Cooperation strategies, signals and symbiosis

The authors of models concerning cooperation found an interesting application point in mutualism and symbiosis. Phenomena which are to be found in symbiosis are integrated by the various models in relation to the 'Prisoner's Dilemma': 'cost-benefit' ratio components, signals, neighbourhood interaction or reciprocity. Reciprocal altruism is found in symbiosis, but others strategies seem more to reflect human societies, where choice is unrestricted. It is very difficult to give a value to cost and benefit equilibriums. The biological environment interferes and a model based on a dominant strategy is often limited or insufficient to report on the living system's evolution.