The Effects of Relatedness on the Evolution of Cooperation and Defection : A systematic investigation of how relatedness affects the adaptive dynamics of cooperative games with continuous investments

Abstract:

Cooperation, and in particular the willingness to cooperate with relatives, is regularly observed in lots of species. Cooperation has earlier been studied using two pure strategies, cooperate or defect. Recently continuous cooperative investment has been studied, where full cooperation and full defection are two poles on a spectrum. In this study we explore a model of accounting for relatedness in the adaptive dynamics of cooperation and defection. We find that under reasonable assumptions, relatedness will be beneficial for cooperation. However, we also find that under some circumstances the emergence of defectors might be favoured in spite of relatedness. We show this for quadratic cost and benefit functions, and then investigate general cost and benefit functions. This is the first study to systematically examine the effects of relatedness on the evolution of cooperation in continuous games, and as such it has importance for the understanding of the role of relatedness in the evolution of cooperation.