Eco-evolutionary interactions between predators and prey: can predator-induced changes to prey communities feed back to shape predator foraging traits?

Question: It is well established that predators can influence the structure and dynamics of prey communities and that changes in prey communities can drive predator evolution. Here we ask whether changes in prey communities, brought on by the effects of predators, can feed back to mould the evolution of predator foraging traits. Study system: We sampled lakes in Connecticut (USA) containing either anadromous or landlocked (freshwater resident) alewife (Alosa pseudoharengus) populations in 2004 and 2005. Methods: We examined alewife populations for differences in (1) seasonal effects on zooplankton communities, (2) feeding morphology, (3) prey size, and (4) prey selectivity. Results: Landlocked alewives, which are year-round residents of lakes, permanently structure lake zooplankton communities, thereby creating a strong feedback on the evolution of their foraging traits. Anadromous alewives, which are seasonal residents of lakes, intermittently structure lake zooplankton communities, preventing a strong feedback on the evolution of their foraging traits. This difference in the strength of the eco-evolutionary feedback between predator and prey appears to have led to the divergence of foraging morphology and prey selectivity between alewife life-history forms. Conclusions: Predator-induced changes to prey communities can feed back to drive the evolution of predator foraging traits under conditions where eco-evolutionary feedbacks are strong. Moreover, variation in the strength of eco-evolutionary feedbacks appears to shape patterns of ecological and evolutionary diversity in this predator-prey system.