Female mate choice and the emergence of male coercion

Abstract: When females choose mates, males may respond in several ways: by allowing an evaluation by the female and investing substantially in subsequent reproduction (here, type 1), by allowing evaluation but withholding investment following mating (type 2), or by preventing evaluation and attempting to coerce the female to mate (type 3). In this modeling analysis, we examine the conditions under which these strategies, individually or in combination, are expected to persist in the population primarily using the criterion of evolutionary stability. We also consider the roles of female resistance, social policing, and extra-pair paternity in influencing these outcomes. Using six focal systems taken from primates, fish, birds, and insects, we derived parameters for a game-theoretical model to determine the expected evolutionary stable frequencies or unstable combinations of the male strategies based on system-specific parameter magnitudes. In chimpanzees, guppies, Japanese water striders, and scorpionflies, males making the highest investment in each reproductive event were the sole persisting type; in mallard ducks, an evolutionarily stable mixture of types 1 and 3 prevailed; and in humans, a stable mixture of types 1 and 2 persisted. In accord with the infrequency of consistent coercion across taxa, our results suggest that coercion may often be evolutionarily unstable and available only opportunistically as the strategy of last resort. Significance statement: Our game theory model examined mate choice in six species of primates, fish birds, and insects to identify patterns predicted to persist from an evolutionary perspective. We found that differences in ecological, physiological, and behavioral characteristics resulted in the persistence of individual or multiple male mating strategies generally consistent with observations in nature. In particular, coercive males could persist in a population when fertilization rates and reproductive outcomes were similar to those of less forceful males.