Average performance of functions OR and EQU by organisms evolved from Ancestor1. Ancestor1 performed each function only once per reproductive cycle. The y-axis shows the number of times a given logic function is output per reproductive cycle. Each point represents the mean value, based on 100 replicate populations in each environment, based on the most common genotype at the end of the experiment. The environment is shown next to each point, and lines connect measurements made on the same set of populations. Error bars indicate one standard error. All 100 populations lost OR in the +EQU/-OR environment, and all 100 populations lost EQU in both the +OR/-EQU and +OR environments.