Hybridization and Embryonic Temperature Adaptation Studies of Rana Temporaria and Rana Sylvatica

Abstract

A study of 5 pr. of R.temporaria embryos obtained from frogs from Vosges, France, and Louvain, Belgium, showed identical rates of embryo development and similar ranges of temperatures for R. temporaria and the North American representative, R. sylvatica, but failure to produce any development, or development beyond either late blastula or early gastrula, between crosses of the French frogs and the related American species. R. temporaria and R. sylvatica may represent the end members of a chain of related species and subspecies extending from western Europe, across Northern Asia, through Alaska and Canada and down to the North American east coast, divergence having proceeded beyond the possibility of any gene interchange.