PARENT SESSION
Oral Session 11: Predator - Prey Ecology I: Modeling.
Presiding: L Prugh
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room C 124.
Predator and prey distributions among patches: The effects of how prey trade-off predation risk and foraging success.
Luttbeg, Barney*,1, Sih, Andrew2, 1 University of California, Davis, CA, USA2 University of California, Davis, CA, USA
ABSTRACT- The spatial overlap of predators and prey shapes their rates of interactions and thus community dynamics. Both intra- and inter-specific games shape how predators and prey distribute themselves among alternative patches. However, most predator-prey studies have ignored the inter-specific game by focusing on how either predators or prey distribute themselves while holding the distribution of the other species fixed. Game theory models in which both species are free to move between patches have produced intriguing predictions, such as predators matching the distribution of the resource consumed by the prey while the prey are uniformly distributed. The game theory approach, however, has required restrictive assumptions. We use a genetic algorithm approach, in which the optimal patch switching rules of predators and prey evolve in tandem, to incorporate more realistic assumptions into the predator and prey space game. We examine how the spatial distributions of predators and prey are driven by how prey balance the costs of predation risk and the benefits of foraging success. As in previous models, we find that like previous models when prey choose patches by minimizing the ratio of predation and foraging rates predators match the distribution of the resource consumed by the prey and prey are uniformly distributed. These distribution are unaffected by the overall magnitude of predation risk. However, when prey choose patches by maximizing their increase in reproductive value over time (which more often produces optimal prey behavior), predator and prey distributions vary with the overall magnitude of predation risk. When predation risk is low, the distributions of prey and predators are shaped mainly by prey competition and the distribution of resources. As the magnitude of predation risk increases, the distribution of prey is increasingly shaped by the distribution of predators. We discuss the community-level consequences of prey modifying their spatial distribution in response to the magnitude of predation risk.
Key words: game, spatial distribution, genetic algorithm