Measurement of the frequency of beneficial mutations. (A) Method to measure the frequency of adaptive mutations. A random mutation library of each RNA was replicated for several generations, and the frequencies of point mutations were measured by next-generation sequencing. The relative fitness gain of each mutation was estimated from the frequencies. The total number of beneficial mutations was used for the later analysis. (B) Distributions of beneficial mutations for each genotype. (C) Relationship between the total number of beneficial mutations and log fitness of each RNA. The error bars represent the standard error of the total number of beneficial mutations for genotypes 01, 34, and 50 (n = 3).
