EVOLUTIONARY GENETICS AND SYSTEMATICS OF NEW WORLD FROGS OF THE GENUS RANA: AN ANALYSIS OF RIBOSOMAL-DNA, ALLOZYMES, AND MORPHOLOGY
Abstract (summary)
There are over 50 species of frogs of the genus Rana in the New World. The phylogenetic relationships of these frogs were studied by analyzing ribosomal DNA, allozymes, and morphology. Ribosomal DNA analyses involved restriction-site mapping of the rDNA repeat with 17 restriction endonucleases. Allozyme analyses were performed using vertical and horizontal starch gel electrophoresis of over 50 enzymes. Morphological analyses included multivariate morphometric studies, examinations of osteological preparations, and examinations of tadpole oral morphology.
Phylogenetic information from all available sources was combined to produce the most parsimonious phylogenetic tree for New World Rana. A primary dichotomy of New World Rana is delineated by the recognition of the subgenera Rana and Lithobates. The subgenus Rana contains the R. boylii group (aurora, boylii, cascadae, muscosa, and pretiosa) and the R. temporaria group (sylvatica and a number of Old World species). Information on membership of other Old World species in the subgenus Rana will require additional data concerning their relationships.
The subgenus Lithobates consists of the R. catesbeiana group (catesbeiana, clamitans, grylio, heckscheri, okaloosae, septentrionalis, and virgatipes), the R. palmipes group (maculata, palmipes, sierramadrensis,, vaillanti, vibicaria, warschewitschii, and at least one undescribed species), the R. tarahumarae group (johni, pueblae, pustulosa, tarahumarae, and zweifeli), the R. areolata group (areolata and palustris), the R. berlandieri group (berlandieri, forreri, magnaocularis, miadis, neovolcanica, omiltemana, spectabilis, taylori, tlaloci, yavapaiensis, and a number of undescribed species), the R. montezumae group (chiricahuensis, dunni, megapoda, and montezumae), the R. pipiens group (blairi, pipiens, and sphenocephala), and the problematical species R. fisheri and R. onca.
The various phylogenetic analyses also provide information concerning the relationships of the species groups and the relationships of taxa within the species groups. These phylogenetic data are used to examine the biogeographic history of New World Rana. This information provides an evolutionary framework that can be used to better understand all aspects of the biology of these species.