Paraphyletic relationships revealed by mitochondrial DNA in the Peromyscus mexicanus species group (Rodentia: Cricetidae)

Abstract

Although deer mice (Peromyscus spp.) are among the most studied small mammals, their species diversity and phylogenetic relationships remain unclear. The lack of taxonomic clarity is mainly due to a conservative morphology and because some taxa are rare, have restricted distributions, or are poorly sampled. One taxon, P. mexicanus, includes southern Mexican subspecies that have not had their systematic placement tested with genetic data. We analyzed the phylogenetic relationships and genetic structure of P. mexicanus populations using sequences of the mitochondrial gene cytochrome b. We inferred that P. mexicanus is paraphyletic, with P. m. teapensis, P. m. tehuantepecus, andP. m. totontepecus more closely related to P. gymnotis than to P. m. mexicanus. This highly divergent clade ranges from northeastern Oaxaca to northern Chiapas, including southern Veracruz, and southern Tabasco. In light of this group’s mitochondrial distinctiveness, cohesive geographic range, and previously reported molecular, biochemical, and morphological differences, we recommend it be treated as P. totontepecus. Our findings demonstrate the need for an improved understanding of the diversity and evolutionary history of these common and abundant members of North American small mammal communities.