Molecular phylogenetics of the Peromyscus boylii species group (Rodentia :Muridae) based on mitochondrial cytochrome b sequences

Variation in the mitochondrial cytochrome b gene (1143 bp) was examined to estimate the phylogenetic relationships of taxa within the Peromyscus boyli i species group. In addition, phylogenetic relationships among the aztecus, boylii, and truei species groups were addressed. Maximum-likelihood, neigh bor-joining, and maximum-parsimony (weighted and equally weighted) analyses produced similar topologies with P. boylii P. beatae, P. simulus, P. steph ani, P. madrensis, P. levipes, and three undescribed taxa from western Mexi co forming a monophyletic unit. At least two of the undescribed taxa from w estern Mexico potentially represent species. Members of the P. aztecus spec ies group formed a clade separate from the P. boylii group and should be re cognized as a distinct species group. P. sagax, P. polius, and P. pectorali s, formerly placed in the P. boylii species group, generally formed an unre solved polytomy with the P. truei, P. aztecus, and P. boylii species groups . P. attwateri formed a sister taxon relationship with members of the P. tr uei species group (P. difficilis and P. nasutus) and should be considered a member of this group. Members of the P. truei species group did not form a monophyletic unit, indicating that this species group is not monophyletic and may be composed of two assemblages, (C) 2000 Academic Press.