HYBRIDIZATION BETWEEN TETRAPLOID AND DIPLOID SPECIES OF TREEFROGS (GENUS HYLA)

An indirect analysis of female meiotic mechanisms in the tetraploid (4 n = 48) grey treefrog, Hyla versicolor, was performed by examining art ificially produced hybrids, First generation hybrids between a H. vers icolor female from Canada (4n = 48) and a H. arborea male from France (2n = 24) were all triploid and appeared to contain two sets of chromo somes from H. versicolor and one set from H. arborea, Males and female s were produced in equal numbers but testes in general were more compl etely developed than ovaries. Electrophoretic analysis of selected all ozyme loci suggested that gene products from the two parents were not equally expressed. Backcross hybrids were triploid, tetraploid, and pe ntaploid but did not appear to contain recognizable chromosomes from t he H. arborea grandparent, Allozymes from these hybrids indicated that only H. versicolor alleles were expressed, as none of the distinctive H. arborea alleles present in the triploid male parent were present i n the offspring, It was concluded that preferential pairing of chromos omes and gene regulatory biases may help to explain factors that relat e to the ability of tetraploids to hybridize with even distantly relat ed taxa and may be involved in the rediploidization process that usual ly follows polyploidization.