Cytological Differentiation of the Diploid-Tetraploid Species Pair of North American Treefrogs (Amphibia, Anura, Hylidae)

Abstract

Current differentation of tetraploid Hyla versicolor LeConte and diploid H. chrysoscelis Cope relies upon acoustical or chromosomal analyses requiring live specimens. The tetraploid cells have larger nuclei and more nucleoli so it is possible to identify both preserved and living specimens simply and reliably. The possibility of identifying preserved museum specimens should ensure a more accurate and complete range for this interesting species pair. * * * Hyla chrysoscelis and H. versicolor represent a diploid-tetraploid species pair (Bogart and Wasserman, 1972). So far, no morphometric or ecological factors have been found to distinguish between these biological species over their combined recognized range (see Conant, 1975). Our current knowledge of the geographical ranges of these two species has been roughly outlined by pulse rate analyses of calls from males of each species (Brown and Brown, 1972; Jaslow and Vogt, 1977; Johnson, 1966; Ralin, 1968; 1977; Zweifel, 1970). The identification of females is conjectural. This study was undertaken to determine new methods of identification applicable to preserved specimens which would allow ranges to be accurately mapped with greater ease and rapidity than that possible with methods using live specimens. Certain cells of tetraploid H. versicolor are larger than those of diploid H. chrysoscelis (Bogart and Wasserman, 1972), and the nuclei of H. versicolor contain almost twice the amount of DNA found in the nuclei of H.