Molecular and morphologic data reveal multiple species in Peromyscus pectoralis

Area of Science:

• Zoology
• Genetics
• Taxonomy

Background:

• The taxonomy and systematics of Peromyscus pectoralis have been historically complex.
• Previous classifications relied on limited data, necessitating a re-evaluation using modern techniques.

Purpose of the Study:

• To re-evaluate the taxonomy and systematics of Peromyscus pectoralis using DNA sequence and morphometric data.
• To clarify the evolutionary relationships and taxonomic status of different Peromyscus populations.

Main Methods:

• Phylogenetic analyses using maximum likelihood and Bayesian inference on mitochondrial cytochrome-b gene sequences from 44 Peromyscus pectoralis samples.
• Multivariate analyses of external and cranial measurements from 63 Peromyscus pectoralis populations.
• Comparison of genetic variation levels and morpho-groups with existing taxonomic assignments.

Main Results:

• DNA analyses revealed two well-supported monophyletic clades with significant genetic variation (~7%) between them, exceeding typical Peromyscus species divergence.
• Morphometric analyses identified four distinct morpho-groups that largely corresponded to the genetic clades.
• Populations north of the Río Grande were assigned to Peromyscus laceianus, while Mexican populations were referred to Peromyscus pectoralis, including a newly described subspecies.

Conclusions:

• The study establishes a revised taxonomy for Peromyscus populations in the United States and Mexico based on integrated genetic and morphometric evidence.
• A new subspecies of Peromyscus pectoralis is described from northern and central Mexico.
• Further research is recommended to determine if Peromyscus p. collinus warrants species-level recognition.