Scientists analyzed the genetic and physical characteristics of gentoo penguin populations around the Southern Hemisphere, namely in the Falkland Islands and South Georgia in the southern Atlantic Ocean, the South Shetland Islands in the Antarctic and the Kerguelen Islands in the Indian Ocean, a news release by the University of Bath explains.
The researchers concluded that Gentoo penguins, which are currently divided into two subspecies, P. p. ellsworthi and P. p. Papua, should instead be separated into four different species.
The researchers suggest that the two new species be named P. poncetii, after the Australian seabird conservationist Sally Poncet, and P. taeniata, to recognize a former proposal for this name dating to the 1920s, the release noted.
The study, published in Ecology and Evolution, used genome data to better understand the relationships between the different populations. The data showed clear physical and genetic differences between the four populations.
"For the first time, we've shown that these penguins are not only genetically distinct, but that they are also physically different too,” lead author Jane Younger said in the release.
"Gentoos tend to stick close to their home colonies, and over hundreds of thousands of years have become geographically isolated from each other to the point where they don't interbreed with each other, even though they could easily swim the distance that separates them,” she added, also noting that the four species the researchers suggest for classifying the birds live in different areas.
"The four species we propose live in quite different latitudes - for example P. ellsworthi lives on the Antarctic continent whereas P. poncetii, P. taeniata and P. papua live further north where conditions are milder, and so it's not that surprising that they have evolved to adapt to their different habitats,” she explained.
Ph.D. student Josh Tyler, who was also involved in the study, noted that while the penguins look similar, there are notable differences in their skeletons.
"They look very similar to the untrained eye, but when we measured their skeletons we found statistical differences in the lengths of their bones and the sizes and shape of their beaks,” he noted.
"It's a similar story to giraffes, which were revealed in 2016 to be four genetically distinct species,” he added.
The researchers also explained that dividing the populations into four species will help conservationists better protect the animals, since a decline in any one species will change its threat status, as designated by the International Union for Conservation of Nature Red List.
"Currently gentoo penguins are fairly stable in numbers, however there is some evidence of the northern populations moving further south as the climate gets warmer, so we need to watch them closely,” Younger explained.