Predicted and observed fitness of the quintuple-mutant allele.

<p>Error bars indicated ± two standard deviation units (for the predicted fitness) or the 95% confidence interval (for the observed fitnesses). The predicted fitness for the quintuple-mutant strain was calculated after assigning a fitness of 1.0 to the two single-mutant strains with observed fitness > 1.0, but with the observed among-replicate variance for all five single-mutant alleles being used to calculate the standard deviation of the predicted fitness.