Figure 4 .

Different mutation rates and selection coefficients. Synthetic lethality, equal mutation rates, and complete recessivity at both loci are assumed ($s_{\text{I,male}}=1$, $s_{\text{I,fem}}=1$, $s_{\text{A,male}}=0$, $s_{\text{A,fem}}=0$, $s_{\text{X,male}}=0$, $s_{\text{X,fem}}=0$, ${\mu }_{\text{A}}={\mu }_{\text{X}}$, $h_{\text{A}}=0$, $h_{\text{X}}=0$). Curves were generated by iterating the equations for allele frequency change for 20,000 generations. Start conditions: A_initial = 0.9, X_initial = μ/S_I. In A, different mutation rates are compared (s_I held constant at 0.1). Higher mutation rates result in faster evolutionary change along the fundamental trajectory. In B, different selection coefficients are compared (μ held constant at 0.01). Shaded curves depict $\mu /s_{\text{I}}=0.1$ and solid curves depict $\mu /s_{\text{I}}=0.01$.