Figure 4

Number of substitutions per replication in mutants The y-axis is the number of base substitutions (d) per replication (or per neutral replication) at the error threshold. The thick solid line represents the average d per neutral replication (i.e., the average d of the sequences which retain the master phenotype per replication): d = Np/(q_mim + p) where p = λ (1 - q_min) and λ = (σ^-1/N- q_min)/(1 - q_min). The thin solid line represents the standard deviation of it, i.e., ± (q_mim + p) Np . The dashed line represents the average d per replication, which is N(1 - q_min). N is 100 and σ is 10. The lines are plotted against q_min (the lower x-axis), and the corresponding λ is shown in the upper x-axis.