THE EFFECTS OF VARYING PARAMETER VALUES AND HETEROGENEITY IN AN INDIVIDUAL-BASED MODEL OF PREDATOR-PREY INTERACTION

An individual-based model which produces nonlinear predator-prey dynamics is described. The importance of individual variation to the stability of the population dynamics predicted by the model and the advantages of the individual-based approach to modelling ecological systems is discussed. The individual-based model is compared with the traditional approach of population ecology — the modelling of populations with state variable equations. The individual-based model built here produces similar patterns of mutual dependence of the populations to those produced by the state variable model but has additional utility. It greatly simplifies the adjustment of individual environmental parameters which may be built into the model and it makes it possible to follow individuals or individual parameter values through the simulation. The cost of the utility of the individual-based approach is in the complexity of the model itself, which is more difficult to build than many state variable models. A common finding in the literature of individual-based modelling in ecology is the importance of individual variation. The individual-based model described here is built with a minimum of biological complexity, but still we find that individual variation in the model has profound effects on the stability of the population levels over long time periods.