Island Biogeography. Ecology, Evolution, and Conservation ROBERT J. WHITTAKER. School of Geography, University of Oxford...:.

Transcription

1 Island Biogeography Ecology, Evolution, and Conservation ROBERT J. WHITTAKER School of Geography, University of Oxford...:. Technische Universitat Darmstadt FACHBEREICH 10 BIOLOGIE BJbliothek SchnittspahnstraBe 10 D Darmstadt» cats I OXFORD NEW YORK TOKYO OXFORD UNIVERSITY PRESS 1998

2 Contents 1 The natural laboratory paradigm 1 2 Island environments Types of islands. / > ' - " Modes of origin Plate boundary islands " '; ~>:. : \ Islands in intra-plate locations - J Environmental changes over long time-scales Changes kurelative sea level reefs, atolls, and-guyots ' ' ' -' ' Eustatic changes in sea level - v : ' ' " Climate change on islands ' ' : ' ' ' Case study of an island at sea: the environmental history of Jamaica over the past 50 million years * ' ' Physical environment of islands, Topographic characteristics Climatic characteristics Water resources " ' " ''' "' ' ' Tracks in the ocean (., Natural disturbance on islands, Magnitude and frequency» Continued volcanism Summary " 31 J 3 Biodiversity hot-spots Introduction: the global significance of island biodiversity :..:«. '.. ' ' The split between continental and oceanic islands.revisited - > Species poverty.'.,', :,. -. _.., ' Disharmony, filters, and regional biogeography, _ ' "..,- : Endemicity.,... >,...-,-....: : ; Neo-and palaeo-endemicity.>.>' :..'.-.-.' -... r Endemic plants > -' " Endemic animals, Extinct island endemics: a cautionary note Summary 51 4 Speciation and the island condition Introduction: first know" your species " ' The species concept and its place in phylogeny 54

3 viii Contents 4.3 The geographical contexts of speciation events Distributional context ' Locational context island or mainland change? 4.4 Mechanisms of speciation Allopatric or geographical speciation Competitive speciation Polyploidy 4.5 One more framework: tree form or phylogeny 4.6 Summary 5 Arrival and change 5.1 Founder effects, genetic drift, and bottlenecks 5.2 Sex on islands x ' 5.3 Niche shifts The loss of dispersability Gigantism and nanism Character displacement Ecological release Other niche shifts and syndromes 5.4 Summary ( 6 Emergent models of island evolution 6.1 Speciation with little or no radiation: anagenesis 6.2 nthe taxon cycle, "6.2.1 Melanesian ants.... ; Caribbean birds Caribbean anoles / Evaluation 6.3 Adaptive radiation Darwin's finches and the Hawaiian honeycreeper-finches Hawaiian crickets and drosophilids Adaptive radiation in plants 6.4 Observations on the forcing factors of island evolution Environmental change as a driving force Rates of speciation vary through time and between taxa Dispersal ability and endemism Biogeographical hierarchies and island evolutionary models 6.5 Summary 7 Species numbers games 7.1 Introduction 7.2 The development of the equilibrium theory of island biogeography

4 Contents ix Species-area patterns.., v Species abundance distributions The distance effect Turnover, the core theory (ETIB) and its immediate derivatives r ;.' Spatial analyses of island species number. ' Area and habitat diversity ' ;. - / The habitat-unit model.!.-. ;..' Competing hypotheses for the species-area effect : Area is not always that important ' Species-energy theory * Isolation and distance r s. \ c Species-area relationships in remote.archipelagos -^.' Scale effects Turnover --.O '. -. ' Pseudoturnover and cryptoturnover. /. \ When is an island in equilibrium? ". r r Propagules and pools The rescue effect and the effect of island area on immigration rate The path to equilibrium * What causes extinctions?,:,.' ' Forms of equilibria and non-equilibria' < ] ' '. ; Summary ". -*' Community assembly and dynamics 144 Introduction 144 Island assembly.theory..... ^^ Assembly rules. ^ Incidence functions and tramps. <. ^^ The dynamics of island assembly ' Checkerboard distributions Combination and compatibility assembly rules for cuckoo-doves Criticisms,'null'models, and responses, Other studies of assembly structure ' Nestedness Successional island ecology: first elements Krakatau succession, dispersal structure, and hierarchies, '... -, Background,., Community succession ' ' A dispersal-structured model of island recolonization. 170! Colonization and turnover the dynamics of species lists, The balance between stochasticism and determinism '... ' : 8.6 Disturbed island ecology revisited ' 180 '8.7 A general critique of island ecology theory v Scale and the dynamics of island biotas Haila's critique Concluding remarks. 189 p.8 Summary ' " ' 189

5 x ' Contents 9 Island theory and conservation. : * Habitats as islands Minimum viable populations and minimum viable areas How many individuals are needed?. :, Minimum viable populations and disturbance How big an area?, Applications of incidence functions ^ - s \ ' Metapopulation dynamics» ' ' The core-sink model variant Deterministic explanations of extinctions within metapopulations '.' Reserve configuration the'single large or several small'debate ',. '. : Dealing with the leftovers The answer depends, in part, on the type of organism Physical changes consequent upon fragmentation ' Relaxation and turnover the evidence Succession in fragmented landscapes u.. " v ' The implications of nestedness..".. *" Edge effects Landscape effects, isolation, and corridors ' The benefits of wildlife corridors. ' The benefits of isolation Reserve systems in the landscape Species that f don't stay put Does conservation biology need island theory? A non-equilibrium world? Ecological hierarchies and fragmented landscapes Climate change and reserve systems Concluding remarks., ;, Summary ' ' The human impact on island ecosystems the lighthouse-keeper's cat and other stories Introduction the scale of loss The agencies of destruction. ' Predation by humans Introduced species Disease. ' Habitat degradation and loss _ Trends in the causes of decline A record of passage patterns of loss across island taxa..-, Pacific Ocean birds., Indian Ocean birds, Reptiles ' ' ' ' " ' ' Caribbean land mammals " Island snails Plants in peril 242

6 4 Contents xi 10.5 How fragile and invasible are island ecosystems? 245^ 10.6 Contemporary problems and solutions Conservation measures ) Contemporary problems in the Galapagos Sustainable development on islands: constraints and remedies Summary 255 Further reading 257 References + - " 259 Index s ' ' 279