Evolutionary Resolutions of Conflicts with Mates and Offspring

Abstract: In sexual conflicts and conflicts between parents and offspring, natural selection acts in different directions on the two sides. For example, males may be selected to achieve many mates, but female fitness may be maximised by monogamy. In this thesis I study the evolutionary outcome of these situations mainly by theoretical modelling. I present an empirical investigation of mating interactions in the marine isopod Idothea baltica L., where males are aggressive to overcome female reluctance to mate, and make a game-theoretical analysis of the system to explain the temporal patterns of male and female aggression from the changing payoffs in the evolutionary conflict. I show that evolutionary arms races of quantitative traits that increase power in conflicts will be halted if their costs increase fast enough. It is also shown that if the traits involved in the arms race are behaviours, the arms race will concomitantly decrease the extent of conflict, so that the conflict is automatically resolved. It is shown that the solution of the sexual conflict over provisioning of young may influence the subsequent evolution of clutch size. A specific insect case is analysed where the conflict is resolved so that females may exploit males, and where the conflict influences social behaviour. It is further shown that in plants, the parent-offspring conflict over seed provisioning is influenced by endosperm ploidy and multiple paternity.