THE COUPLED LOGISTIC MAP - A SIMPLE-MODEL FOR THE EFFECTS OF SPATIAL HETEROGENEITY ON POPULATION-DYNAMICS

A simple model consisting of two diffusively coupled logistic maps is used to examine thf: effects of spatial heterogeneity on population dynamics. Examining the dynamic behaviour of the model using numerical methods, a wide range of behaviours are observed. It is shown that the coupling can stabilize individually chaotic populations, and that under different circumstances the coupling can cause individually stable periodic populations to undergo more complex behaviour. The system exhibits multiple attractors when the qualitative dynamics of the system depend on the initial conditions. Sudden changes in the structure of the attractors are seen for small changes in the parameters; these changes are known as crises. Transient and intermittent behaviours are observed. The implications of all these behaviours for populations are discussed. A linear coupling of the two maps is also considered which leads to counterintuitive behaviour, with chaotic dynamics being obtained by coupling two stable maps. This behaviour occurs because the coupling involves mixing of generations, and is therefore biologically unrealistic.