Skip to main content
Article thumbnail
Location of Repository

Small fitness effects and weak genetic interactions between deleterious mutations in heterozygous loci of the yeast Saccharomyces cerevisiae

By Krzysztof Szafraniec, Dominika M. Wloch, Piotr Sliwa, Rhona H. Borts and Ryszard Korona


Rare, random mutations were induced in budding yeast by ethyl methanesulfonate (EMS). Clones known to bear a single non-neutral mutation were used to obtain mutant heterozygotes and mutant homozygotes that were later compared with wild-type homozygotes. The average homozygous effect of mutation was an approximately 2% decrease in the growth rate. In heterozygotes, the harmful effect of these relatively mild mutations was reduced approximately fivefold. In a test of epistasis, two heterozygous mutant loci were paired at random. Fitness of the double mutants was best explained by multiplicative action of effects at single loci, with little evidence for epistasis and essentially excluding synergism. In other experiments, the same mutations in haploid and heterozygous diploid clones were compared. Regardless of the haploid phenotypes, mildly deleterious or lethal, fitness of the heterozygotes was decreased by less than half a per cent on average. In general, the results presented here suggest that most mutations tend to exhibit small and weakly interacting effects in heterozygous loci regardless of how harmful they are in haploids or homozygotes

Publisher: Cambridge University Press
Year: 2003
DOI identifier: 10.1017/S001667230300630X
OAI identifier:

Suggested articles


  1. (1995). A general model for the evolution of recombination. doi
  2. (1984). A review of the genetic effects of ethyl methanesulfonate. doi
  3. (2000). A test for epistasis among induced mutations in Caenorhabditis elegans.
  4. (1989). After a single treatment with EMS the number of non-colonyforming cells increases for many generations in yeast populations. doi
  5. (1997). An experimental test for synergistic epistasis and its application in Chlamydomonas.
  6. (2001). Comparisons of morphogenetic networks of filamentous fungi and yeast. doi
  7. (1995). Deleterious mutation and the evolution of genetic life cycles. doi
  8. (1988). Deleterious mutations and the evolution of sexual reproduction. doi
  9. (2001). Direct estimate of the mutation rate and the distribution of fitness effects in the yeast Saccharomyces cerevisiae. doi
  10. (2001). Environmental stress and mutational load in diploid strains of the yeast Saccharomyces cerevisiae. doi
  11. (1999). epistasis in yeast 29
  12. (1999). Epistatic interactions can lower the cost of resistance to multiple consumers. doi
  13. (2001). Epistatic interactions of spontaneous mutations in haploid strains of the yeast Saccharomyces cerevisiae. doi
  14. (1994). Evidence for partial dominance of viability genes contributing to inbreeding depression in Mimulus guttatus. doi
  15. (1980). Evolution of recombination in a constant environment. doi
  16. (1999). Genetic load of the yeast Saccharomyces cerevisiae under diverse environmental conditions. doi
  17. (1998). Genetics and Analysis of Quantitative Traits. doi
  18. (1998). Genetics underlying inbreeding depression in Mimulus with contrasting mating systems. doi
  19. (1994). Genome renewal : a new phenomenon revealed from a genetic study of 43 strains of Saccharomyces cerevisiae derived from natural fermentation of grape musts. doi
  20. (1991). Getting started with yeast. doi
  21. (1991). Haploidy or diploidy: which is better. doi
  22. (2001). Masking and purging mutations following EMS treatment in haploid, diploid, and tetraploid yeast (Saccharomyces cerevisiae). doi
  23. (2001). Meiotic recombination frequencies are affected by nutritional states in Saccharomyces cerevisiae. doi
  24. (1993). Muller’s ratchet and mutational meltdowns. doi
  25. (1994). Muller’s ratchet under epistatic selection.
  26. (1993). Mutation accumulation in finite outbreeding and inbreeding populations. doi
  27. (1972). Mutation rate and dominance of genes affecting viability in Drosophila melanogaster.
  28. (1998). Mutation, selection, and the maintenance of life-history variation in natural population. doi
  29. (1999). New estimates of the rates and effects of mildly deleterious mutation in Drosophila melanogaster. doi
  30. (2000). On the average coefficient of dominance of deleterious spontaneous mutations.
  31. (1950). Our load of mutations.
  32. (1990). Pedigree analysis of yeast cells recovering from DNA damage allow assignment of lethal events to individual to posttreatment generations.
  33. (1934). Physiological and evolutionary theories of dominance. doi
  34. (1999). Ploidy regulation of gene expression. doi
  35. (1997). Rapid decline of fitness in panmictic populations of Drosophila melanogaster maintained under relaxed natural selection. doi
  36. (2001). Rapid mutational decline of viability in Drosophila. doi
  37. (1992). Recombination and the evolution of diploidy.
  38. (2002). Resolving the paradox of sex and recombination. doi
  39. (1995). Sex and the single cell : meiosis in yeast. doi
  40. (1998). Some evolutionary consequences of deleterious mutations. doi
  41. (1977). Spontaneous and ethyl methanesulfonate-induced mutations controlling viability in Drosophila melanogaster. II. Homozygous effect of polygenic mutations.
  42. (1977). Spontaneous and ethyl methanesulfonate-induced mutations controlling viability in Drosophila melanogaster. III. Homozygous effect of polygenic mutations.
  43. (1996). Spontaneous mutational variances and covariances for fitnessrelated traits in Drosophila melanogaster.
  44. (1998). Synergistic epistasis between loci affecting fitness: evidence in plants and fungi. doi
  45. (1999). Terumi Mukai and the riddle of deleterious mutation rates.
  46. (1997). Test of interaction between genetic markers that affect fitness in Aspergillus niger. doi
  47. (1997). Test of synergistic interactions among deleterious mutations in bacteria.
  48. (1937). The effect of variation on fitness. doi
  49. (1997). The effects of spontaneous mutation on quantitative traits. II. Dominance of mutations with effects on life-history traits. doi
  50. (1997). The evolution of dominance: a theory whose time has passed? doi
  51. (1999). The evolution of dominance. doi
  52. (2000). The fitness effects of spontaneous mutations in Caenorhabditis elegans. doi
  53. (1964). The genetic structure of natural populations of Drosophila melanogaster. I. Spontaneous mutation rate of polygenes controlling viability.
  54. (1969). The genetic structure of natural populations of Drosophila melanogaster. VII. Synergistic interaction of spontaneous mutant polygenes controlling viability.
  55. (2000). The many faces of mismatch repair in meiosis. doi
  56. (1982). The Masterpiece of Nature. doi
  57. (1981). The molecular basis of dominance.
  58. (1983). The mutation load in Drosophila.
  59. (1966). The mutational load with epistatic gene interactions in fitness.
  60. (2001). The rate of mutation and the homozygous and heterozygous mutational effects for competitive viability : A long-term experiment with Drosophila melanogaster. doi
  61. (1991). Transition from haploidy to diploidy. doi
  62. (1999). Unpredictable fitness transitions between haploid and diploid strains of genetically loaded yeast Saccharomyces cerevisiae.
  63. (2001). Whole-genome effects of ethyl methanesulfonate-induced mutation on nine quantitative traits in outbred Drosophila melanogaster.
  64. (1997). Yeast genetics. doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.