Multilocus phylogeography of the sea snake Hydrophis curtus reveals historical vicariance and cryptic lineage diversity

Abstract

2014). Multilocus phylogeography of the sea snake Hydrophis curtus reveals historical vicariance and cryptic lineage diversity. -Zoologica Scripta, 43, 472-484. The Indo-Australian archipelago (IAA) supports the world's highest diversity of marine fish, invertebrates and reptiles. Many of the marine fish and invertebrates show congruent phylogeographic patterns, supporting a view that the region's complex geo-climatic history has played an important role in generating its exceptional biodiversity. Here, we examine population genetic structure of the viviparous sea snake, Hydrophis curtus, to assess how past and present barriers to gene flow in the IAA 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. Our 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 IAA.

Biogeographic origins of the viviparous sea snake assemblage (Elapidae) of the Indian Ocean

“…In this paper we describe the biogeographic origins of IO sea snakes and the effects of the past and present barriers to dispersal and gene flow between the IO and WP through reinterpretation of our data on the biogeographic origins of IAA sea snakes (Ukuwela et al, 2016) and the effects of the past and present barriers to dispersal and gene flow in the IAA (Ukuwela et al, 2014). For the inclusiveness, we have summarised the methods employed in Ukuwela et al (2014 and2016) here and the readers are requested to refer the original papers if further details are necessary.…”

“…For the inclusiveness, we have summarised the methods employed in Ukuwela et al (2014 and2016) here and the readers are requested to refer the original papers if further details are necessary.…”

“…To evaluate how past and present barriers to dispersal and gene flow have affected the species and genetic diversity of IO sea snakes, we examined the population genetic structure and recent levels of gene flow of the widespread sea snake, Hydrophis curtus (See Ukuwela et al, 2014 for further details). Population genetic structure was assessed by reconstructing mitochondrial DNA lineages and generating nuclear allele networks.…”

“…To estimate microsatellite differentiation between sampling locations and different populations, Fisher's exact probability tests and Fixation indices (F ST ) for all ten loci (combined) were estimated using Arlequin 3.5.1 (Excoffier and Lischer, 2010). See Ukuwela et al (2014) for details of primers, PCR amplification settings, DNA sequencing, voucher numbers and Genbank accession numbers of the three mitochondrial markers and the two nuclear markers, and further details of analyses. …”

“…Thus, they are ideal candidates to examine historical biogeographic events and their role in generating biodiversity. Though recent studies have shed light on the origins, patterns of viviparous sea snake diversity in the IAA (Lukoschek et al, 2007;Lukoschek et al, 2008;Sanders et al, 2013b;Ukuwela et al, 2014;Ukuwela et al, 2016b), this work did not focus on the origins and patterns of viviparous sea snake species diversity in the IO.…”