Simple models for exploitative and interference competition

Abstract

Competition is exploitative when species compete for the same limited resource, and interference when species deplete one another's resources by interferences such as aggressive displays or fighting. If pure exploitative competition is defined as an effect on the carrying capacity, and if pure interference competition is defined as an effect on the rate of increase per individual, then the logistic equation can be modified to describe both pure exploitative and pure interference competition. Both models have identical equilibrium properties and very similar trajectories; it would be difficult to distinguish between these two types of competition using only data on abundances. However, for pure interference competition the relation between the rate of change per individual of one species and abundance of the second is linear, whereas for pure exploitative competition the relation between the rate of change per individual of one species and abundance of the second is non-linear; this is an important consideration when exploiting competitive species.