Sympatric Hybridization and Allozyme Variation in the Toads Bufo americanus and B. fowleri in Southern Ontario

Abstract

Hybridization in the toads Bufo americanus and B. fowleri in Ontario was investigated by electrophoretic examination of allozyme variation of 26 gene loci. Both species of toads were highly polymorphic, in amounts consistent with previous reports. Heterozygosity averaged 0.114 in B. americanus and 0.072 in B. fowleri. Clines or other patterns of geographic divergence were not present or notable. Hybrid individuals were encountered at Long Point, Ontario, on Lake Erie in association with both species. Hybrids were intermediate in morphology and genotype and appeared to be first generation progeny with high individual heterozygosity (x = 0.196). There was no evidence of any substantial introgression between species. Hybridization between B. americanus and B. fowleri appears to be a widespread, but scattered, natural phenomenon that does not interfere with their maintenance of separate gene pools. eia, 1984(1), pp. 18-26