Perceived predation risk affects the development of among-individual behavioral variation in a naturally clonal freshwater fish

Predation risk is a key driver of natural selection, influencing various aspects of prey behavior. While many studies focus on how predation risk affects average behavior at population level, less attention has been given to its potential impact on behavioral variation within prey populations. Here, we investigate the effect of perceived predation risk on among-individual behavioral variation in naturally clonal Amazon mollies. Juveniles were raised in two groups: one exposed to a predator during feeding (visual cues only) and the other one serving as a control group. We observed activity and feeding behavior (time spent feeding, visits to feeding spot) over a four-week period. (I) Individuals in the predator-exposed group were on average less active but there was no difference in average feeding behavior between the two groups, suggesting individuals strategically respond to threats based on behavior-specific cost-benefit trade-offs. (II) Among-individual behavioral variation was affected by perceived predation risk: in the absence of the predator, individuals developed pronounced differences in the time spent feeding while no such development was observed in the predator-exposed group. This result has the potential of affecting a wide range of fitness-relevant intraspecific interactions if lower among-individual feeding variation translate into reduced sizes differences. The presence of the predator initially reduced among-individual variation in activity and visits to the feeding spot, but these differences did not persist over time. Our findings highlight the importance of considering both population-level and individual-level responses to predation risk for a more comprehensive understanding of its ecological and evolutionary consequences.