Group selection in density-regulated populations revisited

Recent theoretical studies have indicated that the evolution of cooperation can be severely constrained by the spatial scales over which density regulation acts. If density regulation occurs on a local scale within a group, variation in productivity among groups is suppressed and the among-group component of selection is eliminated. Here, I present the results from a simple model that shows that there is more scope for the evolution of cooperation under density regulation than previously thought. This statement, however, is conditioned upon the fact that the traits under selection are themselves involved in the density-regulating process. Further-more, the results also suggest that traits directly involved in the density-regulating process, such as various competitive strategies or interference behaviours, are likely candidates for evolution through group selection, since they are not constrained by the ecological population structure to the same degree as other traits are. Laboratory experiments on group selection may provide some support for this hypothesis, since many traits that have been shown to be involved in the response to group selection are either directly or indirectly responsible for determining the strength of intraspeciWc competition