Scientists discover first new penguin species in more than 100 years

Antarctica's four-foot-tall Emperor penguin may be the best-known member of the penguin family, but it is far from alone. Seventeen other penguin species live across the Southern Hemisphere, and many inhabit isolated islands that are difficult for scientists to reach and study. That remoteness may help explain how an entire species of gentoo penguin escaped recognition for so long. The birds live on the Kerguelen Islands, known in French as the Desolation Islands, nearly 2,000 miles from any permanently inhabited landmass. An international team led by researchers in Chile and at the University of California, Berkeley has now identified the population as a distinct species, making it the first new penguin species named in more than 100 years. The findings were published in Communications Biology. DNA Reveals Four Gentoo Penguin Species Genetic evidence shows that what scientists once treated as a single, widely distributed gentoo penguin species is actually made up of four separate species. One of them had never been formally recognized. Apart from subtle differences in body size and vocalizations, it closely resembles other gentoos, with the familiar white underside and black back that help penguins avoid predators and hunt prey in the ocean. Genetically, however, it is clearly distinct. Scientists call this type of organism a cryptic species, meaning it looks very similar to related species despite having significant genetic differences. The researchers also determined that three gentoo populations previously classified as subspecies are different enough genetically to be recognized as full species. The newly recognized southeastern gentoo penguin, Pygoscelis kerguelensis, may face an uncertain future. Two of the other newly defined species could also be vulnerable as global warming reshapes the Antarctic and sub-Antarctic regions where they live. The southern gentoo, now known as Pygoscelis ellsworthi, is the only one of the four that lives in Antarctica. Climate projections suggest it may be affected relatively little and could even expand its range. "In Antarctica, of course, other species, not the gentoo, are threatened by climate change," said Juliana Vianna, one of the paper's senior authors and a professor of ecosystems and environment at Andrés Bello National University in Santiago, Chile. "But the gentoo is of most concern in the sub-Antarctic region," an area of widely separated islands north of Antarctica governed by numerous countries, including Chile, South Africa, France, the Netherlands, Australia and New Zealand, "It's very important that conservation institutions in all the different countries involved recognize and take appropriate action to save these three gentoo penguin species," she added. A Century of Debate Over Gentoo Penguins To settle long-running disagreements over gentoo classification, Vianna joined forces with co-senior authors Rauri Bowie, a professor of integrative biology at UC Berkeley, and Elie Poulin, a professor at the University of Chile in Santiago. Together they brought penguin specialists from around the world into a broad genomic study of gentoo populations. Previous researchers had proposed as many as six gentoo subspecies, but there was no universal agreement. The new work represents a consensus built from whole-genome sequences of 64 penguins collected from 10 breeding colonies. For the first time, the sampling covered nearly the entire geographic range of gentoo penguins. The team also compared physical and behavioral characteristics, including coloration, calls, breeding schedules, diet, and feeding behavior. "There's probably no species of penguin where the taxonomy has been more debated than the gentoo penguin," said Bowie, a curator in UC Berkeley's Museum of Vertebrate Zoology. "For over 100 years it's been controversial as to how many species or how many subspecies there are. What this paper does is try to address that question using cutting-edge integrative approaches." How Penguins Spread Across the Southern Hemisphere Bowie and Vianna have spent nearly a decade studying how penguins evolved and diversified. In 2019, they published research indicating that penguins originated near Australia and New Zealand roughly 22 million years ago. Emperor and King penguins later split from other lineages, with Emperors becoming associated with Antarctica and Kings with the sub-Antarctic. Around 12 million years ago, the development of the circumpolar current helped other penguin groups spread through the sub-Antarctic, eventually colonizing remote islands and archipelagoes and reaching as far north as Africa and South America. Gentoo penguins have one important advantage over many of their relatives: they are flexible eaters. Rather than relying heavily on one type of prey, they will consume almost anything they can catch underwater. That flexibility is becoming increasingly important as krill populations decline. Penguins with narrower diets, including Emperors and Adélies, are decreasing in number in some regions. Gentoos living alongside them on the Antarctic Peninsula, by contrast, are increasing. A Flexible Diet Helped Drive Speciation Ironically, the gentoo's broad diet may also have helped create the distinct species recognized today. Because gentoos can feed on a wide variety of prey, including fish, krill, squid, and cuttlefish, they do not need to travel especially far from their breeding colonies in search of food. They also tend to return to the same nesting sites year after year. Over long periods, populations on isolated islands became increasingly adapted to their local environments. Those behavioral and ecological differences were gradually reinforced by natural selection across their genomes. Researchers estimate that the four gentoo species diverged during the past 300,000 to 500,000 years. Geographic isolation played a major role, along with the Antarctic Polar Front, a major boundary in the Southern Ocean where water temperature and salinity shift sharply. That boundary can also restrict the movement of marine animals. North of the Polar Front, where waters are warmer and saltier, lives the eastern lineage, Pygoscelis taeniata, found on the Crozet, Marion, and Macquarie Islands. The northern lineage, Pygoscelis papua, is restricted to the Falkland/Malvinas and Martillo Islands in South America. The newly described southeastern lineage, Pygoscelis kerguelensis, lives near the Polar Front. This relatively small population evolved on Kerguelen Island and probably nearby Heard Island. Farther south is the most numerous lineage, Pygoscelis ellsworthi. It inhabits the Antarctic Peninsula, coastal Antarctica and South Georgia Island. Penguin Genomes Reveal Local Adaptations The genomic analysis was led by University of Chile graduate student Daly Noll, the paper's first author. Compared with earlier work, the researchers examined a much broader portion of the genome and analyzed thousands of genetic differences called single nucleotide polymorphisms (SNPs). Those data revealed how each gentoo species has adapted to its particular environment. The southern gentoo, which is thriving in Antarctica, carries genetic changes associated with life in extreme polar conditions. Researchers found a greater number of genes linked to heat production, fat and lipid storage, and light perception. Changes involving light perception may help the birds cope with dramatic seasonal shifts in daylight and the intense reflection of light from ice. The eastern gentoo, in contrast, has more genes associated with efficient carbohydrate metabolism and stronger diving performance. These include genes involved in oxygen transport and use, blood vessel formation, mitochondrial activity, and lung development. Together, those traits may allow the birds to remain underwater longer while foraging in oceans with relatively low biological productivity. The northern gentoo of South America showed a different pattern. Its genome was enriched with genes involved in digestion, heart contraction and muscle excitation. Researchers say these changes may support the sustained physical activity required for prolonged underwater feeding. Climate Change Could Leave Island Penguins Stranded The team also used climate models to estimate where suitable gentoo habitat may exist in 2050. Under a moderate climate change scenario, the island-dwelling sub-Antarctic species could lose suitable habitat on all of the islands where they currently live. In many cases, there would be few or no nearby islands offering an appropriate replacement habitat. The Antarctic gentoo may fare very differently. Its suitable range is projected to extend farther into the continent as conditions change. At the same time, Emperor, Adélie and chinstrap penguins are expected to decline as sea ice disappears and populations of krill that grow beneath the ice are affected. Vianna noted that climate change is not the only danger facing penguins outside Antarctica. Warming oceans, habitat destruction, predation by rats and dogs, competition with commercial fisheries and accidental capture in fishing nets are also threatening many populations. "In terms of climate change, island species that have really low population sizes could be compared with the sub-Antarctic gentoo penguins," she said. "Galapagos and other island penguin species, because they're endemic to these islands, will find no place to go after a change in their environment. Those islands are very isolated, and these penguins cannot adapt easily to colonize any other region." Genomics Could Help Protect Penguins The unusually large and diverse dataset assembled for the research could prove valuable far beyond questions of penguin classification, Bowie said. Vianna is already examining penguin genomes for genetic differences associated with survival from avian influenza, a disease currently affecting penguin, bird and mammal populations around the world. Identifying genetic traits linked to resistance or vulnerability could help conservationists determine which populations face the greatest danger. "Whole genome sequencing has transformed our ability to not only look at adaptation from a perspective of how things diversify, but it has really important conservation value," Bowie said. In addition to Bowie and Vianna, the study includes biologists from Australia, Spain, Venezuela, South Africa, the United Kingdom, France, Argentina, Monaco and Brazil. Daly Noll of the University of Chile in Santiago is the paper's first author.