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# Evolution of Interference Competition by Individual, Family, and Group Selection

Proceedings of the National Academy of Sciences of the United States of America
Vol. 79, No. 11, [Part 1: Biological Sciences] (Jun. 1, 1982), pp. 3575-3578
Stable URL: http://www.jstor.org/stable/12326
Page Count: 4
The necessary conditions for the evolution of social behaviors in a population with three levels of biological organization are derived by using a population genetic model (one locus, two alleles, random mating, discrete generations). Total selection on the behavior, Δ q, is partitioned into the sum of three components: (i) $\overline{\Delta q_{I}}$, selection between individuals within families; (ii) $\overline{\Delta q_{F}}$, selection between families within groups; and (iii) $\overline{\Delta q_{G}}$, selection between groups of families. I show that any level of selection can be made to operate in concert with or in opposition to any other, depending upon the fitness effects of the behavior. The implications of the model are discussed in relation to those adaptive explanations of phenotypic traits that generally consider selection to operate only between individuals.