The evolution of cooperation between unrelated individuals is a puzzle that attracts interest both in the social and in the natural sciences. Theoretical concepts may fail to capture essential features of real life cooperation. This paper focuses on the cleaning mutualism between cleaner wrasse and their client fish. A game theoretical model predicts that two providers should offer a higher service quality to clients than single providers, as long as they cooperate among each other. Field observations and an experimental test confirm the model prediction.
- Redouan Bshary
- Alexandra S. Grutter
- Olof Leimar
