Genetic differentiation of the Iberian tree frogs Hyla arborea molleri and Hyla meridionalis (Amphibia: Anura)

Genetic differentiation of Hyla arborea molleri and H. meridionalis was studied through allozyme electrophoresis and through essays of artificial hybridization. Samples were taken at several localities in Portugal, where these species occur either in sympatry or allopatry, and at one locality in France. Of the 21 presumptive loci analyzed, 6 were monoallelic, while 9 loci were discriminative between both species. A relatively high level of genetic differentiation was found between the two species (NEI's D = 0.725), contrasting with their morphological similarity. Remarkably low levels of genetic variability were found within species, with greater differentiation found among samples of H. meridionalis than of H. a. molleri. Although the capacity for interspecific hybridization was low, hybrid embryos resulted from both reciprocal crosses, but with much greater success in the cross ♂H. a. molleri x δH. meridionalis. Hybrids showed greater similarity with the male parent, and showed heterozygote allozymic phenotypes for discriminative loci. Results are compared with those of similar studies on the same and different species of Hyla, and differentiation of H. a. molleri and H. meridionalis is discussed in relation to their taxonomic status and origin.