How genes and a single oxygen atom are responsible towards the changing colour of a bird, explain experts

Across the animal kingdom, birds are some of the most colourful creatures of all. But how did all the amazingly coloured different bird species arise? Nearly all birds with bright red, orange, and yellow feathers or bills use a group of pigments called carotenoids to produce their colours.

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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 colourful pigments, called psittaco-fulvins.

Although scientists have known about these different pigments for some time, understanding the biochemical and genetic basis behind how birds use them to vary in colour has been less clear.

However, two recent separate studies about parrots and finches have provided vital insight into this mystery.

A single enzyme

The two new studies involved large teams of international researchers. They used recent advances in genetic sequencing to examine which regions of the genome (an animal's complete set of DNA) determine natural yellow-to-red colour variation in parrots and finches.

Remarkably, even though these two groups of birds produce their colourful displays using different types of pigments, scientists found they have evolved in similar ways.

Arbore's study looked at the dusky lory (Pseudeos fuscata), a parrot native to New Guinea with bands of feathers that may be coloured yellow, orange or red. The research found that shifts between yellow and red feather colouring 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.