Anatomy of the Lotka-Volterra equations for predator-prey population growth.

How important are these non-consumptive effects in general? Surely the direct effects of predators eating prey must be more important in determining prey population dynamics than the indirect effects associated with stress and altered foraging. Not necessarily, though substantially more research is needed. Evan Pressier and colleagues conducted a recent meta-analysis comparing the relative effects of consumptive and non-consumptive effects of predators on prey populations (Preisser et al. 2005). In studies that measured both effects, non-consumptive effects were, on average, approximately equal in magnitude as the more commonly studied consumptive effects. Or put another way, the vast majority of research in predator-prey interactions has focused on one organism eating another. It appears that what happens to those animals not (yet) eaten is just as important if one wants to understand prey population dynamics. There is substantial research to be done, and great opportunities for this next generation of ecologists.