Meeting Abstract

P2.113  Tuesday, Jan. 5  Historical Demography of Hypsiglena chlorophaea in the Great Basin MYERS, Edward A*; WEAVER, Robert E; ALAMILLO, Hugo; Washington State University; Washington State University; Washington State University edward_myers@wsu.edu

Hypotheses about the effects of glacial mass movement during the Pleistocene (0.01–1.8 mya) have proposed differential responses across taxa. One hypothesis suggests that much of the herpetofauna of the Great Basin would have kept a similar range distribution as what is seen today, while the vegetation changed from a desert scrub community to one dominated by pinyon-juniper woodlands. This hypothesis is in opposition to another prominent hypothesis that relies on more restricted distributional ranges within ‘Mexican refugia’ during this epoch. Given the heterogeneous effects during the Pleistocene, we set out to investigate the response of a clade of Hypsiglena to the recession of the Cordilleran ice sheet and look for evidence supporting either of the two prominent hypotheses. Using mtDNA markers and Bayesian Skyline Plots we show that Hypsiglena chlorophaea experienced a growth in effective population size that began 65 kya and ended 12 kya. This suggests southern regions were not refugia for this clade and that population growth happened earlier than expected.