Towards a cognitive niche: divergent foraging strategies resulting from limited cognitive ability of foraging herbivores in a spatially complex environment

A model was developed to explain one mechanism whereby differential optimal foraging strategies can occur between species as a result of selection for competition avoidance. This is the primary requirement for niche different iation to evolve without a difference in the underlying foraging ability or morphology. The model used an individual-based patch choice mechanism, whe reby herbivores move from patch to patch seeking food with the highest nutr ient intake characteristics. The choice of patch was governed by a paramete r, mu, which determined to what extent information in the landscape at diff erent distances from the herbivore was used by it to make foraging decision s. A genetic algorithm was used to optimise the value, mu, in a complex lan dscape. The value of mu quickly converged to a single value with stabilisin g selection occurring when there was only a single species foraging, When t here was a competing species with a fixed value of mu, the value of mu evol ved to be above or below the mean for the single species mean depending on whether the value of mu for the competitor was below, or above the single-s pecies mean, respectively. This was indicative of niche segregation. Howeve r mu tended to vary unstably over time when allowed to vary simultaneously in both species, although there was evidence for interaction between the tw o values. These results indicate that there can be a competitive advantage in choosing a cognitive strategy that is complementary to that used by othe r species. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.