Stability and Multi-Species Interactions with Delays
The purpose of this chapter is to explore briefly some models for species interactions when time delays are present in at least some of the growth rate responses to interactions with either members of other species or the same species. We will confine ourselves mostly to mathematical investigations of the stability of equilibria for models which involve only quadratic interaction terms (i.e. for models (1.1) with fi linear in Nj). Many ecological models have been proposed and studied in which these response functions fi are not linear, both for models with delay and (even more so) without. For example models with Michaelis-Menten type terms and with delays have been studied by Caperon (1969) and MacDonald (1976) and with In Nj. terms with delays by Gomatam and MacDonald (1976). Caswell (1972) numerically studied a delay model involving complicated rational expressions in Nj. In principle however the linearization techniques we use would of course apply to these and any other more general model as well and in fact the results would be identical (allowing for differences in parameter interpretations) for models with identical linearizations. We will also upon occasion consider models in which the response functions are not necessarily linear.
KeywordsRium Larg Isochrysis
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