CONTINUOUS VERSUS DISCRETE SINGLE-SPECIES POPULATION-MODELS WITH ADJUSTABLE REPRODUCTIVE STRATEGIES

We investigate population models with both continuous and discrete ele ments. Birth is assumed to occur at discrete instants of time whereas death and competition for resources and space occur continuously durin g the season. We compare the dynamics of such discrete-continuous hybr id models with the dynamics of purely discrete models where within-sea son mortality and competition are modelled directly as discrete events . We show that non-monotone discrete single-species maps cannot be der ived from unstructured competition processes. This result is well know n in the case of fixed reproductive strategies and our results extend this to the case of adjustable reproductive strategies. It is also sho wn that the most commonly used non-monotone discrete maps can be deriv ed from structured competition processes. (C) 1997 Society for Mathema tical Biology.