Genetic variation of cytochrome <italic>b</italic> in the prairie vole (<italic>Microtus ochrogaster</italic>)

The prairie vole (<italic>Microtus ochrogaster</italic>) has become a model organism for studying monogamy. A precise account of the phylogeography of this species should increase our understanding of the proximate mechanisms and ultimate factors underlying the observed geographic variation in monogamy. The prairie vole is widespread throughout the North American grasslands, and seven subspecies have been identified based on morphological variation, which suggests the development of genetic structure. However, a prior analysis of allelic diversity at nuclear microsatellite loci showed little geographic differentiation throughout the species’ range. To further address this inconsistency, we sequenced a segment of the mitochondrial cytochrome <italic>b</italic> locus in 34 individuals from separate geographic locations throughout the species’ range. The mitochondrial analysis revealed three widespread genetic clusters without clear geographic patterns. Thus, the results were consistent with the nuclear analysis by demonstrating low geographic differentiation, indicating likely incomplete lineage sorting in the species. Additionally, the observed patterns of mitochondrial and nuclear variation were not consistent with subspecies designations. Based on our analysis and prior genetic and morphological analyses, we suggest that a reevaluation of the subspecies designations in prairie voles is warranted, with the six contiguous subspecies of prairie voles being synonymized. [ABSTRACT FROM AUTHOR]