Theor Ecol (2011) 4:255–267 DOI 10.1007/s12080-011-0120-6 ORIGINAL PAPER Evolutionary ecology of movement by predators and prey Samuel M. Flaxman · Yuan Lou · François G. Meyer Received: 27 August 2010 / Accepted: 26 January 2011 / Published online: 19 February 2011 © Springer Science+Business Media B.V. 2011 Abstract An essential key to explaining the mechanis- tic basis of ecological patterns lies in understanding the consequences of adaptive behavior for distribu- tions and abundances of organisms. We developed a model that simultaneously incorporates (a) ecological dynamics across three trophic levels and (b) evolution of behaviors via the processes of mutation, selection, and drift in populations of variable, unique individ- uals. Using this model to study adaptive movements of predators and prey in a spatially explicit environ- ment produced a number of unexpected results. First, even though predators and prey had limited infor- mation and sometimes moved in the “wrong” direc- tion, evolved movement mechanisms allowed them to achieve average spatial distributions approximating op- timal, ideal free distributions. Second, predators’ demo- graphic parameters had marked, nonlinear effects on the evolution of movement mechanisms in the prey: As the predator mortality rate was increased past a critical point, prey abruptly shifted from making very frequent movements away from predators to making infrequent movements mainly in response to resources. S. M. Flaxman (B ) Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA e-mail: samuel.flaxman@colorado.edu Y. Lou Department of Mathematics, The Ohio State University, Columbus, OH 43210, USA F. G. Meyer Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO 80309, USA Third, time series analyses revealed that adaptive, con- ditional movements coupled ecological dynamics across species and space. Our results provide general predic- tions, heretofore lacking, about how predators and prey should respond to one another on both ecological and evolutionary time scales. Keywords Predator–prey interactions · Individual-based model · Movements · Ideal free distribution · Conditional dispersal · Migration Introduction Adaptive behaviors are key building blocks of ecological and evolutionary patterns (Abrams 2009; Amarasekare 2010; Lazzaro et al. 2009; Levin 1992, 1998, 2005; Nathan 2008; Nathan et al. 2008). Organ- ismal movements—such as those involved in migra- tion, dispersal, and habitat selection—are behaviors of particular importance for such patterns because of the crucial role that movement plays in determining distributions and abundances at a wide variety of bio- logical scales (Gouhier et al. 2010; Nathan 2008; Nathan et al. 2008; Torney et al. 2010). Movement determines where an organism is at a given time, which determines the potential interactions it can have with factors that influence its fitness. Simply put, two organisms (or one organism and a feature of its abiotic environment) can- not directly interact unless they are spatially coincident. Movement is thus a crucial determinant of ecological dynamics (e.g., range limits) and evolutionary fitness and, hence, of populations’ responses to environmental change (Bowler and Benton 2005; Nathan 2008; Nathan et al. 2008).