Editing Mutation rate (section)

===Substitution rates===
Many sites in an organism's genome may admit mutations with small fitness effects. These sites are typically called neutral sites. Theoretically mutations under no selection become [[Fixation (population genetics)|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.<ref name="Wielgoss">{{cite journal | vauthors = Wielgoss S, Barrick JE, Tenaillon O, Cruveiller S, Chane-Woon-Ming B, Médigue C, Lenski RE, Schneider D | title = Mutation Rate Inferred From Synonymous Substitutions in a Long-Term Evolution Experiment With Escherichia coli | journal = G3 | volume = 1 | issue = 3 | pages = 183–186 | date = August 2011 | pmid = 22207905 | pmc = 3246271 | doi = 10.1534/g3.111.000406 }}</ref>