Evolutionary game theory has been used to predict the effect on sperm expenditure of a trade-off between the value of a mating and the cost of its acquisition. This prediction relies on the assumption that, in the absence of sperm competition, ejaculates would always contain enough sperm to ensure complete fertilization after mating. The slightest risk of incomplete fertilization, however, is enough to ensure that favored males expend more than disfavored males in the presence of sperm competition, unless the competition is perfectly fair. Divergence of expenditures increases with unfairness until unfairness reaches a critical value, beyond which a disfavored male should no longer compete. The higher the fertilization risk, the lower the critical unfairness.
All predictions are independent of the probability of mating first or second.
Implications are discussed for the mechanisms that underlie sperm competition. M. Mesterton-Gibbons and L.A. Dugatkin . On the evolution of delayed recruitment to food bonanzas. Two hypotheses have been advanced to explain the evolution of delayed recruitment. Under the status-enhancement hypothesis, delayed recruiting is favored because the recruiter's social status increases with the number of followers it leads to a food source.