Figure 4.—

Fitness effects of two evolved malT mutations and a mutation with upregulated expression of malT, all moved into the ancestral genetic background. Competitions were performed in the same medium used in the long-term evolution experiment. Error bars are 95% confidence intervals based on six replicate competition assays for each genotype. From left to right, the four genotypes are as follows: 606 is the ancestral strain with the ancestral malT allele; malT^Ara+1 and malT^Ara−1 are alleles that evolved in the focal populations Ara + 1 and Ara − 1, respectively, which were then moved into the ancestral chromosome; and malT^up is an upregulated allele also moved into the ancestral chromosome.