Penguins are one of the few mammals capable of surviving the harsh conditions of Antarctica. Emperor penguins, for example, have many layers of insulating plumage, closely packed veins to recycle body heat, and just enough paunch to withstand wind chills of negative 80 degrees Fahrenheit.
It’s hard to imagine penguins surviving anyplace else with all these cold-weather adaptations. Ancient penguin fossils have been discovered near the equator, and many of these seabirds lived before the ice sheets of Antarctica formed. According to palaeontologist Daniel Ksepka of the Bruce Museum in Greenwich, Conn., “they lived through some of the warmest eras in Earth’s history,” when the Equator was five degrees warmer.
Dr. Ksepka and his colleagues examined the genomes of all living penguins, including pipsqueaks like the foot-tall blue penguin, rarities like the endangered yellow-eyed penguin, and showstoppers like the yellow-tufted rockhopper penguin, to determine how penguins made the transition from tropical to polar seas. Modern penguin DNA was able to inform researchers a lot, but only a limited amount. More than half of the 60 million-year history of penguin evolution is obscured by contemporary lineages.
More than three quarters of all penguin species are now extinct, according to Dr. Ksepka.
Ancient sailors’ fossils served as an additional source of information for scholars. Some ancient penguins used spearlike bills to hook fish in warm seas off Peru. It is possible that the tallest was seven feet in height. There were also some birds with patches of rusty red feathers on them.
The team was able to recreate the evolution of penguins by comparing the genomes of present penguins with those of ancient penguins. Researchers published their results in Nature Communications on Tuesday, pinpointing the genes that let penguins adapt from wading in mild waters to mastering the arctic plunge.. Some of these genes made it easier for penguins to put on weight, while others made their shrivelled wings more streamlined so they could swim more efficiently. Some even boosted penguins’ immune systems or helped them withstand low oxygen levels when diving deep.
Researchers also discovered genes that enabled penguins see through the freezing depths of the Antarctic. When compared to other birds, penguins have just three colour cones in their eyes, limiting their capacity to perceive green and red. As a result, their vision has evolved to match the ocean’s natural hue.
Researchers were baffled by the absence of several genes. Despite the fact that current penguins eat krill, the researchers discovered that their progenitors lacked genes necessary for breaking down the shells of crustaceans. This suggests that prehistoric penguins were capable of spearing bigger food, such as fish and squid. Penguins have a limited food selection.
In ancient penguins, these modifications were permanent. It has been shown that penguins have the slowest evolutionary rate of any bird species, according on genetic research. As strange as they are to look at, this glacial pace of change is a shock. That the penguin’s fat yet streamlined body design has only evolved slowly over millions of years indicates how effective it is for the bird. The penguin. Scientists have concluded that cooler temperatures accelerate penguin evolution because of the rapid evolutionary rate of emperor penguins, which reproduce in the harsh Antarctic winter.
An ecologist at the Pontifical Catholic University of Chile believes this theory is compatible with the penguins’ migration southwards during periods of global cooling. A scientist who recently conducted comparable research but was not part in the current study, Dr. Vianna, noted that the development of the species has been closely tied to changes in the temperature and glaciers throughout time.
A better understanding of the evolutionary history of penguins may provide insight into how these cold-weather experts would fare in a hotter climate in the future. According to the study’s lead author, Daniel Thomas, “Warming temperatures will affect the penguins’ biogeographic ranges, the species they depend on as food, and the species that, in turn, hunt them.”
Dr. Ksepka noted that although the study covers all of the penguin species, one seabird is still missing: the last flying penguin. There is some evidence that a tiny, puffin-like bird formerly inhabited New Zealand, although no remains have been found to support this theory.