Further Studies on Rana pipiens Racial Hybrids

Abstract

The data presented in this paper are a continuation of a study of geogr. variation of adaptations in R. pipiens and of hybrids arising from interpopulation crosses. The eggs and jelly mass of Costa Rica pipiens are descr. They are of the northern, cold-adapted type. Hybrids resulting from the cross Vermont female x Colorado male are normal. Hybrids resulting from the cross Vermont female x Costa Rica male have minor defects. This result is discussed in light of the previous cases of defective hybrids arising from crosses of n. and s. pipiens.