Systematics and biogeography of the lizard genus Mesalina (Reptilia: Lacertidae)

Abstract

Mesalina is a widespread lacertid lizard genus that inhabits arid areas from North Africa to Pakistan. With around 13 species, many of them exhibit high genetic diversity and complex phylogenetic and biogeographic patterns. The taxonomic history of Mesalina is troubled, given the confusing morphological differentiation together with the geographical overlap between many species and the lack of samples for both morphological and molecular studies. Previous phylogenetic studies of this genus show that M. guttulata represents a species complex but the phylogenetic position of some populations from the Arabian Peninsula remains unknown. In this talk we will show an updated multilocus time-calibrated phylogeny of the genus Mesalina with especial emphasis on the Arabian species with the aim of revising their systematics and biogeography. In order to achieve our goal, we have include an unprecedented sampling with 13 representatives of the 14 described species of Mesalina collected across more than 12 million square km. Besides the sampling effort, the sequencing effort is equally important with more than 400 new sequences produced including three mitochondrial ( 12S, 16S and cytb ) and one nuclear gene ( mc1r). The recovered phylogeny is very robust and shows that the genus started diversifying 22 Ma ago in Eurasia, dispersing from Arabia to Africa and vice versa several times giving rise to the current species diversity. Within Arabia, we extend the distribution ranges of several species and identify three deep lineages, two from mountain regions in SW Arabia and South Oman and one widespread across central Arabia that correspond to three new species of Mesalina according to molecular and morphological data. Finally, a specific study adding sequences of three more nuclear genes ( acm4, cmos and and rag1 ) of several Arabian species clearly show that the Socotra Archipelago was colonized by a single long range transmarine dispersal by the ancestor of M. ayunensis and the two Socotran species M. kuri and M. balfouri. The two Socotran endemics originated approximately 5 Ma by an intra archipelago colonization event from Socotra Island to Abd al Kuri or vice versa.