Panel A shows as a function of x for different at given the ancestor had Malthusian fitness (blue) or approximately (red). In both cases, the offspring tend to get less fit and the distribution broadens due to additional mutations. Saturated colors correspond to small , light colors large . Panel B shows as a function of for the high (red) and low (blue) fitness ancestor. The dashed lines show the approximation given in Equation (6). In the high fitness case, Equation (6) overestimates since it does not account for the non-sampling contribution. Panel C shows as a function of y, given the offspring is unfit (blue) or fit (red). Ancestors tend to be fit regardless of offspring fitness and both ancestral distributions converge to a common curve far back in time.