title: Comparative evolutionary genetics of spontaneous mutations affecting fitness in rhabditid nematodes.
abstract: 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.
authors.affiliation: Department of Zoology, University of Florida, P. O. Box 118525, Gainesville, FL 32611-8525, USA. cbaer@zoo.ufl.edu
authors.forename: Charles F
authors.initials: CF
authors.lastname: Baer
authors.forename: Frank
authors.initials: F
authors.lastname: Shaw
authors.forename: Catherine
authors.initials: C
authors.lastname: Steding
authors.forename: Margaret
authors.initials: M
authors.lastname: Baumgartner
authors.forename: Alicia
authors.initials: A
authors.lastname: Hawkins
authors.forename: Andrew
authors.initials: A
authors.lastname: Houppert
authors.forename: Nicole
authors.initials: N
authors.lastname: Mason
authors.forename: Marissa
authors.initials: M
authors.lastname: Reed
authors.forename: Kevin
authors.initials: K
authors.lastname: Simonelic
authors.forename: Wayne
authors.initials: W
authors.lastname: Woodard
authors.forename: Michael
authors.initials: M
authors.lastname: Lynch
mesh_terms: D000818:Animals; D005075:Biological Evolution; D014644:Genetic Variation; D009154:Mutation; D017168:Rhabditida / Q000235:genetics* / Q000502:physiology*