Systematic implications of mtDNA sequence variation in a deer mouse species endemic to islands in the Gulf of California

Abstract

The wide distribution and variety of species of deer mice, Peromyscus, provide a unique opportunity to examine the phylogenetic relationships of the mammals of western North America. Recent studies have raised questions concerning the specific validity, systematic relationships and geographic origin of P. sejugis, a species of deer mouse endemic to two islands in the Gulf of California. To determine genetic affinities, sequence variation was analyzed for a 1,439 base pair region (ND3/ND4L/ND4) of the mitochondrial DNA for P. sejugis, P. maniculatus (from Baja California and the central and northwestern United States) and P. keeni (from the Pacific Northwest). Phylogenetic and pairwise distance analyses of the sequence data closely associate P. sejugis with the P. maniculatus from Baja California and place them in a cluster that is genetically closer to P. keeni than it is to P. maniculatus from the central and northwestern United States. These data support the hypothesis that P. sejugis is conspecific with the deer mice currently recognized as P. maniculatus from Baja California. Additionally, the data support the geographically improbable sister-group relationship between the deer mice from Baja California and P. keeni and suggest that the deer mice from Baja California are specifically distinct from the P. maniculatus from the central and northwestern United States.