Meeting Abstract
Evolutionary adaptation to novel environments often requires coordinated changes in independent physiological systems. For example, deer mice (Peromyscus maniculatus) that are native to high elevations in western North America differ from their low-elevation conspecifics in physiological traits that alter many steps in the oxygen transport cascade, and these changes are associated with improvements in aerobic performance under hypoxia. Here, we employed a population genomic approach to gain insight into the genetic basis of these adaptations. First, we sequenced the exomes of 100 mice sampled from low- and high-elevations to identify loci that bear the signatures of positive selection in highland mice. This analysis revealed 436 unique genes that have experienced a history of selection at high elevations, and these genes have functions that may affect each step of the oxygen transport cascade. Second, we performed geographic cline analyses using whole exomes from an additional 160 mice sampled from an elevational transect of the Rocky Mountains in Colorado. This analysis revealed that clines for outlier loci were centered at significantly higher elevations, and were wider, than those for random loci. This result suggests elevational patterns of allele frequency variation for outlier loci cannot be explained by neutral population structure. Together these analyses provide new insights into how natural selection acts to produce integrated adaptive phenotypes and the spatial scales over which this process occurs.
