Barbara Agathe Class, Kasha Strickland, Dominique Potvin, Nicola Jackson, Shinichi Nakagawa, Celine Frere

Social environments impose a number of constraints on individuals’ behaviour. These constraints have been hypothesized to generate behavioural variation among individuals, social responsiveness, and within-individual behavioural consistency (also termed ‘predictability’). In particular, the social niche specialization hypothesis posits that higher levels of competition associated with higher population density should increase among-individual behavioural variation and individual predictability, as a way to reduce conflicts. Being predictable should hence have fitness benefits in group-living animals. However, to date, empirical studies on fitness consequences of behavioural predictability remain scarce. In this study, we investigated the associations between social behaviour, its predictability and fitness in the eastern water dragon (Intellagama lesueurii), a wild gregarious lizard. Since this species is sexually dimorphic, we examined these patterns both between sexes and among individuals. Although females were more sociable than males, there was no evidence for sex-differences in among-individual variation or predictability. However, females exhibited positive associations between social behaviour, its predictability and survival while males only exhibited a positive association between mean social behaviour and fitness. These findings hence partly support predictions from the social niche specialization hypothesis and suggest that the function of social predictability may be sex-dependent.