The brightness of a bird's feathers are dependent both on what version of the gene CYP2J19 they have, and how many berries they eat. Birds with version/allele A can produce extremely bright colors if they are given sufficient berries. Birds with version/allele B also produce bright colors when provided berries, but not as bright as individuals with allele A. Both birds are quite drab if not provided berries. Draw or otherwise produce a norm of reaction plot demonstrating the impact of this gene and environmental factor on feather brightness