Nuclear sex-determining genes cause large sex-ratio variation in the apple snail Pomacea canaliculata.

Evolutionary maintenance of genetic sex-ratio variation is enigmatic since genes for biased sex ratios are disadvantageous in finite populations (the "Verner effect"). However, such variation could be maintained if a small number of nuclear sex-determining genes were responsible, although this has not been fully demonstrated experimentally. Brood sex ratios… (More)