• Corpus ID: 18406633

Rare beneficial mutations can halt Muller's ratchet

  title={Rare beneficial mutations can halt Muller's ratchet},
  author={Sidhartha Goyal and Daniel J. Balick and Elizabeth R. Jerison and Richard A. Neher and Boris I. Shraiman and Michael M. Desai},
  journal={arXiv: Populations and Evolution},
The vast majority of mutations are deleterious, and are eliminated by purifying selection. Yet in finite asexual populations, purifying selection cannot completely prevent the accumulation of deleterious mutations due to Muller's ratchet: once lost by stochastic drift, the most-fit class of genotypes is lost forever. If deleterious mutations are weakly selected, Muller's ratchet turns into a mutational "meltdown" leading to a rapid degradation of population fitness. Evidently, the long term… 

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  • D. BachtrogI. Gordo
  • Biology, Economics
    Evolution; international journal of organic evolution
  • 2004
The population genetics of adaptation in nonequilibrium haploid asexual populations finds that the presence of deleterious mutations of either very weak or very strong effect can marginally increase the rate of accumulation of beneficial mutations over that observed in the absence of such deleteriously mutations.

The accumulation of deleterious genes in a population--Muller's Ratchet.

  • J. Haigh
  • Biology
    Theoretical population biology
  • 1978


It is shown that there is a strong analogy between the Muller's ratchet model of Felsenstein (1974) and the quantitative genetic model considered here, except for the frequency of compensatory mutations, which are defined as all mutations that compensate for the phenotypic effects of a deleterious mutation.

Muller's ratchet under epistatic selection.

If deleterious alleles have synergistic fitness effects, then, as the ratchet advances, the frequency of the best available genotype will necessarily increase, making its loss less and less probable, and sufficiently strong synergistic epistasis can effectively halt the action of Muller's ratchet.


Analytical models for mutation accumulation that obviate the need for time‐consuming computer simulations in certain ranges of the parameter space are developed and it is shown that an intermediate selection coefficient minimizes the time to extinction.

Fitness of RNA virus decreased by Muller's ratchet

Results show that deleterious mutations are generated at a sufficiently high rate to advance Muller's ratchet in an RNA virus and that beneficial, backward and compensatory mutations cannot stop theRatchet in the observed range of fitness decrease.

Compensatory nearly neutral mutations: selection without adaptation.

On a suitably long timescale, every gene incorporates favorable mutations that compensate for detrimental mutations previously fixed, which results in no change or permanent improvement in enzymatic function.

Muller's ratchet and the pattern of variation at a neutral locus.

The levels and patterns of variation at a neutral locus are analyzed in a haploid asexual population undergoing accumulation of deleterious mutations due to Muller's ratchet. We find that the

Muller's ratchet decreases fitness of a DNA-based microbe.

  • D. AnderssonD. Hughes
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1996
Whether Muller's ratchet operates in Salmonella typhimurium, a DNA-based organism with a more typical genomic mutation rate, is examined and suggests that in the absence of sex and with high genetic drift, genetic mechanisms, such as back or compensatory mutations, cannot compensate for the accumulation of deleterious mutations.

Genetic Variation and the Fate of Beneficial Mutations in Asexual Populations

The fate of a newly arising beneficial mutation depends on many factors, such as the population size and the availability and fitness effects of other mutations that accumulate in the population. It