Chapter 10 - Hormones and Reproductive Patterns in Urodele and Gymnophionid Amphibians

Abstract

Publisher Summary Urodela and the Gymnophiona are members of the vertebrate subclass Lissamphibia (class Amphibia). Both Urodela and the Gymnophiona are derived from the Greek words, which mean tail. Reproduction in these groups is timed by environmental factors operating through the central nervous system and the hypothalamus-pituitary-gonadal (HPG) axis. Activation of the HPG axis results in gametogenesis, mating, and production of offspring. Urodele and Gymnophiona amphibians exhibit four basic life-history patterns: biphasic (terrestrial and aquatic phases), paedomorphic (aquatic phase only), direct development (terrestrial phase only), and viviparity (aquatic and/or terrestrial phases). Reproductive cycles of representative patterns are described together with the hormonal factors involved. In terms of fertilization, transfer of sperm from male to female usually is accomplished through the deposition on the substrate of a stalked spermatophore. In a few closely related species, transfer of sperm may occur through cloacal apposition.