Figure 2. Fitness changes over 1000 generations of evolution.
(A) Population fitness trajectories. Replicate populations for each evolution condition are shown in each column. Environments in which the fitnesses of these populations were assayed are shown in the rows. Plots for which evolution and assay environment are the same are indicated by a bold outer border. The black line in each plot indicates the median fitness. Error bars indicate standard error of the mean. (B) Summary of population changes in fitness: generations 0–1000. Populations are categorized according to whether their fitness at generation 1000 is equal to, less than, or greater than their fitness at generation zero. Significance of fitness differences evaluated using one-sided Welch’s unequal variances t-tests, the number of observations for both fitness values is 2.