Phylogenetic relationships among North American Toads, genus Bufo

Relationships among 14 species of North American Bufo were studied using the quantitative immunological technique of micro-complement fixation. Separate antisera to serum albumins of five North American Bufo and one Central American Bufo were used as probes of phylogenetic relationships. A cladogram for these species constructed with the albumin data was compatible with phylogenetic interpretations based on morphological analyses and hybridization studies. Using albumin as a molecular dating device radiations within the B. americanus, B. cognatus and B. boreas species groups were each estimated to be Pleistocene events. Separation of North and Central American lineages is estimated to have occurred as early as the upper Oligocene.