The evolution of prudent choice

Abstract

Question: What mate choice strategies are evolutionarily stable when individuals vary in quality and there is competition over mates? Mathematical method: We analyse a life-history-based game theoretical model of a mating system. The evolutionarily stable strategy (ESS) may be random mating, or any kind of assortative mating dependent on the numerical values of a set of probabilities. We solve for the evolutionarily stable probability values. Key assumptions: Males of high or poor competitive ability pair with highly or poorly fecund females, and can also attempt to take over a female if she has already paired. Only one sex plays an active role in mate choice. Conclusions: We show that increased opportunities for a successful takeover favours the evolution of 'prudent' mate choice, where low-quality males reject high-quality females, and high-quality males reject low-quality females. This solution may also evolve because of high fighting costs. Alternative parameter settings lead to solutions where only one class of males discriminates between females, or when all males mate indiscriminately. We calculate the correlation between male and female quality in pairs, and show that this correlation may be positive, zero or even negative, depending on the ESS mate choice strategy.