Cryptic Speciation in Mouse Lemurs

Mouse lemurs (genus Microcebus) are the world’s smallest living primates. Over the past decade, there has been an explosive increase in the number of recognized species. In 1992, there were two named species. Now, following a series of recent descriptions, there are more than 15 putative species, with more suggested to exist, but not yet formally described. Given the enormous conservation impacts that result from the recognition of new species occurring in threatened habitats, evolutionary biologists are increasingly interested in the balance between the political implications of these discoveries and the application of rigorous systematic criteria in clarifying species numbers. To address these concerns, and in collaboration with Peter Kappeler of the DPZ and David Weisrock of the University of Kentucky, we are conducting the most thoroughly sampled species delimitation study of mouse lemurs ever performed, incorporating nuclear DNA data for the first time. We have sampled individuals from nearly every geographic region of Madagascar and are analyzing them with a diverse genetic data set of mitochondrial and nuclear DNA loci. Phylogenetic methods are being employed to detect patterns of reciprocal monophyly among gene trees, with population genetic methods used to assess the cohesion of populations via gene flow. Our results indicate that Microcebus is indeed one of the world’s most speciose genera of primate. Future work will include even more individuals, localities, and genetic loci.