Theory for the number of genes affecting quantitative characters : II. Biases from drift, dominance, inequality of gene effects, linkage disequilibrium and epistasis.

Bias in the estimation of gene number from a population of finite size will be reduced when the number of generations and the selection differential in the primary selection program are increased. A procedure to minimize bias due to dominance is proposed. Bias due to linkage disequilibrium is decreased by long generations of selection and small change of linkage disequilibrium. Bias due to inequality of gene effects was studied assuming that gene effects follow a half normal distribution. The epistatic bias arising from multiplicative gene effects disappears when the logarithms of the original measurements are considered even though the gene number estimate is unsatisfactory without transformation.