Thursday, August 6, 2009PS 64-88: Niches, Body Sizes, and the Disassembly of Island Mammal Faunas
Jordan Okie, University of New Mexico and James H. Brown, University of New Mexico.
Background/Question/Methods
The rising sea level at the end of the Pleistocene that created the islands of the Sunda Shelf (Indonesia) provides a natural experiment in community disassembly and offers insights into the effects of body size and niches on abundance, distribution, and diversity. In the 11,000 years since isolation, the terrestrial mammal communities of these islands have been reduced by extinction, with virtually no offsetting colonization.Slide 1 In order to investigate this disassembly process, we compiled a database consisting of a list of species and their body masses for the entire terrestrial, non-volant mammal fauna of each island of the Sunda Shelf and used regression and null simulation modelling to evalutate the significance of the observed patterns.
The rising sea level at the end of the Pleistocene that created the islands of the Sunda Shelf (Indonesia) provides a natural experiment in community disassembly and offers insights into the effects of body size and niches on abundance, distribution, and diversity. In the 11,000 years since isolation, the terrestrial mammal communities of these islands have been reduced by extinction, with virtually no offsetting colonization.
Results/Conclusions
We document three empirical patterns of disassembly: 1) a diversity-area relationship: number of taxa is strongly and positively correlated with island area; 2) nested subset composition: the species that occur on small islands tend to be subsets of the more diverse communities inhabiting larger islands; and 3) body size distributions: species of intermediate body sizes occur on the greatest number of islands, and smaller islands have smaller ranges of body sizes, due to absence of species of both very large and extremely small size. These patterns lead to inferences about how body size affects attributes of niches and how niche attributes affect local abundance, geographic distribution, and probability of extinction.
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See more of The 94th ESA Annual Meeting (August 2 -- 7, 2009)