Gentoos should be four species instead of one | Polarjournal
Gentoo penguins are the third largest penguin species and have a wide range. The food generalists are commonly found from the Falkland Islands to the Antarctic continent (here: South Georgia). But researchers say that these different habitats led to segregation and speciation. Picture: Michael Wenger

Penguins are the most popular animals in Antarctica. There are numerous visitors who have made it their mission to observe all types of penguins in their natural habitat at least once. So by now, these enthusiasts must have officially observed 18 species. But the systematics of penguins is changing and two penguin types are debated as to whether they are new species. To complicate matters, an international research group now has presented the results of a study that suggests gentoo penguins are not one, but four species.

“They look pretty similar to the untrained eye.”

Josh Tyler, PhD student and first author

The results of the study, which was led by Dr. Jane Young of the University of Bath was based on the genetic and physical studies of Gentoo penguins in the southern Atlantic, the South Sandwich Islands and the Kerguelen in the Indian Ocean. In doing so, they not only used the data from today’s populations, but also compared them with exhibits on display in museums that come from the same populations. And here the researchers found clear genetic and physical differences. “For the first time, we’ve shown that these penguins are not only genetically distinct, but that they are also physically different too,” explains Dr. Younger. The study’s first author, PhD student Josh Tyler, also says: “They (The Penguins, editor’s note) 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. It’s a similar story to giraffes, which were revealed in 2016 to be four genetically distinct species.”

The scientists show that the gentoo penguins of the Falkland Islands (left) are a distinct species and differ significantly from their relatives living in Antarctica (right). The fact that the habitats of the two species are so different contributed to this. Pictures: Michael Wenger

“The four species that we propose live in quite different latitudes.”

Dr. Jane Younger, Director of Studies, University of Bath

Until now, the Gentoo penguins have been classified into one species (Pygoscelis papua) and two subspecies that live in different habitats. The researchers now propose to declare the two existing subspecies as new species and to introduce two more species: P.ellsworthi for the Antarctic Gentoo Penguins , P. papua, P.poncetii (South Georgia, named after Sally Poncet) and P. taeniata for gentoo penguin forms living further north. According to the scientists, the differences in DNA and physical characteristics they describe are so great and the habitats so far apart that it is no longer possible for the populations to interbreed. “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,” explains Dr. Younger. “The four species that we propose live in quite different latitudes. For example, P. ellsworthilives on the Antarctic continent whereas P. poncetii, P. taeniata and P. papua live further north where conditions are milder. So it’s not that surprising that they have evolved to adapt to their different habitats. “

Gentoos have the advantage over other Antarctic penguin species such as Adélies and chinstrap penguins that they not only depend on krill for food, but also hunt other crustaceans and small fish. Especially around the Antarctic peninsula, these krill stocks have declined in recent decades due to the warming and with it the stocks of Adélies and chinstrap penguins, which have been replaced by gentoos. Picture: Michael Wenger

The proposals for four new species also make sense for the scientists for reasons of protection. Although gentoo penguins are not currently considered endangered, a reclassification could change this status. “There is some evidence of the northern populations moving further south as the climate gets warmer, so we need to watch them closely”, says Dr. Younger. But establishing new species is not as easy as it sounds. An international committee of experts will now carefully examine the results and all of the related literature. Then a decision is made as to whether to make four out of one species. This check will take a while, as above all, the genetic data and the statistics, resp. the methods have to be checked carefully as traditionally, these areas are ones with the most mistakes. So it will be a while before ornithologists and penguin enthusiasts have to go back to Antarctica or the Sub-Antarctic Islands in order to be able to eventually add them to their personal lists.

Dr Michael Wenger, PolarJournal

Link to the study: Joshua Tyler, Matthew T. Bonfitto, Gemma V. Clucas, Sushma Reddy, Jane L. Younger. Morphometric and genetic evidence for four species of gentoo penguin. Ecology and Evolution, 2020 DOI: 10.1002 / ece3.6973

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