Figure 3.

The distribution of the standardized mean group difference D_T for a trait additively determined by k biallelic loci of equal effect. Here, p = 0.35. As the number of loci grows, the distribution approaches a normal distribution with expectation 0 and variance (1 − 4pq)/(pq). The expectation and variance of D_T do not change with k (Eqs. 36, 37). The plot was produced using histograms of the probabilities in Eq. 39, scaled to have total area 1.