Patterns of filial cannibalism and mate choice in fishes point to sexual conflict over infanticide

Through parental care, as well as abandonment, neglect, infanticide, and cannibalism, parents can play an active role in determining which of their offspring do and do not survive. In teleost fish, parental care is most often provided by the male alone and consumption of some offspring by the father is common. If partial brood cannibalism improves survival of the remaining offspring, mothers should favor egg-eating by males. If, however, some offspring are cannibalised to obtain energy for future reproductive attempts, this will result in sexual conflict between parents over cannibalism and may drive the evolution of counterstrategies in females to minimize offspring loss. In a comparative analysis, we find that males under stronger sexual selection, inferred from the degree of sexual dimorphism in body size, consume a greater proportion of their offspring, suggesting that the opportunity for future reproduction is an important driver of this behavior. Furthermore, we find that females show strong preferences for spawning with males that are already caring for broods in species where the risk of cannibalism by fathers is high. Finally, we show that by adding eggs to existing broods, mothers can dilute the risk of their eggs being cannibalized. A preference for caring males thus represents a strategy by which females can minimize reproductive costs arising from selfish investment by males in future mating success.