Speaker: Dr. Ian Hamilton
From: Department of Evolution, Ecology and Organismal Biology and Department of Electrical and Computer Engineering, The Ohio State University and The University of Bern
Date / Time / Room: Friday November 10, 2006 / 2:00 PM / 190 Galvin

Title:Coerced Cooperation: Decision Making Under the Threat of Expulsion

Abstract: Cooperative breeding describes a social system in which some group members stay in or join a group and help raise the offspring of others, but gain little or no direct reproduction. Understanding why ‘helpers’ stay and help, and why they accept low levels of direct reproduction, are questions that have long intrigued evolutionary ecologists. Although groups are often composed of close kin, this is not the case in several cooperatively breeding species; furthermore, kin competition can reduce the benefits of cooperating with kin. Therefore, there has been increased emphasis on non-kin based mechanisms enforcing cooperative behavior in these groups. One such mechanism is coercion – helpers help because they will be punished or expelled if they do not. I discuss the evolutionary stability of punishment and active helping behavior, and present the result of a model that predicts that coercion can lead to helping, but that evolutionary stable levels of help are low. Coercion may also influence growth patterns in fish, a prediction which was supported in a series of experiments using a cooperatively breeding cichlid fish
(Neolamprologus pulcher). Finally, I discuss the role of the social environment as a whole, with particular focus on the role that female mate choice decisions may play in influencing patterns of coercion and cooperation among males in cooperatively breeding groups.