Reconsidering Subspecific Taxonomy of Odocoileus virginianus in Oregon and Washington

Two subspecies of white-tailed deer Odocoileus virginianus are recognized in the northwestern United States: O. v. leucurus (Douglas, 1829), and O. v. ochrourus Bailey, 1932. Historically, O. v. leucurus was common along the Lower Columbia River and the name was applied to all populations in western Oregon as far south as Grants Pass. Today, O. v. leucurus is limited to populations along the Lower Columbia River with another in Douglas County, Oregon. Examination of 35 electrophoretic loci in 1988 did not support current subspecific taxonomy of O. virginianus in Oregon. Analysis of 18 cranial dimensions among three disjunct populations of O. virginianus in 2003 revealed variation that sorted into three corresponding distinct morphological groups in Oregon. Analyses of mtDNA and microsatellites at 15 autosomal loci from three subspecies of O. virginianus and 2 subspecies of O. hemionus (Rafinesque, 1817) revealed that each O. v. leucurus population possessed unique haplotypes, whereas O. v. ochrourus shared haplotypes with populations to the east. The most genetically differentiated whitetails were the 2 populations of O. v. leucurus (FST = 0.31), which were similarly differentiated from O. v. ochrourus (FST = 0.17–0.19); FST between O. h. hemionus and O. h. columbianus (Richarson, 1829) was 0.10. Thus, O. v. leucurus populations appear morphologically and genetically more different from each other than either is from O. v. ochrourus. Moreover, genetic differentiation among the three O. virginianus populations exceeds differentiation for existing subspecies of O. hemionus. We conclude the evidence warrants describing a new subspecies of O. virginianus in southwestern Oregon.