Abstract :
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 differentiation to evolve without a difference in the underlying foraging ability or morphology. The model used an individual-based patch choice mechanism, whereby herbivores move from patch to patch seeking food with the highest nutrient intake characteristics. The choice of patch was governed by a parameter, µ, which determined to what extent information in the landscape at different distances from the herbivore was used by it to make foraging decisions. A genetic algorithm was used to optimise the value, µ, in a complex landscape. The value of µ quickly converged to a single value with stabilising selection occurring when there was only a single species foraging. When there was a competing species with a fixed value of µ, the value of µ evolved to be above or below the mean for the single species mean depending on whether the value of µ for the competitor was below, or above the single-species mean, respectively. This was indicative of niche segregation. However µ tended to vary unstably over time when allowed to vary simultaneously in both species, although there was evidence for interaction between the two values. These results indicate that there can be a competitive advantage in choosing a cognitive strategy that is complementary to that used by other species.
