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.
Using optimal foraging theory to explain how population density affects the degree of individual specialization.
Bolnick, Daniel*,1, Svanbäck, Richard2, 1 Section of Evolution and Ecology, Davis, CA, USA2 Department of Limnology, Uppsala, Sweden
ABSTRACT- Individual specialization occurs when individuals consume a restricted subset of the population resource base. Recent reviews have demonstrated that this within-population niche variation is far more widespread than previously appreciated. Within-population diet variation raises an interesting problem: why would individuals that inhabit the same environment choose to feed on different subsets of the available resources? Optimal foraging theory provides a mechanistic way of addressing this question, proposing that diet variation is due to variation in handling times or attack rates. We outline a flexible model of individual specialization that combines phenotypic variation with optimal diet theory and population dynamics. We then apply this model to investigate the role of intraspecific competition in generating individual specialization, an effect which has been documented empirically. We use numerical simulations to show that optimal foraging theory can account for this effect. However, the qualitative relationship between density and diet variation depends on the form of prey handling trade-offs between alternative phenotypes. Under some models, individual specialization is greatest at low density and declines with increasing competition, while other patterns of trade-offs can yield increasing diet variation with competition. While this limits our ability to make broad generalizations with this model, it likely reflects biologically realistic variation in the mechanisms underlying individual specialization. The modeling approach outlined here will thus be most useful when applied to a specific study system in which the relevant parameters (handling time and attack rate variation) have been parameterized empirically.′
Key words: optimal foraging theory, diet variation, individual specialization, intraspecific competition