Patterns and processes of diversification in an entire primate genus : the case of cryptic mouse lemurs

Madagascar has long been recognized as a model for species diversification and a major conservation priority given the high levels of endemism and critically endangered status of its biodiversity. Yet, the study of the island’s biodiversity and the implementation of effective conservation strategies have likely been impeded by an inflation of its taxonomic diversity. A striking example are the cryptic mouse lemurs (genus Microcebus), which underwent a controversial five-fold increase in species number since 1999. Here, we integrate comprehensive genomic, morphological, ecological and behavioural data to show that the taxonomy of this genus has been inflated. Following a revised taxonomy, we provide the first comprehensive phylogeny for mouse lemurs and show that their diversification occurred during the late Pleistocene, possibly facilitated through climatic fluctuations and species-pump effects of humid rainforests. In addition, we find that the cryptic nature of the genus results from morphological stasis and niche conservatism. Finally, we identify intraspecific conservation units, which should guide the conservation of both species and population genetic diversity. Our work sheds light not only on the diversification of mouse lemurs but also provides a practical framework to facilitate the study of cryptic diversity and conservation worldwide.