Comparative evolutionary genetics of spontaneous mutations affecting fitness in rhabditid nematodes

Charles F. Baer, Frank Shaw, Catherine Steding, Margaret Baumgartner, Alicia Hawkins, Andrew Houppert, Nicole Mason, Marissa Reed, Kevin Simonelic, Wayne Woodard, Michael Lynch

Research output: Contribution to journalArticlepeer-review

109 Scopus citations


Deleterious mutations are of fundamental importance to all aspects of organismal biology. Evolutionary geneticists have expended tremendous effort to estimate the genome-wide rate of mutation and the effects of new mutations on fitness, but the degree to which genomic mutational properties vary within and between taxa is largely unknown, particularly in multicellular organisms. Beginning with two highly inbred strains from each of three species in the nematode family Rhabditidae (Caenorhabditis briggsae, Caenorhabditis elegans, and Oscheius myriophila), we allowed mutations to accumulate in the relative absence of natural selection for 200 generations. We document significant variation in the rate of decay of fitness because of new mutations between strains and between species. Estimates of the per-generation mutational decay of fitness were very consistent within strains between assays 100 generations apart. Rate of mutational decay in fitness was positively associated with genomic mutation rate and negatively associated with average mutational effect. These results provide unambiguous experimental evidence for substantial variation in genome-wide properties of mutation both within and between species and reinforce conclusions from previous experiments that the cumulative effects on fitness of new mutations can differ markedly among related taxa.

Original languageEnglish (US)
Pages (from-to)5785-5790
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
StatePublished - Apr 19 2005
Externally publishedYes


  • Caenorhabditis briggsae
  • Caenorhabditis elegans
  • Deleterious mutation
  • Mutation accumulation
  • Oscheius myriophila

ASJC Scopus subject areas

  • General


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