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Birds are one of the most studied groups of animals in the world, yet we are still finding new species, some of which we have never seen before and others that have been hidden in plain sight for hundreds of years.
The gentoo penguin (Pygoscelis papua) was first discovered in the cold Southern Ocean in 1781. In the following years, scientists divided the populations into two subspecies, one living in the Falkland Islands (P. p.papua) and one that lives in the South Shetland Islands and the West Antarctic Peninsula (P. p. ellsworthi).
It now appears that one species has been divided into four. Despite sharing more or less the same appearance, in not-so-distant habitats, the gentoo penguin appears to have split into four populations that have little to do with each other, according to new research.
“For the first time we have shown that these penguins are not only genetically distinct, but also physically different,” says Jane Younger, who studies population genomics at the University of Bath.
“Gentoos tend to stay close to their colonies of origin and over the course of hundreds of thousands of years they have become geographically isolated from each other to the point where they do not cross each other, even though they could easily swim the distance between them. . ”
And this is essentially the concept of species: a hybridization group reproductively isolated from other similar groups.
Using genome data and measurements from the museum’s samples, the researchers found clear differences in the genes and morphology of the gentoo penguins.
The differences are so great that the authors believe that both recognized “subspecies” should be elevated to their own species, while two new species should also be added.
While these penguins once had a common ancestor, their breeding habitats are quite diverse today, extending over flat beaches, pebble beaches, and tussock grass nests, while their diets consist of various ratios of crustaceans, fish, krill. and squid.
“They look very similar to an inexperienced eye,” says University of Bath evolutionary biologist and study lead author Josh Tyler, “but when we measured their skeletons we found statistical differences in their bone length and size and in the form of their beaks. “
Their DNA alone is a dead giveaway, confirming that these groups are not reproducing each other. This fundamental difference suggests that all four species are evolving independently of each other.
One of the distinct new species was identified on Iles Kerguelen and was briefly classified as a subspecies in 1927 (P. p. taeniata). The fourth species lives on the island of South Georgia and has never been described before.
The team now calls him Pygoscelis poncetii – named after Sally Poncet, an Australian scientist and explorer who spent a lot of time on the South Georgia island examining wildlife and writing conservation reports. She even gave birth on the island after a particularly cold winter in which their boat reportedly froze in the ice.
“Our results clearly support the division of Gentoo penguins into at least four species,” the authors conclude.
If it weren’t for genomic research, we might never have known. This hidden species diversity is something we have just begun to untangle and in the avian tree of life, we have probably overlooked many small branches.
A study published in 2016, for example, estimates that there are around 18,000 bird species in the world, which is almost double what we thought, and that’s because many birds that look similar to each other are actually different species.
Like unpacking a Russian doll, scientists have discovered species within species of giraffes, dolphins, birds and orangutans, all over the past decade.
Researchers have even found the opposite in two distinct penguin species that appear to merge into one.
In practice, of course, such discoveries do not change anything for the animal, but force us to re-evaluate the habits, behavior and conservation status of each species. This will allow us a greater understanding of each species and the threats they may face in the near future.
“Currently, Gentoo penguins are fairly stable in numbers,” says Younger, “however there is some evidence that northern populations move further south as the climate warms, so we need to look closely at them.”
The two new additions, P. taeniata is P. poncetii, both are showing signs of decline, just as we began to notice their existence.
The study was published in Ecology and evolution.
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