Speciation in Malagasy lemurs: a review of the cryptic diversity in genus Lepilemur/Spéciation des lémuriens de Madagascar : synthèse sur l'énigmatique diversité du genre Lepilemur

Madagascar is one of the highest biodiversity hotspots on the planet; however, it is also one of the most heavily impacted countries in the world in terms of forest degradation and general habitat destruction. Genus Lepilemur, in family Lepilemuridae, is a genus of small, nocturnal, exclusively arboreal Malagasy folivores. All species in the genus have small ranges of distribution. Fully forest-dependent, they have a high risk of extinction. Various models and theories of speciation mechanisms have been developed for the fauna and flora of Madagascar. For instance, in the northwestern part of the island, some authors used Lepilemur spp. to test two existing models of distribution: the "Martin model" and "Wilmé model". Regarding the impact of forest destruction and habitat degradation in Madagascar, conservation strategies for Lepilemur need to be put in place. This paper gives an overview of the current knowledge of the genus Lepilemur and examines speciation for Malagasy lemurs. The understanding of species distribution within biodiversity hotspots is important to identify target for conservation. Therefore, we summarize and compare three biogeography models related to lemurs distribution in order to understand the reasons behind the high diversity (26 species in total) among the genus Lepilemur. Particular attention is also given to the concept of species regarding biodiversity issues and the taxonomic explosion in genus Lepilemur.