The effects of predation risk on community dynamics

Non-lethal interactions between predators and their prey can profoundly affect food webs and alter community dynamics. Many organisms are capable of altering phenotypic traits (behavior, development, morphology, etc.) to reduce their risk of predation; changes occurring via the ‘non-consumptive effect’ (NCE) of predators on their prey can nonetheless incur significant demographic and fitness-level costs. I worked with several co-authors on an analysis of published literature in which we found that the magnitude of the effect of NCEs on prey population growth was roughly equal to the direct lethal effect of predators. This led to a working group at the National Center for Ecological Analysis and Synthesis, where I coordinated a group of theoreticians, modelers, and field ecologists in answering when, where, and under what conditions NCEs might be important. I continue to collaborate with several group members on research addressing the effects of resource dynamics on NCE strength (published in 2009) as well as synthetic work exploring the impact of species invasions and spatial structure on NCEs (both published in 2010). I have also begun empirical research on how ontogenetic niche shifts (i.e., changes in predator hunting mode during an organism’s development) alter the direct and indirect impacts of predation on prey populations.