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A Genetic Incompatibility Accelerates Adaptation in Yeast

Duyen T Bui1, Elliot Dine1, James B Anderson2

  • 1Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America.

Plos Genetics
|August 1, 2015
PubMed

Insights

Genetic incompatibilities in DNA mismatch repair (MMR) accelerate adaptation to stress by increasing beneficial mutations. This effect is rapid, reversible, and linked to specific gene mutations, offering insights into eukaryotic evolution.

Area of Science:

  • Evolutionary Biology
  • Genetics
  • Molecular Biology

Background:

  • DNA mismatch repair (MMR) corrects replication errors using MSH and MLH proteins.
  • Naturally occurring polymorphisms in MLH1 and PMS1 genes in yeast exhibit negative epistasis.
  • This genetic interaction creates a mutagenic state with potential adaptive advantages.

Purpose of the Study:

  • To test the hypothesis that a mutagenic MMR state accelerates adaptation to stress conditions.
  • To investigate the role of genetic incompatibilities in promoting beneficial mutations.
  • To link experimental findings to observational population genomics.

Main Methods:

  • Yeast strains with mutagenic (incompatible) and non-mutagenic (compatible) MMR genotypes were stressed.
  • Adaptation rates and fitness costs under high salt stress were measured.
  • Genomic analysis identified mutations responsible for fitness gains, focusing on PMR1.

Main Results:

  • Incompatible yeast populations adapted more rapidly to high salt stress without immediate fitness cost.
  • This fitness advantage was transient, disappearing over time.
  • Adaptation in both compatible and incompatible strains was primarily driven by mutations in PMR1, appearing earlier in incompatible populations.

Conclusions:

  • Genetic incompatibilities within the MMR system can rapidly accelerate adaptation in eukaryotes.
  • The adaptive advantage conferred by these incompatibilities is reversible through mating.
  • This study provides a framework for connecting experimental evolution with population genomics.

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