Spontaneous mutations in diploid Saccharomyces cerevisiae: more beneficial than expected.
We performed a 1012-generation mutation-accumulation (MA) experiment in the yeast, Saccharomyces cerevisiae. The MA lines exhibited a significant reduction in mean fitness and a significant increase in variance in fitness. We found that 5.75% of the fitness-altering mutations accumulated were beneficial. This finding contradicts the widely held belief that nearly all fitness-altering mutations are deleterious. The mutation rate was estimated as 6.3 x 10(-5) mutations per haploid genome per generation and the average heterozygous fitness effect of a mutation as 0.061. These estimates are compatible with previous estimates in yeast.
Joseph
Sarah B
SB
Section of Integrative Biology, University of Texas, Austin, Texas 78712, USA.
Hall
David W
DW
D016013:Likelihood Functions; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology