Phylogenetic position, origin and biogeography of Palearctic and Socotran blind-snakes (Serpentes: Typhlopidae)

摘要

?West Asian R. simoni and R. episcopus form a monophyletic group with R. newtoni and R. feae from sub-Saharan Africa.?Common factors are responsible for the split of R. simoni/R. episcopus and the basal diversification within T. vermicularis.?T. socotranus is a sister species to T. vermicularis, having diverged from each other some 30Mya.?We propose that two dispersal events from north-east Africa and Arabia resulted in the occurrence of Eurasian typhlopids. The majority of the family Typhlopidae occurs in the Neotropic, Australasian, Indo-Malayan and Afrotropic ecoregions. They show a restricted distribution in the western Palearctic, where they include few native species, i.e. Rhinotyphlops simoni, R. episcopus and Typhlops vermicularis. A unique species among typhlopids is T. socotranus, found in Socotra, one of the most endemic-rich archipelagoes. In this study we determine the phylogenetic position of the above mentioned species and discuss their systematics, origin and biogeography. For this purpose we use three protein-coding nuclear markers (AMEL-amelogenin, BDNF-brain-derived neurotrophic factor and NT3-neurotrophin 3) to construct a time-calibrated phylogeny of the family Typhlopidae. Our results show that T. socotranus is a sister-species to T. vermicularis, while R. simoni and R. episcopus are sister-species to each other and are found within the African clade of the family, although they are geographically distributed in west Asia. Additionally we discuss several hypotheses on their origin, as well as the occurence of typhlopids in Eurasia.