As part of the International Kuril Island Project, we collected data on the distribution patterns of native terrestrial, non-volant mammals inhabiting the Kuril archipelago in the northwest Pacific. The Kurils have a complex physical geography, featuring both landbridge and oceanic islands in which small mammal-occupied islands are near mainlands, whereas larger islands are more isolated. This geography, in combination with the Kurils’ cold climate, causes the mammalian fauna to deviate from traditional island biogeographic patterns. We examined these patterns and the mechanisms influencing them using both nestedness analyses and measures of compositional disharmony. We found, as island isolation increases, carnivores constitute an increasing fraction of the mammalian fauna. We suggest that this intriguing pattern of carnivore dominance occurs because species’ dispersal abilities increase with increasing body size in the Kurils’ cold climate. Substantial energy reserves and cold tolerance of large-bodied carnivores may have been a major factor in determining mam- malian colonization patterns, patterns which are perhaps indicative of the complex manners in which challenging climates impact mammalian community assemblages.
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Document Type: Research Article
Department of Zoology and the Burke Museum, University of Washington, Seattle, WA 98195-1800, U.S.A. and Department of Biology, Arizona State University, Tempe, AZ 85287-1501, U.S.A.
May 1, 1998