Abstract

We studied geographic variation in allozymes (22 loci), mitochondrial cytochrome b gene sequences (575 bp), advertisement calls (pulse rate, call duration, and dominant frequency), and snout–vent length among populations of Hyla wrightorum and Hyla eximia in the United States and Mexico. Calls were only available for H. wrightorum, and although populations varied in some advertisement call variables, there was no indication of species level differentiation. Allozyme variation was exhibited among the H. wrightorum populations, but no fixed differences were discovered, and the amount of genetic divergence among populations was small (D_m ≤ 0.0643). Seven mtDNA haplotypes were discovered among the H. wrightorum individuals included in this study. A single haplotype (G) was present in the Huachuca Mountains and was found only in this population restricted to southeast Arizona. Neither the Mogollon Rim nor the Sonora populations were exclusive, with some haplotypes in each being more closely related to haplotypes in the other population. Molecular data (allozymes and mtDNA), as well as the advertisement calls, support continued recognition of two species: H. eximia in central-southern Mexico and H. wrightorum, which consists of disjunct populations in the Sierra Madre Occidental of northern Mexico, the Huachuca Mountains of southeastern Arizona, and the mountains of central Arizona and western New Mexico.