Predation cues amplify the effects of parasites on the personality of a keystone grazer|行为生态学数据集|生态系统健康数据集

1. Parasites can alter species interactions either by modifying infected
host behavior or by influencing behavioral responses in uninfected
individuals. Salt marsh ecosystems are characterized by a predator-prey
interaction between the keystone grazer, Littoraria irrorata, and its main
predator, Callinectes sapidus, both integral players in mediating the
productivity of these habitats. 2. Littoraria also acts as the first
intermediate host for at least four species of digenetic trematode.
Parasite infection has been shown to decrease grazing and climbing in
populations of Littoraria, though effects on infected host response to
predators has not been investigated. Moreover, how infection might
increase or decrease among-individual variation in behavior (i.e., animal
personality) is still unknown. Here we ask how trematode infection affects
the expression of boldness in the antipredator responses of L. irrorata in
both the absence and presence of a predator cue. 3. We find that
individual boldness varies substantially, and repeatability tends to
increase as the number of stressors increases, with infected individuals
exposed to a predator cue showing the strongest expression of behavioral
types. 4. Parasitism amplifies this effect, though the parasite itself
does not appear to directly induce behavioral changes: infected snails
show no evidence of decreased climbing or differences in refuge use as
compared to their uninfected counterparts. Infection might therefore drive
the expression of condition-dependent personality differences evident only
under high-risk conditions. 5. Group infection status strongly influenced
behavioral reaction norms: uninfected individuals grouped with an infected
snail were more responsive to predation risk, exhibiting increased
climbing behavior and spending less time in the water. Here parasites are
influencing personality indirectly by inducing avoidance behaviors in
healthy individuals, though only in high-risk environments. 6. The
potential for exposure to parasites and predators fluctuates greatly
across marsh ecosystems. Given the ecological importance of this
predator-prey relationship, trematode infection can act as an important,
though indirect, determinant of overall salt marsh community structure,
health, and function.