Figure 1.

Dependence of the fixation probability obtained using a multitype branching process on the deleterious mutation rate $U_d$ for two values of the selection coefficient s and compensatory mutation rate $U_b=0$. The points are obtained by numerically solving (2) when the mutation rate of the nonmutator is zero (○,□), and the stationary state solution of (1) when the nonmutator's mutation rate is 50 times lower than that of the mutator (+, ×). The lines show the analytical result (6).