Author of the article: Publication date: July 19, 2022 • 31 minutes ago • 3 minutes reading • Join the discussion A king penguin swims in a pool at the Zurich Zoo, August 15, 2012. Photo by Michael Buholzer/File Photo/REUTERS

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WASHINGTON — The evolution of penguins from their flying seabird ancestors to flightless sea dwellers from frozen Antarctica to the tropical Galapagos Islands is one of the wonders of the animal kingdom.

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Researchers on Tuesday offered the most thorough examination yet of the history of penguins dating back more than 60 million years ago, including the identification of a series of genes critical for adaptations related to underwater vision, deep diving, body temperature regulation, diet and body size. The researchers sequenced the genomes of 20 living species and subspecies of penguins. With more than three-quarters of known penguin species extinct, the researchers also included 50 fossil species in their analysis using skeletal data. The researchers said penguins evolved from a common ancestor shared with a group of seabirds that includes albatrosses and petrels. Penguins first evolved the ability to dive, like puffins, and then lost the ability to fly as they adapted to an aquatic realm, becoming excellent swimmers and divers.

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The oldest known penguin – dating back 61 million years, about 5 million years after the mass extinction event that doomed the dinosaurs – is called Waimanu manneringi, from New Zealand. Emperor penguins are seen in Dumont d’Urville, Antarctica, April 10, 2012. Photo by Martin Passingham/File Photo/REUTERS “To me, penguins are a perfect example of an important evolutionary transition, like the evolution of an aquatic lifestyle in whales or flight in bats,” said avian paleontologist Daniel Ksepka of the Bruce Museum in Greenwich, Connecticut, who co-authored the of study. was published in the journal Nature Communications. “We know that penguins evolved from flying birds, but that happened more than 60 million years ago and we need to look in the fossil record to piece together where, when and how that happened. Plus, penguins are ridiculously charming creatures. They love, they fight, they steal, and because of their funny upright posture it’s really easy to imagine them having the same motivations as humans,” Ksepka said.

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The study demonstrated how changes in global temperature – the oscillations between cold and warm periods – and changes in major ocean currents have been important drivers of penguin evolution. “We calculated how the populations of each penguin species fluctuated over the past 250,000 years from the signatures left in their genomes by population crashes and explosions,” Ksepka said. “The exfoliation and weakening of the ice sheets has had a major impact on penguins, and species vulnerable to receding sea ice may suffer greatly from future global warming.” Penguins were also found to exhibit the lowest evolutionary rates detected among birds. Penguins live mainly in the southern hemisphere, including species such as the Adelie penguin along the coast of Antarctica. The Galapagos penguin is the only one found north of the equator.

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We apologize, but this video failed to load. University of Copenhagen postdoctoral researcher and lead study author Theresa Cole said the research revealed a variety of genes possibly involved in unique physiological adaptations of penguins. They show gene mutations that shift their vision towards the blue end of the color spectrum. Blue light penetrates deeper into the ocean than light at the red end of the spectrum, so this feature helped improve vision for low-light, underwater acuity. Genes that help birds detect salty and sour tastes are active in penguins. But the genes that help detect bitter, sweet and salty tastes are turned off. They may no longer be needed as penguins forage in cold, salty water and usually swallow prey such as fish, shrimp and squid whole.

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Penguins exhibit a flattening and stiffening of their wing bones and a reduction of their flight feathers to tiny structures that help transform feathers into flippers. They also reduced air spaces in the skeleton and increased bone wall thickness to increase diving efficiency, as well as added the ability to store more oxygen in their muscles for long dives. Penguins were once much larger than today’s species. One species, Kumimanu biceae, which inhabited New Zealand between 55 and 60 million years ago, was about 6 feet (1.8 meters) tall. The largest extant species, the emperor penguin, is about 3 feet (1 meter) tall.

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