POPULATION GENETIC PERSPECTIVES ON THE EVOLUTION OF RECOMBINATION

Optimality arguments and modifier theory are reviewed as paradigms for the study of the evolution of recombination. Optimality criteria (suc h as maximization of mean fitness) may agree with results from models developed in terms of the evolution of recombination at modifier loci. Modifier models demonstrate, however, that equilibrium mean fitness c an decrease during the evolution of recombination rates and is not alw ays maximized. Therefore, optimality arguments do not successfully pre dict the conditions under which increased or decreased recombination w ill evolve. The results from modifier models indicate that decreased r ecombination rates are usually favored when the population is initiall y near a polymorphic equilibrium with linkage disequilibrium. When the population is subject to directional selection or to deleterious muta tions, increased recombination may be favored under certain conditions , provided that there is negative epistasis among alleles.