Selection in Reference to Biological Groups

Abstract

Index theory is applied to selection methods which use individuals or ran-domly associated groups of individuals as basic units of selection. An index is developed which combines "direct" and "associate" phenotypic values in such a way as to invariably ensure a maximum, non-negative change in the population mean. The theory is applicable to populations of groups in each of which individuals may interact in any arbitrary manner, whether such interaction be cooperative or competitive in nature.