Multi-decadal warming alters predator’s effect on prey community composition

Predator responses to warming can occur via phenotypic plasticity and evolutionary adaptation, resulting in changes in their prey communities. However, we lack evidence of how warming-induced evolutionary changes in predators can influence the food web. Here, we ask whether fish subject to long-term warming across multiple generations differ in their impacts on prey communities compared to their nearby conspecifics experiencing a natural thermal regime. We carried out a common garden mesocosm experiment with larval perch ( Perca fluviatilis ), originating from one heated or one reference coastal environment, feeding on zooplankton communities under a gradient of experimental temperatures. We found that fish thermal origin influenced the zooplankton communities, and differently so depending on the experimental temperature. In presence of fish of heated origin, there were less zooplankton and also fewer individuals of large size, except for at intermediate experimental temperatures. Our findings show that differences between fish populations, potentially representing adaptation to local thermal environment, caused by multi-generational warming can cascade down via trophic interactions to also affect their zooplankton prey communities. Considering climate warming, our results suggest that rapid evolution in predators might have indirect cross-generational ecological consequences propagating through food webs.