Not one, but multiple radiations underlie the biodiversity of Madagascar’s endangered lemurs

Abstract

AbstractLemurs are a well-known example of adaptive radiation. Since colonizing Madagascar, more than 100 extant lemur species have evolved to fill the variety of ecological niches on the island. However, recent work suggests that lemurs do not exhibit one of the hallmarks of adaptive radiations: explosive speciation rates that decline over time. We test this idea using a phylogenomic dataset with broad taxonomic sampling of lemurs and their sister group, the lorisiforms of Asia and continental Africa. We find higher rates of speciation in Madagascar’s lemurs compared to lorisiforms and we confirm that lemurs did not experience an “early burst” of speciation after colonizing Madagascar. Instead, we identify three independent bursts of speciation approximately 15 million years ago that underly much of today’s lemur diversity. We demonstrate that the lemur clades with exceptionally high diversification rates have higher rates of introgression. This suggests that hybridization in these primates is not an evolutionary dead- end, but a driving force for diversification. Considering the conservation crisis affecting strepsirrhine primates, with approximately 95% of species being threatened with extinction, this phylogenomic study offers a new perspective for explaining Madagascar’s exceptional primate diversity and reveals patterns of speciation, extinction, and gene flow that will help inform future conservation decisions.