Studies of adaptive divergence have traditionally focused on the ecological causes of trait diversification, while the ecological consequences of phenotypic divergence remain relatively unexplored.  Divergence in predator foraging traits, in particular, has the potential to impact the structure and dynamics of ecological communities.  To examine the effects of predator trait divergence on prey communities, we exposed zooplankton communities in lake mesocosms to predation from either anadromous or landlocked (freshwater resident) alewives, which have undergone recent and rapid differentiation in foraging traits.   

Results/Conclusions

Anadromous alewives significantly reduced the total biomass, mean body size, species richness, and diversity of crustacean zooplankton relative to landlocked alewives.  They did so by eliminating large-bodied species from the environment.  The zooplankton responses observed in this experiment are consistent with patterns observed in lakes.  This study provides direct evidence that predator trait evolution, occurring on short time scales, can play a critical role in determining prey community structure.