Dynamic games and field experiments examining intra- and intersexual conflict: Explaining counterintuitive mating behavior in a Mediterranean wrasse, Symphodus ocellatus

Abstract

Intersexual conflict and intrasexual competition are widely recognized as playing critical roles in determining mating systems. Although they occur simultaneously in populations, these processes are usually treated independently. In reality, the fitness of reproductive strategies will depend on the outcome of both within- and between-sex conflicts. Using a modeling approach based on multiple, linked, dynamic state variable models, we examined the reproductive behavior of a Mediterranean wrasse, Symphodus ocellatus. We compared the predictions of models that examine only a single conflict interaction with those that consider multiple within- and between-sex conflicts simultaneously. The observed distribution of sneaker males and females among nests was compared with those predicted by the models. We found that the closest fit with empirical observations and experiments is given by the model that examines conflict between females, sneakers, and nesting males simultaneously. Removal of successful nests indicated that females join nests with few or no sneakers present, whereas sneakers join these nests only later, even though this leads to lower sneaker mating success. This behavior can be explained by observing that although sneakers would have higher fitness at nests where the spawning rate is greater, females would not be willing to spawn at these nests in the presence of sneakers. Presumably, once the nests have achieved high past success, females are willing to spawn in the presence of sneakers because of the associated decreased chance of nesting male desertion.