Studies of sexual selection, interspecific mutualism, and intraspecific cooperation show that individuals exchange commodities to their mutual benefit. The exchange values of commodities are a source of conflict, and behavioral mechanisms such as partner choice and contest between competitors determines the composition of trading pairs or groups. These "biological markets" can be examined to gain a better understanding of the underlying principles of evolutionary ecology. In this volume scientists from different disciplines combine insights from economics, evolutionary biology, and the social...