Speaker
Description
Group selection models combine selection pressure at the individual level with selection pressure at the group level (Boyd and Richerson, 2009; Luo, 2014; Simon, 2010; Simon et al., 2013; Sober and Wilson, 1998; Traulsen and Nowak, 2006; Wilson and Wilson, 2007). Cooperation can be costly for individuals, but beneficial for the group, and therefore, if groups are sufficiently much assorted, and cooperators find themselves in groups with disproportionately many other cooperators, cooperation can evolve. The existing literature on group selection generally assumes that competition between groups occurs in a well-mixed population of groups, where any given group competes with any other group equally intensely. Competition between groups however might very well occur locally; groups may compete more intensely with their neighbours than with far-away groups. We show that if competition is indeed local, then the evolution of cooperation can be hindered by the fact that groups with many cooperators will mostly compete against neighbouring groups that are similarly cooperative, and therefore harder to outcompete. At the individual level, a similar phenomenon is called the cancellation effect, and has been discovered by Wilson et al. (1992) and Taylor (1992a-b). We show that cancellation effects also occur at the group level, and that ignoring them makes empirical estimates of the benefit-to-cost ratios for which a given group structure could sustain cooperation too positive.
