Group selection and kin selection: Two concepts but one process

Abstract

In a recent paper, Traulsen and Nowak use a multilevel selection model to show that cooperation can be favored by group selection in finite populations [Traulsen A, Nowak M (2006) Proc Natl Acad Sci USA 103:10952-10955]. The authors challenge the view that kin selection may be an appropriate interpretation of their results and state that group selection is a distinctive process ''that permeates evolutionary processes from the emergence of the first cells to eusociality and the economics of nations.'' In this paper, we start by addressing Traulsen and Nowak's challenge and demonstrate that all their results can be obtained by an application of kin selection theory. We then extend Traulsen and Nowak's model to life history conditions that have been previously studied. This allows us to highlight the differences and similarities between Traulsen and Nowak's model and typical kin selection models and also to broaden the scope of their results. Our retrospective analyses of Traulsen and Nowak's model illustrate that it is possible to convert group selection models to kin selection models without disturbing the mathematics describing the net effect of selection on cooperation.T raulsen and Nowak (1) (T&N) present a multilevel selection model and demonstrate that a mutant helping allele can be favored to fixation, when introduced as a single copy in a population monomorphic for selfishness ifwhere c is the cost of helping, b the benefit of helping for group members (excluding the actor), N the group size, n g the number of groups, the migration rate between groups, and q the probability of group splitting (T&N, inequality ineq. 2). In their conclusion, T&N challenge the view that kin selection is an appropriate interpretation of their results and state that:''It would be interesting to see how the mathematical methods of kin selection can be used to derive our central results given by eqs. 1-3 and what assumption are needed for such a derivation. The problem is that typical methods of kin selection are based on traditional considerations of evolutionary stability, which are not decisive for games in finite populations.'' Further, in a recent comment on the various possible mechanisms leading to the evolution of cooperation, Nowak (2) states that the group selection model of T&N results in a different process than kin selection. These are surprising statements, given that many authors have emphasized that group selection models are not different from kin selection models (3-8), and that kin selection theory has been extended to finite populations that can follow very diverse demographic regimes (8)(9)(10)(11)(12)(13)(14). To us, the mechanism favoring cooperation in T&N's model is clearly kin selection. Indeed, kin selection operates whenever interactions occur among genetic relatives, that is, among individuals who tend to share a more recent common ancestor than individuals sampled randomly from the whole population. This may happen when interactions take place within families before the dispersal of offspring, or whe...

Positive effects of multiple gene control on the spread of altruism by group selection

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Evaluating the role of reproductive constraints in ant social evolution

“…In general, Hamilton's rule highlights both the genetic factors (as they affect relatedness) and ecological factors (as they affect costs and benefits) that promote cooperation and conflict in social groups (Bourke & Franks 1995). Although kin selection theory has long dominated the field of social evolution, it remains animated with controversy-most often ignited by the ideas and semantic confusion surrounding the alternative theoretical framework of group selection (Wilson & Hö lldobler 2005;Fletcher et al 2006;Foster et al 2006a,b;Lehmann et al 2007;West et al 2007West et al , 2008; Wilson & Wilson 2007;Kohn 2008;Wilson 2008a,b;Pennisi 2009). This is in spite of the fact that theorists in social evolution have for a long time agreed that, if certain conditions are satisfied, the theories of multi-level selection and kin selection are mathematically equivalent to one another and give the same predictions (Bourke & Franks 1995;Lehmann et al 2007).…”

The challenges and scope of theoretical biology

“…These features have highlighted fundamental problems, such as explaining altruism within a framework of individual-based selection (Hamilton et al, 2001;Hamilton, 1971). Recently, progress has been made through the development of theories that have either expanded fundamental selection dynamics in a hierarchical fashion, such as multilevel selection theory (Lehmann et al, 2007a), demonstrating a mathematical isomorphism between kin selection and group selection (Hamilton, 1975;Traulsen and Nowak, 2006;Lehmann et al, 2007b;Frank, 1998), or how individualbased strategies in game theory might accounts for the evolution of behavior. This last case is particularly interesting, as we have subsequently seen an expansion of this concept to account for dynamical interactions at lower levels of complexity such as viral dynamics (Nowak, 2006).…”