Figure 1.—

Fixation probabilities of two new mutations that arise simultaneously (T = 0). Simulation results are illustrated for two mutations that co-occur initially in a single subpopulation (open triangles) and for mutations that arise in two distinct subpopulations (open squares). Noting that the former situation should occur with probability 1/L and the latter with probability (1 − 1/L), average (unconditional) values (solid circles) are obtained by appropriately taking the weighted sum of the two conditional probabilities. Parameters are N = 1000, L = 10 (N_T = 10,000), s = 0.01, and c = 0.5.