For JSTOR Daily, Simon Griffith and Daniel Hooper examined a study by Portuguese biologist Roberto Abore (and Hooper himself) which claimed that a single enzyme could explain why birds can change colour:
Nearly all birds with bright red, orange, and yellow feathers or bills use a group of pigments called carotenoids to produce their colors. However, these animals can’t make carotenoids directly. They must acquire them through their diets from the plants they eat. Parrots are the exception to this rule, having evolved an entirely new way to make colorful pigments, called psittacofulvins.
Common foods that contain carotenoids include carrots and tomatoes but you can also find them in lobsters, salmon, and daffodils. But there’s more to the story:
Arbore’s study looked at the dusky lory (Pseudeos fuscata), a parrot native to New Guinea with bands of feathers that may be colored yellow, orange, or red. The research found that shifts between yellow and red feather coloring were associated with an enzyme called ALDH3A2. This enzyme converts red parrot pigments to yellow ones. When developing feathers contain large amounts of the enzyme, they end up yellow; when they have less, they end up red.
Scientists found the ALDH3A2 enzyme also explains color variation in many other species of parrots which have independently evolved yellow-to-red color variation.
Filed under: animals colour genetics Portugal research