The fixation probability of beneficial mutations

Patwa, Zaheerabbas; Wahl, Lindi M.

doi:10.1098/rsif.2008.0248

Cited by 211 publications

(238 citation statements)

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“…While genetic drift is typically characterized by the random sampling of alleles [4], in our system drift arises primarily from the random position of spores within the inoculum. If we consider inocula as 'generations' in a serial transfer regime, the random sampling of alleles from one generation to the next occurs largely through the random placement of spores in the inoculum, since spores that are close to the boundary have a greater chance of contributing to the next generation.…”

Section: Discussionmentioning

confidence: 99%

“…Extinction probabilities are extremely sensitive to life-history and experimental details [4]. To match theory to experiment, we consider a wild-type fungus growing radially in a circular colony with radial growth rate w. The colony begins as an inoculum in the centre of the plate, containing N i wild-type spores.…”

Section: (B) Modellingmentioning

confidence: 99%

“…Despite a sustained interest in theoretical models, strict model assumptions and an inability to track individual mutations have prevented empirical tests of their predictions. However, recent advances in theoretical and experimental techniques permit us now to develop models with predictions that can be tested directly [4].…”

Section: Introductionmentioning

confidence: 99%

“…The processes driving genetic drift are specific to the organism and its growth environment, which must be incorporated into fixation models through a thorough understanding of life-history traits. Although most models (see [4]) use relative mutant fecundity as a predictor for surviving drift, recent work has shown that other measures of fitness may be more applicable (such as survival or generation time) [5,6]. We developed and tested a model for the probability of surviving drift for mutations arising in the fungus Aspergillus nidulans based on the life history of a radially growing colony [7], with mycelial growth rate [8] and initial frequency as model parameters.…”

Section: Introductionmentioning

confidence: 99%

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Model and test in a fungus of the probability that beneficial mutations survive drift

2013

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Determining the probability of fixation of beneficial mutations is critically important for building predictive models of adaptive evolution. Despite considerable theoretical work, models of fixation probability have stood untested for nearly a century. However, recent advances in experimental and theoretical techniques permit the development of models with testable predictions. We developed a new model for the probability of surviving genetic drift, a major component of fixation probability, for novel beneficial mutations in the fungus Aspergillus nidulans , based on the life-history characteristics of its colony growth on a solid surface. We tested the model by measuring the probability of surviving drift in 11 adapted strains introduced into wild-type populations of different densities. We found that the probability of surviving drift increased with mutant invasion fitness, and decreased with wild-type density, as expected. The model accurately predicted the survival probability for the majority of mutants, yielding one of the first direct tests of the extinction probability of beneficial mutations.

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Section: Discussionmentioning

confidence: 99%

Section: (B) Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Model and test in a fungus of the probability that beneficial mutations survive drift

2013

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“…To address the issues discussed above, we study the fate of a rare nonmutator in a large asexual population of mutators using a multitype branching process (Patwa and Wahl 2008). An important difference between the previous works on mutator hitchhiking (Taddei et al.…”

Section: Introductionmentioning

confidence: 99%

Fixation probability of rare nonmutator and evolution of mutation rates

James

Jain

2016

Ecology and Evolution

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Although mutations drive the evolutionary process, the rates at which the mutations occur are themselves subject to evolutionary forces. Our purpose here is to understand the role of selection and random genetic drift in the evolution of mutation rates, and we address this question in asexual populations at mutation‐selection equilibrium neglecting selective sweeps. Using a multitype branching process, we calculate the fixation probability of a rare nonmutator in a large asexual population of mutators and find that a nonmutator is more likely to fix when the deleterious mutation rate of the mutator population is high. Compensatory mutations in the mutator population are found to decrease the fixation probability of a nonmutator when the selection coefficient is large. But, surprisingly, the fixation probability changes nonmonotonically with increasing compensatory mutation rate when the selection is mild. Using these results for the fixation probability and a drift‐barrier argument, we find a novel relationship between the mutation rates and the population size. We also discuss the time to fix the nonmutator in an adapted population of asexual mutators, and compare our results with experiments.

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Fixation Probabilities and Times

Whitlock

2013

Encyclopedia of Life Sciences

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The fixation probability of an allele is the probability that it will eventually be the ancestor of all the alleles within a population at that locus. Population genetics theory has demonstrated that the probability of fixation is approximately proportional to the selection coefficient of a weak beneficial mutation, because such mutations are susceptible to stochastic loss while being rare despite their advantage. The time to fixation is the number of generations that it takes for an allele to progress from its initial frequency to fixation. This time is inversely proportional to the selection coefficient of a beneficial allele. Interestingly, though deleterious alleles are much less likely to fix, the time that they take to do so is, on average, the same as for a beneficial allele with the same magnitude of selective effect. Key Concepts: The fixation probability of an allele is the probability that it will eventually be the ancestor of all the alleles within a population at that locus. Even beneficial mutations may not fix within a population. The fixation probability of a beneficial allele is approximately proportional to its selection coefficient. Deleterious mutations are unlikely to fix, but they can fix if their selective disadvantage is sufficiently weak and the population size sufficiently small. The time for a new allele to fix within a population is inversely proportional to the magnitude of selection for both beneficial and deleterious alleles.

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The fixation probability of beneficial mutations

Cited by 211 publications

References 115 publications

Model and test in a fungus of the probability that beneficial mutations survive drift

Model and test in a fungus of the probability that beneficial mutations survive drift

Fixation probability of rare nonmutator and evolution of mutation rates

Fixation Probabilities and Times

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