Population Stability of the Northern Desert Nightsnake (Hypsiglena chlorophaea deserticola) during the Pleistocene
Phylogeographic studies that seek to understand how a species responded to past climate change are largely lacking for the Great Basin of North America. Here we investigate the response of the Northern Desert Nightsnake (Hypsiglena chlorophaea deserticola) to the recession of the Cordilleran glacier at the end of the Pleistocene. Using mtDNA markers, we inferred the lineage age and historical demography of this widespread desert taxon. We find that H. c. deserticola maintained a stable population size throughout the late Pleistocene despite ice-sheet advance and retreat. These conclusions agree with other phylogeographic studies that show stable or growing population sizes throughout the Pleistocene as well as fossil evidence that sheds light on the historical distributions of snakes, suggesting that snakes have been adaptable to historical climatic fluctuations.Abstract
Extent of the Cordilleran Ice Sheet and pluvial lakes at their maximum extent during the Pleistocene.
Geographic distribution of Hypsiglena chlorophaea deserticola (Mulcahy, 2008) showing sampling localities. Additional information is listed in Appendix 1.
Bayesian consensus tree based on ND4 sequence and fossil data. Bayesian posterior probability support values are shown above or below each node. Gray bars indicate the 95% credible interval of estimated divergence ages.
Mismatch distribution portraying the demographic history of Hypsiglena chlorophaea deserticola. Diamonds represent observed distributions of pairwise differences and the solid line represents the expected distribution under a model of population expansion.
Demographic history of H. c. deserticola as determined by the Bayesian skyline plot; black center line represents the mean value of the log of the population size (Ne*τ), shaded region represents the 95% highest posterior probability.
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