Genetics informs meaningful intraspecific taxonomy: the black-tailed and mule deer complex

Context. Meaningful intraspecific taxonomy allows for robust classification of within-species diversity and effective conservation and management. Subspecies definitions broadly agree that subspecies are groups of populations that exhibit some degree of geographic separation, phenotypic distinctiveness, and unique evolutionary potential. The most powerful assessments of within-species taxonomy are those that employ multiple lines of evidence, including phenotypic, ecological, geographic and genetic, to delineate evolutionarily definable units. Aims. Here we describe how genetic data can be integrated into intraspecific taxonomy. Methods. We use our experiences incorporating genetic data to assess taxonomy within black-tailed and mule deer (Odocoileus hemionus), a widespread and highly mobile species with significant phenotypic variation and a complex evolutionary history. Key results. High-resolution sampling of individuals across the landscape and loci across the genome yielded accurate estimates of genetic variation in black-tailed and mule deer and better insight into the evolutionary processes that generate and maintain diversity. Conclusions. Integrating genetic data has informed meaningful intraspecific taxonomy within O. hemionus, showing support for the following five subspecies: two black-tailed deer subspecies (Columbian O. h. columbianus and Sitka O. h. sitkensis) and three mule deer subspecies (mainland O. h. hemionus and the two island subspecies, O. h. cerrosensis on Cedros Island and O. h. sheldoni on Tibur ' on Island). Implications. Our integrative approach provides a framework for incorporating genetic data in intraspecific taxonomy in other deer species.