Genes of large effect and the shape of the distribution of a quantitative character

Abstract

The shape of the frequency distribution of a quantitative character will be non-normal if genes of large effect make an appreciable contribution to the variance of that character. The skewness coefficient will be dependent upon the relative frequencies of high and low alleles, while the kurtosis coefficient is negative for intermediate and positive for extreme frequencies of these genes. Two special models are considered in illustration. The frequency distributions of two characters (abdominal chaetae number and progeny number) in large panmictic populations of Drosophila were considered, using the technique developed here and one of Memt (1968). The results suggest that genes of large effect do not make a significant contribution to the variance of these characters in such populations. The sensitivity of the procedure is considered. © 1970 CSIRO.