A Critical Review of the Models of Group Selection

Group selection is defined as that process of genetic change which is caused by the differential extinction or proliferation of groups of organisms. A very large proportion of the literature pertaining to group selection consists of theoretical papers; the genetic problems of group selection have been addressed from many different mathematical viewpoints. The general conclusion has been that, although group selection is possible, it cannot override the effects of individual selection within populations except for a highly restricted set of parameter values. Since it is unlikely that conditions in natural populations would fall within the bounds imposed by the models, group selection, by and large, has been considered an insignificant force for evolutionary change. These theoretical conclusions and the assumptions from which they have been derived are reexamined in the light of recent empirical studies of group selection with laboratory populations of the flour beetle, Tribolium (Wade, 1976, 1977). It is shown that the models have a number of assumptions in common which are inherently unfavorable to the operation of group selection. Alternative assumptions derived from the empirical results are suggested and discussed in the hope that they will stimulate further theoretical and empirical study of this controversial subject.