An ESS model for divorce strategies in birds

We present a theoretical investigation of divorce. Arguments are couched in terms of birds, but should be applicable to other groups of organisms. We model a population in which there is a range of both male and female qualit ies, and decisions on whether to divorce are made by both members of a bree ding pair. The reproductive success of a pair is additive in male and femal e qualities in the baseline case, but we also consider the effect of qualit y interactions. The availability of new mates depends on the divorce strate gy of all population members. We allow for the possibility that mate choice is associative in quality, although we do not explicitly model the mate ch oice process. Using a game-theoretical model which incorporates these facto rs we investigate the following issues: the form of the evolutionary stable strategy and the implications of this strategy for quality correlations in breeding pairs and for the distribution of qualities among unpaired indivi duals; divorce rates, reproductive success and mate quality changes over th e lifetime of an individual, and the dependence of these qualities on the i ndividual's quality mean population divorce rates and their dependence on c osts of divorce, longevity and the extent of quality variation in the two s exes; initiators of divorce and reproductive success before and after divor ce.