Delimiting species in the genus O tospermophilus ( R odentia: S ciuridae), using genetics, ecology, and morphology

We apply an integrative taxonomy approach to delimit species of ground squirrels in the genus O tospermophilus because the diverse evolutionary histories of organisms shape the existence of taxonomic characters. Previous studies of mitochondrial DNA from this group recovered three divergent lineages within O tospermophilus beecheyi separated into northern, central, and southern geographical populations, with O tospermophilus atricapillus nested within the southern lineage of O . beecheyi . To further evaluate species boundaries within this complex, we collected additional genetic data (one mitochondrial locus, 11 microsatellite markers, and 11 nuclear loci), environmental data (eight bioclimatic variables), and morphological data (23 skull measurements). We used the maximum number of possible taxa ( O . atricapillus , Northern O . beecheyi , Central O . beecheyi , and Southern O . beecheyi ) as our operational taxonomic units ( OTU s) and examined patterns of divergence between these OTU s. Phenotypic measures (both environmental and morphological) showed little differentiation among OTU s. By contrast, all genetic datasets supported the evolutionary independence of Northern O . beecheyi , although they were less consistent in their support for other OTU s as distinct species. Based on these data, we support the conclusions from a previous study that synonymized O . atricapillus with O . beecheyi , and we elevate the northern lineage of O . beecheyi to a separate species. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society , 2014, 113 , 1136–1151.