Figure 3.

(a) Finite-population correction to the average occupation numbers (left-hand side of Eq. 37) as a function of population size, N, on a three-mutation landscape as shown in Fig. 1 including back-mutations. Shown are data for a mutation rate of μ = 10⁻⁵ and replication rates of r₀ = 0, r₁ ≈ 0.049, r₂ ≈ 0.010, r₃ ≈ 0.002, r₄ ≈ 0.059, r₅ ≈ 0.051, r₆ ≈ 0.012, and r₇ ≈ 0.061. The time is chosen as T = 157.5 which approximately maximizes ⟨N₀⟩ (T) − Np₀(T). As N increases, the corrections obtained from stochastic simulations — N₀(×), N₁(엯), N₂(+), N₃(*), N₄(◻), N₅(◇), N₆(▿), N₇(▵) — converge to the values predicted by the theory (solid lines). The dashed curves show the second order expansion, given by Eqs. 37 and A.1. The error bars are one standard error. (b) Finite-size correction to the mean population fitness. The average replication rate in the population is linear in the occupation numbers, being equal to $\frac{1}{N}{\sum }_i{r}_i{N}_i\left(t\right)$, and so it too converges to the quasispecies result in the limit of a large population.