Gentoo penguins (Pygoscelis papua) have previously been recognized to be a single species divided into several subspecies. However, a study led by University of Bath researchers has now identified four distinct gentoo penguin species.
South Georgia gentoo penguins (Pygoscelis poncetii) live in more northerly habitats where conditions are milder, than their Southern gentoo cousins which live on the Antarctic ice. Image credit: Gemma Clucas.
Gentoo penguins live in a range of latitudes in the southern hemisphere and are currently split into two subspecies, Pygoscelis papua ellsworthi and Pygoscelis papua papua.
“For the first time, we’ve shown that these penguins are not only genetically distinct, but that they are also physically different too,” said senior author Dr. Jane Younger, a researcher in the Milner Centre for Evolution at the University of Bath.
“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.”
Dr. Younger and colleagues looked at the genomes of gentoo penguins living in the Falkland Islands and South Georgia in the southern Atlantic Ocean, the South Shetland Islands in the Antarctic and Kerguelen Islands in the Indian Ocean.
The scientists used the genome data to create an evolutionary tree to understand the relationship between the different populations.
When they combined these data with measurements of museum specimens from each of the populations, they found clear morphological and genetic differences between the four populations.
They suggest the two known subspecies should be raised to species level: Pygoscelis ellsworthi and Pygoscelis papua.
They also established two new species: Pygoscelis poncetii, named after the Australian seabird conservationist Sally Poncet, and Pygoscelis taeniata, named in recognition of a former proposal for this name dating to the 1920s.
“The four species we propose live in quite different latitudes,” Dr. Younger said.
“For example, Pygoscelis ellsworthi lives on the Antarctic continent whereas Pygoscelis 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.”
“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,” said lead author Josh Tyler, a PhD student at the University of Bath.
“It’s a similar story to giraffes, which were revealed in 2016 to be four genetically distinct species.”
“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,” Dr. Younger said.
“The proposed changes to the classification of gentoos will be reviewed by an international committee of scientists which will assess all the evidence in the scientific literature before the new taxonomy is accepted.”
The study was published online this week in the journal Ecology and Evolution.
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Joshua Tyler et al. Morphometric and genetic evidence for four species of gentoo penguin. Ecology and Evolution, published online November 4, 2020; doi: 10.1002/ece3.6973
