Recombination Speeds Adaptation by Reducing Competition between Beneficial Mutations in Populations of Escherichia coli
Tim F. Cooper
PLoS Biol 5(9): e225 doi:10.1371/journal.pbio.0050225
Identification of the selective forces contributing to the origin and maintenance of sex is a fundamental problem in biology. The Fisher–Muller model proposes that sex is advantageous because it allows beneficial mutations that arise in different lineages to recombine, thereby reducing clonal interference and speeding adaptation. I used the F plasmid to mediate recombination in the bacterium Escherichia coli and measured its effect on adaptation at high and low mutation rates. Recombination increased the rate of adaptation ∼3-fold more in the high mutation rate treatment, where beneficial mutations had to compete for fixation. Sequencing of candidate loci revealed the presence of a beneficial mutation in six high mutation rate lines. In the absence of recombination, this mutation took longer to fix and, over the course of its substitution, conferred a reduced competitive advantage, indicating interference between competing beneficial mutations. Together, these results provide experimental support for the Fisher–Muller modeland demonstrate that plasmid-mediated gene transfer can accelerate bacterial adaptation.
HGT que j’aime 
Des données expérimentales en faveur du modèle Fisher–Muller, un peu plus et cette fois en se servant de la conjugaison bactérienne, moyen d’échange de matériel génétique bien commode. Dire qu’il y en a qui ignorent ce mode de transmission des gènes ! Lecture conseillée pour ceux qui s’intéressent à l’évolution.
