Editor's Summary
31 January 2008
Sex determined by degrees
In mammals and birds, sex is determined by genotype, at fertilization. But many reptiles, hedge their bets, determining the sex of an individual by interaction with the environment, typically temperature. Thirty years ago, Eric Charnov and James Bull (Nature 266, 828–830; 1977) speculated that environmental sex determination will be favoured by selection if it could be shown that different temperature regimes maximized reproductive fitness for each sex. Until now it has not been confirmed, partly because of the difficulty of setting up a 'control' experiment in which the 'wrong' sex is produced at a given temperature. Hormone treatments have been used to overcome this difficulty, and Daniel Warner and Rick Shine now confirm, in a species of Australian lizard, that the Charnov/Bull model is correct.
News and Views: Sex determination: Some like it hot (and some don't)
There is a widely accepted theoretical explanation for why sex in some species is determined at the embryo stage by environmental factors such as temperature. That theory is now supported by experiment.
David Crews & James J. Bull
doi:10.1038/451527a
Letter: The adaptive significance of temperature-dependent sex determination in a reptile
D. A. Warner & R. Shine
doi:10.1038/nature06519