Wednesday, July 23, 2014

Divergence in Shaw's Vivipiparous Sea Snake

Hydrophis curtus
Species are not evenly distributed on earth and regions that are exceptionally rich in endemic species suffering habitat loss are commonly referred to as biodiversity hotspots. The Indo-Australian archipelago has unusual high levels of biodiversity threatened by increasingly human generated activities. The region supports the one of world's highest diversity of marine fish, invertebrates and reptiles. Many of the marine organisms show congruent phylogeographic patterns, supporting the view that the region's complex geo-climatic history has played an important role in generating its exceptional biodiversity.

Ukuwela et al., (in press, 2014) examined the population genetic structure of the viviparous sea snake, Hydrophis curtus, to assess how past and present barriers to gene flow in the Indo-Australian archipelago have contributed to genetic and species diversity in a fully marine reptile.

Mitochondrial and anonymous nuclear sequences and ten microsatellite loci were used to identify patterns of historical genetic structure and population expansion, reconstruct dated genealogies and assess levels of recent gene flow. These markers revealed strong concordant geographic structure within H. curtus with a prominent genetic break between populations broadly distributed in the Indian Ocean and the West Pacific. These populations were estimated to have diverged in the late Pliocene or early Pleistocene, and microsatellite admixture analyses suggested limited recent gene flow between them despite the current lack of barriers to dispersal, indicating possible cryptic species.

Subsequent divergence in the mid–late Pleistocene was detected within the West Pacific clade among the populations in the Phuket-Thailand region, South-East Asia and Australia, and two of these populations also showed genetic signals of recent range expansions. The results show that climatic fluctuations during the Plio-Pleistocene generated high levels of cryptic genetic diversity in H. curtus, and add to similar findings for diverse other marine groups in the archipelago.


Citation

Ukuwela, K. D. B., de Silva, A., Mumpuni, Fry, B. G. & Sanders, K. L. (in press, 2014). Multilocus phylogeography of the sea snake Hydrophis curtus reveals historical vicariance and cryptic lineage diversity. — Zoologica Scripta, 

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