1. The selective advantage (relative fitness) of a mutant genome (with its associated cloud) alters the rate of dominance in a population.
The selective advantage (relative fitness) of a mutant genome (with its associated cloud) alters the rate of dominance in a population. Mutant spectra are depicted as in Fig. 2, with mutations on genomes indicated as colored symbols on the lines. In the upper mutant distribution, the mutation highlighted by a black asterisk in genome 8 of the first distribution confers a selective advantage that results in dominance of that mutation after a given number of replication rounds (several large arrows, but only two are drawn). The selective advantage results in the dominance of genomes with the mutation in the mutant spectrum (upper right distribution) and modification of the consensus sequence (below the upper right distribution). In the bottom mutant distribution, the same mutation in genome 8 confers a modest selective advantage, and despite its frequency increasing in the population, it does not become dominant (bottom right distribution) and the consensus sequence remains invariant (below the bottom right distribution). The mutations that accompanied the relevant one in the initial genome need not be maintained after multiple rounds of copying. This scheme illustrates that fitness gain may not be reflected in a modification of the consensus sequence and, consequently, that selective events can be overlooked if mutant spectra are not analyzed, as discussed in the text.
Esteban Domingo et al. Microbiol. Mol. Biol. Rev. 2012; doi: /MMBR