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The solitary wave of asexual evolution.

TitleThe solitary wave of asexual evolution.
Publication TypeJournal Article
Year of Publication2003
AuthorsIM Rouzine, Wakeley, J, Coffin, JM
JournalProc Natl Acad Sci U S A
Date Published2003 Jan 21
KeywordsBiological Evolution, Chromosome Mapping, Models, Genetic, Mutation

Using a previously undescribed approach, we develop an analytic model that predicts whether an asexual population accumulates advantageous or deleterious mutations over time and the rate at which either process occurs. The model considers a large number of linked identical loci, or nucleotide sites; assumes that the selection coefficient per site is much less than the mutation rate per genome; and includes back and compensating mutations. Using analysis and Monte Carlo simulations, we demonstrate the accuracy of our results over almost the entire range of population sizes. Two limiting cases of our results, when either deleterious or advantageous mutations can be neglected, correspond to the Fisher-Muller effect and Muller's ratchet, respectively. By comparing predictions of our model (no recombination) to those of simple single-locus models (strong recombination), we show that the accumulation of advantageous mutations is slowed by linkage over a broad, finite range of population size. This supports the view of Fisher and Muller, who argued in the 1930s that progressive evolution of organisms is slowed because loci at which beneficial mutations can occur are often linked together on the same chromosome. These results follow from our main finding, that distribution of sequences over the mutation number evolves as a traveling wave whose speed and width depend on population size and other parameters. The model explains a logarithmic dependence of steady-state fitness on the population size reported recently for an RNA virus.

Alternate JournalProc. Natl. Acad. Sci. U.S.A.
PubMed ID12525686
PubMed Central IDPMC141040
Grant ListR01 CA089441 / CA / NCI NIH HHS / United States
CA 89441 / CA / NCI NIH HHS / United States
K25 AI001811 / AI / NIAID NIH HHS / United States
K25 AI 01811 / AI / NIAID NIH HHS / United States
R37 CA089441 / CA / NCI NIH HHS / United States
R35 CA 44385 / CA / NCI NIH HHS / United States

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