if you mean sexual coercion, then it is the third selective force in the evolution related to sex, the other two are intra-sexual selection, and inter-sexual selection. the sexual coercion is the way that individual, especially males, use forceful way to have sex or say, enhance the reproductive opportunity. Females are by no means the passive victims of male coercive strategies, however. they adopt some counter-strategies to respond to male sexual coercion. for example, female can kill the offspring of un-preferred male.