Comparative 2D-shape analyses of collared lemmings in the zone of possible sympatry between Dicrostonyx groenlandicus and Dicrostonyx richardsoni (Rodentia, Arvicolinae)

Abstract

Morphological differentiation and relationships among collared lemmings (Dicrostonyx Gloger, 1841) remain unclear. This issue is particularly important in the Kivalliq Region, Nunavut, Canada, where Dicrostonyx groenlandicus (Traill, 1823) and Dicrostonyx richardsoni Merriam, 1900 ranges overlap. Possible sympatry of both species obscures the taxonomic status of collared lemmings from this area. We compared 2D outline shapes of the skull and three upper molars of collared lemmings collected from seven areas of the Canadian Arctic, including specimens from the Baker Lake – Aberdeen Lake area, in the Kivalliq Region, and Dicrostonyx hudsonius (Pallas, 1778) as an outgroup. Multivariate analyses revealed two distinct groups when considering the molars: D. hudsonius, and the remainder of lemmings. Dicrostonyx richardsoni, D. groenlandicus, and the lemmings from the Baker Lake – Aberdeen Lake area showed significant differences, especially when considering skull shapes, thus suggesting three distinct groups. However, skull shapes proved inefficient in discriminating between species. These differences suggest that collared lemmings from the Baker Lake – Aberdeen Lake area may not be correctly assigned to either of the two species without further genetic evaluation. They also suggest that these lemmings should have a peculiar taxonomic status. Our study calls for further taxonomical investigations for collared lemmings from the overlapping distribution ranges of D. groenlandicus and D. richardsoni.