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From Rio de Janeiro’s vibrant Carnival to the attire of pirates, parrots are recognized globally for their vivid colors. A recent study published in the journal Science reveals a ‘switch’ in parrot DNA that regulates their remarkable array of colors. This research was conducted by scientists from The University of Hong Kong and an international team led by experts at BIOPOLIS-CIBIO in Portugal.
“Parrots are exceptional in numerous aspects, including the way they generate such a rich variety of colors,” explains Professor Simon Yung Wa Sin, a co-author from the School of Biological Sciences at The University of Hong Kong (HKU).
“When it comes to color, parrots have a unique approach,” states Dr. Roberto Arbore from BIOPOLIS-CIBIO, who is also a co-first author of the study. While other birds can have yellow and red feathers, parrots have developed exclusive pigments known as psittacofulvins (with ‘psittakós’ from ancient Greek meaning parrot and ‘fulvus’ from Latin meaning reddish-yellow). “Parrots creatively mix these with other pigments to achieve bright yellows, reds, and greens, making them some of the most colorful creatures in nature,” he adds.
Parrots are popular pets around the world, valued for their color and intelligence. Despite their vibrant appearance, the process behind their unique color creation has remained a mystery. “This is a significant enigma for both scientists and bird enthusiasts,” says Professor Miguel Carneiro, the senior author from BIOPOLIS-CIBIO. He further emphasizes, “It ties into an essential question in biology: how does diversity emerge in nature?”
To investigate this question, the researchers first established that yellow and red feathers in parrots are linked to two specific pigments unique to them. “Although prior literature hinted at the presence of two chemical forms of psittacofulvins, seeing clear evidence side by side for the first time was almost unbelievable. It was only with the genetic data that everything started to align properly,” remarks Dr. JindÅ™ich Brejcha from Charles University in Prague, a co-first author.
The team then chose to study a parrot species that naturally presents red and yellow variations, a rare phenomenon. “The dusky lory, found in New Guinea’s jungles, provided us access, as local certified breeders just a short distance from our lab in Portugal helped us acquire samples to explore the genetics of color in this species,” says Pedro Miguel Araújo from the University of Coimbra, who co-led the research, adding, “The solution to our study was nearly right next door!”
The research team discovered that a single protein governs the color variation observed in lories—specifically, an aldehyde dehydrogenase (ALDH), a crucial component for detoxification in living organisms, contributing to processes like alcohol elimination in the human liver. Dr. Soraia Barbosa, another co-first author from BIOPOLIS-CIBIO, notes, “Parrot feathers have adapted to utilize this protein to convert red psittacofulvins into yellow. This acts like a dial where increased protein activity results in a lighter red hue.”
To further examine this protein’s role in feather coloration across other parrot species, researchers turned their attention to rosy-faced lovebirds, which exhibit both green (yellow psittacofulvins) and red feather patches. “This familiar parrot provides an ideal model to explore the genetic factors that differentiate the colors between red and yellow psittacofulvins in their plumage,” Simon Yung Wa Sin states, leading the HKU team that included Dr. Alison Cloutier and Research Assistant Emily Shui Kei Poon. They discovered that the same aldehyde dehydrogenase gene expressed at higher levels in yellow feathers, but not in red ones. “When this gene is active at elevated levels, the psittacofulvins shift from red to yellow,” explains Simon.
In a groundbreaking effort, scientists then researched the budgerigar, a well-known parrot, to demonstrate this simple dial mechanism. They examined how individual cells activate or deactivate different genes during feather growth, identifying specific cells that utilize this detoxifying protein for pigment transformation. Their final validation was achieved by genetically modifying yeasts with the parrot color gene. “Amazingly, our altered yeast produced parrot colors, showing that this gene is sufficient to elucidate how parrots manage the proportions of yellow and red in their feathers,” comments Professor Joseph C. Corbo from Washington University in St. Louis (USA).
This research highlights how cutting-edge technology is increasingly used to solve nature’s puzzles. “We now comprehend how these stunning colors can evolve in wild animals through a straightforward dial-like ‘molecular switch’ that repurposes a detoxifying protein for a new role,” Carneiro concludes. These findings offer scientists a new perspective on evolution as a process where complexity can stem from simple adaptations.
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