Rate of beneficial mutation (Ua)

Value 2E-05 1/genome/generation
Organism Bacteria Escherichia coli
Reference Perfeito L, Fernandes L, Mota C, Gordo I. Adaptive mutations in bacteria: high rate and small effects. Science. 2007 Aug 10 317(5839):813-5. DOI: 10.1126/science.1142284 abstract & p.814 middle column top paragraphPubMed ID17690297
Primary Source [20] J. F. Crow, M. Kimura, An Introduction to Population Genetics Theory (Harper & Row, New York, 1970). [21] "Ua = k/(Ne×2E(sa)×T), where k is the number of observed mutations, T is the number of generations and E(sa) is the mean selection coefficient. This assumes that there is no clonal interference. If its effect is major, the value of Ua will be greatly underestimated. Also, small effect mutations are likely to be missed because the time it takes for a mutation to increase in frequency is ∝1/sa."
Method P.813 right column 2nd paragraph: "In this work, [investigators] used populations with an intermediate effective population size—big enough that genetic drift is unlikely to drive slightly deleterious mutations to a high frequency but small enough to minimize the effects of clonal interference between beneficial mutations. To estimate the beneficial mutation rate and the distribution of fitness effects of single mutations, [they] used a microsatellite marker system pioneered by Imhof and Schlotterer (ref 4). Mutations at a microsatellite locus coded by a nonconjugative plasmid can generate neutral allelic diversity in a very short time (refs 4, 18), and selective sweeps, occurring in the bacterial genome, can be identified by following the rapid increase in the frequency of the linked microsatellite allele (ref 4)."
Comments Abstract: "[Investigators] found a rate on the order of 10^(-5) per genome per generation, which is 1000 times as high as previous estimates, and a mean selective advantage of 1%." P.814 middle column top paragraph: "Indeed, in the populations of smaller effective size, [their] estimate of the mutation rate was 1000 times as high: Ua = 2 × 10^–5 beneficial mutations per genome, per generation (primary sources [20], [21]). Given that clonal interference is much weaker in these populations, [they] take this value to be a much more accurate measure of the real Ua."
Entered by Uri M
ID 112768