Evolution and maintenance of male care: is increased paternity a neglected benefit of care?

Abstract

Male care often correlates positively with high paternity, both across and within species. This pattern is usually explained by the hypothesis that high paternity is a prerequisite for the evolution of male care because a male should be selected to invest only in his own offspring. However, here I use a simple model to show that this need not be the case. Rather, males providing care may enjoy better success in (avoiding) sperm competition, and the resulting increase in paternity can be sufficient to explain the evolution of male care. This scenario results in the same positive relationship between male care and paternity, but with reversed causality. Empirical examples from various taxa and mating systems support the idea that selection for male care through increased paternity is likely to be widespread. Importantly, a paternity benefit for caring males does not exclude other naturally and sexually selected benefits, such as higher offspring survival or increased mating success. Rather, these factors may reinforce one another. It is well known that nuptial gifts, which males of some insects provide for their mates, can increase both offspring fitness and the probability that the male fertilizes the eggs of the female. Less obviously, other types of male care, especially postzygotic care, also can lead to future paternity benefits. This idea has not yet penetrated into the theoretical framework concerned with the evolution and maintenance of male care. I believe it is high time for this to happen. Key words: extrapair fertilization, nest building, paternal care, paternity, sneaking, sperm competition. [Behav Ecol]