Fig. 3
From: Selection index theory for populations under directional and stabilizing selection
Change in population mean and phenotypic variance during the simulated breeding program for the conventional selection index and the optimum selection index. The parameter of generation 0 is shown by the point on the left-hand side. The conventional index oscillates around the optimum and cannot achieve any further genetic progress once the trait mean has reached the optimum. The optimum index achieves further progress by driving the major QTL to fixation, which reduces the phenotypic variance, and thus causes the phenotypes to be closer to the optimum