Figure 2.

The difference between the fixation probability of a two-patch meta-population and a well-mixed population of the same size, $N=10$. The two patch sizes are $N_1=3$ and $N_2=7$. Lines show analytical results for low migration probabilities (Eq. 4) and migration probability $\lambda =1$ (Eq. 19) as a function of fitness. Symbols show numerical results based on a transition matrix approach³⁹. The numerical result and analytical result for low migration probability and high migration match perfectly. In the low migration regime the two-patch meta-population is a suppressor of selection, indicated by the fact that the symbols are never in the area with a white background. However, in the high migration regime ($\lambda =1$), where simulations and analytical results again match, the two-patch meta-population is an amplifier of selection. The fixation probability for $\lambda =1$ is obtained analytically using the Martingale approach discussed by Monk⁴¹.