English: Left: replacement rates of the two genotypes in Figure 1, w1(1 − μ1) for A1 (solid black line extending to dashes) and w2(1 − μ2) for A2 (gray line). Here we let μ1 = kμ and μ2 = μ, with k > 1 so the two replacement rates can be plotted as lines in the same plane. Since w1 > w2, the constraint on k ensures a higher replacement rate of A1 than of A2 at low mutation rates and the reverse at higher mutation rates. The point at which the lines intersect is the error threshold, beyond which A1 is absent, hence the use of dashes for this part of its replacement rate function. If replacement rate drops below unity, the population goes extinct, so the functions are not extended below one on the vertical axis.