Mechanisms for similarity based cooperation
Program for Evolutionary Dynamics, Harvard University, Cambridge MA 02138, USA and Max-Planck-Institute for Evolutionary Biology, 24306 Plön, Germany
Corresponding author: a firstname.lastname@example.org
Published online: 23 January 2008
Cooperation based on similarity has been discussed since Richard Dawkins introduced the term “green beard” effect. In these models, individuals cooperate based on an aribtrary signal (or tag) such as the famous green beard. Here, two different models for such tag based cooperation are analysed. As neutral drift is important in both models, a finite population framework is applied. The first model, which we term “cooperative tags” considers a situation in which groups of cooperators are formed by some joint signal. Defectors adopting the signal and exploiting the group can lead to a breakdown of cooperation. In this case, conditions are derived under which the average abundance of the more cooperative strategy exceeds 50%. The second model considers a situation in which individuals start defecting towards others that are not similar to them. This situation is termed “defective tags”. It is shown that in this case, individuals using tags to cooperate exclusively with their own kind dominate over unconditional cooperators.
PACS: 02.50.Le – Decision theory and game theory / 87.23.-n – Ecology and evolution
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008