Why is thAT RELEVANT:MAAT: Just quoting an excerpt of a response to the actual article will not do to disproof.
Your understanding has been questioned before.
Taking one example from the above:
full text also provided.
Epistatic interactions between mutations play a prominent role in evolutionary theories. Many studies have found that epistasis is widespread, but they have rarely considered beneficial mutations. We analyzed the effects of epistasis on fitness for the first five mutations to fix in an experimental population of Escherichia coli. Epistasis depended on the effects of the combined mutations—the larger the expected benefit, the more negative the epistatic effect. Epistasis thus tended to produce diminishing returns with genotype fitness, although interactions involving one particular mutation had the opposite effect. These data support models in which negative epistasis contributes to declining rates of adaptation over time. Sign epistasis was rare in this genome-wide study, in contrast to its prevalence in an earlier study of mutations in a single gene.
Do read carefully
Epistasis depended on the effects of the combined mutations—the larger the expected benefit, the more negative the epistatic effect.
In E. coli
An organism's mutation rates can be measured by a number of techniques.
Many sites in an organism's genome may not admit mutations with large fitness effects. These sites are typically called neutral sites. Theoretically mutations under no selection become fixed between organisms at precisely the mutation rate. Fixed synonymous mutations, i.e. synonymous substitutions, are changes to the sequence of a gene that do not change the protein produced by that gene. They are often used as estimates of that mutation rate, despite the fact that some synonymous mutations have fitness effects. As an example, mutation rates have been directly inferred from the whole genome sequences of experimentally evolved replicate lines of Escherichia coli B.
wiki mutation rate
re. The article above thus.