Summary

We conducted a laboratory experiment to test two major predictions from a game-theoretical model for the evolution of lial cannibalism in species with paternal care — that parental males are more cannibalistic when their energy reserve is low and that lial 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 signi cant effect on lial cannibalism, which was facilitatedwhen male somatic condition was poor, the sex ratio was female-biased and the nest space was small. Furthermore, lial 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 lial cannibalism in Rhinogobius sp. OR