Behaviour 2019
Individual plasticity of mating behaviour across sociosexual contexts in Japanese medaka (Oryzias latipes)
Laura K. Weir, Emily R. Allen. Saint Mary's University, Halifax, Nova Scotia, Canada

Flexibility of in mating behaviour can be advantageous when individuals experience variation in sociosexual conditions during breeding, wherein changes in inter- or intra-sexual behaviours may occur. In this study, we examined male mating behaviour in Japanese medaka (Oryzias latipes) across four different sex ratios. We quantified aggression and courtship behaviours for individual males in the four different ratios, and then transferred the males to a different ratio and measured the frequencies of the same behaviours again. The patterns of behaviour were similar in both time periods: as sex ratio increased from 0.5 (males: females) to 5 aggression increased while inter-sexual behaviour decreased. In novel conditions, levels of aggression across sex ratios did not change, but males increased courtship and decreased harassment behaviour. Thus, when in a novel environment with new potential mates, males increase courtship behaviour, but do not adjust aggression when facing novel competitors. Our results suggest that there is considerable individual plasticity in behaviour that may have evolved because of fluctuating sociosexual contexts during natural breeding.