Consuming, Grouping, and Coexisting

Tuesday, June 8, 1999 - 9:30am - 10:30am
Keller 3-180
Will Wilson (Duke University)
We explore a set of detailed models of consumer-resource interactions in pursuit of coexistence mechanisms for a pair of foraging strategies observed across a wide variety of ecological systems. These coexisting foragers, called diggers and grazers, deplete their common resource to different levels. Although diggers consume resource to the lowest level, grazers are able to find new patches more quickly than diggers. Our initial model is an individual-based simulation of a spatially distributed resource renewing logistically and consumers competing exploitatively for this resource. Key to the consumer submodel is the relationship between foraging in local resource patches, movement decisions, and energetic costs of movement. Although no spatial heterogeneities are assumed, the consumers' foraging activities produces consumer grouping, which generates a very heterogeneous resource distribution. This heterogeneity promotes coexistence of different foraging strategies. We then derive an analytic resource-consumer model in which consumer movement is resource dependent. One outcome of this model is consumer grouping and a concomitant heterogeneous resource distribution. Assuming a foraging cost--resource consumption tradeoff, we examine evolutionarily stable foraging strategies.