Molecular phylogeny of the Australian venomous snake genus Hoplocephalus (Serpentes, Elapidae) and conservation genetics of the threatened H. stephensii
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The Australian elapid snakeHoplocephalus stephensii (Stephens' BandedSnake) is patchily distributed in disjunctforest remnants in eastern Australia and islisted as threatened in both states in which itoccurs (Qld and NSW). Here we focus on thephylogeography of H. stephensii toaddress (1) the genetic distinctiveness of thistaxon within its genus and (2) the level ofgenetic diversity present within and betweendisjunct populations from throughout thespecies' range. We sequenced an approximately900 base pair DNA fragment of the mitochondrialgenome that includes half of the ND4 gene andthree tRNA genes. We obtained sequence datafrom 15 H. stephensii individuals drawnfrom four populations, plus representatives ofthe other Hoplocephalus species.Phylogenetic analyses of the data produced asingle fully resolved tree. The two coastaltaxa (H. bungaroides and H. stephensii)are very closely related (2.6–3.1% sequencedivergence) whereas the inland taxon H.bitorquatus is more distantly related to theother two (7.6% vs H. bungaroides;7.8–8.3% vs H. stephensii). Geneticdiversity is low within H. stephensii(nine mitochondrial haplotypes with 1–3haplotypes with only single base pairdifferences within populations). The largestsplit (1.7% sequence divergence) occursbetween the northern population and the threesouthern populations and corresponds to thespecies distribution north and south of theMcPherson Range on the Queensland-New SouthWales border. The three southern populationsdisplay much less molecular divergence (maximumof 0.6% sequence divergence), consistent withthe presence of generally continuous forestthroughout the species' range until Europeaninvasion of Australia 200 years ago, and withradiotelemetric studies that have found highvagility in these arboreal snakes. Thus, onthe basis of genetic distinctiveness we arguethat (1) Hoplocephalus bitorquatus shouldreceive high conservation priority; and (2)managers should treat the Queensland and NSWpopulations of H. stephensi as separateconservation units.
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