Figure 2.

For trajectories where fixation eventually occurs (T = ∞), the quantity s_fict(x) represents the selection coefficient of the fictitious selection. We plot 2N_es_fict(x) against the frequency, x. We give results when the parameter N_es (involving the real selection coefficient s) takes the values −1, 0, and +1. The result 2N_es_fict(x) = 2N_es[coth(2N_esx) − 1] shows that s_fict(x) explicitly depends upon x and therefore exhibits frequency dependence. The neutral limit of s_fict(x) follows from taking s → 0 and is given by s_fict(x) = 1/(2N_ex).