Modelleren in gedragsecologie: de optimale copulatieduur bij insekten en de gevechtsstrategie bij de kokmeeuw

Abstract

Like in many textbooks on modelling in behavioural ecology, the unifying principle of this dissertation is not a single problem, or a single species, but the method used to answer some questions. Optimality models are used to increase our insight in animal behaviour. But almost always, the problem is more complicated than "choose an existing model or make a new one, derive predictions, and test these predictions". For instance, we started with making a model (Ch 2, 3). But we needed another model (Ch 5) to get an estimate of a single parameter for a given species. Then it turned out that the statistical technique used to test this last model had a major influence on the results. So we got involved (at least a bit) in statistics (Ch 6). At the other hand, when I tried to fit a well-known model (Hammerstein and Parker 1982), the predictions of this model were hardly testable. Hence, I needed to calculate testable predictions (Ch 8). We mainly predict optimal strategies using game theory, and where possible we derived results analytically (Ch 2, 3, 4, 8, 9, 10). Only when precise estimates of almost all the variables of a given species were available, I relied on computer simulation, using Stochastic Dynamic Programming (Ch 7), (SDP: for a description of the technique, see Mangel and Clark 1988). In chapters 5 and 6, I present descriptive models necessary as a first step to test a model on the optimal copulation duration in Sympetrum danae. From biological point de vue, I mainly investigate two problems: ( l) how do a number of variables influence the optimal copulation duration in insects, and (2) how do some variables influence the outcome of an interaction in the black-headed gull (Larus ridibundus) ?. ...