Diversification processes in an island radiation of shrews

Abstract

Southeast Asian mammals are known for their remarkable levels of diversity and endemism. However, few explicit tests of the mechanisms that may promote or inhibit speciation have been conducted on regional clades. I use phylogenetic estimates and tree shape analyses to explore the tempo and mode of diversification in Southeast Asian shrews (Soricomorpha: Crocidura), and to consider a set of geological, climatic, and ecological forces that my have shaped current patterns of diversity. I find no association of diversification rates with Pleistocene sea-level fluctuations or volcanic uplift that was concentrated during the Miocene and Pliocene. However, sea-level fluctuations appear to have been a factor in the generation of phylogeographic diversity in the Philippines. In general, Crocidura appears to have diversified at a consistent tempo and usually in allopatry. A lack of ecological innovation may have limited the extent of diversification in the Philippines, but perhaps not on Sulawesi.