Dark grey are populations evolved in the benign environment
and light grey are the populations evolved in the periodic stress environment. A) The average number of mutations found per evolved population in
each treatment. B) Mutation rate for each evolved population calculated from the total number of mutations. ¥ indicates populations with a mutation
rate of 2–10-fold above average. Error bars are 95% confidence intervals C) Mutations found in genes for DNA repair for non-competent (white) and
competent (black) populations. Numbers above each category indicate the number of mutated genes in that category. * Indicates significant
difference between competent and non-competent populations. D) Mean of log-transformed relative mutation rates of the evolved lines compared
to the ancestor. Error bars are SE of the mean.
doi:10.1371/journal.ppat.1003758.g002