Adaptive Mutations in Bacteria: High Rate and Small Effects
Lília Perfeito,1
Lisete Fernandes,1,2
Catarina Mota,1
Isabel Gordo1*
Evolution by natural selection is driven by the continuous generation of adaptive mutations. We measured the genomic mutation rate that generates beneficial mutations and their effects on fitness in Escherichia coli under conditions in which the effect of competition between lineages carrying different beneficial mutations is minimized. We 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%. Such a high rate of adaptive evolution has implications for the evolution of antibiotic resistance and pathogenicity.
1 Instituto Gulbenkian de Ciência, Rua da Quinta Grande, number 6, 2780-156 Oeiras, Portugal.
2 Escola Superior de Tecnologia da Saúde de Lisboa, Lisboa, Portugal.
* To whom correspondence should be addressed. E-mail: igordo{at}igc.gulbenkian.pt
