Uma Ramakrishnan, "Why does the Indian subcontinent have few endemic mammals?"
Apr 08, 2013 (Mon) | 4:00 PM -6:00 PM
393 Serra Mall, Herrin T-175 : Stanford, CA
The Indian subcontinent only became a part of the Asian landmass relatively recently. Given the timing of its collision with Asia, it has been suggested that mammals and birds in the subcontinent may have arrived here relatively recently, suggesting it is a sink for diversity. This sets up the Indian subcontinent as an experimental landmass where we can investigate relative success of species colonizing novel environments. We investigated the importance of environment, area and history in driving patterns of species richness for large and small mammals. Our results revealed that models where species were divided into three groups based on biogeographic history (‘eastern’, palearctic’ and ‘western’) fit the data better than those that ignored species history. Further, species richness declined with distance from eastern-most, western-most and northern-most cells, supporting an ‘Out of Asia’ origin for most mammals in the Indian subcontinent. Genetic data and phylogenies also support a relatively recent colonization of the Indian subcontinent. In a second part of my talk, I investigate biodiversity in two important mountain chains in the subcontinent: the Himalayas and the Western ghats. In the Himalayas, a relatively young mountain chain, we observe a nested pattern of species richness from east to west. This suggests a relatively recent colonization of western regions following glacial retreat. In the Western ghats, a relatively old mountain chain, genetic data from 25 montane bird species revealed a deep divergence for several endemic species across ancient geographic divides. Divergences tend to be deeper for higher elevation species compared to more widespread ones, suggesting that species ecology may interact with mountain topography to drive evolution across this biodiverse mountain chain.
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