Predictions from the FM and ML Models about the Fitness of a Focal Beneficial Mutation during Its Increase in Frequency in the Population

The advantage of recombination, according to the FM model, derives from combining beneficial mutations; the advantage predicted by the ML model results from the liberation of the focal beneficial mutation from linked deleterious mutations in the genome in which it originated. (A) Fitness of the focal beneficial mutation in a recombining (rec+, solid line) and nonrecombining (rec−, dashed line) population measured relative to the ancestor. (B) Fitness of the same mutation relative to that of contemporary clones from the same population. It is assumed that the focal mutant in the rec− populations does not accumulate further beneficial mutations.