Figure 4.

Relative fixation probability of maternal effect (or sib effect in a monandrous population) to direct effect loci in HD with weak negative to weak positive selection. The relative strength of selection experienced by the indirect effect locus, k = 1 (solid line), k = 1.5 (dotted line), and k = 3 (dashed line). The full three-dimensional graph of relative fixation probabilities is shown to the right. In contrast to the DD case, in HD, the relaxed selective constraint experienced by the indirect effect locus is exactly balanced by increased strength of selection when k = 3/2 (i.e., 3/2 * 2/3 = 1). And when k = 3, the indirect effect locus effectively experiences selection twice as strong as the direct effect locus (i.e., 3 * 2/3 = 2). The relatively flatter surface for HD relative to DD indicates that maternal versus direct expression has less of an effect on the probability of fixation in HD.