Figure 4.

Approximate and exact forms of the expected trajectory when fixation is achieved by a specific time T. We have used a final time of T = 200, an effective population size of N_e = 200, a value of the real selection coefficient of s = 0.01, and an initial frequency of y = 0.1. The approximate results follow from Equation 9, while exact results were determined from a Wright–Fisher model (Fisher 1930; Wright 1931). The expected trajectory from simulations is very close to the approximate and Wright–Fisher results and is not displayed; we have, however, plotted 20 simulated trajectories.