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Abstract Consistent inter-individual variation in behaviour within a population, widely referred to as personality variation, can be affected by environmental context. Feedbacks between an individual’s behaviour and state can strengthen (positive feedback) or weaken (negative feedback) individual differences when experiences such as predator encounters or winning contests are dependent on behavioural type. We examined the influence of foraging on individual-level consistency in refuge use (a measure of risk-taking, i.e. boldness) in three-spined sticklebacks, Gasterosteus aculeatus, and particularly whether changes in refuge use depended on boldness measured under control conditions. In the control treatment trials with no food, individuals were repeatable in refuge use across repeated trials, and this behavioural consistency did not differ between the start and end of these trials. In contrast, when food was available, individuals showed a higher degree of consistency in refuge use at the start of the trials versus controls but this consistency significantly reduced by the end of the trials. The effect of the opportunity to forage was dependent on behavioural type, with bolder fish varying more in their refuge use between the start and the end of the feeding trials than shyer fish, and boldness positively predicted the likelihood of feeding at the start but not at the end of the trials. This suggests a state-behaviour feedback, but there was no overall trend in how bolder individuals changed their behaviour. Our study shows that personality variation can be suppressed in foraging contexts and a potential but unpredictable role of feedbacks between state and behaviour. Significance statement In this experimental study, we examined how foraging influences consistency in risk-taking in individual three-spined sticklebacks. We show that bolder individuals become less consistent in their risk-taking behaviour than shyer individuals during foraging. Some bolder individuals reinforce their risk-taking behaviour, suggesting a positive feedback between state and behaviour, while others converge on the behaviour of shyer individuals, suggesting a negative feedback. In support of a role of satiation in driving negative feedback effects, we found that bolder individuals were more likely to feed at the start but not at the end of the trials. Overall, our findings suggest that foraging can influence personality variation in risk-taking behaviour; however, the role of feedbacks may be unpredictable.

One of the major decisions individuals of many species make when deciding who to mate with is whether or not to inbreed. The prevailing theory is that individuals should avoid mating with closely related individuals because of the fitness costs associated with decreased offspring quality. However, theoretical work has suggested that levels of inbreeding depression need to be considerable for these costs to outweigh the possible, kin selected, benefits of inbreeding. While evidence for a preference for inbreeding exists in the literature, empirical results currently lag well behind theory. Here, we conducted an experiment to examine mate discrimination and preference with respect to relatedness in a natural population of the family living lizard, Liopholis whitii. We show that both male and female L. whitii distinguish between related and unrelated individuals and, furthermore, that both sexes preferentially associate with more closely related members of the opposite sex. These results correspond closely with patterns of pairing observed in the wild where both males and females have been shown to choose mating pairs that are more closely related to them than expected by chance. Combined, our findings suggest that mate choice in this system may represent an active preference for mating with related individuals rather than a result of passive constraints associated with population viscosity. In species with long-term pair bonds, who to pair with is one of the most important decisions an organism will make. Much of the research on this topic focusses on avoiding individuals who are closely related, because mating with closely related individuals (e.g. inbreeding) decreases offspring quality. However, avoiding inbreeding may not always be the optimal strategy; it may actually pay to inbreed under certain conditions. Using a family living lizard that forms long-term pair bonds, we show that males and females preferentially associate with more related potential mates when given a choice. These results add to a growing body of literature which suggests that partner choice with respect to relatedness may be the result of an active preference for more related individuals rather than a result of constraints on optimal partner choice.