The Evolution of Social Interactions by Family Selection

A population genetics model for the evolution of social behaviors by selection between families is presented. The effects of dominance and epistasis on both the conditions for an increase in gene frequency and the rate of gene frequency change are described for diploid and haplo-diploid organisms. 1. The conditions for the spread of genes determining social behaviors are identical to those of Hamilton's kinship theory for diploid organisms, namely, rb > c. 2. These conditions are independent of the degree of dominance (one- and two-locus case) or epistasis (two-locus case) for the linear fitness model investigated here. 3. Haplo-diploidy alone confers no advantage in terms of the evolution of social behaviors.