Temperature Adaptations in Amphibians

Past studies of ecogeographic character variations have failed to provide a quantitative relationship between the character being measured and the environmental parameter which impinges upon that character. We offer an example in amphibians directly relating a character variation, the range of temperature tolerance, and the critical environmental parameter for that character, the environmental temperature variation. In this example, the range of temperature tolerance is closely related to the environmental temperature variations. Where the environmental temperature variation increases so does the range of temperature tolerance. In addition, where environmental temperatures decrease, the capacity to tolerate such temperatures is lost. These data are consistent with the thesis that congeneric and conspecific populations in different habitats have partially independent evolutionary pathways and that where populations have been displaced from a less to a more uniform environment, characters which are no longer maintained by selection pressure are lost.