Mutation, selection, and the maintenance of life-history variation in a natural population

Michael Lynch, Leigh Latta, Justin Hicks, Matthew Giorgianni

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


In an effort to provide insight into the role of mutation in the maintenance of genetic variance for life-history traits, we accumulated spontaneous mutations in 10 sets of clonal replicates of Daphnia pulex for approximately 30 generations and compared the variance generated by mutation with the standing level of variation in the wild population. Mutations for quantitative traits appear to arise at a fairly high rate in this species, on the order of at least 0.6 per character per generation, but have relatively small heterozygous effects, changing the phenotype by less than 2.5% of the mean. The mean persistence time of a new mutation affecting life-history/body-size traits is approximately 40 generations in the natural population, which requires an average selection coefficient against new mutations of approximately 3% in the heterozygous state. These data are consistent with the idea that the vast majority of standing genetic variance for life-history characters may be largely a consequence of the recurrent introduction of transient cohorts of mutations that are at least conditionally deleterious and raise issues about the meaning of conventional measures of standing levels of variation for fitness-related traits.

Original languageEnglish (US)
Pages (from-to)727-733
Number of pages7
Issue number3
StatePublished - 1998
Externally publishedYes


  • Daphnia pulex
  • Deleterious mutation
  • Life-history variation
  • Mutation accumulation
  • Mutation-selection balance

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • General Agricultural and Biological Sciences


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