The presence of the viviparous sea snakes in the Indian Ocean poses a unique question in this regard due to their evolutionary origins in Australasia (Australia and New Guinea). In a new paper Ukuwela et al. (2017) examine the origins and patterns of colonization of the Indian Ocean sea snake assemblage through time-calibrated molecular phylogenies and ancestral area reconstructions. They further evaluated how past and present barriers to dispersal affect genetic diversity of the Indian Ocean sea snakes by examining the population genetic structure of the widespread sea snake, Hydrophis curtus. Their phylogenetic analyses and ancestral area reconstructions strongly indicate that the majority of the Indian Ocean sea snakes are derived from the Southeast Asian sea snake fauna through dispersal and colonization with an in situ radiation (Hydrophis stricticollis-Hydrophis obscurus clade). Further, many species have undergone vicariant speciation events across the Sunda Shelf/Indo-Pacific barrier, which formed during the low sea level periods of the Pleistocene. Population genetic analysis of H. curtus revealed a prominent genetic break between populations broadly distributed in the Indian Ocean and Southeast Asia with limited recent gene flow indicating possible cryptic species. These results suggest that compared to the viviparous sea snake stem group that originated 10.6-6.5 million years ago, the Indian Ocean viviparous sea snakes have a relatively long and complex evolutionary history and thus have a unique conservation value.
Ukuwela KD, Lee MS, Rasmussen AR, De Silva A, Sanders KL. 2017. Biogeographic origins of the viviparous sea snake assemblage (Elapidae) of the Indian Ocean. Ceylon Journal of Science. 2017 Nov 23;46(5).