Biochemical Systematics of the Peromyscus aztecus Assemblage

Protein electrophoresis was used to examine genetic variation at 39 loci in 16 populations representing all Mexican species and subspecies of the Peromyscus aztecus assemblage. Variation was detected at 19 loci and values of genetic identity ranged from 0.774 to 0.995. Phenetic analysis produced a phenogram indicating a stepwise association of the subspecies of P. aztecus and indicating affinities between these taxa and P. spidlegus. P. winkelmanni was the most differentiated. The presence of a fixed difference involving a derived allele between two populations of P. spicilegus suggested that these populations may not be conspecific. Cladistic analysis produced 36 equally parsimonious cladograms. The extent of genetic differentiation of P. a. hylocetes from the other subspecies of P. aztecus, in addition to morphological and chromosomal differentiation, indicated that P. hylocetes should be reinstated as a species.