Fig. 3.

Stability and expression changes in evolved populations. (A) Thermodynamic impact of enriched SNPs as predicted by FoldX (24). SNPs are binned according to $\text{ΔΔ}$G. Positive values of enrichment (vertical axis) correspond to a larger number of mutations with a given $\mathrm{\Delta }\mathrm{\Delta }$G in error-prone populations. (B) Fraction of experimentally validated stabilizing SNPs among all nonsynonymous SNPs. (C) Fraction of validated destabilizing SNPs among all nonsynonymous SNPs. (D) Frequencies of sequences with each of three initiation codons (horizontal axis) under relaxed selection. (E) Like D, but for stringent selection. Only codons that appear with a frequency greater than 5% in at least one of the populations are included in D and E. Error bars represent SDs across four replicate populations.