Contents

Preface

Acknowledgements

1 What is biodiversity?

1.1 Marion Island

1.2 What is biodiversity?

1.3 Elements of biodiversity

1.4 Measuring biodiversity

1.5 Summary

Further reading

2 Biodiversity through time

2.1 Introduction

2.2 Sources of information

2.3 A brief history of biodiversity

2.4 How many extant species are there?

2.5 Summary

Further reading

3 Mapping biodiversity

3.1 Introduction

3.2 Issues of scale

3.3 Extremes of high and low diversity

3.4 Gradients in biodiversity

3.5 Congruence

3.6 Summary

Further reading

4 Does biodiversity matter?

4.1 Introduction

4.2 Direct-use value

4.3 Indirect-use value

4.4 Non-use value

4.5 Summary

Further reading

5 Human impacts

5.1 Introduction

5.2 Species extinctions

5.3 Populations, individuals and genetic diversity

5.4 Threats to biodiversity

5.5 The scale of the human enterprise

5.6 Summary

Further reading

6 Maintaining biodiversity

6.1 Introduction

6.2 Objectives of the Convention

6.3 General measures for conservation and sustainable use

6.4 Identification and monitoring

6.5 In-situ conservation

6.6 Ex-situ conservation

6.7 Sustainable use of components of biological diversity

6.8 Incentive measures

6.9 Responses to the Convention

6.10 Summary

Further reading

References

Index

© 1998, 2004 by Blackwell Science Ltd
a Blackwell Publishing company

350 Main Street, Malden, MA 02148-50120, USA
108 Cowley Road, Oxford OX4 1JF, UK
550 Swanston Street, Carlton, Victoria 3053, Australia

The rights of Kevin Gaston and John Spicer to be identified as the Authors of this Work have been asserted in accordance with the UK Copyright, Designs, and Patents Act 1988.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs, and Patents Act 1988, without the prior permission of the publisher.

First edition published 1998
Second edition published 2004

Library of Congress Cataloging-in-Publication Data

Gaston, Kevin J.
Biodiversity: an introduction/
Kevin J. Gaston and John I. Spicer. – 2nd ed.
p. cm.
Includes bibliographical references and index.
ISBN 1-4051-1857-1 (pbk.: alk. paper)
1. Biological diversity. I. Spicer, John I. II. Title.
QH541.15.B56G37 2004
333.95′11–dc21
2003011788

A catalogue record for this title is available from the British Library.

For further information on
Blackwell Publishing, visit our website:
http://www.blackwellpublishing.com

Preface

This is the second edition of Biodiversity: An Introduction. Our goal in writing the first edition was to provide a text that both gave an introduction to biodiversity – what it is, how it arose, how it is distributed, why it is important and what should be done to maintain it – and present an entry point into the wider literature on biodiversity. That remains the goal here. However, much has occurred in the intervening years. First, understanding of many key issues has developed rapidly, with important new models having been developed, experiments having been conducted, and measurements made. Some controversies have been settled, and others have arisen. In short, the study of biodiversity remains vibrant and stimulating. Second, and as a consequence of these advances, the literature on biodiversity has continued to blossom with, for example, few issues of some of the major science journals (e.g. Nature, Science) now passing without containing one or more papers of relevance. Third, there has been a marked change in the structure of botanical, zoological and ecological courses taught in universities, away from inclusion of the more traditional taxonomically centred surveys of different groups of organisms, and towards an approach centred instead on the concept of biodiversity. Fourth, and most importantly, there has been little, if any, reduction in the degree of threat faced by the variety of life on Earth; if anything, there is now a sharpened awareness of how acute that threat is and how pervasive are its implications.

These developments have led us to revise Biodiversity: An Introduction substantially. Much of the book has been rewritten, updated and extended. The six chapters address the nature of biodiversity (Chapter 1), the history of biodiversity (Chapter 2), the spatial distribution of biodiversity (Chapter 3), the value of biodiversity (Chapter 4), human impacts on biodiversity (Chapter 5), and the future maintenance of biodiversity (Chapter 6). In each case, we have sought to draw out the major issues and provide actual examples. All the figures in the book can be downloaded from the Blackwell Publishing website (www.blackwellpublishing.com/gaston). Reference is made throughout the text to relevant papers and books, where possible with an emphasis on those that are more readily accessible. In addition, each chapter concludes with suggestions for further reading. These are sources, usually books, that we hope readers will find useful for exploring particular themes in greater detail, but which have often not been cited elsewhere in the chapter.

Many people have generously provided guidance in this endeavour, commenting on drafts of the first edition of Biodiversity: An Introduction, suggesting ways in which the published version could be improved and developed, commenting on drafts of chapters for the second edition, and responding to multifarious queries and requests. In particular, we are grateful to Dave Bilton, Steven Chown, Andy Foggo, Sian Gaston, Alison Holt, Rhonda Snook, Richard Thompson, Mick Uttley and Clare Vincent. We would also like to thank the students who have taken module APS215 Biodiversity at the University of Sheffield, Tim Caro and the students on his conservation biology course, Lee Hannah, Claudia Moreno and Ana Rodrigues. Rosie Hayden, Cee Pike, Katrina Rainey and Sarah Shannon of Blackwell Publishing cajoled, encouraged and helped steer this volume to its conclusion, with good humour and insight. We are grateful for their assistance.

As before, we dedicate this book to Megan, Ben, Ethan and Ellie, with the desire that their generation is kinder to biodiversity than our own has been.

K.J.G. & J.I.S.
January 2003

Acknowledgements

The authors and publisher gratefully acknowledge the permission granted to reproduce the copyright material in this book:

Fig. 1.2: Fig. 1 from Avise, J.C. & Johns, G.C. (1999) Proposal for a standardized temporal scheme of biological classification for extant species. Proceedings of the National Academy of Sciences, USA 96, 7358–7363. Copyright © 1999 National Academy of Sciences, USA. Reprinted by permission.

Fig. 1.3: Fig. 1 from Purvis, A. & Hector, A. (2000) Getting the measure of biodiversity. Nature 405, 212–219. Reprinted by permission of the publisher and the authors.

Fig. 1.6a: Fig. 4b from Roy, K., Jablonski, D. & Valentine, J.W. (1996) Higher taxa in biodiversity studies: patterns from eastern Pacific marine molluscs. Philosophical Transactions of the Royal Society, London B 351, 1605–1613. Reprinted by permission of the Royal Society.

Fig. 1.6b: Reprinted from Biological Conservation 93, Balmford, A., Lyon, A.J.E. & Lang, R.M. ‘Testing the higher-taxon approach to conservation planning in a megadiverse group: the macro fungi’, pp. 209–217, Copyright © 2000, with permission from Elsevier.

Fig. 1.6c: Fig. 3.7a from Williams, P.H. & Humphries, C.J. (1996) Comparing character diversity among biotas. In: Biodiversity: A Biology of Numbers and Difference (ed. K.J. Gaston), pp. 54–76. Blackwell Science, Oxford. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 1.6d: Fig. 5d from Petchey, O.L. & Gaston, K.J. (2002) Functional diversity (FD), species richness and community composition. Ecology Letters 5, 402–411. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 2.2: Reprinted with permission from Fig. 1, Benton, M.J. (1995) Diversification and extinction in the history of life. Science 268, 52–58. Copyright © 1995 American Association for the Advancement of Science.

Fig. 2.3a: Reprinted with permission from Fig. 3a, Benton, M.J. (1995) Diversification and extinction in the history of life. Science 268, 52–58. Copyright © 1995 American Association for the Advancement of Science.

Fig. 2.3b: Reprinted with permission from Fig. 4a, Benton, M.J. (1995) Diversification and extinction in the history of life. Science 268, 52–58. Copyright © 1995 American Association for the Advancement of Science.

Fig. 2.4: Fig. 28.3b from Van Valkenburgh, B. & Janis, C.M. (1993) Historical diversity patterns in North American large herbivores and carnivores. In: Species Diversity in Ecological Communities: Historical and Geographical Perspectives (eds. R.E. Ricklefs & D. Schluter), pp. 330–340. University of Chicago Press, Chicago, IL. Reprinted by permission of University of Chicago Press.

Fig. 2.5: Fig. 1 from Niklas, K.J. (1986) Large-scale changes in animal and plant terrestrial communities. In: Patterns and Processes in the History of Life (eds. D.M. Raup & D. Jablonski), pp. 383–405. Springer-Verlag, Heidelberg. Reprinted by permission of Springer-Verlag.

Fig. 2.6: Fig. 1 from Benton, M.J. (1985) Mass extinction among non-marine tetrapods. Nature 316, 811–814. Reprinted by permission of the publisher.

Fig. 2.7a: Fig. 5.2 from Boulter, M. (2002) Extinction, Evolution and the End of Man. Fourth Estate, London. Reprinted by permission of the author.

Fig. 2.7b: Fig. 5.3 from Boulter, M. (2002) Extinction, Evolution and the End of Man. Fourth Estate, London. Reprinted by permission of the author.

Fig. 2.8: Fig. 2 from Slowinski, J.B. & Guyer, C. (1989) Testing the stochasticity of patterns of organismal diversity: an improved null model. American Naturalist 134, 907–921. Reprinted by permission of University of Chicago Press.

Fig. 2.9: Fig. 1 from Raup, D.M. (1994) The role of extinction in evolution. Proceedings of the National Academy of Sciences, USA 91, 6758–6763. Reprinted by permission of the National Academy of Sciences.

Fig. 2.10: Fig. 2 from Raup, D.M. (1994) The role of extinction in evolution. Proceedings of the National Academy of Sciences, USA 91, 6758–6763. Reprinted by permission of the National Academy of Sciences.

Fig. 2.12a: Fig. 1a from Dworschak, P.C. (2000) Global diversity in the Thalassinidea (Decapoda). Journal of Crustacean Biology 20 (Special Number 2), 238–245. Reprinted by permission of The Crustacean Society.

Fig. 2.12b: Mammal Species of the World, edited by Don E. Wilson and DeeAnn Reeder. (Washington, DC, Smithsonian Institution Press). Copyright © 1993 by the Smithsonian Institution. Used by permission of the publisher.

Fig. 2.13: Map from Hockey, P. (1997a) New Birds in Africa. Africa – Birds and Birding 2, 39–44. Reprinted by permission of Africa – Birds and Birding.

Fig. 3.1a: Fig. 3 from Lonsdale, W.M. (1999) Global patterns of plant invasions and the concept of invisibility. Ecology 80, 1522–1536. Reprinted by permission of The Ecological Society of America.

Fig. 3.1b: Fig. 1 from Azovsky, A.I. (2002) Size-dependent species–area relationships in benthos: is the world more diverse for microbes? Ecography 25, 273–282. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.3a: Fig. 2 from Ellison, A.M. (2002) Macroecology of mangroves: large-scale patterns and processes in tropical coastal forests. Trees 16, 181–194. Reprinted by permission of Springer-Verlag.

Fig. 3.3c: Fig. 4b from Bini, L.M., Diniz Filho, J.A.F., Bonfim, F. & Bastos, R.P. (2000) Local and regional species richness relationships in viperid snake assemblages from South America: unsaturated patterns at three different spatial scales. Copeia 2000, 799–805. Reprinted by permission of the American Society of Ichthyologists and Herpetologists.

Fig. 3.3d: Reprinted with permission from Fig. 3, Ricklefs, R.E. (1987) Community diversity: relative roles of local and regional processes. Science 235, 167–171. Copyright © 1987 American Association for the Advancement of Science.

Fig. 3.4: Fig. 1 from Olson, D.M., Dinerstein, E., Wikramanayake, E.D., Burgess, N.D., Powell, G.V.N., Underwood, E.C., D’Amico, J.A., Itoua, I., Strand, H.E., Morrison, J.C., Loucks, C.J., Allnutt, T.F., Ricketts, T.H., Kura, Y., Lamoreux, J.F., Wettengel, W.W., Hedao, P. & Kassem, K.R. (2001) Terrestrial ecoregions of the world: a new map of life on Earth. BioScience 51, 933–938. Copyright © American Institute of Biological Sciences. Reprinted by permission of the publisher.

Fig. 3.5: Fig. 2 from Olson, D.M., Dinerstein, E., Wikramanayake, E.D., Burgess, N.D., Powell, G.V.N., Underwood, E.C., D’Amico, J.A., Itoua, I., Strand, H.E., Morrison, J.C., Loucks, C.J., Allnutt, T.F., Ricketts, T.H., Kura, Y., Lamoreux, J.F., Wettengel, W.W., Hedao, P. & Kassem, K.R. (2001) Terrestrial ecoregions of the world: a new map of life on Earth. BioScience 51, 933–938. Copyright © American Institute of Biological Sciences. Reprinted by permission of the publisher.

Fig. 3.6: Reprinted from Ecological Geography of the Sea, Longhurst, A. (Academic Press, San Diego). Copyright © 1998 with permission from Elsevier.

Fig. 3.8: Fig. 1 from Myers, N., Mittermeier, R.A., Mittermeier, C.G., da Fonseca, G.A.B. & Kent, J. (2000) Biodiversity hotspots for conservation priorities. Nature 403, 853–858. Reprinted by permission of the publisher.

Fig. 3.9a: Fig. 1b from Cowling, R.M. & Samways, M.J. (1995) Predicting global patterns of endemic plant species richness. Biodiversity Letters 2, 127–131. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.9b: Fig. 1b from Ceballos, G. & Brown, J.H. (1995) Global patterns of mammalian diversity, endemism and endangerment. Conservation Biology 9, 559–568. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.10: Fig. 1a from Cowling, R.M. & Samways, M.J. (1995) Predicting global patterns of endemic plant species richness. Biodiversity Letters 2, 127–131. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.11: Fig. 7 from Stattersfield, A.J., Crosby, M.J., Long, A.J. & Wege, D.C. (1998) Endemic Bird Areas of the World. Priorities for Biodiversity Conservation. BirdLife International, Cambridge. Reprinted by permission of Birdlife International.

Fig. 3.12a: Fig. 1 from Oberdorff, T. & Guégan, J.-F. (1999) Patterns of endemism in riverine fish of the Northern Hemisphere. Ecology Letters 2, 75–81. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.12b: Fig. 4 from Ceballos, G. & Brown, J.H. (1995) Global patterns of mammalian diversity, endemism and endangerment. Conservation Biology 9, 559–568. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.13a: Fig. 1a from Enquist, B.J. & Niklas, K.J. (2001) Invariant scaling relations across tree-dominated communities. Nature 410, 655–660. Reprinted by permission of the publisher and authors.

Fig. 3.13b: Fig. 1c from Oberdorff, T., Guégan, J.-F. & Hugueny, B. (1995) Global scale patterns of fish species richness in rivers. Ecography 18, 345–352. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.13d: Fig. 2a from Kaufman, D.M. & Willig, M.R. (1998) Latitudinal patterns of mammalian species richness in the New World: the effects of sampling method and faunal group. Journal of Biogeography 25, 795–805. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.14a: Reprinted from Deep Sea Research I 47, Culver, S.J. & Buzas, M.A., Global latitudinal species diversity gradient in deep-sea benthic foraminifera, pp. 259–275. Copyright © 2000 with permission from Elsevier.

Fig. 3.14b: Fig. 12 from Dolan, J.R. & Gallegos, C.L. (2001) Estuarine diversity of tintinnids (planktonic ciliates). Journal of Plankton Research 23, 1009–1027. By permission of Oxford University Press.

Fig. 3.14c: Fig. 2 from Dworschak, P.C. (2000) Global diversity in the Thalassinidea (Decapoda). Journal of Crustacean Biology 20 (Special Number 2), 238–245. Reprinted by permission of The Crustacean Society.

Fig. 3.14d: Fig. 1 from Flessa, K.W. & Jablonski, D. (1995) Biogeography of recent marine bivalve molluscs and its implications for paleobiogeography and the geography of extinction: a progress report. Historical Biology 10, 25–47. Reprinted by permission of Taylor & Francis Ltd, http://www.tandf.co.uk/journals

Fig. 3.15: Fig. 2 from Gaston, K.J., Williams, P.H., Eggleton, P. & Humphries, C.J. (1995) Large scale patterns of biodiversity: spatial variation in family richness. Proceedings of the Royal Society, London B 260, 149–154. Reprinted by permission of the Royal Society.

Fig. 3.16: Reprinted with permission from Fig. 2 (Angiosperms), Crane, P.R. & Lidgard, S. (1989), Angiosperm diversification and paleolatitudinal gradients in Cretaceous floristic diversity, Science 246, 675–678. Copyright © 1989 American Association for the Advancement of Science.

Fig. 3.17: Fig. 2 from Eggleton, P. (1994) Termites live in a pear-shaped world: a response to Platnick. Journal of Natural History 28, 1209–1212. Reprinted by permission of Taylor & Francis Ltd, http://www.tandf.co.uk/ journals

Fig. 3.18a: Fig. 1 from Dixon, A.F.G., Kindlmann, P., Leps, J. & Holman, J. (1987) Why are there so few species of aphids, especially in the tropics? American Naturalist 129, 580–592. Reprinted by permission of University of Chicago Press.

Fig. 3.18b: Fig. 2 from Price, P.W., Fernandes, G.W., Lara, A.C.F., Brawn, J., Barrios, H., Wright, M.G., Ribeiro, S.P. & Rothcliff, N. (1998) Global patterns in local number of insect galling species. Journal of Biogeography 25, 581–591. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.18c: Fig. 2 from Kouki, J., Niemelä, P. & Viitasaari, M. (1994) Reversed latitudinal gradient in species richness of sawflies (Hymenoptera, Symphyta). Annales Zoologici Fennici 31, 83–88. Reprinted by permission of the Finnish Zoological and Botanical Publishing Board.

Fig. 3.18d: Fig. 1 from Järvinen, O., Kouki, J. & Häyrinen, U. (1987) Reversed latitudinal gradients in total density and species richness of birds breeding on Finnish mires. Ornis Fennica 64, 67–73. Reprinted by permission of the Finnish Ornithological Society.

Fig. 3.19a: Fig. 2 from Kerr, J.T & Packer, L. (1999) The environmental basis of North American species richness patterns among Epicauta (Coleoptera: Meloidae). Biodiversity and Conservation 8, 617–628. With kind permission of Kluwer Academic Publishers.

Fig. 3.19b: Fig. 1 from Roy, K., Jablonski, D., Valentine, J.W. & Rosenberg, G. (1998) Marine latitudinal diversity gradients: tests of causal hypotheses. Proceedings of the National Academy of Sciences, USA 95, 3699–3702. Copyright © 1998 National Academy of Sciences, USA.

Fig. 3.19c: Fig. 3a from Lennon, J.J., Greenwood, J.J.D. & Turner, J.R.G. (2000) Bird diversity and environmental gradients in Britain: a test of the species–energy hypthesis. Journal of Animal Ecology 69, 581–598. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.20a: Fig. 2 from Grytnes, J.A. & Vestaas, O.R. (2002) Species richness and altitude: a comparison between null models and interpolated plant species richness along the Himalayan altitudinal gradient, Nepal. American Naturalist 159, 294–304. Reprinted by permission of University of Chicago Press.

Fig. 3.20b: Fig. 1a from Sanders, N.J. (2002) Elevational gradients in ant species richness: area, geometry and Rapoport’s rule. Ecography 25, 25–32. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.20d: Fig. 1b from Patterson, B.D., Stotz, D.E., Solari, S., Fitzpatrick, J.W. & Pacheco, V. (1998) Contrasting patterns of elevational zonation for birds and mammals in the Andes of southeastern Peru. Journal of Biogeography 25, 593–607. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.21: Fig. 2 from Rahbek, C. (1995) The elevational gradient of species richness: a uniform pattern? Ecography 18, 200–205. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.22a: Fig. 2 from Svavarsson, J., Strömberg, J.-O. & Brattegard, T. (1993) The deep-sea asellote (Isopoda, Crustacea) fauna of the Northern Seas: species composition, distributional patterns and origin. Journal of Biogeography 20, 537–555. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.22b: Fig. 5.2 from Rex, M.A., Etter, R.J. & Stuart, C.T. (1997) Large-scale patterns of species diversity in the deep-sea benthos. In: Marine Biodiversity: Patterns and Processes (eds. R.F.G. Ormond, J.D. Gage & M.V. Angel), pp. 94–121. Cambridge University Press, Cambridge. Reprinted by permission of Cambridge University Press.

Fig. 3.22c: Fig. 5a from Morenta, J., Stefanescu, C., Massuti, E., Morales-Nin, B. & Lloris, D. (1998) Fish community structure and depth-related trends on the continental slope of the Balearic Islands (Algerian basin, western Mediterranean). Marine Ecology Progress Series 171, 247–259. Reprinted by permission of the International Ecology Institute, Oldendorf/ Luhe, Germany.

Fig. 3.22d: Fig. 4.13 from Angel, M.V. (1994) Spatial distribution of marine organisms: patterns and processes. In: Large-scale Ecology and Conservation Biology (eds. P.J. Edwards, R.M. May & N.R. Webb), pp. 59–109. Blackwell Science, Oxford. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.23: Fig. 5a from Macpherson, E. & Duarte, C.M. (1994) Patterns in species richness, size and latitudinal range of East Atlantic fishes. Ecography 17, 242–248. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.24a: Fig. 4 from Martin, J. & Gurrea, P. (1990) The peninsula effect in Iberian butterflies (Lepidoptera: Papilionoidea and Hesperioidea). Journal of Biogeography 17, 85–96. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.24b: Fig. 2.22 from Gaston, K.J. & Blackburn, T.M. (2000) Pattern and Process in Macroecology. Blackwell Science, Oxford. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 3.24c: Fig. 3 from Rapoport, E.H. (1994) Remarks on marine and continental biogeography: an aerographical viewpoint. Philosophical Transactions of the Royal Society, London B 343, 71–78. Reprinted by permission of the Royal Society.

Fig. 3.25: Fig. 5.8 from Balmford, A. (2002) Selecting sites for conservation. In: Conserving Bird Biodiversity: General Principles and their Applications (eds. K. Norris & D.J. Pain), pp. 74–104. Cambridge University Press, Cambridge. Reprinted by permission of Cambridge University Press.

Fig. 4.1: Fig. 1 from Naeem, S. (1998) Species redundancy and ecosystem reliability. Conservation Biology 12, 39–45. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 4.2: Fig. 2 from Naeem, S. (2002) Functioning of biodiversity. In: Encyclopedia of Global Environmental Change, Vol. 2 (ed. T. Munn), pp. 20–36. Copyright © 2002 John Wiley & Sons Limited. Reproduced with permission.

Fig. 5.1: Fig. 5.3 from Pimm, S.L., Moulton, M.P. & Justice, L.J. (1995) Bird extinctions in the central Pacific. In: Extinction Rates (eds. J.H. Lawton & R.M. May), pp. 75–87. Oxford University Press, Oxford. Reprinted by permission of Oxford University Press.

Fig. 5.2: Reprinted from Trends in Ecology and Evolution 8, Smith, F.D.M., May, R.M., Pello, R., Johnson, T.H. & Walter, K.R, How much do we know about the current extinction rate? pp. 375–378, Copyright © 1993, with permission from Elsevier.

Fig. 5.3: Fig. 1 from Pauly, D., Christensen, V., Guénette, S., Pitcher, T.J., Sumaila, U.R., Walters, C.J., Watson, R. & Zeller, D. (2002) Towards sustainability in world fisheries. Nature 418, 689–695. Reprinted by permission of the publisher and authors.

Fig. 5.4: Fig. 26 from Grainger, R.J.R. & Garcia, S.M. (1996) Chronicles of marine fishery landings (1950–1994): trend analysis and fisheries potential. FAO Fisheries Technical Paper 359, 1–51. Reprinted by permission of the Food and Agriculture Organization of the United Nations.

Fig. 5.6: Reprinted with permission from Fig. 1, Green, G.M. & Sussman, R.W. (1990) Deforestation history of the eastern rain forests of Madagascar from satellite images, Science 248, 212–215. Copyright © 1990 American Association for the Advancement of Science.

Fig. 5.7: From Anon. (1994) Biodiversity: The UK Action Plan. HMSO, London. Reprinted by permission of HMSO.

Fig. 5.8: Fig. 1 from Ruesink, J.L., Parker, I.M., Groom, M.J. & Kareiva, P.M. (1995) Reducing the risks of nonindigenous species introductions. BioScience 45, 465–477. Copyright © American Institute of Biological Sciences.

Fig. 5.9: Fig. 1 from Vitousek, P.M., Mooney, H.A., Lubchenco, J. & Melillo, J.M. (1997) Human domination of Earth’s ecosystems. Science 277, 494–499.

Fig. 5.10: From Terrestrial Ecoregions of the Indo-Pacific: A Conservation Assessment, by Eric Wikramanayake, Eric Dinerstein, Colby Loukes, et al. Copyright © 2002 Island Press. Republished by permission of Island Press.

Fig. 5.11a: Fig. 2 from Thompson, K. & Jones, A. (1999) Human population density and prediction of local plant extinction in Britain. Conservation Biology 13, 185–189. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 5.11b: Fig. 3 from Hoare, R.E. & du Toit, J.T. (1999) Coexistence between people and elephants in African savannas. Conservation Biology 13, 633–639. Reprinted by permission of Blackwell Publishing Ltd.

Fig. 5.12: Fig. 2 from Woodroffe, R. (2000) Predators and people: using human densities to interpret declines of large carnivores. Animal Conservation 3, 165–173. Reprinted by permission of Cambridge University Press.

Fig. 5.13: Fig. 5.3 from Cohen, J.E. (1995) How Many People Can the Earth Support? W.W. Norton, New York.

Fig. 6.1: Fig. 2 from Green, M.J.B. & Paine, J. (1997) State of the world’s protected areas at the end of the twentieth century. Paper presented at IUCN World Commission on Protected Areas symposium ‘Protected areas in the twenty-first century: from islands to networks’. Albany, Australia. Copyright © 1997 WCMC. Reprinted by permission of UNEP-WCMC, Cambridge.

Fig. 6.2: Fig. 3 from Green, M.J.B. & Paine, J. (1997) State of the world’s protected areas at the end of the twentieth century. Paper presented at lUCN World Commission on Protected Areas symposium ‘Protected areas in the twenty-first century: from islands to networks’. Albany, Australia. Copyright © 1997 WCMC. Reprinted by permission of UNEP-WCMC, Cambridge.

Fig. 6.3: From Requiem for Nature, by John Terborgh. Copyright © 1999 by John Terborgh. Republished by permission of Island Press/Shearwater Books.

Fig. 6.4: Fig. 15.2 from Huston, M.A. (1994) Biological Diversity: The Coexistence of Species on Changing landscapes. Cambridge University Press, Cambridge. Reprinted by permission of Cambridge University Press.

Fig. 6.5: Reprinted with permission from Fig. 2, Soulé, M.E. (1991), Conservation: tactics for a constant crisis, Science 253, 744–749. Copyright © 1991 American Association for the Advancement of Science.

Table 2.3: Table 2 from McKinney, M.L. (1997) Extinction, vulnerability and selectivity: combining ecological and paleontological views. With permission, from the Annual Review of Ecology and Systematics, volume 28 © 1997, by Annual Reviews www.annualreviews.org.

Table 2.4: Table 3.1–2 from Hawksworth, D.L. & Kalin-Arroyo, M.T. (1995) Magnitude and distribution of biodiversity. In: Global Biodiversity Assessment (ed. V.H. Heywood), pp. 107–199. Cambridge University Press, Cambridge. Reprinted by permission of Cambridge University Press.

Table 3.1: Table 7–1 from Reaka-Kudia, M.L. (1997) The global biodiversity of coral reefs: a comparison with rain forests. In: Biodiversity II: Understanding & Protecting our Biological Resources (eds. M.L. Reaka-Kudia, D.E. Wilson & E.O. Wilson), pp. 83–108. Joseph Henry, Washington, DC. Reprinted with permission from Biodiversity II © 1996 by the National Academy of Sciences, courtesy of the National Academies Press, Washington, DC.

Table 4.1: Table 1.1 from Lovelock, J. (1989) The Ages of Gaia: A Biography of our Living Earth. Oxford University Press, Oxford. Reprinted by permission of Oxford University Press.

Table 5.2: Table 2 from Hannah, L., Carr, J.L. & Lankerani, A. (1995) Human disturbance and natural habitat: a biome level analysis of a global data set. Biodiversity and Conservation 4, 128–155. With kind permission of Kluwer Academic Publishers.

Table 5.4: Excerpted from A Plague of Rats and Rubbervines: The Growing Threat of Species Invasions, by Yvonne Baskin. Copyright © 2002 The Scientific Committee on Problems of the Environment (SCOPE). Reprinted by permission of Island Press/Shearwater Books.

Every effort has been made to trace copyright holders and to obtain their permission for the use of copyright material. The publisher apologizes for any errors or omissions in the above list and would be grateful if notified of any corrections that should be incorporated in future reprints or editions of this book.

1

What is biodiversity?

1.1 Marion Island

The biotas of a few sites around the world have received disproportionate attention from biologists. One such is Marion Island, the larger of the two islands that make up the Prince Edward archipelago. Small (c. 290 km²) and remote (c. 2300 km southeast of Cape Town, South Africa), and with no permanent human population, the principal attractions that have led numerous scientists to conduct studies here in the midst of the vast Southern Ocean have been the, often charismatic, birds and mammals that are present. Marion Island is home to breeding populations of about 50,000 elephant seals and fur seals, and perhaps a million seabirds, including penguins, albatrosses, petrels and shearwaters. But these are just some of the more obvious inhabitants, and closer inspection reveals many more kinds of organisms. There are about 150 known species of invertebrates, including 44 species of insects and about 69 species of mites. And then there are, of course, the plants. There are 24 naturally occurring and 13 introduced species of vascular plants on Marion Island, and over 80 species of mosses, 45 species of liverworts, and 100 species of lichens have been identified.

Even given the intensity of study that Marion Island has received much remains unknown. No one has studied the nematode worms, although there seem likely to be more than 50 species present. The protists, bacteria and viruses also remain largely unexamined. Many of the species occur­ring on the island doubtless have associated parasites, but these also are mostly unknown. Indeed, there is a total of more than 500 species inhabiting Marion Island (Fig. 1.1).

Fig. 1.1 The breeding species of sub-Antarctic Marion Island, one of the two remote Prince Edward Islands. Grey scales indicate variation in elevation. (Data from a variety of sources, including Gremmen 1981; Hänel & Chown 1999; Gaston et al. 2001; Øvstedal & Gremmen 2001; S.L. Chown pers. comm.)

Each of these species embraces a diverse range of evolutionary history, genetics, morphology, physiology and ecology. Each typically also com­prises many tens of thousands of individuals, sometimes considerably less, but sometimes orders of magnitude more. For the majority, rather few of these individuals actually occur on Marion Island itself (although there are some species that occur nowhere else), but are scattered over the land- or seascape across many hundreds of square kilometres. Most of these individuals will have a unique genetic make-up, and, if only in the fine details, a unique morphology, physiology and ecology.

Such variety is echoed time and again across the Earth. Indeed, although it is important because some species found there occur nowhere else, and because of the large breeding populations of birds and mammals, Marion Island would scarcely register on any league table of biological variation. It is by most standards a very depauperate place – as well as being small and remote, it is also cool (mean annual air temperature c. 5°C), wet (annual rainfall > 2.5 m), windy (gale-force winds blow for at least 1 h on nearly a third of all days) and was extensively covered in ice during recent periods of glaciation, a combination that would not predispose it to ‘Eden-like’ tendencies. Many areas have many more species, individuals of which exhibit greater diversities of form and function. For example:

• 173 species of lichens have been recorded on a single tree in Papua New Guinea (Aptroot 1997);
• 814 species of trees have been recorded from a 50 ha study plot in Peninsular Malaysia (Manokaran et al. 1992);
• 850 species of invertebrates are estimated to occur at a sandy beach site in the North Sea (Armonies & Reise 2000);
• c. 1300 species of butterflies have been recorded on five field trips, averaging less than 3 weeks each, to an area of < 4000 ha in Brazil (Robbins & Opler 1997);
• 245 resident species of birds have been recorded holding territories on a 97 ha plot in Peru (Terborgh et al. 1990);
• > 200 species of mammals may occur at some sites in the Amazonian rain forest (Voss & Emmons 1996);
• 55–135 animal species have been recorded in individual 30 × 30 cm cores of ocean floor sediment from 2100 m depth (Grassle & Maciolek 1992).

1.2 What is biodiversity?

Most straightforwardly, biological diversity or biodiversity is ‘the variety of life’, and refers collectively to variation at all levels of biological organ­ization. Thus, one can, for example, speak equally of the biodiversity of some small or large part of Marion Island, of the island as a whole, of the islands of the Southern Ocean, of a continent or an ocean basin, or of the entire Earth. Many more formal definitions of biological diversity or biodiversity (we shall use the two terms interchangeably) have been pro­posed, which develop this simple one (DeLong 1996 reviewed 85 such definitions!). Of these, perhaps the most important and far-reaching is that contained within the Convention on Biological Diversity (the defini­tion is provided in Article 2). This landmark treaty was signed by more than 150 nations on 5th June 1992 at the United Nations Conference on Environment and Development, held in Rio de Janeiro, and came into force approximately 18 months later (we shall subsequently refer to it simply as ‘the Convention’, although elsewhere you will commonly find it referred to by its acronym, CBD).

The Convention states that:

‘Biological diversity’ means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.

[‘inter alia’ means ‘among other things’.] Biodiversity is the variety of life, in all of its many manifestations. It encompasses all forms, levels and combinations of natural variation and thus serves as a broad unifying concept.

For the purposes of the exploration of biodiversity embodied in this book we will amplify the full definition from the Convention in one way. At present it does not obviously take into account the tremendous variety of biological life that occurred in the past, some of which is preserved in the fossil record. However, we will want to trace the origins of present-day biodiversity and this will necessitate delving into the past (Chapter 2). To avoid any possible confusion therefore, we will explicitly interpret the definition to embrace the variability of all organisms that have ever lived, and not simply those that are presently extant.

The actual definition of biodiversity, as given above, is neutral with regard to any importance it may be perceived to have. The Convention is, in contrast, far from a neutral document, as amply revealed by its object­ives (Article 1), which are:

… the conservation of biological diversity, the sustainable use of its components and the fair and equitable sharing of the benefits arising out of the utilization of genetic resources, including by appropriate access to genetic resources and by appropriate transfer of relevant technologies, taking into account all rights over those resources and to technologies, and by appropriate funding.

Likewise, much of the usage of the term ‘biodiversity’ is value laden. It carries with it connotations that biodiversity is per se a good thing, that its loss is bad, and that something should be done to maintain it. Con­sequently, it is important to recognize that there is rather more to use of the term than a formal definition in the Convention, or for that matter elsewhere, and its application often reveals just as much about the values of the person using it (see Section 1.4.2 and Chapter 4). This should always be borne in mind when interpreting what is being said about biodiversity, particularly now that the term has become a familiar feature of news programmes and papers, and importance is attached to it by environmental groups, political decision-makers, economists and ordin­ary citizens alike. Many users assume everyone shares the same intuitive definition, but this is not necessarily the case.

Table 1.1 Elements of biodiversity. (Adapted from Heywood & Baste 1995.)

1.3 Elements of biodiversity

The variety of life is expressed in a multiplicity of ways. Some sense of this variety can begin to be made by distinguishing between different key elements. These are the basic building blocks of biodiversity. They can be divided into three groups: (i) genetic diversity; (ii) organismal diversity; and (iii) ecological diversity (Table 1.1). Genetic diversity encompasses the components of the genetic coding that structures organ­isms (nucleotides, genes, chromosomes) and variation in the genetic make-up between individuals within a population and between popula­tions. Organismal diversity encompasses the taxonomic hierarchy and its components, from individuals upwards to species, genera and beyond. Ecological diversity encompasses the scales of ecological differences from populations, through niches and habitats, on up to biomes. Although pre­sented separately, the groups are intimately linked, and in some cases share elements in common (e.g. populations appear in all three).

Some of these elements are more readily, and more consistently, defined than are others. When we consider genetic diversity, nucleotides, genes and chromosomes are discrete, readily recognizable, and comparative units. Things are not quite so straightforward and neat when we move up to individuals and populations, with complications being introduced by, for example, the existence of clonal organisms and difficulties in iden­tifying the spatial limits to populations. When we come to organismal diversity most of the elements are perhaps best viewed foremost simply as convenient human constructs for grouping evolutionarily related sets of individuals (although they do not always manage to do so). For instance, debate persists over exactly how many taxonomic kingdoms of organisms there should be, with a three domain natural classification being increas­ingly widely accepted (Bacteria and Archaea (prokaryotes), and Eukarya (eukaryotes)). When we refer to orders, families, genera or species of dif­ferent groups we are not necessarily comparing like with like, although within a group examples of a given taxonomic level (e.g. different genera) may be broadly comparable. Thus, some species placed in different genera of cichlid fishes last shared common ancestors within the last few thou­sand years, some species placed in different families of primates diverged within the last few million years, and some species in the genus Drosophila diverged more than 40 million years ago (Fig. 1.2). Even the reality and recognition of species, for long considered one of the few biologically meaningful elements, has been a recurrent theme of debate for many decades, and a broad range of opinions and viewpoints have been voiced (Table 1.2; Section 1.4.4). Finally, and perhaps most problematic, is exactly how we define the various elements of ecological diversity. In most cases these elements constitute useful ways of breaking up continua of phenomena. However, they are difficult to distinguish without recourse to what ultimately constitute some essentially arbitrary rules. For example, whilst it is helpful to be able to label different habitat types, it is not always obvious precisely where one should end and another begin, because no such beginnings and endings really exist.

While many of the elements of biodiversity may be difficult to define rigorously, and in some cases may have no strict biological reality, they remain useful and important tools for thinking about and studying biodiversity. Thus, the elements of biodiversity, however defined, are not independent. Within each of the three groups of genetic, organismal and ecological diversity, the elements of biodiversity can be viewed as forming nested hierarchies (see Table 1.1); which serves also to render the com­plexity of biodiversity more tractable. For example, within genetic diver­sity, populations are constituted of individuals, each individual has a complement of chromosomes, these chromosomes comprise numbers of genes, and genes are constructed from nucleotides. Likewise, within organismal diversity kingdoms, phyla, families, genera, species, sub­species, populations and individuals form a nested sequence, in which all elements at lower levels belong to one example of each of the elements at higher levels. Along with the evolutionary process, this hierarchical organization of biodiversity reflects one of the central organizing prin­ciples of modern biology.

Whether any one element of biodiversity, from each or all of the three groups, can be regarded in some way as the most fundamental, essential or even natural is a contentious issue. For some, genes are the basic unit of life. However, in practice, it is often the species that is treated as the most fundamental element of biodiversity. Whether or not such an approach is useful, never mind correct, we will return to shortly (Section 1.4.4).

Fig. 1.2 Examples of disparities of taxonomic assignments in classifications of representatives of: (a) cichlid fish in Lake Victoria (14 species in nine genera); (b) anthropoid primates (seven species of several families); and (c) the genus Drosophila (13 species). (From Avise & Johns 1999.)

Table 1.2 (a) Species concepts; and (b) their strengths and weaknesses. (Adapted from Bisby 1995.)

(a)

(b)

1.4 Measuring biodiversity

1.4.1 Number and difference

For many purposes the concept of biodiversity is useful in its own right, as it can provide a valuable shorthand expression for what is a very complex phenomenon. However, for more general applicability, one needs to be able to measure biodiversity – to quantify it in some way. Only then can one address such fundamental questions as how bio­diversity has changed through time, where it occurs, and how it can be maintained.

Fig. 1.3