerable evidence that the number of species 
in an isolated habitat will decrease over time, although the 
probable rates of such extinctions (and whether the 
equilibrium theory of island biogeography can be used to 
predict these) are in dispute. The crucial issue for 
conservationists now is whether those species which are 
most at risk from extinction following habitat fragmentation 
can be predicted from a knowledge of their biology and 
ecology. At least nine ecological or life history traits (some 
of which may actually be highly correlated with each other) 
have been proposed as factors determining an animal 
species sensitivity to fragmentation (Karr, 1991; Laurance, 
1991): 

Rarity 

Several studies have found that the abundance of a species 
prior to habitat fragmentation is a significant predictor of 
extinction. For example, Newmark (1991) found that after 
fi'agmentation, rare understorey bird species occupied fewer 
forest fragments per species than common ones. This is 
only to be expected, since fewer individuals of a rare 
species than a common species are likely to occur in habitat 
fragments, and the mechanisms of extinction mean that 
small populations are inherently more likely to become 
extinct than large. 



Dispersal ability 

If animals are capable of migrating between firagments or 
between 'mainland' areas and fragments, the effects of 
small population size may be partly or even greatly 
mitigated by the arrival of 'rescuers'. Species that are good 
dispersers may therefore be less prone to extinction in 
fragmented habitats than poor dispersers. 

Degree of specialisation 

Ecological specialists often exploit resources which are 
patchily distributed in space and time, and therefore tend to 
be rare. Specialists may also be vulnerable to successional 
changes in fragments and to the collapse of coevolved 
mutualisms or food webs. 

Niche location 

Species adapted to, or able to tolerate, conditions at the 
interface between different types of habitats may be less 
affected by fragmentation than others. For example, forest 
edge species may actually benefit from habitat 
fragmentation. 

Population variability 

Species with relatively stable populations are less vulnerable 
thaui species with pronounced population fluctuations, since 
they are less likely to decline below some critical threshold 
from which recovery becomes unlikely. 

Trophic status 

Animals occupying high trophic levels usually have small 
populations: e.g. insectivores are far fewer in number than 
their insect prey and, as noted above, rarer species are 
more vulnerable to extinction. 

Adult survival rate 

Species with naturally low adult survival rates may be more 
likely to become extinct, as Karr (1991) has proposed for 
island birds on Barro Colarado Island, Panama. 

Longevity 

Long-lived animals are less vulnerable to extinction than 
short-lived. 

Intrinsic rate of population increase 

Populations which can expand rapidly are more likely to 
recover after population declines than those which cannot. 

Laurance (1991) has, however, studied extinction proneness 
among 16 species of non-flying land mammals in 
fragmented rain forest in Queensland, Australia. Seven 
traits were examined: body size, longevity, fecundity, 
trophic level, dietary specialisation, natural abundance in 
continuous rain forest, and 'matrix' abundance (abundance 
of the species in modified habitats surrounding original 
fragments). Of these, matrix abundance was the best 
predictor of vulnerability. Once its effects were removed, 
partial correlations showed no other significant predictors 
of extinction proneness. 

Laurance therefore suggests that tolerance of modified 
habitats is important in determining survival in firagmented 
habitats. Species that were able to exploit modified habitats 
tended to remain stable or even to increase in number in 



193 



1. Biological Diversity 



fragments, whereas those that avoided these habitats tended 
to disappear. The most vulnerable species even avoided 
using the corridors of secondary growth forest that existed 
along streams, a finding which highlights the importance of 
maintaining corridors of primary vegetation to act as 
pathways for dispersing individuals between patches of 
habitat. 

Viable populations, genetic variation and extinction 

Increasingly the attention of conservationists has become 
focused on the management and preservation of isolated 
small populations confined to habitat islands, usually in 
protected areas. An essential requirement is to ascertain 
how many individuals of a species should be conserved in 
order to ensure its survival in a particular area. There are 
two approaches to estimating such a Minimum Viable 
Population (\{VP) size, the demographic and the genetic. 
The process of applying a demographic or genetic MVP 
model to a particular species or population, and proposing 
the management interventions that should be undertaken to 
increase its chances of survival, is known as Population 
Viability Analysis (PVA). 

In the demographic approach, estimates of a population's 
average growth rate (which is in part determined by the 
species's body size), the variance in this growth rate 
attributable to environmental fluctuations, and the 
population's maximum size, are used in mathematical 
models to calculate its expected persistence time to 
extinction. There are two main factors that need to be 
considered: the population size, and the length of time it 
requires to be preserved. Normally, an MVP is taken to be 
that size of population that has a 95% probability of 
persistence for x number of years, where for consistency x 
is usually taken as either 100 or 1,000. 

Clearly, there is no such thing as a standard MVP that can 
be applied to all species. Belovsky (1987) has calculated 
that over a range of body masses from lOg (the size of a 
European Common Shrew Sorex araneus) to lO'g (the size 
of a Black Rhinoceros Diceros bicornis), MVP sizes for 
mammals range from hundreds to millions. The Minimum 
Area Required (MAR) to support these populations ranges 
from tens to millions of square kilometres. As body mass 
increases, MVP size decreases, but larger mammals require 
proportionately larger ranges. MARs are larger for 
carnivores than for herbivores and larger for tropical than 
for temperate species. 

MVPs can also be examined firom a genetic perspective, in 
which not only the number of individuals surviving but their 
genetic variation or heterozygosity are considered 
important. In the long term, this genetic variation is 
necessary for evolution by natural selection to occur, and is 
required for adaptation to potential future changes in the 
envirotmient. In the short term, heterozygosity is positively 
correlated with fitness, including survival, disease 
resistance, growth and developmental rate and stability 
(Allendorf and Leary, 1986). 

Genetic variation can quickly be lost through breeding with 
closely-related individuals (inbreeding) which leads to low 
levels of heterozygosity and lowered offspring fitness, a 



phenomenon known as inbreeding depression (Falconer, 
1981). The most likely explanation is that new mutations, 
which are almost always harmful, can accumulate in a 
species genome providing they are fiiUy or partially 
recessive and are not therefore expressed. Inbreeding 
increases the probability that the effects of these harmful 
genes will be expressed. 

Franklin (1980) has proposed that in the short term an 
effective population size of 50 is the MVP required to 
guard against the negative effects of inbreeding for a 
population of large mammals with no immigration or 
introduction of unrelated stock. Populations of this size will 
nevertheless eventually become inbred over time, to a 
degree directly related to the generation interval (rimdomly- 
breeding populations of 50 mice will become more inbred 
in a decade than 50 elephants will in a century). In the long 
term an effective population size of 500, corresponding to 
a real population size of several times this number, has 
been suggested as a suitable genetic MVP for large 
mammals, since in a population of this size rates of 
mutation will renew genetic variation as quickly as it is lost 
by inbreeding and genetic drift (Franklin, 1980; Lande and 
Barrowclough, 1987). 

Although biologists have suggested the figures quoted above 
as useful first estimates of MVP sizes, in both the 
demographic and the genetic approach the actual numerical 
value arrived at depends not only on the criteria chosen to 
define the MVP (e.g. the number of years the population is 
required to persist) but also on the values of the parameters 
used in the model. These values cannot always be assigned 
in an objective manner. Thus even for one particular 
species there is no single number that is universally valid, 
and this reservation is doubly true when different species 
are compared. Each situation is unique and should be 
considered separately. For example, a species that exhibits 
a boom and crash population cycle will require a larger 
MVP than one which inhabits a stable environment and 
whose population is relatively stable. 

Both MVPs and PVAs have now been applied to a variety 
of species. Examples include: large mammals such as the 
Sumatran Rhinoceros Didermocerus sumatrensis and the 
Florida Panther Felis concolor coryi; and birds such as the 
Bali Starling Leucopsar rothschildi, Caribbean parrot 
species, and Asian Hornbills. 

Analysis of the existing worldwide protected areas system 
indicates that few if any large mammal species will be 
adequately conserved with the current scale of ecosystem 
coverage, as most protected populations are too small to 
constitute MVPs (Grumbine, 1990). 

The fact that a population has declined in number to below 
the theoretically determined MVP does not automatically 
mean that its situation should be considered hopeless. Some 
species, such as the Northern Elephant Seal Mirounga 
angustirostris (Bonner and Selander, 1974) and captive 
populations of Golden Hamster Mesocricetus auratus have 
survived through population bottlenecks of just a few 
individuals, following which numbers have increased to 
substantial levels. Eventually, if a large population is re- 
established, genetic variation may be regenerated by 
mutation, thus restoring the potential for adaptive evolution. 



194 



Species Extinction 



These examples, however, may be the exceptions rather 
than the rule. Other species that have declined to such low 
levels may have vanished altogether. Even if populations do 
recover numerically from a bottleneck, inbreeding and 
consequent loss of heterozygosity may cause noticeable 
declines in fitness effectively prejudicing the species long- 
term chances of survival. For example, O'Brien et at. 
(1985) found high rates of juvenile mortality, incidence of 
sperm abnormalities, and susceptibility to disease in several 
populations of Cheetah Acinonyxjubatus, and attributed this 
to the low level of genetic variation found in all Cheetah 
populations examined. 

Perhaps the most compelling evidence to date of the 
negative consequences of population bottlenecks comes from 
a study of Lion Panthera leo in Ngorongoro Crater and the 
neighbouring Serengeti Plains in Tanzania. In 1962 the 
relatively isolated Lion population in the Crater dropped 
from around 70 individuals to 10 as a result of an outbreak 
of biting flies Stomoxys calcitrans. The population has since 
recovered to its pre-plague levels. Packer et at. (1991) have 
found that compared to the larger outbred population of 
Serengeti Lions, those in Ngorongoro suffer high levels of 
sperm abnormality. Their reproductive performance has 
also diminished over the years since the bottleneck, and 
both effects are apparently correlated with the lower levels 
of heterozygosity in the Ngorongoro population. 

Metapopulation theory 

The MVP models discussed so far have considered all 
individuals as belonging to a single isolated population, 
which is rarely the case in the real world. In practice most 
species are patchily distributed, and are best regarded as a 
population of subpopulations, or a metapopulation, in which 
subpopulations are geographically isolated but 
intercormected by patterns of gene flow, extinction and 
recolonisation. Thus, studies over a 25-year period by 
Erhlich and colleagues of a purported single population of 
Checkerspot Butterfly Euphydryas editha bayensis in the 
Jasper Ridge Preserve (USA) demonstrated that although 
the population occupied three nearly contiguous habitat 
patches, it actually consisted of three demographic units 
whose sizes fluctuated independently in response to annual 
changes in rainfall. One of these units became extinct, was 
re-established by immigration, and became extinct again 
several years later (Wilcox and Murphy, 1985). Relaxing 
the single population assumption of the MVP model so that 
immigrants can be received from neighbouring populations 
will lengthen the projected persistence times. 

Habitat heterogeneity and the existence of many 
subpopulations are an important element of population 
dynamics, and have profound implications for conservation 
biology. Pulliam (1988) introduced a simple model of 
metapopulation dynamics incorporating density-dependent 
immigration as the linking factor between source and sink 
populations in severely fragmented habitats. In his model, 
a limited number of reproductively successful 'source' 
subpopulations produce an excess of offspring over and 
above the number that the habitat can absorb. The surplus 
individuals migrate to other less favourable areas, occupied 



by 'sink' subpopulations which would be doomed to 
extinction without persistent immigration. 

Supporting evidence for the source-sink metapopulation 
theory is available from a number of field studies; for 
example. King and Mewaldt (1987) found that isolated 
montane populations of White-crowned Sparrows 
Zonotrichia albicollis were unable to persist without 
periodic immigration. 

Metapopulation theory should help biologists determine 
which populations are priorities for conservation. The 
importance of identifying and preserving source populations 
and habitats is obvious: without them the metapopulation 
cannot persist. However, the presence of breeding 
individuals at a particular site does not necessarily indicate 
that it is suitable for the species in the long term, since it 
could still be a sink habitat. In general, source populations 
will not only have higher annual reproduction rates than 
annual mortality rates but will also have more stable 
populations than sink populations. In the case of long-lived 
species the identification of source populations will 
therefore necessitate continuous, long-term monitoring. In 
addition to the identification and protection of demographic 
source populations, the conservation of buffer habitats and 
marginal subpopulations should also be a part of 
comprehensive conservation plans, and the long-term status 
of even apparently secure metapopulations should be 
carefully monitored. 

Conclusion 

Current models of the extinction process and estimates of 
habitat loss, principally tropical forest, predict that species 
extinctions are occurring at very high rates on both a local 
and global scale. The primary cause is habitat modification 
and fragmentation by human activities. This process not 
only decreases overall population sizes of many species but 
splits previously continuous populations into smaller isolated 
sub-populations. Deterministic and stochastic effects mean 
that small populations are more susceptible to extinction 
than large. Conservation biologists have enlisted the help of 
various theories and models to try and predict how many 
species, and which ones, will be lost. It is possible to make 
reasonable predictions of which species will be most 
adversely affected by habitat fragmentation. 

The species-area relationship is not now thought to be a 
good predictor of species loss in habitat fragments, but has 
implications for the design and positioning of reserves. 
With a realisation that ecosystems are often best preserved 
by concentrating on keystone species, efforts have switched 
to conducting population viability analyses for selected 
species in an attempt to estimate the minimum viable 
population sizes that must be conserved to ensure their 
long-term survival. MVPs can be examined from either the 
demographic or genetic perspective - both approaches give 
estimates of a similar order of magnitude. A shortcoming 
of MVP estimates is that they consider only a single 
population. The incorporation of metapopulation theory 
should improve the accuracy and utility of these models, 
and allow the identification of the most important 



195 



/. Biological Diversity 



subpopulations, facilitating the determination of 
conservation priorities. 

A BRIEF fflSTORY OF EXTINCTIONS 

Knowledge of extinction patterns through geological time is 
based on analysis of the fossil record, which represents a 
small and highly biased sample of the taxa that have existed 
- it may represent only one in every 20,000 species that has 
existed. The best preserved group consists of marine 
animals, chiefly invertebrates, with durable, highly 
mineralised exoskeletons. Caution has to be exercised in 
extrapolating from this group to others, particularly plants, 
as they may show different patterns of extinction. 

Mass extinction events in marine organisms 

The fossil record indicates that overall extinction rates have 
not been constant over time (Fig. 16.1). Around 60% of 
extinctions have occurred in a number of relatively short 
episodes. The earliest period for which there is evidence of 
a major loss of diversity is during the late Precambrian, 
around 700 Mya (million years ago) although the 
Precambrian fossil record is too incomplete to allow 
detailed analysis. 

The fossil record for the Phanerozoic (i.e. from the 
Cambrian to the present, see Fig. 16.2) is much more 
detailed. During this time there have been five major 'mass 
extinction events'. These events toolc place late in each of 
the Ordovician, Devonian, Permian, Triassic and 
Cretaceous periods. By far the most severe was in the late 
Permian (245 Mya). At that time, the number of families of 
marine animals recorded in the fossil record declined by 
54% and the number of genera by 78-84%. Extrapolation 
from these figures indicates that species diversity may have 
dropped by as much as 96 % . The second most severe mass 
extinction, at the end of the Ordovician (440 Mya), resulted 
in the loss of 22% of families of marine taxa, a slightly 



Figure 16.1 Extinction events in marine 
organisms 



Figure 16.2 The geological time scale 



Era 



Per i od 



ni 






U 


an 




11 


,*' 


500 


- 






«n 


// 


#^-, y 




300 


t V*. 


^^^iM 




200 


^^^^ 


^^^^^^^MMl^^ 


I^^Ki 





^l| 


IBilllli 


^ 



Mi I I i ons of 
years ago 





Quaternary 



N 


n 


Ten i ary 


IT) 

N 


o 


Cretaceous 


Jurass i c 


Tr iassic 


0) 

Q) 
(D 

N 
O 

O 


Permi an 


Carbon i f erous 


Devon i an 


Si 1 ur i an 


Ordov i c i an 


Cambr i an 



Source: Modified from Erwin, D.H., Valentine, J.W. and Sepkoski, 
J.J. 1987. A comparative study of diversification events: the early 
Palaeozoic versus Ihe Mesozoic. Evolution 41(6). 

Note: The curve plots diversity of marine animal families 
and indicates five major extinction phases. 



66 



138 



195 



2-^5 



290 



34 5 



400 



440 



500 



530 



Note: Dates are approximate; scale covers the Phanerozoic only. 

greater figure than the late Devonian and late Triassic 
events (21% and 20% respectively). The late Cretaceous 
event was the least important, resulting in the loss of 
around 15% of marine families. 

The causes and timespans of these events have been the 
subject of much debate and study. It is now widely accepted 
that the late Permian mass extinction was a long-term event, 
lasting for 5-8 million years. It appears to have been 
associated with geologically-rapid global physical changes 
(including the formation of the supercontinent Pangea), 
climate change, and extensive, tectonically-induced marine 
transgression and increased volcanic activity. There is no 
direct evidence of a single, catastrophic event such as 
impact by an extra-terrestrial body, although this cannot be 



196 



Species Extinction 



ruled out as a contributory factor in the event. Interpretation 
of the late Triassic event is hampered by the absence of a 
good stratigraphic record; some indications suggest this was 
also a protracted period of extinction, although this is 
uncertain. The late Devonian extinction also appears to have 
spanned a considerable length of time, with elevated 
extinction rates throughout much of the middle and late 
Devonian. However, this extinction phase probably 
consisted of a series of discrete shorter extinction events 
rather than one protracted episode. 

Id contrast to these, the late Ordovician and late Cretaceous 
extinctions are thought to have taken place over a much 
shorter period. The late Ordovician event appears to be 
correlated with global glaciation 439 Mya (the Hirnantian 
glaciation) with three separate episodes of extinction spread 
over only 500,000 years. 

The late Cretaceous extinction is probably the best known, 
but in terms of overall loss of diversity is also the least 
important. There is some evidence that this extinction event 
was associated with an extra-terrestrial impact, although this 
remains controversial. 

As well as these major mass extinction events, a large 
number of less dramatic, but still significant, episodes can 
be identified from the marine fossil record. It has been 
argued that those following the late Permian extinction 
event have a periodicity of 26-28 million years, indicating 
some underlying unifying cause, although this remains 
unproven. It is notable that these more minor events 
account in total for more extinctions than the five major 
events outlined above. 

Mass extinctions in vertebrates 

The vertebrate fossil record, especially for terrestrial 
tetrapods, is much less amenable to analysis of extinction 
rates than the invertebrate record chiefly because it is less 
complete and less diverse. However, studies indicate that 
tetrapods have been subject to at least six mass extinction 
events since their appearance in the late Devonian, while 
fishes have experienced eight such events since their 
recorded origin in the Silurian. Some of these events 
coincide with each other and with those recorded for marine 
invertebrates; in particular, the five major mass extinction 
events outlined above are paralleled by losses in vertebrate 
diversity. The most significant is the late Permian event, 
which is the largest recorded extinction both for fishes 
(44% of families disappearing from the fossil record) and 
tetrapods (58% of families disappearing). The late 
Cretaceous event was more significant for tetrapods than for 
other groups, with 36 of the 89 families in the fossil record 
disappearing at this time. These families were, however, 
virtually confined to three major groups which suffered 
complete extirpation - the dinosaurs, plesiosaurs and 
pterosaurs. Most other major vertebrate taxa were almost 
completely unaffected. 

Evidence for correlation between the more minor extinction 
events in vertebrates and the postulated periodic extinctions 
in marine invertebrates is currently poor. 



Extinctions in vascular plants 

In general, the plant fossil record does not clearly show the 
same sudden mass-extinction events seen in the animal 
record. Part of the explanation for this may lie in the nature 
of the plant fossil record itself and in the difficulties in 
interpreting it, but there also seem likely to be genuine 
differences between plants and animals in patterns of 
species origination and extinction. Plant extinction rates 
(based on analysis of families and genera) do vary with 
time, but in general, periods of elevated plant extinction 
appear to be more protracted than animal extinction events 
and do not usually coincide with them. It is argued that 
these periods may be more to do with competitive 
displacement by more developed plant forms, or with 
gradual climatic change, than with any sudden catastrophic 
events (Knoll, 1984). 

The major exception to this is the end-Cretaceous 
catastrophe, which appears to have had a major influence 
on the structure and composition of terrestrial vegetation 
and on the survival of species. Data from fossil leaves 
suggest that perhaps 75 % of late Cretaceous species became 
extinct, although data from fossil pollens indicate a lower 
though still significant level of extinction. During the 
Tertiary there are two other periods of widespread enhanced 
extinction rates, during the late Eocene and from the late 
Miocene to the Quaternary, although in the latter, extinction 
of taxa at generic level and above appears to have been 
mainly regional rather than global. 

Background extinction rates 

A corollary of the finding that the majority of extinctions 
recorded in the fossil record have taken place over 
relatively short time periods (geologically speaking) is that 
extinction rates for the remainder of the Phanerozoic have 
been low. 

The average lifespan of species in the fossil record is 
around four million years which would give, at a very gross 
estimate, a background extinction rate of four species each 
year out of a total number of species of around 10 million. 
However, it can be argued that the fossil record is heavily 
biased towards successful, often geographically wide- 
ranging, species which undoubtedly have a far longer than 
average persistence time. Most species will therefore 
survive for less than four million years, and real extinction 
rates at any given time will be correspondingly higher. 
Nevertheless, even if background extinction rates were ten 
times higher than this, extinctions amongst the 4,000 or so 
living mammals would be expected to occur at a rate of 
around one every 400 years, and amongst birds at one 
every 200 years. 

It is indisputable that the extinction rate in recent times has 
been far higher than this and that man has been the 
overwhelming cause. It is also widely accepted that 
mankind is in danger of precipitating fiirther extinctions on 
a scale and at a rate at least comparable with those of the 
major extinction events in the distant past. 



197 



1. Biological Diversity 



Extinctions and the spread of mankind 

Documenting man's impact on the world's biota, and in 
particular quantifying species extinctions induced by man, 
is difficult for a variety of reasons, associated with: 
identifying species, especially those known only from sub- 
fossil or fossil remains; unequivocally demonstrating that 
extinction has occurred; and establishing a causal link 
between man's activities and extinction of the species in 
question. 

Man may have first had a sigtuficant impact on the survival 
of other species during the late Pleistocene. Humans spread 
into Europe and Asia about one million years ago but slow 
advances in culture and technology seem to have restricted 
the impact on the fauna of these regions. However, man's 
arrival on previously isolated continents, around 50,000 
years ago in the case of Austreilia and 1 1 ,000 years ago for 
North and South America, seems to coincide with large- 
scale extinctions in certain taxa. The exact timings are 
unclear and hence the cause and effect in each case are 
open to debate. However, Australia lost nearly all its 
species of very large mammals, giant snakes and reptiles, 
and nearly half its large flightless birds around this time. 
Similarly, North America lost 73 % and South America 80% 
of their genera of large mammals at around the time of the 
arrival of the first humans. In these cases there is more 
direct evidence to link the events, although climatic 
upheavals at around the same time could also be implicated. 

EXTINCTIONS IN RECENT fflSTORY 

The European Age of Expansion in the 15th and 16th 
centuries initiated another wave of extinctions. Indeed it has 
often been assumed that all, or at least the great majority, 
of modern man-induced extinctions date from this period. 
However, this may well be based more on the fact that a 
dramatic increase in documentation of natural phenomena, 
in large measure induced by the great voyages of discovery, 
also dates from this time. 

It is now known that in some parts of the world a 
significant number of extinctions occurred before the arrival 
of Europeans. The Polynesians, who colonised the 
Hawaiian Islands in the 4th and 5th centuries AD, appear 
to have been responsible for exterminating around 50 of the 
100 or so species of endemic land birds in the period 
between their arrival and that of the Europeans in the late 
18th century. A similar impact seems to have been felt in 
New Zealand, which was colonised some 500 years later 
than Hawaii. Here an entire avian megafauna, consisting of 
members of the family Anomalopterygidae (the Moas) was 
apparently exterminated, also by the end of the 18th 
century. As with the late Pleistocene extinctions, there has 
been some controversy over the extent to which humans 
were responsible; however there is now a broad consensus 
that man was indeed responsible, probably through a 
combination of direct hunting and large-scale habitat 
destruction through burning. 

Although most information from this period relates to avian 
extinctions, there is evidence that other groups, particularly 
mammals, had been similarly affected. On Madagascar, in 
addition to 6-12 ratites, including the Giant Elephantbird 



Aepyornis maximus (the largest bird ever recorded), at least 
14 lemur species, most of them larger than any surviving 
species, have become extinct within the last 1,500 years, as 
have two giant tortoises. In the Caribbean, at least two 
ground sloths in the family MegaJonychidae, several large 
rodents and three insectivores in the family Nesophontidae 
survived into the period of Amerindian settlement, but had 
become extinct before Europeans arrived at the end of the 
I5th century. The case for man being solely responsible for 
these extinctions is more equivocal than it is for New 
Zealand. However, on balance this appears to remain the 
most likely explanation, although it is possible that, on 
Madagascar at least, climate change leading to progressive 
desiccation of the environment also played a part. 

While documentation has improved considerably since the 
15th and 16th centuries, it still remains far from complete. 
This applies even to the best known groups, namely birds 
and mammals; for most lower vertebrates and virtually all 
invertebrates knowledge of extinction rates remains 
extremely scanty. 

The main problem for documentation is that the majority of 
the world's species, especieilly tropical invertebrates, have 
not been scientifically named. A significant percentage of 
these may well become extinct before they have ever been 
collected and described. Of described taxa, numbering 
eiround 1 . 1 million animal species and around 270,000 
vascular plants, accurate information on status and 
abundance is available for only a tiny proportion. The vast 
majority of the world's species, even in the best-known 
groups such as mammals and birds, are not subject to 
systematic monitoring and species may be locally or 
completely extirpated before their plight becomes known. 

In general, it can only be stated with smy confidence that a 
taxon is extinct when unsuccessful attempts have been made 
to locate it, or when it has not been sighted for several 
decades. Animal species thought to have become extinct, 
using this criterion and expert opinion, are listed in Table 
16.1. Even here it is often difficult to demonstrate 
unequivocally that a species has become extinct and 
consequently several species are marked as possibly still 
being extant. Many species may persist unrecorded (albeit 
often in very low numbers) despite intensive efforts to 
locate them. This is borne out by the periodic reappearance 
of 'Lazarus taxa', after many years or decades of presumed 
extinction. Plants (Table 16.2), some of which produce 
seeds that can lie dormant and undetected for many years 
before germination, present particular monitoring problems. 

Historical records of extinctions may thus be expected to be 
heavily biased, both taxonomically and geographically. 
Taxonomically,informationon snails, particularly terrestrial 
species, birds and mammals is good, while that for most 
other groups is poor. Geographically, information on 
Europe and North America (including Hawaii) is much 
better than that for the rest of the world, although relatively 
few species extinctions have been recorded in Europe in 
recent times. Figures 16.6-16.10, taken from Table 16.6, 
illustrate these biases. 

These biases make analysis of extinction patterns 
problematic. However, certain generalised patterns do 



198 



Species Extinction 



Table 16.1 Si 


jmmaries of anim; 


al extinctions on 


islands an 


d continents 






MOLLUSCS 


BIRDS 


MAMMALS 


OTHER 


TOTAL 


ISLANDS 


151 


104 


34 


74 


363 


% of islands total 


41.6 


28.7 


9.4 


20.4 


100 


% of grand total 


31.2 


21.5 


7 


15.3 


75 


CONTINENTS 


40 


11 


24 


46 


121 


% of continents total 


33.1 


9.1 


20 


38 


100 


% of grand total 


8,3 


2.3 


5 


9.5 


25 


TOTALS 


191 


115 


58 


120 


484 


% of total on islands 


79 


90.4 


59 


61.7 


75 


% of TOTALS 


39.5 


23.8 


12 


24.8 


100 



Note; these summaries do not lake inlo accouDi 4 species (2 birds, 1 mammal aod one 'other') which are not assignable to either island or continent. 



emerge. The most important of these is the preponderance 
of extinctions on islands over those in continental areas 
(Table 16.1). Exactly 75% of recorded animal extinctions 
since 1600 have been on islands. For the three groups with 
best information, the proportion of island extinctions varies 
from 90% for birds to 58% for mammals, with molluscs 
intermediate at 80 % . Of the continental extinctions, at least 
66% can be classified as aquatic species (this includes 
amphibians and insects with aquatic larval stages but 
excludes birds such as ducks and grebes). Most striking, 
perhaps, is the very small number of extinctions recorded 
to date in continental tropical forest ecosystems, which are 
precisely the areas where mass extinction phenomena are 
predicted to be taking place at present (see below). 

There appear to be several reasons for the elevated 
extinction level amongst island species. Most 
straightforwardly, island species, especially those confined 
to single islands, tend to have very restricted and 
completely circumscribed ranges: they consist effectively of 
single populations. Adverse factors are thus likely to affect 
the entire species and bring about its extinction. In contrast, 
continental species tend to occupy larger ranges existing as 
meta-populations, with a number of more-or-less isolated 
subpopulations. It is likely that some of these 
subpopulatioQS will not be affected by a given adverse 
factor. Thus, the species itself will survive even if a number 
of subpopulations are extirpated. These concepts apply both 
to real islands and ecological islands, that is, areas of 
habitat separated from other such areas by inhospitable 
environments which act as an effective barrier to dispersal. 
In this context, aquatic species in isolated inland waters 
behave similarly to terrestrial species on isolated oceanic 
islands, which helps to explain the significantly elevated 
number of extinctions amongst continental freshwater 
species. 

Many island species are iimately vulnerable to extinction 
because of their biology. Species on islands have often 
evolved in the absence of terrestrial predators and may 
therefore be highly vulnerable to introduced predators. 
Tameness, flightlessness and reduced reproductive rates 
characterise many island birds and appear to have been 
major contributory factors in their extinction, through 
predationby humans or introduced species. Similarly, many 
island land snails, such as the Hawaiian Achatinella and 
French Polynesian Partula species, have low reproductive 
rates and, apparently, no defences against introduced 



predators, most notably the snail Euglandina. The elevated 
species extinction rates on islands can also be ascribed to 
taxonomic practices, as there has been a tendency for island 
populations to be designated as full species when they may 
more reasonably be regarded as subspecies of species on 
adjacent islands or on the mainland. 

Causes of Extinction 

A brief analysis of the 'Possible causes' column of Table 
16.4 shows that introduced animals and direct habitat 
destruction by man have been major factors involved in 
these extinctions, being implicated in 17% Jind 16% 
respectively (see Fig. 16.3). These are equivalent to 39% 
and 36% if only those extinctions for which causes are 
assigned are counted. Hunting and deliberate extermination 
also contribute significantly (23 % of extinctions with known 
cause). For a large number of animals, no information on 
cause of extinction was known. 

Figure 16.3 Causes of animal extinction 



cause assigned 




"Habitat destruction C B) 



Notes: These figures were compiled by giving each species a score of 
I in the appropriate category if there was only one cause, 0.5 in each 
for two. etc. Where there were multiple causes C/D was counted as 
one part, C and D as two parts. 

Time Series 

Figures 16.4 and 16.5 and Table 16.2 present a breakdown 
of recorded extinctions in 30-year intervals from the year 



199 



1. Biological Diversity 



Table 16.2 Time series of animal extinctions on islands and continents 



TOTALS 

1600-1629 


MOLLUSCS 
151 




BIRDS 
104 
2 


ISLANDS 
MAMMALS 
34 




OTHER 
74 

1 


TOTAL 
303 

3 


MOLLUSCS 
40 




BIROS 
11 




CONTINErnS 
MAMMALS 
24 




OTHER 
46 




TOTAL 
121 




COMBINED 

TOTAL 

4S4 

3 


1630-1659 





4 





1 


5 

















5 


1660-1689 





9 








9 

















9 


1690-1719 





5 





2 


7 

















7 


1720-1749 





4 








4 

















4 


1750-1779 





10 


1 





11 

















11 


1780-1809 





2 





4 


6 








1 





1 


7 


1810-1839 





8 





1 


9 





1 


2 





3 


12 


1840-1869 


2 


9 


2 


3 


16 





1 


1 


1 


3 


19 


1870-1899 


67 


16 


3 


4 


90 





1 


6 


1 


8 


98 


1900-1929 


11 


19 


3 


18 


51 


6 


4 


3 


7 


20 


71 


1930-1959 


37 


10 


Z 


6 


55 


25 


2 


7 


15 


49 


104 


1960- 


9 


5 


3 


7 


24 


4 


2 


2 


12 


20 


44 


Nodate 


25 


1 


20 


27 


73 


5 





2 


10 


17 


90 



Note: these summaries do not take into account 4 species (2 birds. I mauimal and 1 'other') which are not assignable to either island or continent. 



1600. These data should be interpreted cautiously. In only 
a few cases are the extinction dates reasonably certain; 
more often they are approximate to within one or two 
decades. In other cases, they are simply the date when the 
species was last recorded, and it is unknown how accurately 
they reflect the actual date of extinction (assuming the 
species is truly extinct). The uncertainties are most marked 
for species in areas which have only been occasionally 
surveyed (e.g. land snails on many tropical islands), and 
create difficulty in interpreting trends in extinction rates. 

Of the individual taxa presented, island birds are the best 
documented group. There is no consistent trend over the 
full 400 years; peaks occur in the mid-17th and mid-1 8th 
centuries, and there is a clearer increase for the early 19th 
century until the 1930s. The apparent fluctuations for the 
first 200 years may represent real effects from introduced 
species, hunting and habitat modification associated with 
increasing levels of human settlement. Continental bird 
extinctions and the entire mammal data set are numerically 
smaller and thus harder to interpret. Of the 14 dated 
mammalian extinctions on islands, 13 have taken place 
since 1840. Most of the 20 undated mammalian extinctions 
(chiefly Caribbean rodents and insectivores) are believed to 
have taken place before the middle of the 19th century, 
showing little indication of a marked overall trend. 

Information on mollusc extinctions was not available prior 
to the mid-19th century, and although high numbers of 
extinctions are documented for island molluscs in two 30- 
year periods, uncertainty in the dates again confuses 
interpretation. 

Two trends are apparent in the time-series data for all taxa: 
first, that documented island extinctions began almost two 
centuries earlier than continental extinctions; second, that 
both island and continental extinctions have increased 
rapidly from early or mid- 19th century to the mid-20th 
century. This increase has been more pronounced for 
continental species, although the island extinctions exceed 



continental ones numerically in all periods. The late 19th 
century for islands has the highest rate of all periods, 
reflecting a high contribution for mollusc extinctions on 
islands during this period. 

The apparent decline in rate for both continental and islands 
for 1960-1989 is probably attributable to two causes; one is 
the expected time-lag in recording extinctions from 1960 
onwards. As noted above, extinction is normally only 
attributed when a species has not been recorded over a 
significant time span. For some purposes, such as the 
designation of 'Extinct' under the Convention on Trade in 
Endangered Species of Wild Fauna and Flora (CITES), this 
time period is arbitrarily taken as 50 years. By this 
criterion, therefore, no species would be accepted as having 
become extinct since 1960 as 50 years would not have 
elapsed since its last being recorded. A more realistic and 
flexible approach has been adopted here, on the grounds 
that some species recorded since 1960 are regarded with a 
high degree of certainty to have become extinct, while 
conversely many species not observed by specialists in the 
wild for over 50 years are almost certainly still extant. 
Nevertheless, the general principle holds that the longer a 
species has not been recorded the more likely it is to be 
regarded as extinct, and vice-versa. A significant number of 
species are therefore likely to have become extinct recently 
without being recorded as such. 

A second, more positive contributory factor to explain the 
apparent recent decline in extinction rates is the great 
increase in conservation action over the past 30 years. 
During this time, attention has focused largely on saving 
well-known species under imminent threat of extinction; 
most efforts to preserve these species havesucceeded, at 
least in the short or medium term. Several projects have 
taken the last wild individuals into captivity to build up 
populations until environmental conditions and populations 
are suitable for re-introduction to the wild (Tables 16.7 and 
16.8). Thus well-documented species most vulnerable to 



200 



Species Extinction 
Figure 16.4 Time series of animal extinctions on islands and continents: selected taxa 



60 



40 



20 



Molluscs 




no date 




o 

E 



1600-1629 1660-1689 1720-1749 1780-1809 1840-1869 1900-1929 1960- 
1630-1659 1690-1719 1750-1779 1810-1839 1870-1899 1930-1959 



20 




1600-1629 1660-1689 1720-1749 1780-1809 1840-1869 1900-1929 1960- 
1630-1659 1690-1719 1750-1779 1810-1839 1870-1899 1930-1959 



20 




1600-1629 1660-1689 1720-1749 1780-1809 1840-1869 1900-1929 1960- 

1630-1659 1690-1719 1750-1779 1810-1839 1870-1899 1930-1959 



Islands ^H continents 



Year period 



201 



1. Biological Diversity 



Figure 16.5 Time series of animal extinctions on islands and continents: all taxa 




1600-1629 1660-1689 1720-1749 1780-1809 1840-1869 1900-1929 1960- 
1630-1659 1690-1719 1750-1779 1810-1839 1870-1899 1930-1959 



Islands 



continents Year period 



extinction during the past 30 years have often not become 
so, as a result of direct manipulative intervention. As noted 
above, it seems probable that significant numbers of 
undocumented continental species will have become extinct 
during this time. 

CURRENT AND FUTURE EXTINCTION RATES 

Habitat destruction, modification, and fragmentation are 
widely recognised as the most serious current threats to 
biological diversity, and the primary cause of recent 
extinctions. Estimates for present and projected global 
extinction rates have not been based on observed or 
recorded species extinctions, but rather on extrapolations 
from estimates of habitat loss coupled with assumptions 
derived from biogeography, relating numbers of species to 
area of habitat. A range of estimates are given in 
Table 16.3 

In practice, most predictions of global extinction rates have 
been based on estimates of species richness in tropical 
forests, combined with estimates of actual and projected 
deforestation rates. Equating global species extinction with 
tropical forest species extinction has been justified by the 
recognition that the vast majority of terrestrial species occur 
in tropical moist forests. 

The extrapolations from estimates of habitat loss are 
coupled with biogeographic assumptions using the species- 
area (Arrhenius) relation (log5 = c + ziogA) where S = 
number of species, A = area and c and z are constants (see 
Chapter 5). Values for z used are between 0.15 and 0.40. 



The most widely quoted generalisation is that a ten-fold 
reduction in area (i.e. loss of 90% of habitat) results in the 
loss of half the species present (30% with z = 0.15; 60% 
with z = 0.40). 

Recent estimates based on these assumptions include those 
of Ehrlich and Wilson (1991) and Reid and Miller (1989). 
The former, on the basis of a 1.8% loss of rain forest per 
year, and using 'conservative' estimates from biogeographic 
theory (i.e. low z values), estimate a loss of 2-3% of rain 
forest species per decade. Reid and Miller, using z values 
of 0. 15-0.40 and the assumption that forest loss is 1-2 times 
that projected by FAO for the period 1980-85, derive a 
similar figure of 2-5% loss per decade. This translates into 
a loss of some 5-15% by the year 2020, assuming rates of 
forest loss continue to increase. 

Reid (1992) has refined the analysis somewhat, applying 
figures for forest area and rates of loss separately to Latin 
America, Africa and Asia, and accounting for observed 
differences in species diversity between the three regions. 
Using z values of 0. 15-0.35 he concludes that global loss of 
closed-forest species will be of the order of 1-5% per 
decade, or 2-8% in total between 1990 and 2015. Reid 
stresses (and this applies to other estimates of species loss) 
that this is the number of species 'committed' to eventual 
extinction as a result of forest loss, not the number which 
will actually become extinct during that time - in many 
cases, there will be a delay between reduction in area of 
habitat and the extinction of species dependent on that 
habitat, especially for longer-living species. 



202 



Table 16.3 Estimated rates of extinction 



Species Extinction 



ESTIMATE 



% GLOBAL 
LOSS PER 
DECADE 



One million species between 1975 and 4 
2000 

15-20% of species between 1980 and 8-1 1 
2000 



12% of plant species in neotropics. 
1 5% of bird species in Amazon basin 

2000 plant species per year in tropics 8 
and subtropics 

25% of species between 1985 and 9 

2015 

At least 7% of plant species 7 



METHOD OF ESTIMATION 



Extrapolation of past 
exponentially increasing trend 

Estimated species-area curve; 
forest loss based on Global 
2000 projections 

Species-area curve {z = 0.25) 



REFERENCE 

Myers (1979) 
Lovejoy (1980) 

Simberloff (1986) 



Loss of half the species in area Raven (1987) 
likely to be deforested by 2015 



0.2-0.3% per year 



5-15% forest species by 2020 



2-3 



2-5 



2-8% loss between 1990 and 2015 1-5 



As above 



Half of species lost over next 
decade in 10 'hot spots' 
covering 3.5% of forest area 

Half of rain forest species 
assumed lost in tropical rain 
forests to be local endemics 
and becoming extinct with 
forest loss 

Species-area curve {0.15 < z 
<0.35); forest loss assumed 
twice rate projected by FAO for 
1980-85 

Species-area curve (0.15 < z 
< 0.35); range includes current 
rate of forest loss and 50% 
increase 



Raven (1988a.b) 



Myers (1988) 



Wilson (1988, 
1989) 



Reid and Miller 
(1989) 



Reid (1992) 



Source: Reid, W.V. 1992. How many species will there be? In: Whitmore, T.C. and Sayer, J. A. (Eds), Tropical Deforestation and Species 

Extinction, Chapman Hall, London, UK. 

Notes: See original source for additional notes referring to this table and reference citations. 



Estimates such as these are often combined with estimates 
of species numbers in tropical rain forests to provide figures 
for numbers of species disappearing daily, yearly or each 
decade. Figures of 100,000 species lost per year (based on 
estimates of 20 million tropical forest species) are 
frequently quoted. The vast majority of the hypothesised 
extinctions would occur among undescribed arthropods 
because these comprise the majority of the total number of 
species estimated to occur in tropical forest. 

Earlier estimates, some based on similar biogeographic 
assumptions and others using different models, gave even 
higher projected rates of extinction, with figures of 20-50 % 
species loss by the end of the century (Myers, 1979; 
Ehrlich and Ehrlich, 1981). In the light of the more recent 
estimates based on increased sophistication of the model, 
these earlier predictions now look exaggerated. 

Problems with the model 

Both the theoretical assumptions and the figures used in 
deriving estimates from the species-area model are open to 
question. 

The principal assumption underlying the model is that 
species richness and habitat destruction within tropical 



forests are distributed evenly. This is not the case, as 
richness is known to vary considerably between different 
areas of tropical moist forest at all scales of comparison 
(see Chapter 4). Many ecologists and taxonomists would 
agree that, given the inadequate data available on the 
poorly-known groups which make up most of the world's 
total complement of species, no realistic assessment can be 
made of the extent to which reduction of an area of forest 
habitat will affect the species present. 

Areas also differ greatly in the nutnber of species confined 
to them (i.e. endemics). Self-evidently, the complete 
destruction of even a small area with a large number of 
endemics will contribute more to global exfinction than the 
destruction of the same-sized area with few or no local 
endemics, even if the latter is richer in species. Thus, if 
habitat destruction preferentially takes place in areas with 
large numbers of endemics it will lead to extinction rates 
higher than those estimated from mean species-area 
relationships, while if it is concentrated in areas with few 
endemics, the reverse will be the case. 

Figures for rates of habitat destruction are also open to 
question (see Chapter 20). Calculations tend to take figures 
for forest conversion as equivalent to forest loss, that is 
complete destruction of forest and replacement by habitats 



203 



1. Biological Diversity 



in which none of the original biota can survive. In reality, 
forest conversion covers a range of conditions, from 
selective logging which may have relatively little impact on 
species composition, through small-scale patch-work 
clearing for agriculture, to clear-felling of extensive areas. 
Forest conversion thus covers a range of degrees of 
degradation, with only the most extreme resulting in 
complete elimination of all species from a particular area. 
This will tend therefore to reduce the estimates for 
extinction rates. In addition, projections of extinction rates 
are based on an assumption that deforestation rates will 
remain constant. This is evidently not the case. It is widely 
agreed that rates of forest conversion are increasing, and 
will continue to increase until easily accessible areas which 
are not legally protected have been cleared, following which 
they will decrease. 

Furthermore, the estimate from a straightforward global 
species-area curve does not take into account the presumed 
'residual' extinctions which will occur through remaining 
forest becoming fragmented: on the basis of island 
biogeographic theory it is argued that these fragments will 
suffer elevated rates of extinction through stochastic 
processes. Already many species may be committed to 
extinction in that without direct human intervention, their 
residual numbers are non-viable. The list of threatened 
species in Table 17.1 show 140 species of mammals as 
endangered and likely to become extinct in the near future 
unless the threat to their survival is alleviated: this is more 
than twice the total number of mammals that has gone 
extinct over the last four hundred years. Instead of 
concentrating on extinctions, it is important to monitor the 
status and threats to a wide array of species if global trends 
of species diversity are to be assessed. 

Finally, estimates of extinction rates do not - and cannot - 
take into account the impact of unpredictable large-scale 
changes in environmental conditions, such as global climate 
change, which is likely to have a profound influence upon 
species survival. 

Conclusion 

There are many unsatisfactory assumptions underlying 
current estimates of global extinction rates, and the 
resulting numerical values are fraught with imprecision. 
Alternative models, possibly based on a greater 
understanding of the ecological or life history traits 
correlated to extinction proneness, would be highly 
instructive in either confirming current estimates or refining 
them by avoiding some of the major short-comings in the 
species - area method. However in the absence of such 
alternatives, conclusions from the different studies using the 
current model must be examined, even if the methodology 
is known to be flawed. In large measure, these agree about 
the accelerating rates of species extinctions arising from the 
continued loss of tropical forests. The most recent 
refinement of the estimates (Reid, 1992) predicts that at 
current rates of deforestation, we will commit some 2-8% 
of the planet's species to extinction in the next 25 years. 

However, what is equally clear is that quantifying the 
precise rate of extinction is of no greater relevance to 
conservation practice than is determining a precise figure 



for the number of species on earth. Policymakers and the 
public may like to assess the magnitude of the extinction 
crisis, and thus the priority to be given to the issue, on the 
basis of an absolute rate, but investment of time and effort 
in refining such predictions contributes little to tackling the 
root causes of the problem. Indeed, obsession with an 
absolute extinction rate may give an unrealistically 
optimistic impression in that no allowance is made for the 
genetic impoverishment of the multitude of species brought 
to the verge of extinction through the progressive loss of 
discrete sub-populations. 

Rather than focus on refining extinction rates, we need to 
develop the capability to identify areas or localities of high 
species endemism and diversity (see Chapter 15), and 
ensure that these sites are placed under a system of 
conservation management that maintains their ecological 
integrity before they are perturbated by logging, mining or 
forest clearance. Such proactive conservation practice 
could stem the tide of the accelerating species extinction 



References 

AJlendorf. F.W. and Leary. R.F. 1986. Heterozygosity and fitness in 

natural populations of animals. In: Soule, M.E. (Ed.), 

Conservation Biology: the science of scarcity and diversity. 

Sinauer Associates, Inc., Mass. Pp. 57-76. 
Belovsky, G.E. 1987. Extinction models and mammalian persistence. 

In: Soule, M.E. (Ed.), Viable Populations for Conservation. 

Cambindge University Press, Cambridge, New York. Pp. 35-58. 
Boeckeln, W.J. and Gotelli, N.J. 1984. Island biogeographic theory 

and conservation practice; species-area or specious-area 

relationships? Biological Conservation 29:63-80. 
Bonner, M.L. and Selander, R.K. 1974. Elephant seals: genetic 

variation and near extinction. Science 184:908-909. 
Brown, J. H. and Kodric-Brown, A. (1977). Turnover rales in insular 

biogeography: effect of immigration on extinction. Ecology 58, 

445-449. 
Ehrlich, P.R. and Ehrlich, A.M. 1981. Extinction: the causes and 

consequences of the disappearance of species. Random House, 

New York. 
Ehrlich, P.R. and Wilson, E.O. 1991. Biodiversity studies: science and 

policy. Science 253:758-762. 
Erwin, D.H., Valentine, J. W. and Sepkoski, J.J. 1987. A comparative 

study of diversification events: the early Palaeozoic versus the 

Mesozoic. Evolution 41(6). 
Falconer, D.S. 1981. Introdttction to Quantitative Genetics^ 2nd 

edition. Longman. London. 
Franklin. I.R. 1980. Evolutionary change in small populations. In: 

Soule, M.E. and Wilcox, B.A. (Eds), Conservation Biology: an 

evolutionary-ecological perspective. Sinauer Associates, Inc., 

Mass. Pp. 135-149. 
Grumbine, R.E. 1990. Viable populations, reserve size, and federal 

lands management: a critique. Conservation Biology 4(2):127-134. 
Karr, J.R. 1991. Avian survival rates and the extinction process on 

Barro Colarado Island, Panama. Conservation Biology 4(4):391- 

397. 
King, J.R. and Mewaldt, L.R. 1987. The summer biology of an 

unstable insular population of White-crowned Sparrows in Oregon. 

Comior 89:549-565. 
Klein, B.C. 1989. Effects of forest fragmentation on dung and carrion 

beetle communities in central Amazonia. Ecology 70:1715-1752. 
Knoll, A.H. 1984. Pauems of extinction in the fossil record of 

vascular plants. In: Nitecki. M.H. (Ed.), Extinctions. University 

of Chicago Press, Chicago, IL. Pp. 22-68. 
Lande, R. and Barrowclough. G.F. 1987. Effective population size, 

genetic variation, and their use in population management. In: 

Soule, M.E. (Ed.), Viable Populations for Conservation. 



204 



Species Extinction 



Cambridge University Press, Cambridge, New York. Pp. 87-124 
Laurance, W.F. 1991 . Ecological correlates of extinction proneness in 

Australian tropical rain forest mammals. Conservation Biology 

5(l):79-89. 
MacArthur, R.H. and Wilson, E.O. 1963. An equilibrium theory of 

insular zoogeography. £vo/urion 17:373-387. 
MacArthur, R.H. and Wilson, E.O. 1967. The Theory of Island 

Biogeography. Princeton University Press, Princeton, N.J. 
Myers, N. 1979. The Sinking Ark: a new look al the problem of 

disappearing species. Pergamon Press, Oxford, UK. 
Newmark, W.D. 1991. Tropical forest fragmenution and the local 

extinction of understory birds in the eastern Usambara Mountains, 

Tanzania. Conservation Biology 5(l):67-78. 
O'Brien, S.J., Roelke, M.E., Marker, L., Newman, C.A., Winkler, 

D., Meltzer, D., Colly, L., Evermann, J.F., Bush, M. and Wildt, 

D.E. 1985. Genetic basis for species vulnerability in the cheetah. 

Science 227:1428-1434. 
Packer, C, Pusey, A.E., Rowley, H., Gilbert, D.A., Martenson, J. 

and O'Brien, S.J. 1991. Case study of a population bottleneck: 

lions of the Ngorongoro Crater. Conservation Biology 5(2):219- 

230. 
PuUiam, H.R. 1988. Sources, sinks and population regulation. 

American Naturalist 132:652-661. 
Reid, W.V. 1992. How many species will there be? In: Whitmore, 

T.C. and Sayer, J. A. (Eds), Tropical Deforestation and Species 

Extinction. Chapman Hall, London, UK. Pp.S5-73. 



Reid, W.V. and Miller, K.R. 1989. Keeping Options Alive: the 

scientific basis for conserving biodiversity. World Resources 

Institute, Washington, DC. 
Schaffer, M. 1987. Minimum viable populations: coping with 

uncertainty. In: Soule, M.E. (Ed.), Viable Populations for 

Conservation. Cambridge University Press, Cambridge, New 

York. Pp.70-86. 
Soul(£, M.E., Wilcox, B.A. and Holtby, C. 1979. Benign neglect: a 

model of faunal collapse in the game reserves of East Africa. 

Biological Conservation 15:259-272. 
Western, D. and Ssemakula, J. 1981. The future of savannah 

ecosystems: ecological islands or faunal enclaves? /4^"can Journal 

of Ecology 19:7-19. 
Wilcox, B.A. and Murphy, D.D. 1985. Conservation strategy: the 

effects of fragmentation on extinction. American Naturalist 

125:879-887. 
Zimmerman, B.L. and Bierregard, R.O. 1986. Relevance of the 

equilibrium theory of island biogeography and species-area 

relations to conservation with a case from Amazonia. Journal of 

Biogeography 13:137-143. 



Based on text prepared by Martin Jenkins with additions by 
WCMC staff 



205 



1. Biological Diversity 



Eelgrass Limpet 



Umbilicate Pebblesnail 



Closed Elimia 
FusHorm Elimia 
High-spired Elimia 
Constricted Elimia 
Hearty Elim'a 
Ribbed Elimia 
Rough-lined Elimia 
Pupa Elimia 
Pygmy Elimia 
Puzzle Elimia 
Excised Slitshell 
Striate Slitshell 
Pagoda Slitshell 
Ribbed Slitshell 
Pyramid Slitshell 
Round Slitshell 
Agate Rocksnail 
Interrupted Rocksnail 
Rotund Rocksnail 
Lirate Rocksnail 
Bigmouth Rocksnail 
Coosa Rocksnail 
Striped Rocksnail 



Panama 



Table 16.4 Animal species extinct since circa 1600 

SPECIES ENGLISH NAME DISTTIIBIJTION 

CORALS ETC. (CNIDARIA) 

Order MILLEPORINA 

Family Milleporidae 
Millepora sp. 

Moauscs 

Order ARCHAEOGASTBOPOOA 

Family Acmaeidae 
Lottia ah/eus 

Order MESO GASTROPODA 

Family Hydrobiidae 

Bythiospeum pfeffferi 

Clappia umbHicatn 

Ohridohauffenia ckimica 
Family Pleuroceridae 

Elimia clausa 

Elimia fusHbrmis 

Elimia hartmaniana 

Elimia impressa 

Elimia Jonesi 

Elimia laeta 

Elimia pilsbryi 

Elimia pupaeformis 

Elimia pygmaea 

Elimia varians 

Gyrotoma incisa 

Gyrotoma lewisi 

Gyrotoma pagoda 

Gyrotoma pumila 

Gyrotoma pyramidata 

Gyrotoma walkeri 

Leptoxis clipeata 

Leptoxis formanii 

Leptoxis ligata 

Leptoxis lirata 

Leptoxis occultata 

Leptoxis showalterii 

Leptoxis vittata 
Family Pomatiasidae 

Tropidophora carinata 

Order STYLO MMATOP MORA 

Family Endodontidae 

Discus guerinianus 

Kondoconcha othnius 

Libera subcavernula 

Libera tumuloides 

Mautodonta acuticosta 

Mautodonta boraborensis 

Mautodonta ceuthma 

Mautodonta consimifs 

Mautodonta consobrina 

Mautodonta maupiensis 

Mautodonta parvidens 

Mautodonta punctiperforata 

Mautodonta saintjohni 

Mautodonta subtilis 

Mautodonta unilamellata 

Mautodonta zebrina 
. Opanara attiapica 
. Oparyara areaense 
. Opanara bitridentata 
. Opanara caliculata 
. Opanara depasoapicata 
. Opanara dupliddentata 
. Opanara fost>ergi 
. Opanara megomphala 
. Opanara perahuensis 
. Orangiacooki 
. Orangia maituatensis 
. Orangia sporadica 
* PHula cycloria 
. Rhysoconcha atanuiensis 
. Rhysoconcha variumbiScata 
. Ruatara koarana 
. Ruatara oparica 

Taipidon anceyana 

Taipidon marquesana 

Taipidon octolamellata 

Thaumatodon muttilame/latus 
Family BulimuBdae 

Amphibulima patula 

Bulimukis duncanus 

Leuchocharis loyaltyensis 

Leuchocharis porphyrocheila 



Austria 

USA 

Yugoslavia 

USA 
USA 

USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 
USA 



Madeira (Portugal) 
Rapa (F. Polynesia) 
Raratonga (Cook Is) 
Raratonga (Cook Is) 
Raiatea (F. Polynesia) 
Borabora (F. Polynesia) 
Raivavae (F. Polynesia) 
Raiatea (F. Polynesia) 
Huahine (F. Polynesi^ 
Maupiti (F. Polynesif^ 
Society Is (F. Polynesia) 
Moorea (F. Polynesia) 
Borabora (F. Polynesia) 
Huahine (F. Polynesia 
Raratonga (Cook Is) 
Raratonga (Cook Is) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia^ 
Rapa (F. Polynesia) 
Rapa (F. Polynesia^ 
Rapa (F. Polynesia) 
Mauritius 

Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Rapa (F. Polynesia) 
Hiva Da (F. Polynesia) 
Nuku Hiva (F. Polynesia) 
Hiva Oa (F. Polynesia) 
Raratonga (Cook Is) 

Guadeloupe 
Galapagos (Ecuador) 
New Caledonia 
New Caledonia 



LAST POSSIBLE 

RECORDED CAUSE 



1083 



1924 
1924 
1924 
1924 
1924 
1924 



1870s 

1934 

1880s 

1880s 

1880s 

1880s 

1880s 

1880s 

1880s 

1880s 

1880s 

1880s 

1880s 

1880s 

1880s 

1880s 

1934 

1934 

1934 

1934 

1934 

1934 

1934 

1934 

1934 

1934 

1934 

1934 

1934 
1934 

1934 

1934 

1880s 

1880s 

1880s 

1880s 

8 
late 1 800s H 
1900s B 
1900s B 



206 



Table 16.4 Animal species extinct since circa 1600 (continued) 



Species Extinction 



SPECIES 



MOU.USCS (eonliniMd) 

Family Charopidae 

Helenoconcha leptalea 

Helenoconcha minutissima 

Helenoconcha polyodon 

Helenoconcha pseustes 

Helenoconcha sexdentata 

Helenodlscus bilamellata 

Helenodiscus vernoni 

Pseudohelenoconcha dianae 

Pseudohelenoconcha laetissima 

Pseudohelenoconcha persoluta 

Pseudohelenoconcha spurca 

Sinployea canalis 

Sinployea decort'cata 

Sinployea harveyensis 

Sinployea otareae 

Sinployea planospira 

Sinployea proxima 

Sinployea rudis 

Sinployea tenuicostata 

Sinployea youngi 
Family Achatinelidae 

Achatinelb abbreviata 

Achatinelkt buddii 

Achatinella caesia 

Achatinella casta 

Achatinella decora 

Achatinelb elegans 

Achatinelb Juddii 

Achatinelb juncea 

Achatinelb lehutensis 

Achatinelb papyracea 

Achatinelb rosea 

Achatinelb spaldin^i 

Achatinelb stewarti 

Achatinelb thaanumi 

Achatinelb valida 

Achatinelb vittata 
X Elasmbs jauffreti 
X Elasmbs sp. 

Partulina crassa 

Partulina montagui 
Family Partulidae 

Partula exigua 

Partula filosa 

Partula producta 

Partula salifana 

Samoana abtxeviata 
Family Amastridae 

Carefia anceophila 

Carelia bicolor 

Care/ia cumingiana 

Carelia glossema 

Carelia Katalauensis 

Carelia knudseni 

Carelia olivacea 

Carelia paradoxa 

Carelia periscelis 

Carelia tenebrosa 

Carelia turricuta 
Family Vertiginidae 

Campolaemus perexiUs 

Nesopupa turtoni 
Family Pupillidae 
X Gibbulinopsis sp. 

Leiostyb abtxeviata 

Leiostyb cassida 

Leiostyb concinna 

Leiostyb gibtia 

Leiostyb laevigata 

Leiostyb tamellosa 

Leiostyb simubtor 

Pupa obliquicostata 
Family Helixarbnidae 

Colparion madgei 

Ctenoglypta newtoni 
X Ctenophile planorbina 

Diastole matafaoi 
X Erepta thiriouxi 
X Erepta sp. 

Pachystyla ruforonaia 
X Plegma bewsheri 
X Plegma duponii 
X Plegma sp. 
Family Ferussaciidae 

Cecilioides euHma 
Family Subulinidae 

Chilonopsis blofeldi 

Chilonopsis exulatus 

Chilonopsis helena 



ENGLISH NAME 



Moorean Viviparous Tree Snail 
Tahiti Viviparous Tree Snail 
Tahiti Viviparous Tree Snail 



DISTRIBUTION 


LAST 


POSSIBLE 




RECORDED CAUSE 


St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 




Raratonga (Cook Is] 


1 1872 




Raratonga (Cook Is 


1 1872 




Raratonga (Cook Is 


1 1872 




Raratonga (Cook Is 


1 1872 




Raratonga (Cook Is 


1 1872 




Raratonga (Cook Is; 


( 1872 




Raratonga (Cook Is] 


1 1872 




Raratonga (Cook Is 


1 1872 




Raratonga (Cook Is] 


1 1872 




Hawaii (USA) 


1963 


A.C.D 


Hawaii (USA) 


early igoOs 


A.CD 


Hawaii (USA) 


early 1900s 


A.C.D 


Hawaii (USA) 




A.C.D 


Hawaii (USA) 


early 1900s 


A.C.D 


Hawaii (USA) 


1952 


A.C.D 


Hawaii (USA) 


1958 


A.C.D 


Hawaii (USA) 




A.C.D 


Hawaii (USA) 


1922 


A.C.D 


Hawaii (USA) 


1945 


A.C.D 


Hawaii (USA) 


1949 


A.C.D 


Hawaii (USA) 


1938 


A.C.D 


Hawaii (USA) 


1961 


A.C.D 


Hawaii (USA) 


1900s 


A.C.D 


Hawaii USA) 


1951 


A.C.D 


Hawaii (USA) 


1953 


A.C.D 


Rodrigues (Maurlius) 




Mauritius 






Hawaii (USA) 


1914 


C? 


Hawaii (USAi 


1913 


C? 


Moorea (F. Polynesia) 1977 


C? 


Tahiti (F. Polynesia) 






Tahiti (F. Polynesia) 






Guam 






American Samoa 


1940 


B 


Hawaii (USA) 


1930 


B.C.D 


Hawaii (USA) 


1970 


B.C.D 


Hawaii (USA 


1930 


B.C.D 


Hawaii (USA 


1930 


B.C.D 


Hawaii (USA 


1945/47 


B.CD 


Hawaii AJSA 


1930 


B.C.D 


Hawaii (USA 


1930 


B.C.D 


Hawaii (USA 


1930 


B.C.D 


Hawaii (USA 


1930 


B.C.D 


Hawaii USA 


1930 


B.C.D 


Hawaii (USA 


1930 


B.C.D 


St Helena 


1870s 




St Helena 


1870s 




Rocfrigues (Mauritius) 




Madeira (Portugal) 


1870s 




Madeira (Portugal) 


1870s 




Madeira (Portugal) 


1870s 




Madeira (Portugal) 


1870s 




Madeira (Portugal) 


1870s 




Madeira (Portugal) 


1870s 




Madeira (Portugal) 


1870s 




St Helena 


1870s 




Rockigues (Mauritius) 1938 


B 


Mauritius 


1871 


B 


Mauritius 






American Samoa 


1940 


?D 


Mauritius 






MauritiLS 






Mauritius 


1869 


B 


Rodrigues (Mauritius) 




Mauritius 






Mauritius 






Madeira (Portugal) 


1870s 




St Helena 


1870s 




St Helena 


1870s 




St Helena 


1870s 





207 



1. Biological Diversity 



Table 16.4 Animal species extinct since circa 1600 (continued) 

SPECIES 



MOLLUSCS (continusd) 

Chifonopsis melanoides 

Chifonopsis nonpareil 

Chihnopsis subplicatus 

ChHonopsis subtruncatus 

Chifonopsis turioni 
Family Helicidae 

Discula lyeliiana 

Discuki tetrica 

GeomHra delphinuhides 

Lmmniscia gahata 

Psmudocampylaea fowai 
Family Strcpteudda* 

Edentu/ina thonvisaiti 

Gfbbus lyonetianus 

Gonidomus newtoni 
X Gonospira cirneensis 
X Gonospira haliodas 
X Gonospira majuscukjs 

Imperturbata violescens? 
Family Assimineidae 
X Omphalotropis plicoss 
X Omphalotropis caldwelU 
X Omphalotropis dupontiana 
X Omphalotropis maxima 
X Omphalotropis mult'frata 
X Omphalotropis sp. 
Family Pomatiasida* 
X Tropidophora bewsheri 
X Tropidophora bipartita 
X Tropidophora deHorata 
X Tropidophora lienardi 
X Tropide^hora mai^ftjane 

Ord«r UNIONOIDA 

Family Unionidae 
Aiasmidonta mccordi 
Aiasmidonta v^ightiana 
Epioblasma arcaeformis 

tploblasma biemarginata 
Epioblasma ffexuosa 
Epioblasma haysiarKi 
Epioblasma lenior 
Epioblasma lewisi 
Epioblasma personata 
epioblasma proplnqua 
Epioblasma sampsoni 
Epioblasma ste^ardsoni 
Medionidus mcglameriae 

CRUSTACEANS 

Ord«r AMPHIPODA 

Family Crangonyctidae 
Stygobromus hayi 
Stygobromus lucihigus 

Ord«r DECAPODA 

Family Astacida* 

Pactfastacus ni^escens 
Family Atyidaa 

Syncaris pasadanas 

INSECTS 

Ord«r EPHEMEROPTERA 

Family Siphlonurldae 

Acanthometropus pecatonia 
Family Ephamerida* 

Pantagenia robusta 

Ordar ORTHOPTERA 

Family Tattigoniidaa 
Neduba exb'ncta 

Ordar PHASMATOPTERA 

Family Phasmatidae 
Dryococmlus austraSs 

Ordar DERMAPTERA 

Family Labtduridaa 
* Labidura herculaana 

Ordar PLECOFTERA 

Family Chkxoparidaa 
Alktperla roberU 



ENGLISH NAME 


DISTRIBUTION 


LAST 


POSSIBLE 






RECORDED CAUSE 




St Helena 


1870s 






St Helena 


1870s 






St Helena 


1870s 






St Helena 


1870s 






St Helena 


1870s 






Madeira (Portugal) 


1870s 






Madeira (Portugal) 


1870s 






Madeira (Portugal) 


1870s 






Madeira (Portugal) 


1870s 






Madeira (Portugal) 


late 19th C 






Seychelles 


1908 




, 


Mauritius 


1905 


B 




Mauritius 


1867 


B 




Mauritius 








Mauritius 








Mauritius 








Seychelles 








Mauritius 


1878 


B 




Mauritius 








Mauritius 








Mauritius 








Mauritius 








Mauritius 








Ro<tigues (Maurlius) 








Rockigues (MaurKus) 








Reunion 








Mauritius 








Mauritius 






Coosa Elktoe 


USA 






Ochtackne« Arc-mussel 


USA 






Sugarspoon 


USA 


1940s 


B 


Angled Riffleshell 


USA 


1960s 


B 


Leafs hell 


USA 


1940s 


B 


Acofnshel 


USA 






Narrow Cats paw 


USA 


1965 


B 


Forksheli 


USA 


1964 


B 


Round Combshell 


USA 


1930 


B 


Tennessee Riffleshell 


USA 


1930 


B 


Wabask Riffleshell 


USA 


1950S/60S 


B 


Cumberland Leafshel 


USA 


1930 


B 


Tombigbee Moccasinshell 


USA 







Hay's Spring Scud 
Rubious Cave Amphipod 


USA 
USA 


Sooty Crayfish 


USA 


Pasadena Freshwater Shrinp 


USA 



Pecatonica River Mayfly 
Robust Burrowing Mayfly 

Antioch Dunes Shieldback Katydid 

Lord Howe Island Stick-insect 

St Helena Earwig 

Robert's Stonetly 



USA 
USA 



1957 



1860s 
1933 



1927 



1937 



Lord Howe I (Australia) 



St Helena 



1907 



USA 



208 



Species Extinction 



Pitt Island Longhorn Bwer 



Hypena laysanensis 
+ hfypen 
+ hfypen 
+ Hypena senicuta 



ena piagjota 



Pen'<±oma porphyrea 
Ord«f HYMENOPTERA 
Family Colletida* 

Nesoprosopis angushia 
Nesoprosopis blackburni 
Nesoprosopis connectens 



Volutine Stoneyian Tabanid Fly 



Table 16.4 Animal species extinct since circa 1600 (continued) 

SPECIES ENGLISH ^4AME DISTRIBUTION 

INSECTS (continimi) 

Ordw HOMOPTERA 

Family Pseudococcidae 
Clavicoccus erinaceus 
Phyllococcus oahuensis 

Order COLEOPTERA 

Family Cerambycidae 

Xytoteles costatus 
Family Curculbnidae 

Dryophthofus distinguendus 

Dryotibus mimeticus 

Hactamphus tubercutatus 

Macrancylus linearis 

Oedemasylus laysanensis 

Pentarthfum blackburnii 

Rhyncogonus bryani 
Family Carabidae 

* Aplothorax burcheUi 

* Mecodema punctellum 

Order OIPTERA 

Family Tabanidae 

Stonemyia volutina 
Family Dolichopodidae 

Campsicnemus mirabilb 
Family Drosophiidae 

Drosophia lanaiensis 

Order 7RICHOPTERA 

Family Rhyacophilldae 

Rhyacophila amabilis 
Family Hycfropsychidae 

Hyctopsyche tobiasi 
Family Leptoceridae 

Triaenodes phatacris 

Triaenodes Iridonata 

Order LEPIDOPTERA 

Family Zygaentdae 

Levuana iridescens 
Family Lycaenidae 

Gtaucopsyche xerces 
Family Libytheidae 

Libythea cinyras 
Family Nymphalidae 

EuthalB malapana 
Family Pyralidae 

GenophantJs leahi 

Hedylepta asaphombra 

Heaylepta coninuaialis 

Hedylepta epicenta 
+ Heaylepta euryprora 
+ Heaylepta fullawayi 

Hedylepta laysanensis 
+ Hedylepta meyricki 
+ Heaylepta musicola 

Heaylepta telegrapha 

Oeobia sp. 
Family Geometridae 

Scotorhythra nesiotes 

Scotorhythra megalophylla 

Scotorhythra paratacb's 

Tritoclets microphylla 
Family Sphingidae 

Mandura blackburni 
Family Noctuidae 

Agrotis crinigera 

Agrob's ^sciata 

Agrotis kerri 

Agrotis laysanensis 

Agrotis pnotophila 

Agrotis procellaris 

Helicoverpa corrfusa 

Helicoverpa miniia 



Castle Lake Caddis -fly 

Tobias' Caddis— fly 

Athens Caddis -fly 
Three -tooth Caddis -fly 

Levuana Moth 
Xerces Blue 



Poco Noctuid Moth 
Midwiy Noctuid Moth 



Minute Noctuid Moth 

Laysan Dropseed Noctuid Moth 



Lanai Yelbw-feced Bee 
Blackburn's Yellow-faced Bee 
Connected Yellow-faced Bee 



Hawaii (USA) 
Hawaii (USA) 



Chatham I (NZ) 

Hawaii (USA) 
Hawaii (USA) 
New Zealand 
Hawaii (USA) 
Hawaii (USA) 
Hawaii (USA) 
Hawaii (USA) 

St Helena 
Stephens I (NZ) 



USA 

Hawaii (USA) 
Hawaii (USA) 

USA 

Germany 

USA 
USA 

Fiji 
USA 
Mauritius 
Taiwan 



Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
htawaii 
Hawaii 
Hawaii 



(USA) 
(USA) 

(USA) 
(USA) 

njsA) 

(USA) 
(USA) 
(USA) 
(USA) 
(USA) 
(USA) 



Hawaii (USA) 
Hawaii (USA) 
Hawaii (USA) 
Hawaii (USA) 

Hawaii (USA) 



Hawaii 
Hawaii 
Ha^Miii 
Ha^ii 
Hawaii 
hla^ii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
hlawaii 



(USA) 
(USA) 
(USA 
(USA) 
USA) 
(USA) 
(USA 
(USA 
(USA! 
(USA) 
(USA) 
(USA) 
(USA) 



LAST POSSIBLE 

RECORDED CAUSE 



1930s B,C 



1910 C 



1967? 



B.-G 



1929 E 

early 1 9405 
1865 



early 1 900s 
1970s 
1958 
early 1 900s 



1911 

early 1900s 
early 19005 
early 1 dOOs 
1890s 

1960s 



1923 
1911 

pre -1900 
post- 1927 
pre-1911 
1911 



hlawaii (USA) 
Hawaii (USA) 
Hawaii (USA) 



209 



7. Biological Diversity 



Table 16.4 Animal species extinct since circa 1600 (continued) 

SPECIES ENGLISH NAME DtSTRIBUTION 

RSHES 

Order PETROMYZONTIFORMES 

Family Petromyzontidae 



Lampe&a minrna 

Order CYPRINIFORMES 

Family CyprJnidae 

Evarra bustamantei 

Evarra eigenmanni 

Evarra tiahuacensis 

Gila crassicauda 

Lepidomeda altivmlis 

Notropis amecae 

Notropis aulidion 

Notropis orca 

Pogonichthys ciscoides 

Rhinichthys deaconi 

Stypodon signrfer 
Family CatostomJdae 

Chasmistes muriei 

Lagochila lacera 

Order SALMONIFORMES 

Family Retropinnidae 

* Prototroctes oxyrhynchus 
Family Salmonidae 

Coregonus alpenae 
Coregonus johannae 
Satvelinus agassizi 

Order CYPRINODOKTIFORMES 

Family Fundulidae 
Fundulus albolineatus 

Family Poeciliidae 

Gambusia amistadensis 

* Gambusia georgei 

* Priapella bonita 
Family Goodeidae 

Characodon garmani 
Empetich^ys merriami 
Family Cyprinodontidae 
Cyprinodon latifasciatus 
Cyprinodon sp, 
Cyprinodon sp. 
Cyprinodon sp. 

Order SCORPAENIFORMES 

Famlty Cottidae 
Cottus echinatus 

AMPHIBIANS 

Order ANURA 

Family Discoglossidae 
Discoglossus nigriventer 
Rana Usheri 

REPTILES 

Order TESTUDINES 

Family Testudinidae 
Cylind-aspis borbonica 
Cylindraspis indica 
Cylinctaspis inepta 
Cylinctaspis pekastes 
Cy/inctaspis tiserrata 
Cylinctaspis vosmaeri 

Order SAURIA 

Family Gekkonidae 
Hopfodactylus delcourti 
Phelsuma edwardnewtoni 
Phelsuma gigas 

Family Iguanidae 
Leiocephalus eremitus 
L0ioc«phalus h^tminieri 

Family Teiidae 
Ameiva cineracea 

* Amsiva major 
Family Anguidaa 

Celmstus occiduus 
Family Sclncidae 

* Leiolopisma mauriUana 
Macroscincus coctei 

* Tiliqua adelaidensis 



Miller Lake Lamprey 



Thicktail Chub 
Pahranagat Spinedace 

Ameca Shiner 
Ourango Shiner 
Phantom Shiner 
Clear Lake Splittail 
Las Vegas Dace 
Stumptooth Minnow 

Srtake River Sucker 
hlarelip Sucker 



New Zealand Grayling 

Longjaw Cisco 
Deepwater Cisco 
Silver Trout 



Whiteline Topminnow 

Amistad Gambusia 
San Marcos Gambusia 
Guayacon Ojiazul 

Parras Characodon 
Ash Meadows KilBfish 

Perrito de Parras 
Monkey Spring Pupfish 



Utah Lake Sculpin 



Israel Painted Frog 
Relict Leopard Frog 



Newtori's Day Gecko 
Giant Day Gecko 



Martinique Giant Ameiva 
Jamaican Giant Galliwasp 



Cape Verde Giant Skink 
Adelaide Pigmy Bluetongue 



USA 



Mexico 

Mexico 

Mexico 

USA 

USA 

Mexico 

Mexico 

Mexico. USA 

USA 

USA 

Mexico 



USA 
USA 



New Zealand 

USA. Canada 
USA, Canada 
USA 



USA 

USA 
USA 

Mexico 

Mexico 
USA 

Mexico 
USA 
Mexico 
Mexico 



USA 



LAST POSSIBLE 

RECORDED CAUSE 



1953 



1970 


B 


1970 


B 


1970 


B 


1857 


B.C/D 


1940 


C/D 


1970 


C/D 


1965 


C/D 


1975 


B.C/D 


1970 


B,C/D 


1955 


B 


1930 


B 


1928 


B 


1910 


G 



1978 


A.C 


955 


A.C/D 


1930 


A,C/D 



1928 



B.C/D 



1973 
1983 


B 
B.C/D 


1900 
1953 


?B 
B.C/D 


1930 
1971 


B 

B.C/D 



B.C/D 



Israel 


1940 


B 


USA 


1960 


B 


Reunion 


1800 




Reunion 
Mauritius 

Rodrigues (Mauritius) 
Mauritius 
Rodrigues (Mauriius) 


1800 

early 18th C 

1800 

early 18th C 

1800 


A 

A.C/D 

A,B.C/D 

A.C/D 

A.C/D 


NewZealand(?) 
Rodrigues (Mauritius) 
Ro*igues (Mauritius) 


mid 19th C? 
1917 
end 19th C 


C 
C 


Navassa 1 (USA) 
Martinique 


1900 
1830s 


c 


Guadeloupe 
Martinique 


early 20th C 


c? 


Jamaica 


1840 


c? 


Mauritius 


1600 


c 


Cape Verde 
Austraia 


early 20th C 
1959 


A? 
B.C 



210 



Species Extinction 



Tcdsie 16.4 Animal species extinct since circa 1600 (continued) 



SPECIES 



ENGLISH NAME 



DISTBIBUnON 



LAST POSSIBLE 

RECORDED CAUSE 



REPTILES (eonkinuftcQ 
Ordv SERPENTES 

Family BoJda* 

* Bofy^ia multocarinata 
Family Typhlopldae 

Typhfops cariei 
Famity Colubrldae 

* Alsophisater 
AIsophiB aancticrucis 

* Lhphis cursor 

* Liophis p^rfuscus 



BIRDS 

Oritor STniJTHIONIR>RMES 

Famity Dromaiidae 
Dromaius diemenianus 

Family Aepyornlhidae 
A^yorr)ia maximus 

Famity Anomatopterygidae 
Dinornis torosus 
Eurapteryx gravis 
Megataperyx didinus 

Ord«r GALLIFORMES 

Family Phasianidae 

Coturnix novaezBlar>diae 
Ophrysia superciliosa 

Orctar ANSERIFORMES 

Family Anatidae 
Afopochen mauritianus 
Anas theodori 

Camptorhynchus labradorius 
Cygnus sumnerensi's 
Mergus australis 

* Rhodonessa caryophyllacea 
Sh0tdgoose sp. 

Orctor CORACHFORMES 

Family Alcedinidae 
Halcyon miyakoensis 

Orctor CUCUUFORMES 

Family Cuculidae 

* Coua delatandei 

Ordm PSnTACIFORMES 

Family Psittacidae 
Anodorhyrtchus glaucus 
Ara tricolor 
Charmosyna dtadema 
Conuropsis caroHnensis 
Cyanoramphus ulietanus 
Cyanoramphus zsalandicus 
lophopsitiacus ' bensoni 
Lophopsfttacus mauritianus 
Mascarinus mascarinus 

'N^cropsittacus 'rodericanus 
Nestor productus 

Psfttacuia exsul 
Psfttacula wBfdi 

Order TROCHIUFORMES 

Famity Trochiidae 

ChforosHlbon bracei 
Family Caprimulgidae 

* Siphonorhis americanus 

Order STRIGIFORMES 

Family Strigidae 
Athene bfewOti 
'Athene ' murivora 
TSauzieri sp. 

* Sceloglaux afbifycies 
Scops ' commersoni 

Family Aegothelidae 

* Aegotheles sav^i 

Ordw COLUMBIFORMES 

Family Raphidao 

'Ornrthaptera' solftmia 
Pezophaps soUtarius 
Raphus cucultatus 



Jamaican Tree Snake 
St Croix Racer 
Martinique Racer 
Barbados Racer 



Round 1 (Maurlius) 


1975 


Mauritius 


17th C C 


Jamaica 


1950 A,C 


Virgin Is (US) 

Martinique 

Barbados 


20th C A,C 
1S63 C 
mid 20th C? C 



Kangaroo Island Emu 


Kangaroo 1 (Australia) 


1803 


B 


GraalElaphantbird 


Madagascar 


1650 


A.B 


Brawny Great Moa 
Burly Lesser Moa 
South Island Tokoweka 


New Zealand 
New Zealand 
New Zealand 


1670 
1640 
1785 


A.B 
A.B 
A,B 


New Zealand Quail 


New Zealand 


1875 


F 


Himalayan Mountain Quail 


India 


1868 


A 


Mauritian Shelduck 


Mauritius 


1698 




Mauritian Duck 
Labrador Duck 
Chatham Island Swan 
Auckland Island Merganser 
Pink-headed Duck 


Mauritius, ?R6union 
Canada, USA 
Chatham 1 (NZ) 
New Zealand 
India, Nepal 
Reunion 


1696 

1878 

1590-1690 

1905 

1935 

1674 


A,B 

A,B,C 
A 



Ryukyu Kingfisher 



Snail-eating Coua 



Glaucous Macaw 
Cuban Red Macaw 
New Caledonia Lorikeet 
Carolina Parakeet 
Raiatea Parakeet 
Black-fronted Parakeet 
Mauritius Grey Parrot 
Mauritius Parrot 
Mascarene Parrot 

Rodrigues Parrot 
Norfolk Island Kaka 
Rodrigues Ring-necked Parakeet 
Seychelles Alexandrine Parrot 



New Providence Hummingbird 
Jamaica Least Pauraque 



Forest Owlet 

Rodrigues Little Owl 
Mauritian Owl 
Laughing Owl 
Mauritian Owl 

New Caledonia Owtet-frogmouth 



Reunion Solitare 
Rodrigues Solitare 
Dodo 



Nansei-shoto (Japan) 



Madagascar 



1841 



1930 



A,B.C/D 



Brazil, Uruguay 


1855 




Cuba 


1885 


A,E 


New Caledonia 


1860 


B 


USA 


1914 


E 


Raiatea (F. Polynesia) 


1773 


— 


Tahiti (F. Polynesia) 


1844 


B 


Mauritius 


1765 


C/D 


Mauritius 


1675 


A,C 


Reunion 


1775(1834 
in captivity) 


B 


Rockigues (Maurlius) 


1761 


A,C/D 


Phillip 1 (AustraPa) 


1851 


A,E 


Rodrigues (Mauritius) 


1876 


B 


Seychelles 


1870 


A.B 


Bahamas 


1877 




Jamaica 


185S 


C 


India 


1914 




Roctigues (Mauritius) 


1726 


B 


Mauritius 






New Zealand 


1914 


B,C 


Mauritius 


1836 




New Caledonia 


1880 


- 


Reunion 


1710-1715 


A 


Rodrigues (Mauritius) 


1765 


A 


Mauritius 


1665 


A,C.D 



211 



1 . Biological Diversity 



Table 16.4 Animal species extinct since circa 1600 (continued) 



SPECIES 



BIRDS (continued) 



ENGLISH NAME 



DISTRIBUTION 



LAST POSSIBLE 

RECORDED CAUSE 



Family Columbidaa 
Atextroenas nib'dissi'ma 
'Ahxtomnas 'rodtricana 
Columba jouyi 
Columba versicolor 
Ectopistes migratorius 

* Microgoura meeki 

* Ptilinopus mercierii 

Order GRUIFORMES 

Family Rallidae 
Aphanapteryx bonasia 
Aphanapteryx leguab' 
Atiantista elpenor 
Fulica newtoni 
GalllniMa neshds 
GalliniJa pacrfica 
Galliralus pacrficus 
Nesoclopeus woodfordi 
Porphyrio albus 
Porzana monasa 
Porzana palmeri 
Porzana sandwichensis 
Rallus dieffenbachi 
Ralfus modestus 
Rallus wakensis 

* Tricholimnas lafresnayanus 

Order CICONIIFORMES 

Family Scolopacidae 
Prosobonia leucoptera 

Family Chafadridae 

Haematopus meadewaldoi 
Vanellus rnacropterus 

Family Laridae 
AIca impennis 

Family Falconidae 

Faico sp. 

Polyborus lutosus 
Family PodJcipedidae 

Podiceps andinus 

Podilymbus gigas 

Tachybaptus rufolarvatus 
Family Phalacrocoracidae 

Phalacrocorax perspicilbtus 
Family Ardeidae 

Ixobrychus novaezelarxlia 

Nycticorax mauritanus 

Nycticorax megacephalus 

Nycticorax sp. 
Family Threskiof nithidae 

Borbonibis latipes 
Family Ciconiidae 

Ciconia sp. 
Family Procellariidae 
' Oceanodroma macrodactyla 

Pterodroma sp. 

Order PASSERIFORMES 

Family Acanthisittidae 

Xenicus longipos 

Xenicus lyalli 
Family Pycnonotidae 

Hypsipetes sp. 
Family Muscicapidae 

Acrocephalus familiaris 

Eutrichomyias rowleyi 

Myiagra freycinett 

* Turnagra capensis 
Tardus ravidus 
Zoothera terrestis 
Babbler sp. 

Family Dicaeidae 

Dicaeum quadricolor 
Family Zosteroptdae 

Zosterops strenua 
Family Meliphagidae 

Chaetoptila angustipluma 

Moho apicalis 

* Moho nobilis 



Pigeon Hollandais 


Mauritius 


1835 


A,C 


Rodrigues Pigeon 


Rodrigues (Maurlius) 


1726 


C/D 


Ryultyu Wood Pigeon 


Nansei-shoto (Japan) 


1S36 


B 


Benin Wood Pigeon 


Ogasawara-shoto (Japan) 


1889 


C 


Passenger Pigeon 


USA 


1914 


A,B 


Solomon Island Crowned-pigeon 


Choiseii (Solomon Is) 


1904 


C 


Marquesas Fruit-dove 


Marquesas Is (F Polynesia) 


1922 


C/D 


Red Rail 


Mauritiis 


1700 


A,C/D 


Rodrigues Rail 


Rodrigues (Maurijus) 


1761 


- 


Ascension Flightless Crake 


Ascensbn 1 (UK) 


1656 


G(A.C) 


Mascarene Coot 


Mauritius, Reunion 


1693 




Tristan Moorhen 


Tristan da Cunha (UK) 


1875-1900 





Samoan Woodhen 


Savaii (Western Samoa) 


1908-1926 


C 


Tahiti Rail 


French Polynesia 


1773-4 




Woodford's Rail 


Bougainville (Papua New Guinea) 


1936 


— 


Lord Howe Purple Gallinule 


Lord Howe 1 (Australia) 


1834 


A 


Kosrae Crake 


Federated States of Micronesia 


1827 


C 


Laysan Rail 


Hawaii (USA) 


1944 


C.D 


Hawaiian Rail 


Havraii (USA) 


1B98 


C 


Chatham Island Banded Rail 


Chatham 1 (NZ) 


1840 


B.C 


Chatham Island Rail 


Chatham 1 (NZ) 


1900 


D 


Wake Island Rail 


Wake 1 (USA) 


1045 


A 


New Caledonia Rail 


New Caledonia 


1004 


- 



Tahitian Sandpiper 

Canarian Black Oystercatcher 
Javanese Wattled Lapwing 

Great Auk 



Guadalupe Carac£ira 

Colombian Grebe 
Atitlan Grebe 
Lake Alaotra Grebe 

Spectacled Cormorant 

New Zealand Little Bittern 

Mauritius Night-heron 
Rodrigues Night- heron 



Reunion Flightless Ibis 



Guadalupe Storm-petrel 



Bush Wren 
Stephens Island Wren 



Laysan Millerbird 

Caerulean Paradise -flycatch 

Guam Broadbill 

Piopio 

Grand Cayman Thrush 

Kittlitz's Thrush 



Four -coloured Flowerpecker 

Lord Howe White-eye 

Kioea 
Oahu Oo 
Hawaii Oo 



Tahiti, Moorea (F. Polynesia) 

Canary Is (Spain) 
Java (Indonesia) 

Canada. Iceland. Faeroes 
UK, USSR'. Greenland 



Guadalupe (Mexico) 
Rodrigues (Mauritius) 



New Zealand 
Stephens 1 (NZ) 

Rodrigues (Mauritius) 

Hawaii (USA) 

Sangihe (Indonesia) 

Guam 

New Zealand 

Cayman Is 

Ogasawara-shoto (Japan) 

Rodrigues (Mauritius) 

Cebu (Philippines) 

Lord Howe I (Australia) 

Hawaii (USA) 
Hawaii (USA) 
l-iawaii (USA) 



1913 
1040 



G 
A.B 



Reunion 


1674 


Guadalupe (Mexico) 


1900 A,D, 


Colombia 


1977 


Guatemala 
Madagascar 


1980-1986/7 A,D 


Bering Straits (USSR) 


1852 A 


New Zealand 


1900 


Mauritius 

Rodrigues (Maurftius) 

Reunion 


by 1700 
1761 
by 1700 


Reunion 


1773 


Reunion 


1674 



1912-1922 
1726 



1972 
1874 



1600s? 



B.C 
C 



1912-1923 


B,D 


1978 


B 


1983 




1955 


B.C 


1938 


B 


1928 


C 


1600s? 


- 



1906 



A.B.C/D 



1860 B 

1837 A.B.C/D 

1934 A.B.C/D 



212 



species Extinction 



Table 16.4 Animal species extinct since circa 1600 (continued) 



SPECIES 



BIRDS (continued) 

Ciridops anna 
Drepanis funerea 
Drepania pacffica 

* Hemignathus obscurus 
Hemignathus sagittirostis 

* Paroreomyza flammea 
Psftb'rostra kona 
fthodacanthis fJaviceps 
Rhodacanthis palmeri 

Family Icteridae 

Quiscalus palustris 
Family Ploceidae 

Foucta sp. 
Family Fringilidae 

Chaunoproctus f&reorostris 

Spt'za townsendi 
Family Sturnidae 

Aplonis corvina 

Aplonis fusca 

Aplonis mavornata 

* Aplonis p«l2elni 
Fregilupus varius 
Necrospar rodericanus 

Family Callaeidae 
Heteralocha acutirostris 

MAMMALS 



ENGLISH NAME 



Ula-ai-hawane 

Black Mamo 

Hawaii Mamo 

Akialoa 

Greater Amakihi 

Kakawihia or Molokai Creeper 

Kona Grosbeak 

Lesser Koa-finch 

Gireater Koa-finch 

Slender-billed Grackle 



DISTRIBUTION 



Reunion Fody 



Huia 




Mexico 



Reunion 



LAST 


POSSIBLE 


RECORDED CAUSE 


1892 


_ 


1907 


_ 


1899 


A.B 


1960 




1S00 


B 


1963 


— 


1894 


— 


1891 


— 


1896 


— 



1910 



1671 



Bonin Grosbeak 


Ogasawara-shoto (Japan) 


1890 


B,C/D 


Townsend's Finch 


USA 


1833 




Kosrae Mountain Starling 


Kosrae (Fed. States Micronesia) 


1828 


C 


Norfoll< Island Starling 


Norfolk 1 (Australia) 


1925 


_ 


Mysterious Starling 


Cook Is 


1825 


C/D 


Pohnpei Mountain Starling 


Pohnpei (Fed. States Micronesia) 


1956 


B 


Reunion Starling 


Reunion 


1850-1860 


B,C/D 


Rodrigues Starling 


Rodrigues (Mauriius) 


1726 





New Zealand 



1907 



A,B,C/D 



Order MARSUPIALIA 

Family Macropodidae 

# Caloprymnus campestris 
+ Lagofchestes asomatus 

Lagorchestes leporides 

Macropus ^eyi 

Onychogalea lunata 

Potofous platyops 
Family Perameiidae 

Chaeropus ecaudatus 

Perameles eremiana 
Family Thylacomyidae 

Macrotis leucura 
Family Thylacinidae 

Thytachus cynocephalus 

Order CHIROPTERA 

Family Pteropodidae 

Acerodon lucifer 
Dobsonia chapmani 
Pteropus pilosus 
Pteropus subniger 
Pteropus tokuc^e 
Family Molossidae 
Mystacina robusta 

Order INSECT1V0RA 

Family Nesophontidae 

# Nesophontes hypomicrus 

# Nesophontes micrus 

# Nesophontes paramicrus 

# Nesophontes zamicrus 

# Nesophontes sp. 

Order LAGOMORPHA 

Family Ochotonidae 

Prolagus sardus 
Family Leporidae 

# Syivilagus insonus 

Order RODENTIA 

Family Arvicolidae 

Pitymys bavancus 
Family Capromyidae 

# Capromys sp. 

# Geocapromys colombianus 
Geocapfomys thoractus 

# Geocapromys sp. 

# Isolobodon portoricensis 

# Plagiodontia velozi 
Family Cricetidae 

Megalomys desmarestii 
Megalomys luciae 
Megaloryzomys curioi 
Megaloryzomys sp. 
Nesoryzomys darwini 
Nesoryzomys sp. 



Desert Rat-kangaroo 
Central Hare-wallaby 

Eastern Hare-wallaby 
Tootache Wallaby 
Crescent Nailtail Wallaby 
Broad -feced Poloroo 

Pig-footed Bandicoot 
Desert Bandicoot 

Lesser Bilby 

Thylacine 



Panay Giant Fruit Bat 

Chapman's Bare-backed Flying Fox 

Palau Flying Fox 

Lesser Mascarene Flying Fox 

Guam Flying Fox 

New Zealand Lesser Short-tailed Bat 



Atalaye Nesophontes 
Western Cuban Nesophontes 
St Michel Nesophontes 
Haitian Nesophontes 



Sardinian Pika 
Omilteme Cottontail 



Bavarian Pine Vole 



Austraia 
Austraia 
Austraia 
Austraia 
Austraia 
Austraia 


1935 
1931 
1890 
1927 
1964 
1875 


A.B. 

C 

CD 

C 


Austraia 
Austraia 


1907 
1935 


C,D 


Austraia 


1931 


A,C 


Tasmania (Australia) 


1934 


E 


Philippines 

Philippines 

Palau 

Mauritius, Reunion 

Guam 


1888 

1964 
19thC 

1968 




New Zealand 


1960s 




Haiti, Dominican Republic 

Cuba 

Haiti, Dominican Republic 

Haiti, Dominican Republic 

Cayman Is 




C 
C 
C 

c 



Martinique Rice Rat 
St Lucia Rice Rat 



Santa Cruz Rice Rat 



Corsica (France), Sardinia (Italy) 
Mexico 

Gernnany 

Caynun Is 

Cuba 

Little Swan I (Honduras) 

Cayman Is 

Haiti, Dominican Republic 

Haiti, Dominican Republic 

Martinique 
Saint Lucta 
Galapagos fEcuadorJ 
Galapagos (Ecuador) 
Galapagos (Ecuador) 
Galapagos (Ecuador) 



1902 
19thC 



213 



1. Biological Diversity 



Table 16.4 Animal species extinct since circa 1600 (continued) 

SPECIES 



MAMMALS ^ontintMd) 

Oryzomys victus 

* Pmromyscus pemtMtioni 

Family Echimyklac 

* Bofomys offetla 

* Boromys torrei 

* BfOtomys voratus 
Family Muridaa 

Coniltrus albipms 

* Cratfomys paulut 
LmporilluB aptcalis 

* Notomys amplus 

* Notomys longicaudatus 
+ Notomys macfobs 

+ Notomys mordax 
+ Psmudomys fhlcU 
+ Pseudomys goultM 

Rattus macleari 

Rattus nativitatis 

Ordor CARNIVORA 

Family Canidaa 

Dusicyon australis 
Family Procyonidaa 
+ Procyon gtovwalleni 

Orciar PINNIPEDIA 

Family Phocidae 
Monachus tropicalis 

Ordw SIRENIA 

Family Dugongidaa 
Hytkodamalis gigas 

Ordw PERISSODACTYLA 

Family Equidaa 
Equus quagga 

Ordw ART10DACTYLA 

Family Bovidae 

Gazmlfa rufina 

Hippotragus feucopha^us 
Family Carvidaa 

Carvus schomburgki 



ENGLISH NAME 


DISTHIBiniON 


LAST 
RECORDE 


St Vincent Rice Rat 


Saint Vincent 


1897 


PamtMrton's Oe«r Mouse 


Mexico 

Cuba 
Cuba 

Haiti, Dominican Republic 




RabbK-eared Tree-rat 


Austraia 


1875 


Ilin Bushy-tailed Cloud-rat 


Philippines 




Lesser Stick-nest Rat 


Austraia 


1833 


Short-tailed Hopping-mouse 


Austraia 


1SS4 


Long-tailed Hopping-mouse 


Austraia 


1801 


Big-eared Hopping-mouse 


Austraia 


pre-1850 


Darling Downs Hopping-mouse 


Austraia 


pre-184e 


Alice Springs Mouse 


Austraia 


1885 


Gould's Mouse 


Austraia 


1930 


Maclears Rat 


Christmas 1 (Austraia) 


1808 


Bulldog Rat 


Christmas 1 (Austraia) 


1808 


Falkland Island Wolf 


Falklands Is 


1876 


Barbados Racoon 


Barbados 





Caribbean Monk Seal 



Steltar's Sea Cow 



Quagga 



Red Gazelle 
Bluebuck 

Schomburgk's Deer 



Caribbean 



Bering Straits ('USSR') 



South Africa 



Algeria? 
South Africa 

Thailand 



POSSIBLE 



1962 



19thC 
1800 



1032 



A.E 



Key: ' iudkates species generally regarded as extinct but for which there may still be some chance of survival. + indicates taxa which may be 
conspecific witb extant forms. # indicates species known from post— Columbian (i.e. pc^l 1500) deposits in the Caribbean: some may have become extinct 
before 1600. . indk:ates species last recorded from Rapa in 1934, and which were considered ukely to become rapidly extinct, x indicates species recorded 
from subfossU deposits in the Mascarenes which are considered very Ukely to have become extinct following settlement in 1723 although may possibly have 
become extinct earlier. 

Possible causes column': A Hunting (includes for food, skin, sport, live trade, feathers); B Direct habitat alteration by man: C Introduced predators 
(e.g. cats, rats, musteUds, mongooses, snails, monkeys): (C/D predators or others not specified); D Olber introduced animals (e.g. goats, rabbit, pigs); 
E Destroyed as a pest species; P Introduced disease; G Indirect effects; H Natural Causes; ~ causes uncertain. 

Note: The proceedings of a symposium entitled St Hehaa Natural Treasury (Edited by P. Pearce-KeUy and Q.C.B. Crook, published by the Zoologkal 
Society of London, 1990) were procured too late to include data in these lists. Aa additional eight extinct endemic bird species are listed from that isbnd, six 
of which should t>e included in our analysis. They are thought to have become extinct as a result of the human discovery of the island in 1502, and should 
therefore be iiKluded in the same sort of category as those species recovered from post -Columbian deposits in the Caribbean (i.e. those marked #). The 
report would also seem to indicate that it may be premature to declare the two insects Labidura herculeaaa and Aphtborax burcbeUJ txt'wct, and they 
should perhaps be excluded from this list at present. The effect these additions and changes have on the graphs and maps should be borne in mind, 
especially the increase in early island bird extiiKtions. 

Somce; compiled from multiple sources: details available from WCMC Most bird data compiled by A Stattersfield. and kindly made available by the 
International Council for Bird Preservation. Mollusc data assembled by Sue Wells with the assistance of members of the SSC Mollusc Specialist Group and 
other malacologists. 



214 



Species Extinction 



Table 16.5 Extinct higher plant taxa* 

MAJOR GROUP (DIVISION) 
FAMILY 

TAXON COMMON NAME 

Fern Allies 

Lycopodiaceae 

Huperzia nutans Brackenr. 
Selaginellaceae 

Selaginella on'zabensis Hieron. 
Isoetaceae 

Isoetes dixitii Shende 

Isoetes sampathkumamii L.N. Rao 

True Ferns 

Aspidiaceae 

Diplazium laffam'anum (Baker) C.Chr. 

Dryopteris spe/uncae (L.) Underwood 

Lastreopsis watzH (Beddome) Tagawa 
Aspleniaceae 

Asplenium fragile K. Presl var. insu/aris C. Morton 

Asplenium leucostegioides Baker 

Diellia manii 

Diellia unisora Wagner 
Blechnaceae 

Doodia /yon/ Degener 
Marslteaceae 

Marsilea paradoxa Diels 
Ophioglossaceae 

Botrychium subbifoliatum Brackenr. makou 

Thelypteridaceae 

Chn'stella altissima Holttum 

Thelypteris madfenta E. St. John Edward's maiden fern 

GymnoGperms 

Zamiaceae 

Encepha/artos woodU Sander 
Zamia monticola Chamberlain 

Dlcots 

Acanthaceae 

Dicliptera abuensis Blatter 

Dicliptera falcata (Lam.) Bosser & Heine 

Hypoestes inconspicua Balf. f. 

Hypoestes rodn'gues/ana Balf. f, 

Hypoestes serpens R. Br. 

Justicia brachystachya Thouars ex Schultz 

Justicia eranthemoides F. Muell. 

Justice psychotrioides Thouars ex Schultz 
Aizoaceae 

Gibbaeum esterhuyseniae L. Bolus 

Trianthema cypse/oides (Fenzl) Benth. 
Amaranthaceae 

Achyrar)thes atollensis St. John 

Achyranthes mutica A. Gray ex H. Mann 

Amaranthus mentegazzianus Passer. 

Blutaparon rigidum (Robinson & Greenman) Mears 

Ptilotus caespitulosus F. Muell. 

Ptilotus extenuatus BenI 

Ptilotus fasciculatus Fitzg. 

Ptilotus pyramidatus (Moq.) F. Muell. 
Anacardiaceae 

Buchanania mangoides F. Muell. 
Aquifoliaceae 

Ilex ternatiflora (C. Wright) R.A. Howard 
Asclepiadaceae 

Caralluma arenlcola N.E. Brown 

Marsdenia coronata Benth. 

Marsdenia tubulosa F. Muell. 



Matelea balbisii (Dene.) Woods. 

Matelea radiata Correll 
Begonlaceae 

Begonia cowellii Nash 

Begonia opuliflora Putz. 
Boraginaceae 

Cryptantha aperta (Eastw.) Payson 

Cryptantha insolita (J.F. Macbr,) Payson 

Heliotfopium muticum Domin 



Balbis' milkvine 
Falfurrias Anglepod 



Grand Junction cat's-eye 
unusual cat's-eye 



HISTORIC RANGE 



United States - Hawaii 
Mexico - Veracruz 



India - Maharashtra State 
India - Karnataka State 



Bermuda 
Bermuda 
India - Manipur State 

United States - Hawaii 

United States - Hawaii 
United States - Hawaii 
United States - Hawaii 

United States - Hawaii 

Australia - Western Australia 

United States - Hawaii 

South Africa - Natal 
United States - Florida 



South Africa - Natal 
Mexico 



India • Rajasthan State 

Mauritius 

Mauritius 

Mauritius 

Mauritius 

Mauritius 

Australia - 

Mauritius 



Rodrigues 
Rodrigues 



New South Wales 



South Africa - Cape Province 
Australia - New South Wales 

United States - Hawaii 
United States - Hawaii 
Argentina 

Ecuador- Galapagos 
Australia - Western Australia 
Australia - New South Wales 
Australia - Western Australia 
Australia - Western Australia 

Australia - Queensland 



South Africa - Cape Province 

Australia - Queensland 

Australia - NSW - Lord Howe Island 

United States - Arizona 

United States - Texas 

Cuba 

Panama 

United States - Colorado 
United States - Nevada 
Australia • Western Australia 



215 



I. Biological Diversity 



Table 16.5 Extinct higher plant taxa^ 

MAJOR GROUP (DIVISION) • 

FAMILY 

TAXON 

Heliotropium pannifo/ium Burchell ex Hemsley 

Lindelofia angusttfo/ia (Schrenk) A. Brand. 

Myosotis petiolata Hook.f. var. pottsi'ana L. Moore 

Onosma affine Hausskn. ex H. Rield 

Onosma discedens Hausskn. ex Bornm. 

Pfagiobothrys di'ffusus (Greene) I.M. Johnston 

Ptagiobothrys lamprocarpus (Piper) I.M. Johnston 

Piagiobothr/s orthostatus J. Black 
Bruniaceae 

Staavia trichotoma (Thunb.) Pillans 

Thamnea depressa Oliver 

Thamnea uniflora Solander ex Brongn. 
Cactaceae 

Hylocereus cubensis Brrtton & Rose 

Leptocereus wn'ghtii Leon 

Lobivia vatteri Krainz 

Opunt/a lindheimeri Engelmann var. linguiformis 

(Griffiths) L. Benson 

Pyrrhocactus ar/censis Ritt. 

Pyrrhocactus longirama Ritt. 

Pyrrhocactus nuda Ritt. 

Pyrrhocactus occultus Ritt. 
Campanulaceae 

Campanula oh'gosperma Damboldt 

C/ermontia multiflora Hillebrand 

Cyanea arborea (H. Mann) Hillebrand var. arborea 

Cyanea asplenifoUa (H. Mann) Hillebrand 

Cyanea comata Hillebrand 

Cyanea dunbarii Rock 

Cyanea giffardii Rock 

Cyanea glabra (F. Wimmer) St. John 

Cyanea grimes/ana Gaudich. ssp. cylindrocalyx 

(Rock) Lammers 

Cyanea Hnearifolia Rock 

Cyanea tongissima (Rock) St. John 

Cyanea obtusa (A. Gray) Hillebrand 

Cyanea pohaku Lammers 

Cyanea procera Hillebrand 

Cyanea profuga C. Forbes 

Cyanea pycnocarpa (Hillebrand) F.E. Wimmer 

Cyanea quercifol'ia (Hillebrand) F.E. Wimmer var. 

quercifolia 

Cyanea recta (Wawra) Hillebrand 

Cyanea scabra Hillebrand var. longissi'ma Rock 

Cyanea undulata C. Forbes 

Delissea fallax Hillebrand 

Delissea laciniata Hillebrand var. laciniata 

Delissea lauliiana Lammers 

Delissea parviflora Hillebrand 

Delissea rivularis (Rock) F.E. Wimmer 

Delissea sinuata Hillebrand ssp. lanaiensis (Rock) 

Lammers 

Delissea sinuata Hillebrand var. sinuata 

Delissea undulata Gaudich. 

Lobelia monostachya (Rock) Lammers 

Lobelia remyi Rock 

Rollandia parvifolia C. Forbes 

Rollandia purpurellifolia Rock 

Wahlenbergia burchellU A. DC. 

Wah/enbergia roxburghii A. DC. 

Wahlenbergia saxifragoides V. Brehm. 
Caryophyllaceae 

Alsinidendron viscosum (H. Mann) Sherff 

Schiedea amplexicaulis H. Mann 

Schiedea helleri Sherff 

Schiedea implexa (Hillebrand) Sherff 

Schiedea sperguHna A. Gray var. leiopoda Sherff 

Schiedea stellarioides H. Mann var. stellarioides 

Silene cryptopetala Hillebrand 

Silene oligotricha Huber-Mor. 

Silene rectiramea Robinson 



COMMON NAME 



San Francisco popcornflower 
popcomflower 



s p lee nv/ort- leaved cyanea 



smooth cyanea 



cut-leaf delissea 
small-fiowered delissea 



wavy-leaf delissea 

undulata delissea 



HISTORIC RANQE 

St Helena 

former Union of Soviet Socialist 

Republics 

New Zealand - North Island 

Turkey 

Turkey 

United States - California 

United States - Oregon 

Australia - South Australia 

South Africa - Cape Province 
South Africa - Cape Province 
South Africa - Cape Province 

Cuba 
Cuba 

Argentina 

United States - Texas 

Chile 
Chile 
Chile 
Chile 



Turkey 

United States - 
United States ■ 
United States • 
United Staces - 
United States - 
United States - 
United States - 
United States - 



Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 



United 
United 
United 
United 

United 
United 
United 
United 

United 
United 
United 
United 
United 
United 
United 
United 
United 



States • Hawaii 
States - Hawaii 
States • Hawaii 
States - Hawaii 
States - Hawaii 
States - Hawaii 
States - Hawaii 
States - Hawaii 



States - 
States - 
States - 
States - 
States - 
States - 
States - 
States - 
States - 



United States 
United States 
United States 
United States 
United States 
United States 
St Helena 
St Helena 
South Africa - 



Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 

Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 
Hawaii 



Cape ft-ovince 



laulihilihi; kawelu; ma'oli'oli 



United 
United 
United 
United 
United 
United 
United 
Turkey 
United 



States - Hawaii 
States - Hawaii 
States - Hawaii 
States - Hawaii 
States - Hawaii 
States - Hawaii 
States - Hawaii 

States - Arizona 



216 



Species Extinction 



Table 16.5 Extinct higher plant taxa^ 

MAJOR GROUP (DIVISION) 
FAMILY 

TAXON 

Stellaria elatinoides Hook. f. 
Celastraceas 

Hexaspora pubescens C. White 

Maytenus Uneata C. Wright 
Chanopodiaceae 

Hemichroa mesembryanthema F. Muell. 

Sclerolaena ramsayae (Willis) A.J. Scott 

Suaeda duripes I.M. Johnston 
Co mpo sitae 

Abrotanella rhynchocarpa Balf. f. 

Acanthocladium dockeri F. Muell. 

Argyroxiphium virescons Hillebrand var. virescens 

Artemisia insipida VIM. 

Brachycome mueHeri Sonder 

Caiocephalus globosus M. Scott & Hutch. 

Cirsium toyoshimae Koidz. 

Commidendrum rotundifoUum (Roxb.) DC. 

Crepidia strum ameristophyllum (Koidz.) Nakai 

Crepidiastrum grandicollum (Koidz.) Nakal 

Erigeron perglaber Blake 

Felicia annectens (Harvey) Grau 

Helianthus praetermissus E. Watson 

Helichrysum oligochaetum F. Muell. 

Helichrysum selaginoides (Sonder & F. Muell.) 

Benth. 

Helichrysum spiceri F, Muell. 

Helipterum guilfoylei Ewart 

Hemizonia mohavensis Keck 

Leptorh ynchos gatesii {VJWWamson) J.H. Willis 

Lipochaeta bryanii Sherff 

Upochaeta ovata R. Gardner 

Lipochaeta perdita Sherff 

Marasmodes undulata Compton 

Olearia arida Pritzel 

Olearia flocktoniae Maiden & E. Betcke 
Olearia oUganthema Benth. 
Osteospermum hirsutum Thunb. 
Perityle inyoensis (Ferris) A. Powell 
Perityle vil/osa (Blake) Shinn. 
Senecio behrianus Sonder & F. Muell. 

Senecio georgianus DC. 

Senecio laticostatus Belcher 

Senecio sandwicensis Less. 

Solidago porteri Small 

Tetramolopium arenarium (A. Gray) Hillebrand var. 

arenarium 

Tetramolopium arenarium (A. Gray) Hillebrand var. 

confertum Sherff 

Tetramolopium arenarium (A. Gray) Hillebrand ssp. 

laxum Lowrey 

Tetramolopium capillare (Gaudich.) H. St. John 

Tetramolopium consanguineum (A. Gray) 

Hillebrand ssp. consanguineum 

Tetramolopium conyzoldes (A. Gray) Hillebrand 

Tetramolopium lepidotum Less. ssp. arbusculum 

(A. Gray) T.K. Lowrey 

Tetramolopium tenerrimum (Less.) Nees 

Tracyina rostrata Blake 

Vernonia africana (Sonder) Druce 
Crassulaceaa 

Crassu/a alcicornis Schonl. 

Crassula subulata Hermann var. hfspida (Schonl. & 

E.G. Baker) Toelken 

Echeveria laui Moran & Meyran 

Sedum pinetorum Brandegee 

Sedum polystriatum R.T. Clausen 

Tacitus bellus Moran & Meyran 
Cruciferae 



COMMON NAME 



hardtoe seepweed 



greensword 



Mojave tarweed; Mojave tarplant 



ko'oko'otau; nehe 



Inyo laphamia 
Hanaupah laphamia 



Porter's goldenrod 



showy Indian clover 



Pine City stonecrop 



HISTORIC RANGE 
New Zealand 

Australia - Queensland 
Cuba 

Australia - South Australia 
Australia - Victoria 
United States - Texas 

Mauritius • Rodrigues 

Australia - New South Wales, South 

Australia 

United States - Hawaii 

France 

Australia - South Australia 

Australia - Western Australia 

Japan 

St Helena 

Japan - Ogasawara-Shoto 

Japan - Ogasawara-Shoto 

United States - Arizona 

South Africa - Cape Province 

United States - New Mexico 

Australia - Western Australia 

Australia - Tasmania 

Australia - Tasmania 

Australia - Western Australia 

United States - California 

Australia - Victoria 

United States - Hawaii 

United States - Hawaii 

United States - Hawaii 

South Africa - Cape Province 

Australia - South Australia, Western 

Australia 

Australia - New South Wales 

Australia - New South Wales 

South Africa - Cape Province 

United States - California 

United States - California 

Australia - New South Wales, South 

Australia, Victoria 

Australia - South Australia, Victoria, 

Western Australia 

Australia - Victoria 

United States ■ Hawaii 

United States - Georgia, North Carolina 

United States - Hawaii 

United States - Hawaii 

United States - Hawaii 

United States - Hawaii 
United States - Hawaii 

United States - Hawaii 
United States - Hawaii 

United States - Hawaii 
United States - California 
South Africa - Natal 

South Africa - Cape Province 
South Africa - Cape Province 

Mexico - Oaxaca 

United States - California 

Turkey 

Mexico - Chihuahua 



217 



1. Biological Diversity 



Table 16.5 Extinct higher plant taxa^ 

MAJOR GROUP (DIVISION) 
FAMILY 

TAXON 

Ballantinia anti'poda (F. Muell.) E. Shaw 
Caulanthus lemmonii 
Diptotaxis sfettiana Maire 
Hutchinsia tasmanica Hook. 
Isatis arnoldiana N. Busch. 

iridium drummondii Thell. 

Lepidium merrallii F. Muell. 

Lepidium obtusatum Kirk 

Lepidium peregrinum Thall. 

Menkea draboides (Hook.f.) Benth. 

Ph/egmatospermum drummondii (Benth.) O. 

Schultz 

Ph/egmatospermum richardsii iF. Muell.) E. Shaw 

Rorippa coloradensis Stuckey 
Stroganowia sagittata Karelin & Kir. 

Tropidocarpum capparideum Greene 
Cucurbitaceae 

Ber^incasa hispida (Thunb.) Cogn. 

S/cyos hif/ebrarydii H. St. John 

Sicyos villosa Hook. f. 
Oicra&tYlidaceae 

Dicrastylis morrisonii Munir 
Dilleniaceae 

Hibbertia sargentUS. Moore 
Epacridaceae 

Andersonia bifida L. Watson 

Andersor^ia longifolia (Benth.) L. Watson 

Choristemon humifis Williamson 

Co/eanthera coelophylla (DC.) Benth. 

Coleanthera virgata Stschegl. 

Leucopogon cryptanthus Benth. 

Leucopogon pogonocalyx Benth. 
Ericaceae 

Arctostaphylos uva-ursi (L.) Sprengel var. 

franciscana (Eastw.) Roof 

Arctostaphylos uva-ursi (L.) Sprengel var. 

leobreweri Roof 

Erica acocAr// Compton 

Erica bolusiae Salter 

Erica jasminiflora Salisb. 

Erica pyramidalis Sotander 

Erica turgida Salisb. 

Erica verticillata Bergius 

Rhododendron mucronu/atum Turcz. var. albiflora 

Nakai 
Erythroxylaceae 

Erythroxylum echinodendron Ekman 
Euphorbiaceae 

Acalypha rubra Roxb. 

Amperea protensa Nees 

Beyer/a cygnorum (Muell. Arg.) Benth. 

Beyeria lepidopetala F. Muell. 

Bonanza myrcifo/ia (Griseb.) Benth. & Hook. 

Chamaesyce celastroides (Boiss.) Croizat & 

Degener var. tomentella 

Ciaoxylon grandifolium (Poiret) Muell. Arg. 

Cnidoscolus fragrans (H.B.K.) Pohl 

Croton magneticus Airy Shaw 

Euphorbia carissoides Bailey 

Euphorbia daphnoides Balf. f. 

Pseudanthus nematophorus F. Muell. 
Fagaceae 

Quercus boytoni Beadle 
Frankeniaceae 

Franker)ia conferta Dials 

Frankenia decurrens Summerh. 

Frankenia parvula Turcz. 
Gesneriaceae 

Cyrtandra cyaneoides Rock 



COMMON NAME 



Colorado watercress 



caper-fruited tropidocarpum 



'akoko: koko; 'ekoko; kokomalei 



Boyton's sand post oak 



HISTORIC RANGE 

Australia - Tasmania, Victoria 

United States - Arizona 

Spain 

Australia ■ Tasmania 

former Union of Soviet Socialist 

Republics 

Australia - Western Australia 

Australia - Western Australia 

NEW ZEALAND - North Island 

Australia - New South Wales 

Australia - Western Australia 

Australia - Western Australia 

Australia - South Australia, Western 

Australia 

United States - Colorado 

Asiatic former Union of Soviet Socialist 

Republics 

United States - California 

Australia - Queensland 
United States - Hawaii 
Ecuador- Galapagos 

Australia - Western Australia 

Australia - Western Australia 

Australia - Western Australia 
Australia - Western Australia 
Australia - Victoria 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 

United States - California 

United States - California 



South Africa - 
South Africa - 
South Africa - 
South Africa - 
South Africa - 
South Africa - 
Republic of Ko 



Cape Province 
Cape Province 
Cape Province 
Cape Province 
Cape Province 
Cape Province 
re a 



St Helena 

Australia - Western Australia 

Australia - Western Australia 

Australia - Western Australia 

Cuba 

United States - Hawaii 



Mauritius; France 

Cuba 

Australia 

Australia 

Mauritius 

Australia 



Reunion 

Queensland 
Queensland 
Rodrigues 
Western Australia 



United States - Texas 

Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 

United States - Hawaii 



218 



Species Extinction 



ha'iwale; kanawao ke'oke'o 



Saline Valley phacetia 
ashy phacelia 
Nevada phacelia 



Table 16.5 Extinct higher plant taxa* 

MAJOR GROUP (DIVISION) 
FAMILY 

TAXON COMMON NAME 

Cyrtandra gracilis Hillebrand 

Cyrtandra honolulensis Wawra 

Cyrtandra kohalae Rock 

Cyrtandra o/ona C. Forbes 

Cyrtandra pickeringii A. Gray var. pickeringff 

Cyrtandra waiolani \Navjr a var. capitata Hillebrand 

Cyrtandra waiolani Wawra var. waiolani 
Goodeniaceae 

Dampiera helmsii Krause 

Dampiera humilis (F. Muell.) E. Pritzel 

Dampiera rupicola S. Moore 

Goodenia clementii Krause 

Scaevola attenuata R. Br. 

Scaevola macrophylla (Vriese) Benth. 

Scaevola oldfieldii F. Muell. 

Verreauxia verreauxH (Vriese) Carolin 
Grossulariaceae 

Ribes kolymense (Trautv.) Komarov ex Pojark 

Haloragaceae 

Gonocarpus intricatus (Benth.) Orch. 
Haloragis stn'cta R. Br. 

Haloragis tenuHolia Benth. 

Haloragodendron lucasii {.Uiaid&n & E. Betch) Orch. 

Meziella trifida (Nees) Schindler 
Hydrophyilaceae 

Phacelia amabilis Constance 

Phacelia cinerea Eastw. 

Phacelia nevadensis J. Howell 
Labiatae 

Haplostachys bryanii Sherff var. bryanii 

Haplostachys linearifolia (Drake) Sherff var. 

linearifolia 

Haplostachys munroi C Forbes 

Haplostachys truncata (A. Gray) Hillebrand 

Hemigenia exHis S. Moore 

Hemigenia obtusa Benth. 

Hemigenia pimelifolia F. Muell. 

Hemigenia podalyrina F. Muell. 

Hemigenia ramosissima Benth. 

Hemigenia tysonlF. Muell. 

Hemigenia tysonii F. Muell. 

Microcorys pimeloides F. Muell. 

Monardella leucocephala A. Gray 

Monardella pringlei k. Gray 

Phyllostegia brevidens A. Gray var. brevidens 

Phyllostegia hillebrandU Mann ex Hillebrand 

Phyllostegia immunata (Sherff) St. John 

Phyllostegia knudsenii Hillebrand 

Phyllostegia rockii Sherff 

Phyllostegia variabilis Bitter 

Phyllostegia wawrana Sherff 

Prostanthera staurophylla F. Muell. 

Pycnanthemum monotrichum Fern. mountain mint 

Stenogyne cinerea Hillebrand 

Stenogyne haliakalae Wawra 

Stenogyne oxygona Degener & Sherff 

Stenogyne viridis Hillebrand 

Teucrium leucophyllum Montbret & Aucher ex 

Bentham 

Thymus oehmianus Ronn. & Soska 
Lauraceae 

Cassytha pedicellosa J.Z. Webb 
Leguminosae 

Acacia forrestiana E. Pritzel 

Acacia murruboensis Maiden & Blakely 

Acacia prismifolia E. Pritzel 

Acacia vassaUi Maslin 

Aspalathus variegata Ecklon & Zeyher 

Astragalus pseudocylindraceus Bornm. 

Astragalus robbinsU (Cakes) A. Gray var. robbinsii 



Merced monardella 
Pringle monardella 



HISTORIC RANGE 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 



Australia - 
Australia ■ 
Australia ■ 
Australia ■ 
Australia ■ 
Australia - 
Australia 
Australia - 



Western 
Western 
Western 
Western 
Western 
Western 
Western 
Western 



Australia 
Australia 
Australia 
Australia 
Australia 
Australia 
Australia 
Australia 



former Union of Soviet Socialist 
Republics 

Australia - Western Australia 

Australia - New South Wales, 

Queensland 

Australia - Western Australia 

Australia - New South Wales 

Australia - Western Australia 

United States - California 
United States - California 
United States - Nevada 



United States - 
United States - 



Hawaii 
Hawaii 



United States - Hawaii 
United States - Hawaii 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
United States - California 
United States - California 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
Australia - New South Wales 
United States - Virginia 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
United States - Hawaii 
Turkey 

Yugoslavia 

Australia - Tasmania 

Australia - Western Australia 

Australia - New South Wales 

Australia ■ Western Australia 

Australia - Western Australia 

South Africa - Cape Province 

Turkey 

United States - Vermont 



219 



7. Biological Diversity 



Table 16.5 Extinct higher plant taxa* 



MAJOR GROUP (DIVISION) 
FAMILY 

TAXON 

Chorizema varium Benth. 

Crotalaria urbaniana Senn 

Gastro/obium crispifoUum Domin 

Genista melia Boiss. 

Jacksonia hemisericea D. Horbert 

Lathyrus dominianus Litv. 

Lupinus subfanatus Eaetw. 

Mirbelia densiflora C. Gardner 

Onobrychis aliacmonia Reich, f. 

Orbexilum macrophyllum Rydb. 

Oxylobium acutum (Benth.) Benth. 

Phyllota gracilis Turcz. 

Psoralea macrophylla Rowlee ex Small 

Psoraiea stipulata Torroy ex A. Gray 

Pultenaea paucif/ora M. Scott 

Sophora toromiro (Philippi) Skottsb. 

Streblorrhiza speciosa Endl. 

Taverniera sericophylla Balf. f. 

Tephrosia A:s5sas/Boulos 

Tetragonofobus wiedemannii Boiss. 

Trifolium amoenum E. Greene 

Vicia dennesiana H.C. Watson 
Lentibulariaceae 

Utricularia mairii Cheeseman 
Loasaceae 

Mentzelia nitens Greene var. leptocaulis J. Darl. 
Loganiaceae 

Mitrasacme pafustrisVJ. Ftag. 
Loranthaceae 

Dendrophthora termina/is Kuijt 

Psfttacanthus nudus (A. Molina) Kuijt & Fcuer 

Trilepidea adamsU (Cheeseman) Treghem 
Malvaceae 

Abutilon maun'tianum (Jacq.) Medik. 

Anisodontea alexandri (Baker f.) Bates 

Hibiscadelphus bombycinus C. Forbes 

Hibiscadelpbus cruc/bracteatus Hobdy 

Hibiscadelphus wilderianus Rock 

Hibiscus nelsonii Rose & Standley 

Kokia tanceolata Lewton 

Malacothamnus abbottH (Eastw.) Kearney 

Malacothamnus mendocinensis (Eastw.) Kearney 

Sida pritzellii C Gardner 

Sidalcea ArecA:// Wiggins 

Sphaeralcea procera C.L. Porter 
Menispermaceae 

Hyperbaena obovata Urban 
Menyanthaceae 

Nymphoides stygia (J. Black) H. Eichler 
Myoporaceae 

EremophUa adenotricha F. Muell. 

Eremophila scaberula Fitzg. 
Myrsinaceae 

Badula ovalifolia A. DC. 

Myrsine mezii Hosaka 
Myrtaceae 

Cahthamnus b/epharantherus F. Muell. 

Hypocalymma longifob'um F. Muell. 

Melaleuca arenaria C. Gardner 

Melaleuca arenicola S. Moore 

Melaleuca graminea S. Moore 

Monimiastrum fasciculatum Gueho & A.J. Scott 

Syzygium balfouni (Baker) Gueho & A.J. Scott 
Verticordia can'nata Turcz. 
Nyctaginacaae 

Pfsonia floridana Britton 
Ochnaceae 

Ouratea attemifolia (A. Rich.) M. Gomez 
Oleaceae 

Hesperelaea pa/meri A. Gray 
Onagraceae 



COMMON NAME 



Santa Catalina Island desert-thorn 



bigleaf scurpea 
scurf-pea 



showy indian clover 



Abbott's bush-mallow 
Mendocino bush-mallow 



Keck sidalcea: Keck checker-mallow 
Luna County globemallow 



rock dey devil's-claws 



HISTORIC RANGE 

Australia - Western Australia 

Cuba 

Australia - Western Australia 

Greece 

Australia - Western Australia 

former Union of Soviet Socialist 

Republics 

United States - California 

Australia - Western Australia 

Greece 

United States - North Carolina 

Australia - Western Australia 

Australia - Western Australia 

United States - North Carolina 

United States - Indiana, Kentucky 

Australia - Western Australia 

Chile - Easter Island 

Australia - Norfolk Island 

Democratic Yemen - Socotra 

Egypt 

Greece 

United States - California 

Portugal - Azores 

New Zealand - North Island 

United States - Arizona 

Australia - Western Australia 

Costa Rica 

Honduras 

New Zealand - North Island 



Mauritius 
South Africa - 
United States 
United States 
United States 
Mexico 
United States 
United States 
United States 



Cape Province 

- Hawaii 
■ Hawaii 

- Hawaii 

- Hawaii 

- California 

- Arkansas. California 



Australia - Western Australia 
United States - California 
United States - New Mexico 

Cuba 

Australia • South Australia 

Australia - Western Australia 
Australia - Western Australia 

France - Reunion 
United States - Hawaii 



Australia 
Australia 
Australia 
Australia 
Australia 
Mauritius 
Mauritius 
Australia 



Western Australia 
Western Australia 
Western Australia 
Western Australia 
Western Australia 

- Rodrigues 

Western Australia 



United States - Florida 

Cuba 

Mexico 



220 



species Extinction 



Table 16.5 Extinct higher plant taxa^ 

MAJOR GROUP (DIVISION) 
FAMILY 

TAXON 

Clarkia mosquiniiE. Small ssp. xerophila E. Small 

Lopezia conjugens Brandegee 

Lopezia sinaloensis Munz 

Oenothera kfein/iVJX. Wagner & S.W. Mill 

Papaveraceao 

Eschscholzia rhombipetala E. Greene 
Penaeaceae 

Stylapterus micranthus R. Dahlgren 
Piperaceae 

Peperomia degeneri YunckeT 

Peperomia hi'rta Balf. f. 

Peperomia rodriguezt Balf. f . 

Peperomia rossU Rendle 
Plumbaginaceae 

Armeria arcuata Welw. ex Boiss. & Reuter 
Polygalaceae 

Comesperma fanceofatum Benth. 

Comesperma rhadinocarpum F. Muell. 
Polygonaceae 

Eriogonum truncatum Ton-ey & A. Gray 

Portulacaceae 

Calandrinia composite Nees 

Calandrinia dielsH Poelln. 

Caiandrinia fe/tonii Skottsb. 

Calandrinia sphaerophylla J. Black 
Primulacaae 

Lysimachia forbesH Rock 

Lysimachia minoricensis J.D. Rodriguez 
Proteaceae 

Grevillea batrachioides McGillivray 

Grevii/ea divaricata R. Br. 

Grevillea flexuosa (Lindley) Meissner 

Grevillea scabra Meissner 

Hakea crassinervia Meissner 

Hakea pulvinifera L. Johnson 

Hakea tamminensis C. Gardner 

Isopogon uncinatus R. Br. 

Leucadendron comosum (Thunb.) R. Br. ssp. 

homoeophyllum (Meisn.) I. Williams 

Leucadendron spirale (Salisb. ox Knight) I. Williams 

Mimetes stokoei Phillips & Hutch. 

Persoonia leucopogon S. Moore 

Sorocephalus tenuifolius R. Br. 

Triunia robusta (C. White) D. Foreman 
Pyrolaceae 

Pyrola oxypetala Austin 
Rhamnaceae 

Cryptandra tubulosa Fenzl. 

Cryptandra uncinata Gmn. 

Spyndium kalganense Diels 

Spyridium microcephalum (Turcz.) Benth. 

Trymalium albicans (Steudel) Reisseck 

Trymalium urceolare {F. Muell.) Diels 
Rosaceae 

Potentilla multijuga Lehm. 
Rubiaceae 

Danais corymbosa Balf. f. 

Gaertnera calycina Bojer 

Gaertnera crassiflora Bojer 

Gaertnera longifolia Baler var. pubescens Verde. 

Gaertnera quadriseta A. DC. 

Hedyotis foUosa (Hillebrand) Fosb. 

Oldenlandia adscensionis (DC.) Cronk 

Oldenlandia polyclada (F. Muell.) F. Muell. 

Oldenlandia sieberi Baker var. sieberi 

Opercularia hirsuta F. Muell ex Benth. 

Opercularia ocolytantha Diels. 

Ophiorrhiza brunonis Wight & Arn. 

Ophiorrhiza caudate C. Fischer 



COMMON NAME 



Klein's evening-primrose; Wolf Creek 
evening-primrose 



diamond-petaled; California poppy 



Contra Costa eriogonum; Mt Diablo 
buckwheat 



sharp-petal wintergreen 



Ballona cJnquefoil 



HISTORIC RANGE 

United States • California 

Mexico 

Mexico 

United States - Colorado 



United States - California 

South Africa - Cape Province 

United States - Havt/sii 
Mauritius - Rodrigues 
Mauritius - Rodrigues 
Australia - Christmas Island 

Portugal 

Australia - Western Australia 
Australia - Western Australia 

United States - California 



Australia - Western Australia 
Australia - Western Australia 
Falkland Islands 
Australia - South Australia 

United States - Hawaii 
Spain - Balearic Islands 

Australia - Western Australia 
Australia - New South Wales 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - New South Wales 
Australia - Western Australia 
Australia - Western Australia 
South Africa - Cape Province 

South Africa - Cape Province 
South Africa - Cape Province 
Australia - Western Australia 
South Africa - Cape Province 
Australia - Queensland 

United States - New York 

Australia - Western Australia 
Australia - South Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 

United States - California 

Mauritius - Rodrigues 

Mauritius 

Mauritius 

Mauritius 

Mauritius 

United States - Hawaii 

Ascension Island 

Australia - Queensland 

Mauritius 

Australia • Western Australia 

Australia - Western Australia 

India • Kamataka State, Kerala State. 

Tamil Nadu State 

India - Kerala State 



221 



7. Biological Diversity 



^able 16.5 Extinct higher plant taxa^ 



MAJOR GROUP (DIVISION} 
FAMILY 

TAXON 

Ophiorrhiza radicans Gardn. 
Phyllacanthus grisebachianus Hook. f. 
Psychotria banaona Urban 
Pyrostria fernjginea Verde. 
Rondcletia odorata Jacq. var. breviftora Hook. 
Wend/and/a angustifolia Wight 
Rutaceae 

Acmadenia Candida I. Williams 

Agathosma orbicularis Bartl. & Wendl. f. 

Eriostemon falcatus P.G. Wilson 

Galipea ossana DC. 

Koda/yodertdron cubens/s Borh. & Acuna 

Me/icope adscendens (St. John & Hume) T. 

Hartley & B. Stone 

Melicope ballouii (Rock) T. Hartley & B. Stone 

Me/icope degeneri (B. Stone) T. Hartley & B. Stone 

Melicope lydgatei (Hillebrand) T. Hartley & B. 

Stone 

Melicope avails (St. John) T. Hartley & B. Stone 

Melicope quadrangularis (St. John & E. Hume) T. 

Hartley & B. Stone 

Melicope reflexa (St. John) T. Hartley & B. Stone 

Melicope wailauensis (St. John) T. Hartley & B. 

Stone 

Pelea fatuh/vensis F. Brown 

Pelea obovata H. St. John 

Phebalium da vie sU Hook. f. 

Phebalium lachnaeoides Cunn. 

Zanthoxylum leonis Alain 

Zieria adenophora Blakely 
Santalaceae 

Leptomeria dielsiana Pilger 

Santalum fernandezianum F. Philippi 
Sapindaceae 

Euchorium cubense Ekman & Radlk. 
Saxifragaceae 

Astilbe crenatiloba (Britton) Small 



COMMON NAME 



crenate-lobed false goat's-beard 



Mitella prostrata Michaux 
Saxifraga lactea Turcz. 

Saxifrage oppositifolia L. ssp. amphibia (Sundemn.) 
Braun-Blanquet 
Scrophulariaceae 

Agalinis stenophyffa Penned 

Agalinis strict/folia Pennell 

Castilleja cruenta Standley 

Castilleja leschkeana J. Howell 

Euphrasia arguta R. Br. 

Euphrasia collina R.Br. ssp. muellen' (Wettst.) 

Barker 

Umosella pubiflora Pennell 

Micranthemum micrartthemoides (Nutt.) Wettst. 



nan'ow-leaved false foxglove 

Indian paintbrush 

Point Reyes Indian paintbrush 



Nuttall's micranthemum 



Mimulus brartdegei Pennell 
Mimulus dementi/ Domin 
Mimulus traskiae A.L. Grant 
Mimulus whipplei A.L. Grant 
Orthocarpus pachystachyus A. Gray 
Penstemon leptanthus Pennell 
Penstemon pulchellus Lindl. 
Seymeria havardii (Pennell) Stand 
Verbascum calycosum Hausskn. & Murb. 
Veronica euxina Turrill 
Solanaceae 

Lycium hassei Greene 
Mellissia begonifoHa (Roxb.) Hook. f. 
Solanum bahamense L. var. rugelii D'Arcy 
Solanum bauerianum Endl. 



Santa Cruz Island monkey-flower 

Santa Catalina monkey-flower 
Whipple's monkey-flower 
Shasta owl-clover 
Sevier Plateau beardtongue 
beautiful beardtongue 
Eagle Pass seymeria 



HISTORIC RANGE 

India - Kerala State; Sri Lanka 

Cuba 

Cuba 

Mauritius 

Panama 

India - Tamil Nadu State 

South Africa - Cape Province 

South Africa - Cape Province 

Australia - Western Australia 

Cuba 

Cuba 

United States - Hawaii 

United States - Hawaii 
United States - Hawaii 
United States - Hawaii 

United States - Hawaii 
United States - Hawaii 



United States - 
United States - 



Hawaii 
Hawaii 



France - French Polynesia - Marquesas 

Is 

United States - Hawaii 

Australia - Tasmania 

Australia - New South Wales 

Cuba 

Australia - New South Wales 

Australia - Western Australia 
Chile - Juan Fernandez 



United States - North Carolina, 

Tennessee 

Canada 

former Union of Soviet Socialist 

Republics 

Germany; Swrtzeriand 



United States - Florida 

United States - Louisiana 

United States • Arizona 

United States - California 

Australia - New South Wales 

Australia • New South Wales, South 

Australia. Victoria 

United States - Arizona 

United States - Delaware, District of 

Columbia, Maryland, New Jersey, New 

York, Pennsylvania, Virginia 

United States • California 

Australia - Western Australia 

United States - California 

United States - California 

United States - California 

United States - Utah 

United States - New Mexico 

United States - Texas 

Turkey 

Bulgaria 

United States - California 

St Helena 

United States - Florida 

Australia - NSW 

Lord Howe Island 

Australia - Norfolk Island 



222 



species Extinction 



COMMON NAME 



Franklin tree 



Table 16.5 Extinct higher plant taxa* 

MAJOR GROUP (DrVISION) 
FAMILY 

TAXON 

Solanum ca/amarcense Ochoa 

Solanum nava Webb & Barthel. 
Sterculiaceae 

Astiria rosea LIndley 

Sterculia khasiana Deb. 

Trochetia parviflora Bojer ex Baker 
Stvlidiaceae 

Stylidium merraUii (F.Muell.) E. Pritzel 

Stylidium neglectum Mildbr. 

Stylidium pseudocaespitosum Mildbr. 
Styracaceae 

Styrax portoricensis Krug & Urban 
Theaceae 

Franklinia alatamaha Marshall 
Tremandracaaa 

Tetratheca deltoidea J. Thompson 

Tetratheca elUptica J. Thompson 

Tetratheca fascicuiata J. Thompson 

Tetratheca gunnii Hook. f. 
Umbelllferae 

Geocaryum bornmuelleri (Wolff) Engstr. 

Geocaryum divaricatum (Bolss. & Orph.) Engstr. 

Ptatysace dissecta (Benth.) Nonnan 

Pfatysace eatoniae (F. Muell.) Nonman 

Trachymene croniniana F. Muell. 

Xanthosia singuliflora F. Muell. 

ZizJa latifolia Small 
Uftlcaceaa 

Pilea thouarsiana Wedd. 

Pilea trilobata (Poiret) Wedd. 
Valerianaceae 

Valeriana pratens/s (Benth.) Steud. 
Violaceae 

Isodendrion pyrifolium A. Gray 

Viola cryana Glllot 
Zygophyllaceae 

Fagonia taeckholmiana Hadldl 

Monocota 

AmaryllidacBae 

Caliphruria tenera Baker 

Eucharis lehmannii Regel 

Eucrosia mirahilis (Baker) Pax 

Gethyllis esterhuyseniae 

Gethyllis latifolia Masson ex Baker 

Habranthus caeruleus (Griseb.) Traub 

Mathieua galanthoides Klotzsch 

Plagiolirion horsmannii Baker 
Araceae 

Anthurium leuconeurum Lemaire 

Philodendron dementis C.Wright ex Griseb. 
Bumiannlaceae 

Thismia amerlcana N. Pfolffer 
Centra lepidaceae 

Centrolepis caespitosa D. Cooke 
Commelinaceae 

Sauvallea blainii C. Wright 
Cyperaceae 

Bulbostylis neglecta (Hemsley) C.B. Clarke 

Carex aboriginum M.E. Jones 

Carex paupera Nelmes 

Carex repanda C.B. Clarke 

Cladium drummondii C.B. Clarke 

Eleocharis bermudiana Britton 

Fimbristylis compacta Turrill 

Schoenus acumiriatus R. Br. 

Schoenus natans (F. Muetl.) Benth. 

Tetraria australiensis C.B. Clarke 
DioGCoreaceae 

Dioscorea pentaphylla L. 

Rafania prestoniensis Knuth 
Eriocaulaceae 

Eriocaulon echinospermoideum Ruhl. 



bristol golden alexanders 



wahine noho kula 



Indian Valley sedge 



HISTORIC RANGE 
Penj 

Spain - Canary Islands 

Mauritius 

India - Meghalaya State 

Mauritius 

Australia - Western Australia 
Australia - Western Australia 
Australia • Western Australia 

Puerto Rico 

United States - Georgia 

Australia - Western Australia 
Australia - Western Australia 
Australia - Western Australia 
Australia - Tasmania 

Greece 

Greece 

Australia - Western Australia 

Australia - Western Australia 

Australia - Western Australia 

Australia - Western Australia 

United States ■ Florida 

Mauritius 
Mauritius 



United States - Hawaii 
France 



Egypt 



Colombia 

Colombia 

Ecuador 

South Africa - Cape Province 

South Africa - Cape Province 

Argentina 

Peru 

Colombia 

Mexico 
Cuba 

United States - Illinois 

Australia - Western Australia 

Cuba 

St Helena 

United States - Idaho 

Australia - Victoria 

India - Meghalaya State 

Australia - Western Australia 

Bermuda 

Australia - Northern Territory 

Australia - Western Australia 

Australia - Western Australia 

Australia - Western Australia 

Australia - Queensland 
Cuba 

Cuba 



223 



L Biological Diversity 



Table 16.5 Extinct higher plant taxa^ 



MAJOR GROUP (DIVISION) 
FAMILY 

TAXON 

Eriocaulon johnstonU Ruhl. 
EriocBulon minutessimum Ruhl. 
Lachnocaulon cubense Ruhl. 
GramJneae 

Agrostis adamsonii VIck. 

Agrostis limitanea J. Black 

Bromus brachystachys Homung 

Bromus bromoideus (Lej.) Crepin 

Bromus grossus Desf. ex DC. 

Bromus interruptus (Hackel) Druce 

Cenchrus agrimoniot'des Trin. var. laysanensis F. 

Brown 

Deyeuxia drummondii (Steudel) Vick. 

Deyeuxia lawrericei Vick. 

Digitaria pittieri (Hackel) Henrard 

Dissanthelium caltfomicum (Nutt.) Banth. 

Eragrostis deflexa Hitchc. 

Eragrostis fosbergii Whitney 

Eragrostis hosakai Degener 

Eragrostis mauiensis Hrtchc. 

Eragrostis rottleri Stapf 

Eriochrysis rangacharii Fischer 

Festuca benthamiana Vick. 

Glyceria drumondii (Steudel) C.E. Hubb. 

Heterachne baileyi C.E. Hubb. 

Homopholis 6e/so/)// C.E. Hubb. 

Hubbardia heptaneuron Bor 

f^spalum amphicarpum Ekman 

f^spalum jimenezii Chase 

Pfectrachne bromoides (F. Muell.) C.E. Hubb. 

Poa manii Munroe ex Hillebrand 

f^a mannii Munro 

Streptochaeta angustifolia Soderstrom 

Sucrea sampaiana (A. Hitch.) Soderstrom 

Trisetum burnoufH Heq. ex Pari. 

Zea mays L. ssp. mexicana (Schrad.) Witkes raza 

durango 
Hydatellaceae 

Hydatelia australis Diets 

Hydatella leptogyne Dieis 
Hydrocharitaceae 

Elodea linearis H. St. John 

Elodea schweinitzii (Planchon) Casper 
Iridaceae 

Gladiolus alatus L. var. atgoensis Herb. 

Hesperarttha saldanhae P. Goldblatt 

Iris antilibanotica Dinsm. 

Iris damascena Mont. 

Iris westii Dinsm. 

Moraea incurva Lewis 

Romulea papyracea W. Dod 

Romulea sulphurea Beguinot 

Sisyrinchium farwellU Bickn. 

Sisyrinchium hastile Bickn. 
Juncaceae 

Juncus griscomii 

Juncus oronensis Fern. 

Juncus pervetus Fern. 
Lillaceae 

Allium rouyi Gaut. 

Calochortus indecorus Ownbey & M. Peck 

Calochortus monanthus Ownbey 

Dipcadi concanense (Dalz.) Baker 
Dipcadi reidii Deb & Dasgupta 
Ipheion tweedianum (Griseb.) Traub 
Lachenalia mathewsii Barker 
Smilax leptanthera Pennell 
Tulipa sprengeri Baker 
Urginea duthiae Adamson 
Urginea ecklonii Baker 



COMMON NAME 



kamanomano; kumanomano 



California dissanthelium 
Pacific lovegrass 
Fosberg's lovegrass 



Mann's bluegrass 



Nashville waterweed 
Schweinitz's waterweed 



HISTORIC RANGE 

Mauritius 

Cuba 

Cuba 

Australia - Victoria 

Australia - South Australia 

Germany 

Belgium 

Belgium; Luxembourg 

United Kingdom 

United States - Hawaii 

Australia - Western Australia 

Australia - Tasmania 

Costa Rica 

United States - California; Mex 

United States - Hawaii 

United States - Hawaii 

United States - Hawaii 

United States - Hawaii 

India - Tamil Nadu State 

India - Tamil Nadu State 

Australia - South Australia 

Australia - Western Australia 

Australia - Queensland 

Australia - New South Wales, 

Queensland 

India - Karnataka State 

Cuba 

Costa Rica 

Australia - Western Australia 

United States - Hawaii 

United States - Hawaii 

Brazil 

Brazil 

France - Corsica 

Mexico 



Australia - Western Australia 

Australia - Western Australia 



United States - Tennessee 
United States - Pennsylvania 



Farwell's blue-eyed-grass 
spear-like blue-eyed-grass 

Griscom's rush 

Maine rush 

Barnstable bog rush; old veteran rush 



Sexton Mt mariposa-lity 
Shasta River mariposa; 
single-flowered mariposa lily 



South Africa - 
South Africa - 
Syria 
Syria 
Lebanon 
South Africa - 
South Africa - 
South Africa - 
Un'rted States 
United States 



Cape Province 
Cape Province 



Cape Province 
Capo Province 
Cape Province 

■ Michigan 

■ Michigan 



United States - Virginia 

United States - Maine 

United States - Massachusetts 

Spain 

United States - Oregon 

United States • California 

India 

India 

Argentina 

South Africa - Cape Province 

United States - Georgia 

Turkey 

South Africa - Cape Province 

South Africa - Cape Province 



224 



Extinct Species 



Table 16.5 Extinct higher plant taxa* 



MAJOR GROUP (DIVISrON) 
FAMILY 

TAXON 

Urginea polyphylla Hook. f. 
Orchidaceae 

Acrolophia ustulata Schlecther & Bolus 

Caladenia atkinsonii Rodway 

Caladenia pumila R. Rogers 

Calanthe whiteana King & Pantl. 

Corycium vest/turn Sweet 

D/'uris fastidiosa R. Rogers 

Paphiopedilum deienatU Guillaumin 

Pleione lagenaria Lindley 

Prasophyllum colemaniae R. Rogers 

Prasophyllum subbisectum Nicholls 

Satyrium guthnet Bo\us 

Triphora lati'folia G. Luer 

Zeuxine boninensis Tuy 
Palmae 

Acrocomia submermis Leon ex L.H. Bailey 

Corypha taliera Roxb. 

Paschalococos disperta Dransf ield 

Pritchardiopsis jennencyi Becc. 
Pandanaceae 

Pandanus bark/yi Be\1 . F. var. macrocarpus 

Vaughan & Wiehe 

Pandanus conglomeratus Balf. f. 

Pandanus iceryi Home ex Balf. f. 

Pandanus incertus Vaughan & Wiehe 

Pandanus macrostigma Martelli 

Pandanus obsoletus Vaughan & Wiehe 

Pandanus spathulatus Martelle 
Restionaceae 

Elegia extensa Pillans 

Blegia fastlgiata Mast. 

Leptocarpus ramosiss/mus Pillans 

Lepyrodia heleocharoides Gilg 

Restio chaunocoleus F. Muell 
Tecophilaeaceae 

Tecophilaea cyanocrocus Leybold 
Zingiberaceae 

Hedychium marginatum C.B. Clarke 



COMMON NAME 



nodding cape 



HISTORIC RANGE 
India 

South Africa ■ Cape Province 

Australia - Tasmania 

Australia - Victoria 

India - Sikkim State 

South Africa - Cape Province 

Australia - Victoria 

Vietnam 

India - Meghalaya State 

Australia - Victoria 

Australia - Victoria 

South Africa - Cape Province 

United States - Florida 

Japan - Ogasawara-Shoto 

Cuba 
India 
Chile - Easter Island 

France - Ue\N Caledonia 



Mauritius 
Mauritius 
Mauritius 
Mauritius 
Mauritius 
Mauritius 

South Africa - Cape Province 
South Africa - Cape Province 
South Africa - Cape Province 
Australia - Western Australia 
Australia - Western Australia 

Chile 

India - Nagaland State 



Notes: This list represents information available to WCMC in computerised form as of March 1992. It is intended to include species that are extinct 
(or presumed extinct) in the wild, whether or not they are in cultivation. Several of these plants, such as Franklinia alatamaha, Paphiopedilum 
delenatii and Tecophilaea cyanocrocus, are, in fact, well known in the horticultural trade. Others, such as Encephalartos woodii, are known only 
from relatively few specimens, mostly held in botanic gardens. A few others have become extinct in the wild but have been reintroduced from 
cultivated material grown in botanic gardens. 

The information available is strongly biased geographically: many other species of higher plants have undoubtedly become extinct but lack of 
country-based data prevents their inclusion here. Some of the species in this list are almost certainly still extant in remote, isolated areas; publication 
of this list should stimulate searching for them. 



* Includes some taxa below species level. 



Notes for Table 16.6, overleaf: (1) Two amphibians (USA and Israel), one coral (Panama) and one mammal (Caribbean) are not included in this 
table. (2) The above species may have lived in more than one country therefore total numbers do not necessarily agree with other tables. * indicates 
islands which are not on the standard country list. They have been included separately because of the importance of islands when considering 

extinctions. 



225 



1. Biological Diversity 



Table 16.6 Known animal extinctions since c. 1600 by country 

MOLLUSCS INSECTS RSHES REPTILES BIRDS MAMMALS 



ASIA 

India 

Indonesia 

Nansei-shoto (Japan)* 



Navassa Island (USA)* 

Saint Lucia 

Saint Vincent and the Grenadines 

United States 38 

Virgin Islands (US) 

SOl/m AMERICA 

Brazil 

Colombia 

Galapagos (Ecuador)* 1 

Uruguay 

OCEANIA 

American Samoa 2 

Austraia 

Bougainville (PNG)* 

Chatham Island (NZ)* 

ChristrTMa Island (Austraial* 



17 



17 

2 



TOTAL 



Nepal 

Ogasawara-shoto (Japan)* 






3 




1 
3 


Philippines 

Taiwan 

Thailand 

'USSR- 
Bering Straits (■USSRT 
EUROPE 

Austria 1 
Carury Islands (Spain)* 
Corsica (France)* 
Faeroe Islands 
Germany 


1 
1 






3 
1 

1 

1 
1 


4 
1 
1 

1 
2 

1 

1 
1 
1 
2 


Iceland 

Sardinia (Italy)* 

United Kir^dom 

Yugoslavia 1 


2 






1 


1 
1 

1 
1 


NORTH & CENTRAL AMERICA 


1 








Bahamas 
Bartiados 
Canada 
Cayman Is 
Cuba 


2 


1 

3 

4 


1 
2 
4 
4 
5 


Dominican Rep 

Greenland 

Guadalupe (Mexico)* 

Guadeloupe 1 

Guatemala 




1 


2 


6 


6 

1 
2 
2 
1 


Haiti 

Jamaica 

Little Swan Island (Honduras)* 

Martinique 

Mexico 


12 


2 
3 




6 

1 
1 
2 


6 
3 

1 

4 
15 



1 
1 
1 

68 
1 



Cook Islarxjs 

Fiji 

French Polynesia 

Guam 

Havvaii (USA)* 



33 

1 

29 



1 
42 



5 

1 

15 



15 
1 

38 
3 

88 



Kangaroo Island (Australia)* 
Lord Howe Island (Australia)* 
Micronesia, Federated States of 
New Caledonia 2 
New Zealand 



1 
2 
3 

3 
10 



1 
3 
3 
S 
14 



Norfolk Island (Australia)* 

Patau 

Philip Island (Austraia)* 

Solomon Islands 

Stephens Island (NZ)* 



Tasmania (Australia)* 
Wake Island (USA)* 
Western Samoa 

ANTARCTICA 

Falkland Islands (Malvinas) & dependencies 

AFRICA 

Algeria 

Ascensbn Island (UK)* 

Cape Verde 

Madagascar 

Madeira (Portuaan* 14 



1 
1 
1 
3 
14 



Mauritius 

Reunion 

Rockigues (MaurKus)* 

Saint Helena 

Seychelles 



23 
1 
6 

22 
2 



11 
11 
11 



41 
IS 
21 
24 
3 



South Africa 

Tristan da Cunha (UK)* 



226 



Species Extinction 



Figure 16.6 Known animal extinctions since c. 1600: Molluscs 



sepeds io jeqiuni^ 
8 S 




227 



1. Biological Diversity 



Figure 16.7 Known animal extinctions since c. 1600: Arthropods 

sepeds p jeqairiN 

S 8 S 




228 



Species Extinction 

Figure 16.8 Known animal extinctions since c. 1600: Fishes, reptiles and amphibians 



sepeds )o jeqaintg 
8 




229 



1. Biological Diversity 



Figure 16.9 Known animal extinctions since c. 1600: Birds 



sepeds p JsqiunN 
8 a o 




230 



Species Extinction 



Figure 16.10 Known animal extinctions since c. 1600: Mammals 



sspeds (0 jsqiunfsi 

8 2 




231 



1. Biological Diversity 



Table 16.7 Animal species surviving only in captivity 

SPECIES ENGLISH NAME NOTES 

MOLLUSCS 

Order STYLOMMATOPHORA 

Family Partulidae 
Partula spp. 



Viviparous Tree Snails 



French Polynesia. Exterminated in wild after 
introduction of Euglandina rosea in 1977. 
Various captive colonies around the world. 
Population status information as at March 
1991 *. 



Partula affinis 


Partula aurantia 


Partula clara 


Partula hyalina 


Partula mirabilis 


Partula mooreana 


Partula nodosa 


Partula otaheitana 


Partula suturalis 


Partula taeniata 


Partula tohiveana 


FISHES 


Order CYPRINODONTIFORMES 


Family Cyprinodontidae * * 


Cyprinodon alvarezi 



Megupsilon aporus 



Family Poeciliidae 

Xiphophorus couchianus 

Family Goodeidae 
Skiffia francesae 

BIRDS 

Order CICONIIFOMES 

Family Ciconiidae 

Gymnogyps californianus 

Family Columbidae 
Zenaida graysoni 

MAMMALS 

Order PERISSODACTYLA 

Family Equidae 
Equus ferus 



Order ARTIODACTYLA 

Family Bovidae 
Bos taurus 



Monterrey Platyfish 



Golden Sawfin 



Californian Condor 



Socorro Dove 



Wild Horse 



Domestic cattle 



Tahiti. Functionally extinct, only 1 left alive. 

Moorea. Functionally extinct, only 1 left alive. 

Tahiti. Critical. 

Tahiti. Increasing. 

Moorea. Critical. 

Moorea. Seriously declining. 

Tahiti. Increasing. 

Tahiti. Increasing but low numbers. 

Moorea. Declining/stable. 

Moorea. Increasing, good numbers. 

Moorea. Increasing but all from 4 individuals. 



Mexico. Last specimens removed from wild 
February 1992. 

Mexico. Last specimens removed from wild 
February 1 992; a number of captive 
populations exist. 

Mexico. Extinct in the wild in 1960s; three 
captive populations. 

Mexico; widespread in captivity. 



USA. Last individual taken from wild 1 987. 52 
in captivity at end of 1991. 

Socorro I (Mexico). Extinct post-1958. Large 
captive populations. 



China, Mongolia. Some disagreement on 
taxonomic status. E. ferus gmelini, theTarpan, 
exterminated late 1 9th century. £. f. 
przewalskii, Przewalski's Horse survives in 
zoos, last seen in wild in 1968. 



Europe, North Africa and the Near East. The 
Aurochs B. t. primigenius, the wild ancestor 
was exterminated in 1627. 



Notes: * Reference: Partula '91, Proceedings of Ihe Partula Propagation Group Meeting, 16 May 1991. Compiled by S. Tonge, JWPT. •• Note 
two further Cyprinodon species, Charco Azul and Charco Palma will probably also soon be extirpated in the wild (P. Loiselle, pers. comm.). 



232 



Species Extinction 



Table 16.8 Animal species extirpated in wild and reintroduced 



BIRDS 

Order GRUIFORMES 

Family Rallidae 
Rallus owstoni 

MAMMALS 

Order CARNIVORA 

Family Mustelidae 
Mustela nigripes 

Family Canidae 
Canis rufus 

Order ARTIODACTYLA 

Family Bovidae 
Bison bonasus 

Oryx leucoryx 

Family Cervidae 

Elaphurus davidianus 



Guam Rail 



Black-footed Ferret 
Red Wolf 

WIsent 
Arabian Oryx 

P6re David's Deer 



Guam (USA). Extinct 
Reintroduced 1990/91. 



wild 1985. 



USA. Last specimen taken from wild in 1987. 
Reintroduced 1990/91. 

USA. Extinct in wild 1980, reintroduced late 
1980s. 



Europe. Exterminated in wild by 1927. 
Reintroduced to several locations. 
Middle East. Last recorded in the wild in 1 972. 
Reintroduced in Oman in 1982. 

Discovered in captivity in 1861. Now exists in 
zoos worldwide. Reintroduced to China. 



233 



1. Biological Diversity 

17. THREATE>fED SPECIES 



A threatened species is one thought to be at significant risk 
of extinction in the foreseeable future, because of stochastic 
or deterministic factors affecting its populations, or by 
virtue of inherent rarity. This convenient working definition 
is deceptively simple; deciding what level of risk is 
significant, and what part of the future is foreseeable, is 
problematic. 

WHAT IS A THREATE^fED SPECIES? 

The growth in public awareness of the problem of depletion 
and possible extinction of species is largely attributable to 
the development of the Red Data Book (RDB) concept by 
Sir Peter Scott during the 1960s. This involves an attempt 
to categorise species at risk according to the severity of the 
threats facing them and the estimated imminence of their 
extinction. The RDBs were compiled on a global basis by 
lUCN, so far as available information allowed, but the 
concept was soon adopted at a national or sub-national level 
in several countries. Attention also spread from the 
terrestrial vertebrates, which were the principal focus of 
early RDBs, to invertebrates and plants. 

As the volume of information has increased, the traditional 
Red Data Book approach, which included publication of a 
range of data on each threatened species, has been to some 
extent replaced by a direct listing of globally-threatened 
species recognised by lUCN. The lUCN Red List of 
Threatened Animals (lUCN, 1990, latest edition) is the only 
accepted worldwide attempt to list threatened animal species 
individually, and has provided the basis for the discussion 
below. 

The animals Red List has been compiled every two years 
since 1986 by the World Conservation Monitoring Centre, 
in collaboration with the lUCN Species Survival 
Commission network of Specialist Groups. The Red List is 
based on information provided by numerous scientists, 
naturalists and conservationists working in the field, much 
of it collated by the lUCN SSC Specialist Groups. The 
categorisation of threatened bird species is undertaken by 
the International Council for Bird Preservation (ICBP). 

Each species covered in the Red List is assigned a threat 
category determined by a review of the factors affecting it 
and the extent of the effect that these are having throughout 
its range. Key factors examined include changes in 
distribution or numbers, degree and type of threat, and 
population biology. lUCN Red List categories are applied 
to species on an international or global scale, and should 
not be confused with the national threat categories assigned 
to species by countries which have prepared Red Lists or 
Red Data Books dealing with the status of species within 
their own borders. 

It is important to note that although the lUCN Red List is 
a comprehensive global compendium of animal species 
known to be threatened, many more species than those listed 
will in fact be threatened. Those not listed fall into two 
categories: first, and probably the largest number of 
species, are those not yet described by science; and second, 
the status of many described species has not been reviewed. 



Birds have been comprehensively reviewed by ICBP; only 
50% of mammal species, and probably less than 20% of 
reptiles, 10% of amphibians and 5% offish are estimated 
to have been reviewed. 

lUCN threat categories 

The main lUCN threat categories currently used, together 
with their definitions (as used in the Red Lists) are: 

Extinct (Ex) 

Species not definitely located in the wild during the past 50 
years. On a few occasions, the category Ex? has been 
assigned, denoting that it is virtually certain that the taxon 
has recently become extinct. 

Endangered (E) 

Taxa in danger of extinction and whose survival is unlikely 
if the causal factors continue to operate. Included are taxa 
whose numbers have been reduced to a critical level or 
whose habitats have been so drastically reduced that they 
are deemed to be in immediate danger of extinction. Also 
included are taxa that may now be extinct although they 
have been seen in the wild in the past 50 years. 

Vulnerable (V) 

Taxa believed likely to move into the Endangered category 
in the near future if the causal factors continue operating. 
Included are taxa of which most or all the populations are 
decreasing because of over-exploitation, extensive 
destruction of habitat or other environmental disturbance; 
taxa with populations that have been seriously depleted and 
whose ultimate security has not been assured; and taxa with 
populations that are still abundant but are under threat fi-om 
severe adverse factors throughout their range. 

Rare (R) 

Taxa with small world populations that are not at present 
Endangered or Vulnerable but are at risk. These taxa are 
usually localised within restricted geographical areas or 
habitats or are thinly scattered over a more extensive range. 

Indeterminate (I) 

Taxa known to be Endangered, Vulnerable or Rare but 
where there is not enough information to say which of the 
three categories is appropriate. 

Insufnciently Known (K) 

Taxa that are suspected but not definitely known to belong 
to any of the above categories, because of lack of 
information. 

The general term threatened is used to refer to a species 
considered to belong to any one of the above categories. 
The same definitions have been applied to plants, although 
they have often been interpreted in a significantly different 
manner, mainly because of biological differences between 
animals and plants, and intermediate categories (e.g. Ex/E 
or E/R) are also employed. 

The definition and application of such status categories has 
been a matter of some discussion, principally because they 



234 



Threatened Species 



provide such an important tool in assessing needs and 
mobilising resources for conservation at the international, 
national or sub-national level. In the opinion of many 
scientists, the existing lUCN threat category definitions are 
excessively subjective, and as a result categorisations made 
by different authorities can vary and may not accurately 
reflect real extinction risks. Mace and Lande (1991) have 
recently proposed a new system based on quantitative (and 
therefore theoretically objective) Population Viability 
Analysis techniques. 

The threats 

Most of the causal factors currently threatening species are 
anthropogenic in nature, i.e. induced or influenced by man. 
These factors include: 

• Habitat loss or modification, often associated with 
habitat fragmentation. Causes include pastoral 
development, cultivation and settlement, forestry 
operations and plantations, fire, and pollution 

• Over-exploitation for commercial or subsistence reasons, 
including meat, fur, hides, collection of live animals for 
the pet trade and plants for the horticultural trade 

• Accidental or deliberate introduction of exotic species, 
which may compete with, prey on or hybridise with 
native species 

• Disturbance, persecution and uprooting, including 
deliberate eradication of species considered to be pests 

• Incidental take, particularly the drowning of aquatic 
reptiles and mammals in fishing nets 

• Disease, both exotic and endemic, exacerbated by the 
presence of large numbers of domestic livestock or 
introduced plant species 



• Limited distribution, which may compound the effects of 
other factors. 

In the majority of cases individual species are faced by 
several of these threats operating simultaneously, and it is 
often difficult or impossible to identify with confidence the 
primary cause of decline. 

Some understanding of the relative importance of different 
threat types, as measured by frequency of occurrence, can 
be gained from an examination of threats facing the 
mammals (excluding Cetacea) of Australasia and the 
Americas (comprehensively reviewed by Thornback and 
Jenkins, 1982), and those facing the birds of the world 
(Diamond, 1987). 

Of the 119 species of mammals from these continents 
considered threatened, 75% (94) are threatened by more 
than one factor, and of these, 27 face four or more threats. 

The major category of threat, which affects 76 % of species, 
is habitat loss and modification (Fig. 17.1). This has a 
variety of causes, of which the most frequent is cultivation 
and settlement. Over-exploitation affects half the species, 
the most significant cause being hunting for meat. 
Introduced predators and competitors affect 18% of 
threatened species. The most serious other factor is limited 
distribution, which affects one quarter of species. 

Fig. 17.2 compares the major threats affecting the birds of 
the world with those affecting the mammals of Australasia 
and the Americas. There is a high degree of similarity 
between the two groups. Habitat destruction is the single 
most important threat, affecting 60% of birds and 76% of 



Figure 17.1 Analysis of tiireats: mammals 



Habitat loss 8< 
modlf Icat ion 




Threats and classes of threat -> 



235 



1. Biological Diversity 



Figure 17.2 Analysis of threats: mammals and birds 



Q> 50 



0) 4Q _ 




Mammals C°'' Australasia & 

the Americas^ 



Hob i test destruction 



Introduced species 



Wetland drainage 



Incidental take 



Hunt i ng 



international trade 



Threat type 



Po I I ut i on 



mammals. A major difference is that almost double the 
number of mamlnals as birds are threatened by hunting 
(54% versus 29%). 

GLOBALLY THREATENED ANIMALS 

Taxonomic distribution of threatened animals 

The term 'threatened' in the following discussion refers to 
taxa assigned a relevant status category by lUCN. In all, 
some 4,452 animal species are listed as threatened in the 
1990 Red List, or much less than 0.5% of the world's 
estimated total of well over 1.5 million described animal 
species (Tables 17.1 and 17.2). Some species are also listed 
in part otdy, i.e. one or more subspecies are included in the 
Red List, but only fiill species are considered here. 

The two classes with the greatest number of threatened 
species are birds with 1,029 and insects with 1,083. Other 
major listings include 507 mammals, 169 reptiles, 57 
amphibians, 713 fish, 409 molluscs, 154 corals and 
sponges, 139 annelid worms and 126 crustaceans. Clearly, 
the number of threatened species in a taxonomic group is 
not directly proportional to the overall number of species in 
that group: some groups, particularly vertebrates, have 
higher proportions listed as threatened than other groups. 

The four major groups with the highest percentage of 
threatened species are mammals (11.7% threatened), birds 
(10.6%), fish (3.6%) and reptiles (3.5%). In comparison, 
although a large number (1,083) of insects is listed, this 
represents less than 0.15% of the world's total. This 
dichotomy between vertebrates and invertebrates becomes 
even more extreme when Endangered species, the most 
severely threatened category, are examined. Each of the 



five vertebrate groupings have a higher percentage of listed 
Endangered species than all of the invertebrate taxa added 
together (Fig. 17.3). 

Considering only the mammals among vertebrates, several 
smaller orders have a very high proportion of threatened 
species (Proboscidea with two out of two species, Sirenia 
with four out of four species and Perissodactyla with 12 out 
of 16 species). Among the larger orders, Primates, 
Carnivora and Artiodactyla are the most threatened, with 
respectively 53 % , 32 % and 3 1 % of their constituent species 
listed. Although these three orders combined only contain 
some 14.6% of the world's mammal species, they account 
for just under half of the listed threatened species and just 
over half of the Endangered species. 

To some extent, vertebrates may be more vulnerable to 
extinction than invertebrates because they are typically 
much larger and therefore require more resources and 
larger ranges. On the other hand, many invertebrates have 
an extremely small range, which would render them liable 
to extinction by habitat loss. It seems reasonable to 
conclude that the proportion of species in a group listed as 
threatened reflects popular and scientific attention in 
addition to biological reality. 

Geopolitical distribution of threatened animals 

Table 17.3 shows the geopolitical distribution of threatened 
animal species according to the lUCN Red List (1990) 
together with threatened plants; Table 17.4 shows a subset 
of the animal data, with the countries listed in descending 
order according to the number of threatened species in each 
higher grouping. The top ten countries are listed for each 
taxon. 



236 



Threatened Species 



Table 17.1 lUCN Threatened Vertebrates {1990 Red List) 



CLASS 

ORDER 
MAMMALS 

Monotremata 
Marsupialia 
Xenarthra 
Insectivora 
Scandentia 
Dermoptera 
Chiroptera 
Primates 
Pholidota 
Lagomorpha 
Macroscelidia 
Rodentia 
Cetacea 
Carnivore 
Pinnipedia 
Sirenia 
Proboscidea 
Perissodactyla 
Hyracoidea 
Tubulidentata 
Artiodactyla 
BIRDS 

Struthioniformes 
Tinamitormes 
Sphenisciformes 
Podicipediformes 
Procellariformes 
Pelecaniformes 
Ciconiiformes 
Anseriformes 
Falconiformes 
Galtiformes 
Gruiformes 
Charadriiformes 
Columbiformes 
Psittaciformes 
Cuculiformes 
Strigiformes 
Caprimulgiformes 
Apodiformes 
Trogoniformes 
Coraciiformes 
Piciformes 
Passeriformes 
REPTILES 

Testudines 
Rhynchocephalia 



NUMBER OF SPECIES 



THREATENED 


ENDANGERED 


507 


140 


1 





25 


6 


6 


1 


79 


3 














45 


11 


106 


47 








9 


6 


2 





54 


15 


21 


6 


76 


12 


4 


2 


4 





2 


1 


12 


7 


1 











60 


23 


1,029 


132 


1 





8 





3 





4 


2 


25 


4 


8 


3 


21 


8 


20 


3 


45 


6 


68 


11 


51 


9 


31 


4 


49 


6 


78 


16 


11 


2 


20 


1 


11 





39 


3 


3 





20 





14 


4 


499 


50 


169 


38 


78 


11 


1 






APPROXIMATE TOTAL 
OF DESCRIBED SPECIES 
4,327 

3 

282 

29 

365 

16 

2 

977 

201 

7 

65 

15 

1,793 

77 

235 

34 

5 

2 

16 

8 

1 

194 

9,672 

10 

47 

17? 

217 

115? 

97 

19? 

168 

311? 

214 

196 

350? 

313 

358 

143 

178? 

105? 

103 

39 

152 

355 

5,712 

4,771 

2? 



237 



1. Biological Diversity 



Table 17.1 lUCN Threatened Vertebrates (1990 Red List) 



CLASS 

ORDER 
REPTILES (continued) 

Sauria 
Serpentes 
Crocodylia 
;|MMPHIBIANS 

Caudata 
Anura 

LAMPREYS 
SHARKS, etc. 
BONY FISH 
TOTAL VERTEBRATES 



NUMBER OF SPECIES 
THREATENED ENDANGERED 



APPROXIMATE TOTAL 
OF DESCRIBED SPECIES 



43 
33 
15 
67 

25 

32 

713 

3 

3 

707 

2,475 



9 

7 
11 

8 

2 

6 

368 





368 

686 



2,000 
2,500 

4.014 



ao.oofr 



42,784 



Sources: World species totals for groups of animals are derived from the following sources - mammals: Corbet, G.B. and Hill, J.E. 1991 . yl World 

List of Mammalian Species. 3rd edn. Natural History Museum, London and Oxford Univerity Press, Oxford; birds: Sibley, C.G. and Monroe, B. 

L. 1990. Distribution and Taxonomy of Birds of the World. Yale University Press, New Haven & London; reptiles, amphibians and fishes: varioua 

sources. 

Note: Table only includes groups of animals of which one or more species are listed as threatened, with the exception of mammals for which all 

orders are included. Species categorised as Extinct are not included, those as Extinct? are. 



Table 17.2 lUCN Threatened Invertebrates (1990 Red List) 



PHYLUM 



CLASS 



CILIOPHORA 




1 


CNIDARIA 




154 


PLATYHELMINTHES 


TURBELLARIA 


4 


NEMERTEA 




10 


MOLLUSCA 




409 


ANNELIDA 




139 


ARTHROPODA 


INSECTA 


1,083 




MEROSTOMATA 


4 




ARACHNIDA 


. 18 




CRUSTACEA 


126 


ONCHYOPHORA 




27 


ECHINODERMATA 




2 


TOTAL INVERTEBRATES 




1,977 



NO. OF SPECIES 
THREATENED ENDANGERED 







2 



85 

2 

56 



1 

3 





149 



Sources: various. 

Notes: Table only includes groups of animals of which one or more species are listed as threatened. 

Species categorised as Extinct are not included, those as Extinct? are. 



APPROXIMATE TOTAL 
OF DESCRIBED SPECIES 



? 

9,000 

1 2.700 

650 

50,000 

8,700 

750,000 

4 

68,000 

42,000 

65 

6,000 

947,119 



238 



Threatened Species 



Table 17.3 Country totals of threatened plants and vertebrates 



ASIA 

Afghanistan 

Bahrain 

Bangladesh 

Bhutan 

British Indian Ocean Terriory 



Brunei 
CamlMdia 
China 
Cyprus 
Hong Kong 



India 

IndonesB 

Iran, Islamic Rep 

Iraq 

Israel 



Japan 

Jordan 

Korea, Dem People's Rep 

Korea, Rep 

Kuvwiit 



Laos 

Lebanon 

Malaysia 

Maldives 

Mongolia 



Myanmar 

Nepal 

Oman 

Pakistan 

Philippines 



Qatar 

Saudi Arabia 
Singapore 
Sri Lanka 



Taiwan 

Thailand 

Turkey 

United Arab Emirates 

Viet Nam 



Bermuda 
Canada 

Cayman Islands 
Costa Rica 



PLAffTS 



4 



33 

15 





MAMMALS 



13 
1 

15 

IS 





13 

4 

27 

10 





40 

11 

350 

43 

5 



« 

21 

40 

1 

1 



10 
13 
83 
17 
9 



1336 

70 

301 

1 

3 



39 

49 

15 

9 

8 



72 
135 
20 
17 
15 



41 

752 



33 

1 



31 
11 
25 
22 

7 



3 

5 

522 







23 
4 

23 
1 



18 
15 
35 
1 
13 



33 

2 

14 

159 



23 
22 
6 
15 
12 



42 
20 
8 
25 
39 




2 

19 

220 

11 



95 

68 

1944 



338 




9 
4 
7 
4 
4 

26 
5 
4 

28 



3 

12 

5 

8 

15 



16 
34 

18 

7 

34 



36 

11 

12 



419 




5 


10 



4 
2 
6 
2 
14 



REPTILES 



1 

14 
1 




3 
6 

7 
1 
2 
17 
13 
4 

1 








5 
1 
12 





10 
9 

6 
6 



AMPHIBIANS 



RSH 

124 


1 






2 
29 
2 
2 




2 

2 

21 





1 
12 




Yemen 


134 


6 


9 











•USSR- 




20 


38 


3 





5 


EUROPE 


2677 ** 


66 


396 


16 


IS 


48 


Albania 


76 


2 


14 


1 





1 


Andorra 








1 











2 


Austria 


25 


2 


13 





Belgium 


9 


2 


13 










Bulgaria 


88 


3 


15 


1 





3 


Czechoslovakia 


29 


2 


18 








2 




1 
3 


Dennnark 


7 


1 


16 









Faeroe Islands 








2 





Finland 


11 


3 


12 





France 


143 


6 


21 


2 


1 


Germany 


•• 


2 


17 










Greece 


526 


4 


19 


3 




e 

2 

1 

1 


Hungary 


21 


2 


16 







Iceland 


2 


1 


2 








Ireland 


4 





10 








Italy 


210 


3 


19 


2 


7 


3 


Liechtanstert 








3 












Luxembourg 


1 


1 


8 





Malta 


4 





13 









Monaco 




















Netherlands 


7 


2 


13 








1 


Norway 
Poland 


13 
16 


3 
4 


8 
16 









1 


Portugal 


240 


6 


18 





1 





Romania 


67 


2 


18 


1 





San Marino 




















Spain 


936 


6 


23 


5 


3 


2 
1 
3 
1 


Sweden 


10 


1 


14 






Switzerland 


18 


2 


15 






United Kingdom 


24 ' 


3 


22 








Vatican City 




















Yugoslavia 


190 


3 


17 


1 


2 


5 


NORTH AND CENinAL AMERICA 


5747 


145 


219 


88 


27 


277 


Anguila 


















Antigua and Barbuda 


1 





2 













Aruba 
Bahamas 



24 



2 




4 



3 






Barbados 


1 


1 


1 











15 





239 



1. Biological Diversity 

Table 17.3 Country totals of threatened plants and vertebrates (continued) 



PLANTS 



MAMMALS 



BIROS 



REFTILES 



AMPHIBIANS 



RSH 



NORTH AND CENTTIAL AMERICA (continued) 



Cuba 


860 


11 


15 


4 








Dominica 


62 





3 











Dominican R«public 


SO 


1 


5 


4 








El Salvador 


26 


6 


2 


1 








Gt««nland (Denmark) 





2 


1 











Grenada 


4 





2 











Guadeloupe 


14 





1 











Guatemala 


282 


10 


10 


4 








Haiti 


13 


1 


4 


4 








Honduras 


43 


7 


11 


3 








Jamaica 


10 


5 


2 


3 








Martinique 


12 





3 











Mexico 


883 


25 


35 


16 


4 


98 


Moots errat 


1 





1 











Netherlands Antiles 








3 


2 








Nicaragua 


88 


8 


7 


2 








Panama 


549 


13 


14 


2 








Puerto Rico 


84 


2 


4 


5 


1 





St Lucia 


3 





5 











St Vincent and the Grer^dines 







3 











SI Kitts and Nevis 








1 











Trinidad and Tobago 


S 


1 


3 











Turks and Caicos Islands 


1 








1 








United States 


2262 


27 


43 


25 


22 


164 


Virain Islands (British) 


1 





3 


1 








Virgin Islands (US) 


10 





3 


1 








SOl/m AMERICA 


2061 


239 


535 


58 


2 


14 


Argentiru 


159 


23 


53 


4 


1 


1 


Bolivia 


39 


21 


34 


4 





1 


Brazil 


318 


40 


123 


11 





9 


Chile 


284 


9 


18 








1 


Colombia 


327 


25 


69 


10 








Ecuador{a} 


256 


21 


64 


8 








French Guiana 


47 


10 


5 


2 








Guyana 


68 


12 


9 


3 





1 


Paraguay 


15 


14 


34 


4 








Peru 


360 


29 


75 


6 


1 


1 


Suriname 


68 


11 


6 


1 








Uruguay 


14 


5 


11 


2 








Venezuela 


106 


19 


34 


3 








OCEANIA 


2673 


60 


168 


21 


7 


18 


American Samoa 




1 


1 











Austraia 


2024 


38 


39 


9 


3 


16 


Cook IslarKis 








1 











Fiji 


25' 


1 


5 


4 


1 





French Polynesia 


65 





20 











Guam 


12 


2 


4 











Kiriiati 








2 











Marshall Islands 








1 











Micronesia. Federated States of 





5 


3 


1 








Nauru 








2 











New Caledonia 


168 


1 


5 











New Zealand 


232 


1 


26 


1 


3 


2 


Niue 




















North Mariaruis Islands 


8 


1 


2 











Palau 





1 


3 











Papua New Guinea 


88 


5 


25 


1 








Pjtcairn Island 


3 





1 











Solomon Islands 


28 


2 


20 


3 








Tokelau 




















Tonga 








2 


1 








Tuvalu 








1 











Vanuatu 


8 


1 


3 


1 








Wallis and Futuna Islands 



















Western Samoa 


12 


1 


2 











ANTARCTICA 


4 

















Antarctica 




















Falkland Islands (Malvinas) 


4 

















French Southern Territories 




















AFRICA 


3308 


688 


453 


89 


8 


49 


Algeria 


145 


12 


15 








1 


Angola 


19 


14 


12 


2 








Benin 


3 


11 


1 


2 








Botswana 


4 


S 


6 


1 








Burkina Faso 





10 


1 


2 








Burundi 





4 


5 


1 








Cameroon 


74 


27 


17 


2 


1 


11 


Cape Verde 


1 





3 


1 








Central African Rep 





12 


2 


2 








Chad 


14 


IB 


4 


2 








Comoros 


3 


3 


5 








1 


Congo 


4 


12 


3 


2 








Cote d'lvoire 


70 


18 


9 


1 


1 





Djibouti 


3 


6 


3 











Egypt 


91 


9 


16 


2 





1 



240 



Threatened Species 



Table 17.3 Country totals of threatened plants and vertebrates (continued) 



AFRICA (continued) 

Equatorial Guinea 

Ethiopia 

Gabon 

Gambia 

Ghana 



8 
44 
80 


34 



MAMMALS 



15 
25 
17 

7 
13 



BIROS 



3 

14 
4 
1 
8 



AMPHIBIANS 



Guinea 


36 


17 


6 


1 


1 





Guinea-Bissau 





5 


2 


2 








Kenya 


144 


17 


18 


2 








Lesotho 


7 


2 


7 











Lit)«fia 


1 


18 


10 


2 








Libya 


58 


12 





1 








Madagascar 


1S4 


50 


28 


10 








Malawi 


61 


10 


7 


1 








Mali 


15 


16 


4 


2 








Mauritania 


3 


14 


5 


1 








Mauritius 


26S 


3 


10 


6 








Mayotte 







1 











Morocco 


194 


9 


14 








1 


Mozambique, People's Rep 


89 


10 


11 


1 





1 


Namibia 


17 


11 


7 


2 





4 


Niger 


1 


15 


1 


1 








Nigeria 


8 


25 


10 


2 








Reunion 


96 





1 











Rwanda 





11 


7 


2 








St Helena 







1 











Sao Tome and Principe 


1 ^ 


1 


7 











Senegal 


32 


11 


5 


2 








Seychelles 


75 


1 


9 


2 


3 





Sierra Leone 


12 


13 


7 


2 








Sonnalia 


52 


17 


7 


1 








South Africa 


1016 


25 


13 


3 


1 


28 


Sudan 


9 


17 


8 


1 








Swaziland 


25 





5 


1 








Tanzania 


158 


30 


26 


3 








Togo 





9 


1 


2 








Tunisia 


26 


6 


14 


1 








Uganda 


11 


16 


12 


1 








Western Sahara 





5 


5 











Zaire 


3 


31 


27 


2 





1 


Zambia 


1 


10 


10 


2 








Zimtsabwe 


96 


9 


6 


1 









Sources: RICN 1990. 1990 lUCN Red Usi of Threatened Animals, lUCN, Gland and Cambridge. Additional range data from WCMC Animal 
Database and other sources. Bird ranges from Sibley, C.G. and Monroe, B.L. 1990. Distribution and Taxonomy of Birds of the World. Yale 
University Press, New Haven and London. 

Notes: Plants: numbers include many taxa below species level and also Ex/E species. Vertebrates: marine species are excluded. Extinct taxa are 
excluded. Only full species are accounted for. Includes K categories - i.e. all threatened species as defined by lUCN. Mammals: cetaceans are 
excluded. Birds: the countries within the breeding and wintering range are included (where data available). Fishes: not included arc c. 252 spp. of 
Lake Victoria cichlids, many thought to be extinct or severiey threatened. •♦ excludes figures for Germany (German Dem Rep = 11; Germany, 
Fed Rep = 15). ' includes Gibralter (UK = 23; Gibralter = 1). ^ includes Rotuma. ' total for Sao Tome only. 



The majority of threatened mammalian species occur in 
mainly tropical countries, with highest numbers recorded 
from Madagascar (53), Indonesia (49), China (40) and 
Brazil (40). India, Australia, Zaire and Tanzania also have 
large numbers of species at risk, as do Mexico, USA, 
'USSR' and most South American and Southeast Asian 
countries. 

A regression analysis (Fig. 17.4) shows that Madagascar 
and Indonesia in particular have more threatened species in 
relation to country area than would be predicted statistically 
(points above the line) whereas USA, for example, has 
fewer. 

There are approximately twice as many threatened bird 
species as mammals (1,029 versus 507) but they show a 
similar distributional pattern. The majority are concentrated 
in southern and Southeast Asia, USA, Mexico, and South 
America. The ten countries listed all have more than 40 
threatened species. In comparison, Europe, Africa, Canada, 
the Middle East and the Arabian Peninsula have relatively 
few globally threatened bird or mammal species. 



Figure 17.3 Per cent of known species 
classed as Endangered 









_ 






3 


- 


"D 


3 


S 


- 


■R 




2 


— 


C 






- 


*-> 
C 

<l; 


-1 


5 


- 


k 




^ 


- 







5 


~ 




I i 



Taxonom t c group i hq 



241 



1. Biological Diversity 



Table 17.4 Countries with greatest numbers of threatened vertebrates 



MAMMALS 


BIRDS 




REPTILES 




AMPHIBIANS 


FISHES 




COUNTRY 


TOTAL 


COUNTRY 


TOTAL 


COUNTRY 


TOTAL 


COUNTRY 


TOTAL 


COUNTRY 


TOTAL 


Madagascar 


63 


Indonesia 


135 


USA 


25 


USA 


22 


USA 


164 


Indonesia 


49 


Brazil 


123 


India 


17 


Italy 


7 


Mexico 


98 


Brazil 


40 


China 


83 


Mexico 


16 


Mexico 


4 


Indonesia 


29 


China 


40 


India 


72 


Bangladesh 


14 


Australia 


3 


South Africa 


28 


India 


39 


Colombia 


69 


Indonesia 


13 


India 


3 


Philippines 


21 


Australia 


38 


Peru 


65 


Malaysia 


12 


New Zealand 


3 


Australia 


16 


Zaire 


31 


Ecuador 


64 


Brazil 


11 


Seychelles 


3 


Canada 


15 


Tanzania 


30 


Argentina 


63 


Colombia 


10 


Spain 


3 


Thailand 


13 


Peru 


29 


USA 


43 


Madagascar 


10 


Yugoslavia 


2 


Sri Lanka 


12 


Viet Nam 


28 


Myanmar 


42 


Myanmar 


10 






Cameroon 


11 



Sources: lUCN 1990. 1990 IVCN Red List of Threatened Animals. lUCN, Gland and Cambridge; WCMC 1991. The World Conservation 
Monitoring Centre Animal Database. WCMC, Cambridge; Bird ranges estimated from Sibley, C.G. and Monroe, B.L. 1990. Distribution and 
Taxonomy of Birds of the World. Yale University Press, New Haven and London. 

Notes: Mammals - Cetacea (whales, dolphins) are excluded; Birds - estimates include breeding and overwintering species (where data available); 
Reptiles - nurine turtles are excluded; Fishes - the estimates do not include c. 252 species of cichlids in Lake Victoria. Marine species are also 
excluded. Extinct taxa in all groups are excluded; only full species, not subspecies, are accounted for. Numerous countries had 1 threatened 
amphibian species, therefore the last row could not be filled for this column. 



Several factors may be involved in this distribution. Other 
things being equal, the number of threatened species in a 
country should be correlated with the total number of 
species present, and tropical countries generally have a 
higher species richness than temperate ones. The high 
current rate of human population increase, and consequent 
high rates of habitat loss and modification in tropical 
countries, is doubtless an important factor. 

The global distribution of species richness, the non- 
matching and uneven geographic spread of conservation 
activity and field survey work, and the patchy review to 
which most taxonomic groups have been subjected jointly 
mean that the lUCN Red List gives an as yet incomplete 
picture of the global distribution of species which may be 
under threat. 

Habitat distribution of threatened animals 

Information on habitat requirements is not consistently 
available for all threatened species. A useful indication of 
the global situation can be derived from analysis of the 
threats facing, and habitat types occupied by, the mammals 
of Australasia and the Americas and the birds of the world. 

As stated above, habitat loss or modification is the main 
category of threat affecting these species. The two habitat 
types in which the largest number of threatened mammals 
occur are lowland tropical rain forest (TRF) (37%) and 
montane TRF (19%), which together are occupied by 43% 
of all threatened Australian and American mammal species 
(Fig. 17.5). Both these habitat types are found exclusively 
in tropical regions, between latitudes 28°S and 28''N. Other 
tropical and subtropical habitats such as dry savanna, humid 
savaima, desert and semi-desert also possess large numbers 
of threatened mammals. In contrast, temperate and polar 



habitats such as coniferous and boreal forest, Mediterranean 
forest and scrub, tundra and polar ice harbour relatively 
few threatened species. 

In general the world's threatened bird species occupy a 
range of habitat types remarkably similar to the threatened 
mammals of Australasia and the Americas, with 43% 
occurring in TRF. The percentages occurring in marine, 
freshwater, grassland and polar habitats are also very 
similar, but there are some notable differences (Fig. 17.6). 
The major disparity is that some 38% of threatened birds 
are found on oceanic islands. These are primarily flightless 
or ground-nesting species which are threatened by 
introduced predators, for example rats and mongooses. A 
direct comparison with mammals is not possible because 
Thornback and Jenkins did not include oceanic islands; 
however, there are few mammals on such islands. A higher 
percentage of threatened birds than mammals occurs in 
seasonal woodlands (20% v. 8.4%), while this trend is 
reversed in arid (1% v. 14%), and coastal and estuarine 
habitats (5% v. 14%). 

Madagascar has the highest number of threatened mammal 
species (50). Most of these are forest-dwelling lemurs. 
Harcourt and Thornback (1990) identify habitat destruction 
as the main threat to lemurs, and estimate that at current 
rates of cutting (1.2% per year) only forests on the steepest 
slopes will survive the next 35 years. 

AQUATIC HABITATS 

These systems have received little attention in comparison 
with terrestrial habitats, and very little survey work has so 
far been undertaken in tropical areas. A recent synthesis 
(Moyle and Leidy, in press) demonstrated that fishes 
provide reliable indicators of trends in aquatic diversity. 



242 



Threatened Species 

Figure 17.4 Relationship between number of threatened species and country area 



60 
55 
50 



a 35 



20 
10, 



Madagascar ^ 



I ndones I a 

w 




-Perti 
Cameroon 

..Ito»4.4a«l ^....^1^ !j^. 

Nigeria South Af r i 



Zaire- 



Co I omb i a 



United States 
5(^ 



5K 

Laos 



Argent i na 



_L 



_L 



_L 



_L 



20, DOO 



50,000 100,000 200,000 

Country area C10D0 ha;) 



X 



J 



500,000 1,000,000 2,000,000 



Figure 17.5 Habitat distribution of threatened mammals 



40 



I 
I 



•5. 
a 



30 



20 



° 10 



I 



c 
1 



2 






CO 

J 



S 



sy; ^:jS:$ ^^^ - -w^v 



i~A" 






00 

I 

a 
3 



I 
I 



.s 






Note: Data for Australasia and the Americas, excludes cetaceans. 



Habitat Type 



243 



1. Biological Diversity 



Figure 17.6 Habitat distribution of threatened mammals and birds 

50 



Mammals 
Birds 




Tropical Grassland Coasts & 
forest heath & estuaries 
scrub 



Arid Freshwater Mountains Seasonal Marine 
woodlands 



Tundra & 
polar Ice 



Oceanic 
Islands 



Habitat type 

Note: Mammal data for Australasia and the Americas, excludes Cetacea; bird data are global. 



Information on the fish faunas of North America, Europe, 
Iran, South Africa, Sri Lanka, Australia, Costa Rica, Brazil 
and Chile was analysed. The well-supported conclusion of 
this review was that at least 20% (c. 1,800 species) of the 
world's freshwater fish species are seriously threatened or 
extinct. Declines usually resulted from cumulative effects of 
several long-term factors. Habitat modification (competition 
for water, drainage, pollution), introduced species and 
commercial exploitation were identified as the major causes 
of decline. Recent fieldwork in Madagascar (Reinthal and 
Stiassny, 1991) corroborates these general conclusions: the 
native fish fauna in eastern and central Madagascar had 
declined severely because of introductions and habitat 
degradation as a result of forest clearance. These trends, 
coupled with inadequate knowledge of freshwater faunas 
and the strong representation of freshwater species in the 
list of known extinct species (see Chapter 16), indicate that 
aquatic systems require increased conservation attention. 

THREATENED SPECIES ON ISLANDS: PLANTS 

About one in six plant species grows on oceanic islands; 
one in three of all known threatened plants are island 
endemics. This is a measure of the diversity and fragility of 
island ecosystems and their importance in plant 
conservation. 

Damage to most island floras occurred in the era of 
European exploration and colonisation, when oceanic 
islands became strategically important to the maritime 
powers. Most island floras evolved in the absence of large 
grazing animals and few endemic plants had defences 
against grazing animals. 



On St Helena, goats were introduced in 1513 and within 75 
years had formed vast herds. Botanists only reached the 
island in 1805-10, long after the damage had been done, 
and so one can only speculate on the original flora. Today 
46 endemic species are known, seven of them extinct 
(Cronk in litt. , 199 1), but J.D. Hooker estimated that there 
must have been originally over 100 endemic species (quoted 
in Lucas and Synge, 1978). Most of these species will 
never be known. 

Philip Island, near the penal colony of Norfolk Island, has 
been affected even more severely. The island was believed 
to have carried a mixture of scrub and dense forest when 
discovered by Captain Cook in 1744. The introduction of 
goats, pigs and later rabbits reduced this vegetation to a 
near desert in which by 1964 the endemic Philip Island 
Glory Pea Streblorrhiza speciosa had become extinct and 
the endemic hibiscus Hibiscus insularis reduced to four 
aged bushes. 

Whereas goats, sheep, pigs and even rabbits can be 
controlled and even eliminated, the problem of introduced 
plants is much more intractable. Enthusiastic gardeners 
often brought to islands the plants they used to grow at 
home, and some of these plants proved to be devastatingly 
invasive in the native vegetation, outcompeting the native 
flora. In Mauritius, for example, visitors today see rich 
green thickets and forests covering the hills, but few realise 
that virtually all this vegetation is of introduced plants. The 
only viable strategy for saving the Mauritian endemic flora 
in the short term is to make small weeded plots within the 
forest, a few hectares at a time. Other islands where the 
native flora is greatly threatened by introduced plants 



244 



Threatened Species 



include Rodrigues, St Helena, Hawaii and Juan Fernandez. 
It is noticeable that introduced plants tend to be much more 
destructive of island ecosystems than of continental ones. 

Following the TDWG geographical classification (see 
Chapter 14), there are about SO islands or island groups 
with significant endemic floras (here defined as more than 
five endemic species). For nearly half of these islands, a 
detailed assessment has been made of which species are 
threatened (Table 17.6). 

Degree of threat to species varies greatly from one island 
or island group to another. Islands with severely affected 
floras include: 

• Hawaii: 108 endemic taxa have already gone extinct, IS 
are either Extinct or Endangered, 138 are Endangered, 
37 are Vulnerable, 126 are Rare, and 9 are 
Indeterminate - a total of 433 threatened taxa. Hawaii 
has, therefore, one of the most distinctive and one of the 
most threatened floras in the world. 

• St Helena, in the Atlantic Ocean, where all of the 46 
endemic known species are threatened, 7 of them Extinct 
and 19 Endangered 

• Bermuda, north of the Caribbean: all but one of the 15 
endemic species are threatened, 3 of them Extinct and 4 
Endangered 

• Rodrigues, a dependency of Mauritius in the Indian 
Ocean: all but 2 of the 45 endemic species are 
threatened, 27 of them Endangered or Extinct 

• Norfolk Island, east of Australia: where all but 2 of the 
36 endemic species are threatened, 1 of them Extinct and 
11 Endangered. 

On each of these islands, the native plants are reduced to 
small patches of relict vegetation, and often have 
populations of ten individuals or fewer. It is, however, 
encouraging to see that on all the four islands listed above, 
there are active programmes to rescue the threatened plants 
although it may take centuries to restore the native 
vegetation. 

Other islands have fared better. For example, the native 
forests on Lord Howe Island, a dependency of Australia, 
are still intact and are now well protected in a national 
park. Of the 84 endemic species in the Table, only one is 
Extinct and three Endangered, but 72 are Rare, meaning 
their world populations are low but they are not under 
threat. Among coral islands, the important endemic floras 
of Aldabra (Indian Ocean) and Henderson Island (Pacific 
Ocean) are intact and both are now effectively protected as 
nature reserves. 

For some of the islands with larger floras, the flora has 
only been partly assessed. The true numbers of threatened 
species may be higher than those quoted. This is probably 
true, for example, of Cuba and Jamaica, with their very 
large endemic floras. 

The islands listed in Table 17.5 all have more than 10 
endemic species of plants but the conservation status of 
those plants is not known. The immediate priority here is 
for field surveys to assess the situation and provide a basis 
for conservation action. For more details see Table 14. 1. 



Table 17.5 Priority islands for surveys 
of endemic flora 







ESTIMATED ENDEMIC 






PLANT SPECIES 


AFRICA 






Annobon 




17 


Bioko 




49 


Cape Verde 




92 


Principe 




35 


Sao Tome 




108 


CARIBBEAN 






Bahamas 




112 


Cayman Is 




18 


Dominican Republic/Haiti 


1800 


Trinidad-Tobago 




215 


Virgin Is, US and Briti: 


sh 


28 -t- 


Most Lesser Antillean 


Islands 


total 327 


INDIAN OCEAN 






Andaman Is 




144 


Nicobar Is 




72 


Comoros 




136 


PACIFIC 






American Samoa 




27 


Coco, Isia del 




15 


Fiji 




700 


Marquesas Is 




105 


New Caledonia 




2480 


Northern Marianas 




81 


Society Is 




? 


Taiwan 




892 


Tonga 




25 


Tuamotu Is 




20 


Tubuai Is 




140 


Vanuatu 




150 


Western Samoa 




57 



Table 17.6 covers higher plants (flowering plants, ferns, 
gymnosperms) endemic to the island or island group 
concerned. The main figures are of species; the figures in 
brackets are of additional endemic infraspecies (subspecies 
and varieties). Where an endemic species is divided into 
several infraspecies in the database, it has been counted 
only at the infraspecies level; however the parallel table in 
Chapter 14 adds these endemic species into the endemic 
species totals. Thus, the total for Mauritius here is 236 (54) 
but above is 246 species, since the 54 infraspecies include 
10 species that are wholly endemic to Mauritius. 

THREATENED SPECIES ON ISLANDS: BIRDS 

Islands are important for bird conservation: over 1,750 
species (some 17% of the world's bird species) are confined 
to islands and of these, 402 (23%) are threatened (Johnson 
and Stattersfield, 1990) compared with only 11% of birds 
worldwide (Collar and Andrew, 1988). In addition, island 
birds have suffered the majority of bird extinctions which 
have occurred during historic times. 

Distribution of island endemics 

A high proportion of threatened island species are 
concentrated in a few geopolitical units: a total of 92 such 
units have one or more threatened species; 11 of these 
(Cuba, Hawaiian Islands, Indonesia, Marquesas Islands, 
Mauritius, New Zealand, Papua New Guinea, Philippines, 
Sao Tome, and Principe, Seychelles and Solomons) support 



245 



1. Biological Diversity 



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246 



Threatened Species 



over half the threatened species restricted to islands. Over 
90% of threatened species restricted to islands are endemic 
to their geopolitical units, with a few island groups having 
particularly large numbers of threatened endemics (e.g. 
Indonesia 91, and the Philippines 34). Some 25 islands 
support a single threatened endemic only. 

After Indonesia and the Philippines, the islands of the 
Pacific Ocean support the largest number of threatened 
species (110). Although when compared to the Atlantic 
islands this constitutes a much lower portion of the 
endemics occurring in the region (38% and 50%, 
respectively) it nonetheless accounts for 27% of threatened 
species restricted to islands. 

Degree of threat 

Of the 402 species restricted to islands, the greatest number 
of those considered Endangered or Vulnerable occur within 
the Pacific region: 31 of the 66 Endangered species and 29 
of the 71 Vulnerable species. These include a wide range 
of species, such as the severely endangered Barred-wing 
Rail Nesoclopeus poeciloptera, known only from Fiji, and 
the New Caledonian endemic Kagu R/tynochetos jubatus, 
belonging to a monotypic family and therefore regarded as 
a high priority for conservation action. 

Habitat requirements 

The majority of threatened island birds are forest species. 
Rain forest supports 2(X) (50%) of the threatened species. 
Lx)wland and montane forests contribute almost equally, 
being used by 101 and 1 12 species, respectively (42 species 
use both types; 29 rain forest species could not be assigned 
to the lowland/montane division). The other major forest- 
type, seasonal/temperate forest, supports 113 species. In 
total, forests of all categories support 310 species, 
accounting for 77% of threatened island endemics. 

Threats 



species. Given the number of extinctions attributable to 
introductions, it is of interest that introduced species now 
appear to be a major threat to only 20% of threatened island 
endemics, a much smaller proportion than might be 
expected and a considerably smaller proportion than the 
41 % of island species which are at risk simply by having a 
limited range. Other factors (hunting, trade, human 
disturbance, natural causes and fisheries) each affect less 
than 10% of threatened island birds. For some 60 
threatened island endemic birds, further field research is 
needed to identify the cause of decline. 

References 

Collar, N.J. and Andrew, P. 1988. Birds to Watch: the ICBP world 

checklist of threatened birds. ICBP Technical Publication No. 8, 

ICBP Cambridge, UK. 
Corbet, G.B. and Hill, J. E. 199\.A World List of Mammalian Species. 

Third edition. Oxford University Press, UK. 
Diamond, AW. 1987. Save the Birds. ICBP, Girton, Cambridge. 
Harcourt, C. and Thomback, J. 1990. Lemurs of Madagascar and the 

Comoros. The lUCN Red Data Book. lUCN, Gland, Switzerland 

and Cambridge, UK. 
lUCN, 1990. 1990 lUCN Red List of Threatened Animals. lUCN, 

Gland and Cambridge. 
Johnson, T.H. and Slauersfield, A.J. 1990. Global review of island 

endemic birds. Ibis 132:167-180. 
Lucas, G. and Synge, H. 1978. The lUCN Plant Red Data Book. 

lUCN, Switzerland. 
Mace, G.M. and Lande, R. 1991. Assessing extinction threats: toward 

a re-evaluation of lUCN threatened species categories. 

Conservation Biology 5(2): 1 48- 157. 
Moyle, P.B. and Leidy, R.A. (in press). Loss of biodiversity in 

aquatic ecosystems: evidence from fish faunas. In: Feidler, P.L. 

and Jain, S.K. (Eds), Conservation Biology: the theory andpractice 

of nature conservation, preservation, and management. Chapman 

and Hall, New York. 
Reinlhal, P.N. and Sliassny, M.L.J. 1991. The freshwater fishes of 

Madagascar: a study of an endangered fauna with recommendations 

for a conservation strategy. Conservation Biology 5(2):23l-243. 
Sibley, C.G. and Monroe, B.L. 1990. Distributionand Taxonomy of 

Birds of the World Yale University Press, New Haven and London. 
Thomback, J. and Jenkins, M. 1982. The WCN Mammal Red Data 

Book Part I. lUCN, Gland, Switzerland and Cambridge, UK. 



The most important factor threatening island species is 
habitat destruction, affecting over 50% of threatened island 



Vie section on threatened plants on oceanic islands was 
prepared by Hugh Synge. 



247 



1. Biological Diversity 

18. GLOBAL HABITAT CLASSIFICATION 



The world encompasses an enormous range of terrestrial 
and aquatic environments, from polar ice-caps to forests, 
and coral reefs to deep ocean trenches. The classification of 
this immense range of variation into a manageable system 
is a major problem in biology and underpins much of the 
sciences of ecology and biogeography. It has not merely 
theoretical interest, but is of fundamental importance in the 
management and conservation of the biosphere. 

Within ecology, a wide variety of terms has been coined - 
community, habitat, ecosystem, biome - intended to help in 
such a classification. Some of these can be seen as forming 
a loose and ill-defined hierarchy analogous in some ways 
with the taxonomic system developed for classifying 
organisms, discussed fully in Chapters 2 and 3. However, 
the classification of the natural environment is far more 
problematic than the classification of organisms and none of 
the above terms has a rigid, satisfactory and universally 
accepted definition. Indeed there are good theoretical 
grounds for questioning the basis of such a classification. 
This is because these systems are ultimately based on an 
assumption that the natural environment can be divided into 
a series of discrete, discontinuous units rather than 
representing different parts of a highly variable natural 
continuum, whereas in reality the latter is undoubtedly a 
more accurate description of the world. 

In general, attempts to classify ecological units are based on 
identification of the species which occur in them along with 
a description of the physical characteristics of the area. 
Most terrestrial ecosystems, for example, are generally 
identified on the basis of plant communities, that is areas 
with similar plant species composition and structure. The 
basic principle underlying this is that different species may 
habitually be closely associated with each other over a wide 
geographical range. The extent to which this is true is still 
controversial - it can reasonably be argued that the 
distribution of plant species is generally dependant on the 
physical environment and historical accident rather than on 
the occurrence or otherwise of other plant species, although 
within a particular geographical region, species with similar 
ecological requirements may, of course, be expected to 
have similar distributions. Even if the concept of a 
community is accepted, it is widely acknowledged that the 
more rigidly a community is defined the more site-specific 
it becomes and hence the more limited its use in analysis 
and planning. 

At the other extreme, very general habitat classifications 
('forests', 'grasslands', 'wetlands') are based on the 
physical characteristics and appearance of an area, 
independent of species composition. They cover such a 
wide range of possible conditions that they have little 
heuristic use: the term 'forest' applies both to highly 
diverse lowland tropical rainforest and coniferous 
monoculture, two systems which may have no, or virtually 
no, species in common. Furthermore these general terms 
are virtually impossible to define and delimit in a 
universally applicable way. Thus, for example, the density 
of tree cover necessary before an area can be called a 
woodland is undefinable and any limit used will always be 
arbitrary. Similarly, it is impossible to determine for how 



long and how intensely an area must be flooded before it 
can be classified as a wetland rather than a terrestrial 
ecosystem. This naturally makes any mapping of habitats a 
problematic task. 

ECOSYSTEM MAPPING 

Most global habitat classification systems have attempted to 
steer a middle course between the complexities of 
community ec