Evolutionary genetic theory shows that genetic variation can be maintained when selection favors different versions of the same genes in males and females—an inevitable outcome of having separate sexes. That is, for many genes, there may not be a universally ‘best’ version, but rather one is best for males and one is best for females. This is known as sexually antagonistic genetic variation, but it might only be maintained under a narrow set of conditions, limiting its prevalence in nature. However, a new study by Dr. Karl Grieshop and Professor Göran Arnqvist, published in PLoS Biology, may change this view.

“One of the simplest ways for sexually antagonistic selection to maintain genetic variation in fitness is via sex-specific dominance reversal, where neither version of a gene is always dominant or recessive, but rather the version that benefits a given sex is also dominant in that sex. So whether a given version of a gene is dominant or recessive to the other will depend upon which sex it is in,” says Dr. Karl Grieshop.