ARCUS | Arctic Research Consortium of the United States

7th Annual ARCUS Award for Arctic Research Excellence


Submitted by   Kurt Galbreath
Authors   Kurt E. Galbreath and J. A. Cook
Category   Life Science
Title   Genetic Consequences of Pleistocene Glaciations for the Tundra Vole (Microtus oeconomus) in Beringia
Affiliation   Ecology and Evolutionary Biology, Cornell University , Ithaca, NY, USA

Abstract

Repeated glacial events during the Pleistocene fragmented and displaced populations throughout the northern continents. Different models of the effects of these climate-driven events predict distinct phylogeographic and population genetic outcomes for high latitude faunas. The role of glaciations in 1) driving genetic differentiation and 2) structuring genetic diversity was tested within a molecular phylogeographic framework using the rodent Microtus oeconomus. Variation in mitochondrial (cytochrome b and control region) and nuclear (ALDH1 intron) DNA for 214 individuals across the Beringian region was investigated. A genetic discontinuity observed in western Beringia between members of a Central Asian clade and individuals representing a Beringian clade is geographically congruent with regions that were historically glaciated, but maintenance of differentiation during interglacials implies additional persistent historical barriers to gene flow. Similarly, island populations in southcoastal Alaska were probably initially isolated by glacial vicariance, but subsequent differentiation has resulted from insularity. Post-glacial colonization may have played a role in structuring genetic diversity in Central Asian clade populations, but not in Beringian populations. Population genetic structure in Beringia was largely defined by a strong reduction in genetic diversity that probably predates the most recent glacial maximum and may not be associated with a glacial period.