Data and R codes

Data for the manuscript: Double trouble? Behaviour and health of pumpkinseed sunfish influence and are influenced by parasitic co-infectionDetailed information about the archived files is included in the "readme.txt" file.Abstract: Parasitism is increasingly seen as an ecological factor contributing to behavioural variation among individuals. Yet, the causal direction of the relationship between animal personality and parasites remains unclear. We measured behavioural traits (i.e. exploration, activity, boldness) in pumpkinseed sunfish (<i>Lepomis gibbosus</i>) before and after an experimental infection using cages in a lake where sunfish were naturally exposed to cestode and trematode infection for one month. Despite our initial assumptions (i.e. that all individuals have the same risk of infection within a cage), we found that initial behavioural traits strongly influenced infection susceptibility: initially bolder and less active fish acquired a higher density of trematode and cestode parasite during the infection period. Following infection, fish body condition decreased with increasing cestode density, suggesting that infection is costly to hosts. Body condition was positively correlated with distance moved, a measure of activity, regardless of individual infection status. The repeatability of exploration and activity behaviour and the strength of the activity-exploration correlation (i.e. behavioural syndrome) were reduced after experimental infection. Distance moved and trematode density were negatively correlated, suggesting that this infection decreases host activity levels. Since trematodes have a complex life cycle with piscivorous birds as a final host, a decrease in activity following infection may make infected fish more susceptible to bird predation, benefiting the parasite. Our results highlight the close links between behaviour and parasitism. We propose that two mechanisms may simultaneously operate: initial host behaviour influences their risk of infection, and infection can create variation in the behavioural traits of infected hosts.