Int. J. Dev. Biol. 44: 807 - 810 (2000)

Vol 44, Issue 7

Sex reversal of the newt Triturus cristatus reared at extreme temperatures

Published: 1 October 2000

H Wallace and B M Wallace

School of Biosciences, University of Birmingham, Edgbaston, United Kingdom. H.Wallace@bham.ac.uk

Abstract

Crested newt larvae were reared at defined temperatures, either from uncleaved eggs or from early feeding larvae, until metamorphosis when sexual differentiation had occurred. Trials at 18-24 degrees C showed a 1:1 sex ratio. A higher temperature trial produced more males than females, including some XX neomales. Lower temperatures resulted in a significant excess of females, including XY neofemales. Sex reversal only occurred in about half the possible cases on average. Extreme temperatures must perturb the normal XX/XY system of sex determination, to reveal either an ancestral ZZ/ZW system or a still more primitive environmental control. It is suggested that neofemales (but not neomales) could occur in nature.