Molecular phylogeographic structure within the Perognathus fasciatus species-group
There are four recognized species-group assemblages of silky pocket mice in the genus Perognathus. This study used molecular data to address phylogenetic and biogeographic hypotheses within the Perognathus fasciatus species group, which includes three species: P. fasciatus, P. flavescens, and P. apache. DNA sequence analysis of mitochondrial DNA (mtDNA) revealed that these three species comprise a monophyletic clade relative to other species of Perognathus. MtDNA sequence divergence and nucleotide diversity are much higher within populations of P. apache than within P. flavescens. While this difference could be attributed to a higher rate of mtDNA lineage divergence in P. apache, a more likely explanation is that the high nucleotide diversity within P. apache is the result of a lower rate of mtDNA lineage extinction relative to P. flavescens. Differences in the rate of mtDNA lineage extinction could be due to historical differences in the population structure of P. apache and P. flavescens.