Simulation of Genetic Systems by Automatic Digital Computers VI. Epistasis

Simulation, by Monte Carlo methods, of the effect on the genotype of seleotion against phenotypic extremes has shown that selection will lead to fixation of a simple additive genetic system at an extremely slow rate in all but very small populations. In oomplex epistatio systems, such selection operates to modify the relation of the genotype to the phenotype. The relationship beoomes an S�shaped function. The efficienoy of seleotion is independent of population size. The deviation from initial gene frequencies due to selection is far less per unit decrease of phenotypio variability in the epistatic than in the additive lines.