Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

Aim

I propose and develop a new classification system to explain diversity patterns in habitat fragments, equally applicable to islands and other inherently patchy ecosystems. My primary goal is to provide an inclusive model to improve the comparability of studies and enhance future efforts to synthesize their findings, yielding a generalized basis for understanding species composition in patchy ecosystems.



Results

Differentiating islands from fragments and incorporating patch age and patch: matrix contrast, eight classes of patch are distinguished, spanning a range of geographical features. To compare studies of diversity patterns among and between patch types, patch biota are divided into three categories based on their origin—relict species (present before fragmentation), matrix-derived species and interpatch dispersers. Applying this novel scheme to existing data, the effects of insularization are synthesized. Direct comparisons among fragments revealed broad similarity in the long-term effects of habitat fragmentation compared with highly divergent patterns in younger landscapes (<200 years). Holding patch: matrix contrast and age constant, fragments and islands were compared. Despite initial differences in community assembly, the biota of islands and fragments converge in several properties over time, as diversities stabilize and patch biotas become distinct from the surrounding matrix.



Main conclusions

Although necessarily broad, this framework provides an explicit context within which to test forty-four specific predictions regarding the distribution of diversity in patchy landscapes and thereby gain a clearer understanding of the long-term biological consequences of insularization. I propose that the fragments-as-islands analogy be revisited, potentially yielding valuable insight into the long-term future awaiting anthropogenically altered ecosystems.

/pdf/a-conceptual-framework-for-studying-species-composition-in-2mbkz1u3px.pdf

A conceptual framework for studying species composition in fragments, islands and other patchy ecosystems

The Current Geographic Faunal Pattern of Reptiles and Amphibians of the Ryukyu Archipelago and Adjacent Regions.

Multilocus phylogeography can uncover taxonomically unrecognized lineage diversity across complex biomes. The Australian monsoonal tropics include vast, ecologically intact savanna-woodland plains interspersed with ancient sandstone uplands. Although recognized in general for its high species richness and endemism, the biodiversity of the region remains underexplored due to its remoteness. This is despite a high rate of ongoing species discovery, especially in wetter regions and for rock-restricted taxa. To provide a baseline for ongoing comparative analyses, we tested for phylogeographic structure in an ecologically generalized and widespread taxon, the gecko Heteronotia binoei. We apply coalescent analyses to multilocus sequence data (mitochondrial DNA and eight nuclear DNA introns) from individuals sampled extensively and at fine scale across the region. The results demonstrate surprisingly deep and geographically nested lineage diversity. Several intra-specific clades previously shown to be endemic to the region were themselves found to contain multiple, short-range lineages. To infer landscapes with concentrations of unique phylogeographic diversity, we probabilistically estimate the ranges of lineages from point data and then, combining these estimates with the nDNA species tree, estimate phyloendemism across the region. Highest levels of phyloendemism occur in northern Top End, especially on islands, across the topographically complex Arnhem escarpment, and across the sandstone ranges of the western Gulf region. These results drive home that deep phylogeographic structure is prevalent in tropical low-dispersal taxa, even ones that are ubiquitous across geography and habitats.

Multilocus phylogeography reveals nested endemism in a gecko across the monsoonal tropics of Australia

Aim
The small-island effect (SIE) has become a widely accepted part of the theoretical framework of island biogeography. A major criticism of SIE studies is the exclusion of empty islands from analyses. However, the generality and underlying factors determining the role of empty islands in generating SIEs remain obscure because few published datasets include islands with no species. The aim of this study was thus to evaluate the prevalence and underlying factors determining the role of empty islands in generating SIEs.

Location
Global.

Methods
We compiled 278 datasets that included empty islands. For each dataset, we compared the fit of a logarithmic model with two breakpoint models separately for all the islands and for datasets excluding empty islands to determine the role of empty islands in generating SIEs. We then employed multinomial logistic regressions and an information-theoretic approach to determine which combination of island characteristics was important in determining the role of empty islands in generating SIEs.

Results
Among 211 datasets with adequate fits, the exclusion of empty islands changed the evidence for an SIE in 68 cases (32.2%). SIEs were quite prevalent, both for all the islands (104 cases, 49.3%) and for datasets excluding empty islands (73 cases, 34.6%). Our results were not consistent with the hypothesis that excluding empty islands would increase the evidence for an SIE. Model selection and relative variable importance indicated that the number of empty islands, the minimum area of empty islands and area ratio were important variables that determined the role of empty islands in generating SIEs.

Main conclusions
Our study demonstrates that the effect of empty islands in generating SIEs is quite prevalent. The exclusion of empty islands is thus an important methodological shortcoming for the detection of SIEs. We conclude that, for the robust detection of SIEs, empty islands should not be excluded in future studies.

On empty islands and the small-island effect

Forty-four species of terrestrial reptiles and eight species of frogs were recorded from 60 continental islands of the Wessel and English Company groups off northeastern Arnhem Land, Northern Territory. Two gecko species, Oedura rhombifer and Heteronotia binoei, were present on the most islands (34 and 31, respectively), and occurred on islands

Distributional patterning of terrestrial herpetofauna on the Wessel and English Company Island groups, northeastern Arnhem Land, Northern Territory, Australia

The bird faunas of the adjacent Wessel and English Company island chains were sampled at two scales (0.25 ha quadrats and entire islands). Ninety-six species were recorded from 226 quadrats, with the most frequently recorded species being mistletoebird Dicaeum hirundinaceum, brown honeyeater Lichmera indistincta, silver-crowned friarbird Philemon argenticeps, bar-shouldered dove Geopelia humeralis, northern fantail Rhipidura rufiventris and yellow white-eye Zosterops iutea. At the quadrat scale, vegetation type was a major determinant of the abundance of individual species (and hence species composition), species richness and total bird abundance. Bird species composition and richness at the quadrat scale was also significantly affected by island isolation (particularly the amount of land within 20 km of the island perimeter). Island size had no effect on quadrat-scale richness or total abundance. However, the abundance of 10 of the 38 most frequently recorded individual species was significantly related to island size, in most cases even when the comparison was restricted to similar habitats. The most striking cases were rufous fantail Rhipidura rufifrons, mangrove golden whistler Pachycephala melanura, brown honeyeater and yellow white-eye, which were all significantly more abundant on smaller islands. One hundred and seventy-one species were recorded from the 62 islands sampled. There was a very tight relationship between island size and the number of terrestrial species (73% of deviance explained) and of all species (84% of deviance explained). This relationship was improved (marginally) when isolation was included in the model. Ordination of islands by their terrestrial bird species composition was related to island size and isolation, and suggested an erratic species composition on small islands.

Patterns of bird species richness and composition on islands off Arnhem Land, Northern Territory, Australia

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Distributional patterning of terrestrial herpetofauna on the Wessel and English Company Island groups, northeastern Arnhem Land, Northern Territory, Australia

Patterns of bird species richness and composition on islands off Arnhem Land, Northern Territory, Australia