Symposium: Insect Behavioral Ecology--'90: Chaos and Coevolution: Evolutionary Warfare in a Chaotic Predatory-Prey System

J. C. Allen


A model of coevolution in a simple but potentially chaotic predatory-prey system is developed. Coevolution is introduced by making parameters functions of lagged density as if natural selection had affected them. Increasing attack rate and decreasing predator mortality rate were found to be destabilizing, producing more chaos and less phase-locking as revealed by bifurcation diagrams. In general, when the prey was more responsive to natural selection the model was more stable, and when the predator was more responsive to selection, the model was less stable, having more chaotic behavior and less phase-locking. It is concluded that in this simple, phenomenological model that coevolution is not a priori a stabilizing force, and it depends on the circumstances whether coevolution will work for or against chaotic dynamics.

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