Evol Ecol Res 5: 1163-1182 (2003)     Full PDF if your library subscribes.

Competitive co-existence caused by adaptive predators

Vlastimil Křivan*

Department of Theoretical Biology, Institute of Entomology, and Faculty of Biological Sciences, Branišovská 31, 370 05 České Budějovice, Czech Republic

e-mail: krivan@entu.cas.cz


Food web dynamics are usually studied using model systems in which food web features, such as distribution of interaction strength, are fixed. This neglects adaptive foraging behaviour, which makes interaction strength a function of consumer preferences. In an endeavour to understand the effects of adaptive foraging behaviour on food web persistence, I consider here a diamond-like food web consisting of resources, two consumer species and top predators. Using a simple Lotka-Volterra type food web dynamics, I compare stability of this model when top predators are inflexible with the case where they are adaptive foragers that maximize their fitness. I show that adaptive consumer switching by predators significantly enlarges the set of parameters for which the two consumer species co-exist in the food web. Moreover, adaptive consumer switching leads to the ideal free distribution of predators. The results suggest that predator species which behave in an adaptive way are more likely to be keystones than those species which are inflexible foragers.

Keywords: adaptive foraging, competition, food web, keystone predator, persistence, stability.

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