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. 2012 Apr 23;29(10):3153–3159. doi: 10.1093/molbev/mss122

FIG. 3.

FIG. 3.

Outcome of competition experiments. Summary of competition experiments. Each arrow indicates the result of a competition experiment. Arrows point toward the genotypes with a higher probability of fixation in the populations, while the numbers above the arrows represent the ratios of the outcomes of parallel evolved populations. As can be seen on the figure, both IS carrying (IS+) and mutator (ΔmutS) genotypes outcompete MDS42 (χ2 = 39.8 degrees of freedom [df] = 1, P < 10−4 and χ2 = 454 df = 1, P << 10−4, respectively). Moreover, direct competition between IS+ and ΔmutS showed a higher selection of the latter (χ2 = 7.8 df = 1, P = 0.005). Remarkably, when competing genotypes have high underlying mutation rates (ΔmutS), selection of IS+ over IS− is significantly reduced (χ2 = 32.6 df = 1, P << 10−4): genotypes can fix in ∼61% of the adapted populations. Similarly, when both genotypes contain an IS element (ΔmutS IS+ vs. IS+), spread of ΔmutS mutator in the population is significantly lower compared with that in populations with IS-free genotypes (χ2 = 271 df = 1, P << 10−4). For more details on the outcome of competition experiments, see supplementary table 2 (Supplementary Material online).