Personality-dependent dispersal and breeding success in three-spined sticklebacks

Behavioural ecologists are well aware of the fact that individuals within populations consistently differ in behavioural expression over time and across context (i.e. animal personality). While many studies focused on the proximate mechanisms responsible for such consistent differences in behaviour, empirical investigations of fitness consequences, especially in the animal’s natural environment, remain challenging. By investigating how activity and aggression of three-spined sticklebacks (Gasterosteus aculeatus), as measured in the lab, correlate with movement behaviour, territory acquisition and male mating success in a semi-natural mesocosm, we aimed to address two typical shortcoming of animal personality studies: 1) we explored the relationship between personality differences and male success in establishing a territory as well egg acquisition, two important proxies of fitness and 2) we investigated whether, and if so how behaviour measured in classical laboratory setups translates to behavioural expression in an ecologically relevant environment.We found that male phonotype (behavioural and morphological) partially predicted territory acquisition and mating success in the mesocosm and that behaviour measured in the lab correlated with movement behaviour in the mesocosm, but less than expected. We here shine light on the often unclear relationship between personality differences and fitness and exemplify how the use of mesocosms can be a valuable tool to bridge the gap between behavioural studies in the laboratory and the wild