Alternative beneficial mutations are selected in the absence of the main driver.
(A) The copy number of SUL1 was assessed using qPCR of samples taken from two independent experiments in which SUL1 was not amplified (green and pink) and compared with previously published data from wild-type strains (in grey) . (B) The fitness coefficient as compared to the ancestral strain of population samples at generations 5, 50, and 200 and the fitness of two clones isolated at generation 200. (C) A small deletion (~5kb) encompassing four genes on chromosome IV was detected in a population from one experiment (between brackets); polyT sequences are present at the breakpoints. The colors of the boxes represent the orientation of the genes (yellow: gene on the Watson strand, grey: genes on the Crick strand). (D) Fitness coefficients of the deletion strains ipt1Δ and snf11Δ and those of both deletion strains complemented with IPT1 or SNF11 on a low-copy plasmid grown in sulfate limitation.