South Asia supports a major endemic radiation of Hemidactylus geckos

摘要

Hemidactylus geckos are a species-rich component of many tropical lizard assemblages. We sampled deeply among tropical Asian, and especially South Asian, taxa and used a multi-gene approach to establish the affinities of Indian and Sri Lankan Hemidactylus and to evaluate the monophyly of previously proposed taxa within the genus. There is only weak support for the monophyly of tropical Asian Hemidactylus as a whole, but two strongly supported subclades were retrieved: the bowringii group is a predominantly East Asian clade that reaches South Asia only peripherally; the brookii group is a morphologically diverse clade that represents a previously unrecognized, species-rich (25 species), chiefly South Asian radiation. Deep genetic divergences support the specific recognition of three Sri Lankan taxa previously regarded as subspecies of mainland forms and validate H. subtriedrus as a species distinct from H. triedrus. Unlike several other vertebrate groups, Sri Lankan Hemidactylus do not represent a single insular radiation. Rather, each of six Sri Lankan species reached the island independently from different continental sources. There have been extensive Quaternary land connections between India and Sri Lanka but sister-species pairs of Hemidactylus on the two land masses diverged from one another much earlier, probably in the mid-Miocene.