Mate choice in the face of costly competition

Studies of mate choice commonly ignore variation in preferences and assume that all individuals should favor the highest-quality mate available. However, individuals may differ in their mate preferences according to their own age, experience, size, or genotype. In the present study, we highlight another simple reason why preferences may differ: if there is costly competition for mates, the poorest competitors might be better off avoiding the highest-quality partners and instead targeting low-quality partners, so that they minimize the costs they incur. We present a game-theoretical model of mate choice in which males of differing quality compete for access to females and try to retain them till the time of mating. Our model predicts that high-quality males, who are better competitors, have a preference for the best females that is typically several times stronger than that of low-quality males. Early in the competitive period, the latter may even prefer low-quality females over high-quality females. Thus, variation in competitive ability generates variation in both the strength and direction of preferences. Differences in competitive ability result in assortative mating with respect to quality, which is reinforced by variation in preferences. As the time of mating draws near and there is an increased risk of ending up unpaired, all males become indifferent to the quality of potential mates. Our findings are equally applicable to female choice for males, and offer a new explanation for adaptive variation in mating preferences based on differing abilities to cope with the costs of mate choice. Copyright 2003.