Jameson, David L.2022-09-202022-09-201970197023157149https://hdl.handle.net/10657/11536Toads in the Bufo americanus group are capable of extensive interbreeding. In the laboratory hybridization frequently results in viable sexually mature offspring. The complex of toads found in eastern Texas and western Louisiana is remarkably heterogeneous suggesting either extremely close phylogenetic relationships among the toads, or wide-spread hybridization and introgression. Morphological and biochemical characters of individual toads sampled from this complex were examined. Blood proteins were analysed by acrylamide gel disc electrophoresis and the morphological characters by multiple-group discriminant analysis. Analysis of the electrophoretic banding patterns over a wide range of protein systems by cluster analysis failed to reveal meaningful differences between species or populations. Discriminant analysis showed significant overlap between populations indicating that successful hybridization is occurring. Isolation mechanisms appear to be inoperative. The breakdown of these isolating mechanisms appear to be contributing to the removal of reproductive separation between the populations and the formation of a heterogeneous interbreeding complex.application/pdfenThis item is protected by copyright but is made available here under a claim of fair use (17 U.S.C. Section 107) for non-profit research and educational purposes. Users of this work assume the responsibility for determining copyright status prior to reusing, publishing, or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires express permission of the copyright holder.Thesisreformatted digital