Intralocus sexual conflict resolved through gene duplication.

Gene duplication is mainly recognized by its primary role in the origin of new genes and functions. However, the idea that gene duplication can be a central player in resolving sexual genetic conflicts through its potential to generate sex-biased and sex-specifically expressed genes, has been almost entirely overlooked. We review recent data and theory that support gene duplication as a theoretically predicted and experimentally supported means of resolving intralocus sexual antagonism. We believe that this role is probably the consequence of sexual conflict for housekeeping genes that are required in males and females, and which are expressed in sexually dimorphic tissues (i.e. where sexually antagonistic selection is exerted). We think that these genes cannot evolve tissue-specific expression unless they duplicate.