S5-2.3 Thursday, Jan. 5 Ecological innovation and speciation in viviparous sea snakes (Hydrophiinae) SANDERS, K L*; RASMUSSEN, A R; DE SILVA, A; MUMPUNI, n/a; UKUWELA, D B; University of Adelaide, Australia; Royal Danish Academy of Fine Arts, Denmark; Amphibia and Reptile Research Organisation of Sri Lanka; Museum of Zoology, Bogor; University of Adelaide, Australia email@example.com
The viviparous sea snakes provide a rare model of recent adaptive radiation in the marine environment. We present the first near-complete dated molecular phylogeny for the group, using coalescent analyses of 6 independent mitochondrial and anonymous nuclear loci for 85% of nominal species. Lineage-through-time plots reveal a dramatic increase in diversification rate ~3-5 million years after the initial invasion of marine habitats. Patterns of adaptive radiation and geographic range evolution are explored by: i) reconstructing rates of morphological and ecological (dietary) character change on the phylogeny and fitting alternative (constant and variable rate) likelihood models to these data; ii) generating ordination plots of diet disparity and generalised phenotype to test whether sea snake radiation is characterised by early partitioning of trait diversity among clades or recurrent evolution of ecomorphs within clades (resulting in an overall increase in homoplasy); iii) examining the role and mode of geographic isolation in sea snake speciation by regressing the degree of range overlap between species and clades against the age of their most recent common ancestor. Overall, our results highlight the dynamic and complex history of phenotypic evolution in sea snakes and reveal an important role for adaptive shifts in driving their rapid diversification.