Assemblage and genetic structure of insectivorous bats in Peninsular Malaysia.
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Past climate change and recent human activity have had major impacts on the distribution of habitats as well as the community and population genetic structure of the species occupying these habitats. In temperate zones, glaciation forced many taxa into southern refugia. In contrast, little is understood about the extent to which tropical taxa and habitats were affected by colder periods. In Southeast Asia, some argue that the tropical forest was replaced by savannah at the Last Glacial Maximum (LGM), whereas others suggest that the forest persisted. Studying population genetic and community structure of forest-dependent species in this region may shed light on which of these scenarios is most likely, as well as provide crucial information on the effects of recent habitat loss. To address these issues, I studied the genetic and community structure of forest-dependent insectivorous bat species in Peninsular Malaysia. Data collected at 22 sites indicated that species richness declined with latitude, consistent with post-glacial expansion of forest. To test this further, I undertook mitochondrial DNA sequencing of a widespread species, Rhinolophus affinis, and found high haplotype diversity, little phylogeographic structure and no demographic growth. These all suggest a long population history in the region with no post-LGM range expansion. Subsequent microsatellite analyses of R. affinis and the congeneric R. lepidus showed that genetic distance followed an isolation-by-distance model, and that allelic diversity was unexpectedly higher in the northern populations. Taken together, my results from the community and genetic analyses disagree with each other. These conflicts are perhaps best explained if observed clines in species richness pre-date the LGM. I conclude that there is little evidence of forest contraction in the LGM. The fact that the highest species diversity was detected in the south, which is experiencing the most forest loss due to human activity, has important conservation consequences.
AuthorsLim, Lee Sim
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