Figure 4 .

Separation of genetic drift and gene flow as causes of genetic differentiation. In the simulated case study consisting of two identical populations, F_ST and the subpopulation-level coancestry coefficients depend on the parameters a₁ = a₂ (measuring genetic drift) and k₁₂ = k₂₁ (measuring gene flow). The black lines show isoclines of F_ST in (k₁₂, a₁) space (A) and in (θ₁₂,θ₁₁) space (B). The brown line shows the isocline of F_ST = 0.18 corresponding to the true value in all three simulated scenarios, and the solid circles show the true parameter values for each of the scenarios. The lines show the parameter estimates of the fitted models, measured by 75% polytope quantiles of the posterior distributions. The thick gray lines show the 75% polytope quantiles for the prior distribution.