Mate availability and somatic condition affect filial cannibalism in a paternal brooding goby

Abstract

AbstractWe conducted a laboratory experiment to test two major predictions from a game-theoretical model for the evolution of filial cannibalism in species with paternal care — that parental males are more cannibalistic when their energy reserve is low and that filial cannibalism increases when mate availability is high. We used a freshwater goby, Rhinogobius sp. OR, in which males care for eggs from multiple females in a nest. For each breeding male, we manipulated food ration, sex ratio and nest space: the former to control its energy reserve and the latter two to control its mate availability. The ANOVA showed that all three factors had a significant effect on filial cannibalism, which was facilitated when male somatic condition was poor, the sex ratio was female-biased and the nest space was small. Furthermore, filial cannibalism became more intense with increasing brood size and with decreasing female body size. In conclusion, the parental energy reserve and the quality and availability of mates are important factors affecting filial cannibalism in Rhinogobius sp. OR.