Adélie and emperor penguins were the focus of the study published in the open data journal GigaScience.
“Penguins show distinct evolution relative to other bird species,” said Guojie Zhang, assistant professor at the University of Copenhagen and associate director at China National GeneBank in China, in explaining the reasons behind the study.
“They can't fly, have specialized skin and feathers, degenerated wings, and live in a cold environment in which most other birds could not survive.”
Antarctic penguins have complicated biological systems to regulate temperature and to store energy for long periods when they can’t find food.
The scientists found that both penguins have expanded genes related to beta-keratins – proteins that compose 90 per cent of feathers.
Most importantly, the penguins had at least 13 genes responsible for a particular beta-keratin — the highest number compared with other birds — which ensured their feathers were short, stiff and packed densely to minimize heat loss, remain waterproof and help underwater motion.
Another gene, called DSG1, was responsible for the penguins' thick skin. This gene is also known in humans who have a disease that causes thick skin on the soles and palms.
In addition, Adélie penguins had eight genes involved in the metabolism of lipids (fats), while the emperor had three.
Zhang said the discoveries could help in understanding “evolutionary changes and how organisms deal with the conditions they are exposed to.”