The pressures caused by females choosing males will lead to two types of evolutionary selection: inter-sexual selection (adaptations to win members of the other sex), and intrasexual selection (adaptations to win access to mates over members of the same sex). Both vary in importance according to species and environments.
Inter-sexual selection leads to the development of adaptations, morphological, physiological, or behavioral, to seduce mates. Typically, females are choosers, so most of the intersexual selection targets males. Adaptations resulting from inter-sexual selection are meant to reveal genetic quality, so males will harbor features, or perform behaviors that indicate quality. Examples of inter-sexual selection are numerous in mammals, and the best known morphological examples are probably the growth of horns in ungulates such as giraffe (Giraffa camelopardalis), or bighorn sheep (Ovis canadensis).
In contrast to inter-sexual selection, which arises from pressures imposed by the other sex, intra-sexual selection leads to adaptations as a result of pressures imposed by the same sex. Displays of strength or resources may serve to indicate dominance and establish hierarchy among males, allowing better individuals to access more mates.