Meeting Abstract
Species distributed across heterogeneous environments may adapt to local conditions as a result of differing selection pressures. This process can lead to adaptive divergence, where populations are subdivided based on the different environments they inhabit. High levels of gene flow have the potential to homogenize genetic variation across the landscape, particularly if migration rates are high and the strength of selection for locally adapted loci is low. In this case gene flow is only limited by dispersal, and population structure will arise as a result of geographic distance. However, local adaptation can still occur in the face of gene flow if selection for a local optimum is sufficiently strong. High altitude environments impose strong selective pressures on homeothermic endotherms, as the dual stressors of cold temperatures and hypobaric hypoxia constrain their ability to maintain a stable body temperature via aerobic thermogenesis. The deer mouse (Peromyscus maniculatus) is continuously distributed from sea level to over 4,300 meters in elevation, so this species is an ideal system to investigate the interaction between gene flow and local adaptation to high altitude. We sampled thirty deer mouse populations along seven transects spanning a 3200-meter elevational gradient in the Colorado Front Range in the summers of 2016 and 2017. We then used restriction-site associated DNA (RAD) sequencing to generate a dataset of thousands of single nucleotide polymorphisms. The program STRUCTURE and R-package BEDASSLE were employed to examine population structure and test the relative strength of geographic versus environmental distance on population structure.
