Further Studies on Rana pipiens Racial Hybrids

Abstract

The data presented in this paper are a continuation of a study of geographic variation of adaptations in Rana pipiens Schreber and of hybrids arising from interpopulation crosses. The eggs and jelly mass of Costa Rica pipiens are described. 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 northern and southern pipiens.