Neotropical Social Wasps

Abstract

Wasps are a true model in studies on the origin and evolution of cooperative behavior and the mechanisms that help to stabilize sociality and resolve internal conflicts. Indeed, the wide variety of social organizations found in the group -ranging from solitary to highly social -provides unique opportunities to test how cooperation evolved and how conflicts are suppressed in societies with different degrees of social complexity. As the individuals in wasp colonies are not genetic clones of each other, inclusive fitness theory predicts that there should often be significant scope for conflicts between the queen and worker castes arising from specific genetic relatedness asymmetries within the colony. In many species, for example, the workers retain the ability to develop their ovaries and lay unfertilized male-destined eggs, thereby allowing them to challenge the reproductive monopoly of the queen. The amount of worker reproduction that is tolerated within the colony is a function of the genetic relatedness patterns within the colony and the costs and benefits of cheating, which under some circumstances can drive social enforcement mechanisms, whereby eggs laid by workers are selectively cannibalized or "policed" by the queen herself or by other workers. In some wasp species, such policing is so effective that workers are better off not trying to reproduce in the first place because nearly all the workers' eggs would be policed anyway. The fact that policing can align the evolutionary interests of the queens and workers in turn has selected for queen signaling systems, i.e. queen pheromones that act as honest signals for the presence of a healthy and fertile queen, which in many species cause the workers to refrain from reproducing in her presence. In many other species though, queen-worker conflict can be severe, with workers sometimes even engaging in matricide -killing their own mother queen to be able to reproduce without interference. This chapter provides an overview of both current and past research on reproductive conflicts within the Vespidae wasps and how their study has been instrumental in testing some key predictions of inclusive fitness theory.