Unisexual Salamanders in the Genus Ambystoma

Unisexual salamanders present a novel evolutionary phenomenon that has led to many speculations with respect to their origin and persistence. These salamanders do not comply with basic evolutionary theory with respect to any of the factors that guide speciation. Indeed, none of the various unisexual salamanders can be considered a distinct species. I outline the history of the unisexual Ambystoma from their discovery by Clanton in 1934 and attempt to show how our current understanding of the unisexuals has been influenced by discovering new populations and advances in technology.