Facing different predators: Adaptiveness of behavioral and morphological traits under predation

Abstract

Predation is thought to be one of the main structuring forces in animal communities. However, selectivepredation is often measured on isolated traits in response to a single predatory species, butonly rarely are selective forces on several traits quantified or even compared between differentpredators naturally occurring in the same system. In the present study, we therefore measured behavioraland morphological traits in young-of-the-year Eurasian perch Perca fluviatilis and comparedtheir selective values in response to the 2 most common predators, adult perch and pikeEsox lucius. Using mixed effects models and model averaging to analyze our data, we quantifiedand compared the selectivity of the 2 predators on the different morphological and behavioraltraits. We found that selection on the behavioral traits was higher than on morphological traits andperch predators preyed overall more selectively than pike predators. Pike tended to positively selectshallow bodied and nonvigilant individuals (i.e. individuals not performing predator inspection).In contrast, perch predators selected mainly for bolder juvenile perch (i.e. individuals spendingmore time in the open, more active), which was most important. Our results are to the best ofour knowledge the first that analyzed behavioral and morphological adaptations of juvenile perchfacing 2 different predation strategies. We found that relative specific predation intensity for the divergenttraits differed between the predators, providing some additional ideas why juvenile perchdisplay such a high degree of phenotypic plasticity.