Midwest Fish & Wildlife Conference 2016

AUTHORS: Emily K. Latch*, Dawn M. Reding, James R. Heffelfinger, Olin E. Rhodes, Jr.

ABSTRACT: The spatial distribution of genetic diversity provides interesting and sometimes unexpected insights into mechanisms of evolutionary diversification in nature, as well as valuable resources for the development of efficient conservation strategies. For species that exist in isolated populations without direct genetic or ecological connections, delineating populations across a landscape can be straightforward. As connectivity among populations increases, defining discrete populations and identifying dispersal barriers becomes more challenging. Characterization of spatial genetic structure is perhaps most challenging in continuously distributed species with no apparent population boundaries. Widespread, highly mobile species with the ability to thrive in a wide range of habitats are expected to show little genetic differentiation across their range. In this study, we provide a continent-scale assessment of genetic variability for mule deer across their full range in western North America. Our primary goal was to quantify broad-scale patterns of spatial genetic structure in this common species, to test whether historical and contemporary processes have resulted in cryptic spatial genetic structure, as has been found for carnivores. We also examined potential mechanisms involved in establishing and maintaining population divergence in this widespread, mobile ungulate. To achieve this goal, we sampled over 1900 geo-referenced individuals collected throughout the mule deer range, and assessed genetic variation at 10 microsatellite loci using both individual and population-based analyses. Despite the potential for high levels of gene flow in mule deer, our data revealed the presence of broad-scale spatial genetic structure. Both individual-based and population-based analyses supported the existence of three main genetic lineages, and resolved additional substructure within each lineage. The locations of these lineages correspond well to predictions based on the biogeographic history of mule deer, and suggest that the broad-scale patterns of spatial genetic structure we observed are primarily due to historical restrictions of gene flow.