Shifts in Mutation Bias Promote Mutators by Altering the Distribution of Fitness Effects

Marwa Z. Tuffaha, Saranya Varakunan, David Castellano, Ryan N. Gutenkunst, Lindi M. Wahl

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Recent experimental evidence demonstrates that shifts in mutational biases—for example, increases in transversion frequency— can change the distribution of fitness effects of mutations (DFE). In particular, reducing or reversing a prevailing bias can increase the probability that a de novo mutation is beneficial. It has also been shown that mutator bacteria are more likely to emerge if the beneficial mutations they generate have a larger effect size than observed in the wild type. Here, we connect these two results, demonstrating that mutator strains that reduce or reverse a prevailing bias have a positively shifted DFE, which in turn can dramatically increase their emergence probability. Since changes in mutation rate and bias are often coupled through the gain and loss of DNA repair enzymes, our results predict that the invasion of mutator strains will be facilitated by shifts in mutation bias that offer improved access to previously undersampled beneficial mutations.

Original languageEnglish (US)
Pages (from-to)503-518
Number of pages16
JournalAmerican Naturalist
Issue number4
StatePublished - Oct 2023


  • bacteria
  • microbial evolution
  • mutation bias
  • mutation rate
  • mutation spectra
  • mutator

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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