On Kin and Group Selection, and the Haystack Model

Abstract

Kin and group selection are two different ways to describe the evolution of social behaviour. Although these two explanations are compatible in many cases, they lead to a different perspective on the interpretation of the drivers of the evolution of social behaviour. Here, I will illustrate in a model based on the haystack model, which is often used in the context of group selection, that it allows a kin selection as well as a group selection interpretation. To do so I will analyse a variant of the haystack model in which the local dynamics are specified through a continuous time model. From the description of the dynamics the cost and the benefits of the interaction can be calculated, as well as the relatedness. We also revisit the interpretation of Maynard-Smith, who originally described the model, and show that this interpretation can be found if one assumes strong selection. This shows how the various interpretations of the evolution of social behaviour all can follow from the same model. It also shows how ecological details of the interaction are crucially important in interpreting and understanding the process of evolution.