Sexual conflict about parental care: the role of reserves.

Parental care often increases the survival of offspring, but it is costly to parents. Because of this trade-off, a sexual conflict over care arises. The solution to this conflict depends on the interactions between the male and female parents, the behavior of other animals in the population, and the individual differences within a sex. We take an integrated approach and develop a state-dependent dynamic game model of parental care. The model investigates a single breeding season in which the animals can breed several times. Each parent's decision about whether to care for the brood or desert depends on its own energy reserves, its mate's reserves, and the time in the season. We develop a fully consistent solution in which the behavior of an animal is the best given the behavior of its mate and of all other animals in the population. The model predicts that females may strategically reduce their own reserves so as to "force" their mate to provide care. We investigate how the energy costs of caring and searching for a mate, values of care (how the probability of offspring survival depends on the pattern of care), and population sex ratio influence the pattern of care over the breeding season.