Over millennia, penguins have evolved from their flying ancestors into the strong swimmers and divers we know and love today. In a study published yesterday in the journal Nature Communications, researchers used evidence from both penguin genomes and the fossil record to map the historical evolution of penguins and identify which genes spurred the development of particular traits.
The research suggests that the tuxedo-wearing waddlers might struggle to adapt to and survive the planet’s current rate of global warming. “The current speed of rising temperature far exceeds the adaptive capabilities of penguins,” Sankar Subramanian, a geneticist at the University of the Sunshine Coast in Australia who wasn’t involved in the study, tells the Australian Broadcasting Corporation’s Anna Salleh. “I think this is the important message from this paper.”
The study is the first to combine genomes of all living and recently extinct penguin lineages with the complete fossil record, writes Rebecca Dzombak for National Geographic. The fossil evidence is important since about three-quarters of penguin species are extinct. “You have to look at the fossil record, or you’re only getting a fragment of the story,” study co-author Daniel Ksepka, a paleontologist at the Bruce Museum in Greenwich, Connecticut, told the New York Times’ Jack Tamisiea.
The researchers were able to pinpoint which genes helped penguins adapt to swimming underwater and living in cold climates. The University of Copenhagen’s Theresa Cole, a lead author of the study, tells the ABC that she and her colleagues found genes that led to the formation of flippers by making shorter, denser and more rigid forearm bones. The denser bones also help penguins to dive deep underwater.
According to the New York Times, the researchers also determined which genes tuned penguins’ vision to the blue depths of the ocean by hindering their perception of red and green colors. Penguins also have genes for white fat, a crucial insulator and energy source not found in other birds that aids in migrating and surviving cold temperatures, per the ABC.
“This is an impressive approach to understanding penguin evolution,” Nic Rawlence, a paleogeneticist at New Zealand’s University of Otago who was not involved in the study, told National Geographic.
Jane Younger, an evolutionary biologist at the University of Bath in the U.K. who was not involved in the study, agrees. “I think what’s really cool about this study is it shows us, in the genomic work, the actual changes in the genes that make this sort of lifestyle possible,” she tells the ABC.
The study also shows that early penguins quickly adapted to marine life in the Southern Hemisphere after a mass extinction event around 66 million years ago. From there, their evolution continued in spurts in response to periods of climate change, such as at the start of the most recent ice age, per National Geographic. Juliana Vianna, an ecologist at the Pontifical Catholic University of Chile who was not involved in the study, tells the New York Times that penguin evolutionary history “is pretty much associated with historical climate change and glaciation.”
But according to National Geographic, the researchers found that penguins have the slowest known rate of evolution among birds, suggesting they might not be able to handle modern climate change, which is occurring more rapidly than past change.
“The slow evolutionary rates among penguins, and the speed at which Earth’s climate is currently changing, does not bode well for penguins,” Australian Antarctic Division seabird ecologist Barbara Wienecke, who was not involved in the study, told the ABC. Per National Geographic, the International Union for Conservation of Nature categorizes over half of living penguin species as endangered or vulnerable.