ABSTRACT
A major aim of behavioural ecology is to test predictions about the way in which behaviour influences lifetime reproductive success. Ideally, predictions in behavioural ecology would be made in terms of the influence of behaviour on lifetime reproductive success, and this is often difficult. For qualitative predictions of the kind “Waterhole visits will diminish as lion density increases”, there is little problem. It can safely be assumed that more lions mean greater predation risk and that fewer waterhole visits will reduce that risk. Parker’s model employs a theorem, the marginal value theorem, which is used widely in behavioural ecology to predict how animals exploit resources, and gives a flavour of the optimality approach. It starts with the fact that resources are distributed patchily and that the male must travel from female to female in order to mate. A selection pressure is a feature of the animal’s environment that influences fitness by acting on features of its phenotype.
