Predator Effects in Predator-Free Space: the Remote Effects of Predators on Prey

Earl E Werner,Barbara L Peckarsky,Andrew Sih,James R Vonesh,Lawrence M Dill,Scott D Peacor,Jonathan H Grabowski,John L Orrock,Evan L Preisser

doi:10.2174/1874213001003030022

Abstract

Predators can have effects on prey populations that are connected by migration (i.e. prey metapopulations) because predator-mediated changes in prey behavior and abundance effectively transmit the impact of predators into predator-free prey populations. Behavioral changes in prey that might give rise to effects are altered rates of migration or activity in the presence of predation risk (called non-consumptive effects, fear- or µ-driven effects, and risk effects). Changes in prey abundance that may result in effects arise from changes in prey density due to direct predation (i.e. consumptive effects, also called N-driven effects and predation effects). Remote effects provide a different perspective on both predator-prey interactions and spatial subsidies, illustrating how the interplay among space, time, behavior, and consumption generates emergent spatial dynamics in places where we might not expect them. We describe how strong effects of predators may essentially generate remote control over the dynamics of local populations, alter the persistence of metapopulations, shift the importance of particular paradigms of metacommunity structure, alter spatial subsidies, and affect evolutionary dynamics. We suggest how experiments might document effects and predict that effects will be an important component of prey dynamics under several common scenarios: when predators induce large changes in prey dispersal behavior, when predators dramatically reduce the number of prey available to disperse, when prey movement dynamics occur over greater distances or shorter timescales than predator movement, and when prey abundance is not already limited by competitors or conspecifics.

Highlights

Predators can affect prey dynamics by consuming prey or by non-consumptive effects, including influences on the morphological, developmental or behavioral traits of prey
Remote Control of Prey by Predators predators on prey in patches where the two coincide. This focus persists despite evidence that migration of prey may be an important component of prey population dynamics (e.g., Cooper et al 1990, Sih and Wooster 1994), that the effect of predators can be transmitted across ecosystems via prey (Vonesh and Osenberg 2003, Knight et al 2005, Resetarits and Binckley 2009), and that ecological interactions and ecosystem services are mediated by organisms that cross patch boundaries (Polis et al 1997, Baxter et al 2005, Kremen et al 2007, Marczak et al 2007, McCoy et al 2009)
We distinguish between remote effects and other examples of changes in prey foraging behavior due to predation risk, e.g. changes in foraging behavior within a patch, and shifts in prey foraging among different microhabitats within a patch. Such responses of prey are undoubtedly important; to highlight the spatial dynamics that characterize remote effects, we focus on situations where prey populations are structured as metapopulations

Summary

Introduction

Predators can affect prey dynamics by consuming prey or by non-consumptive effects, including influences on the morphological, developmental or behavioral traits of prey Remote effects arise via two mechanisms: 1) consumptive effects, where predators reduce rates of prey flux among patches by directly consuming prey within local populations, Fig.

Results

Conclusion