What Is a Species?

The world around us is full of life. In biology, we use the word species to categorize living creatures. In the past, scientists mostly told species apart based on how they looked. It is easy to tell species apart when they look very different, like a blue whale and a horse, for example. When species are closely related, it can be more challenging to tell them apart, like horses and zebras, turtles and tortoise, frogs and toads, butterflies and moths, or even types of tigers. Sometimes, species look so similar that we cannot tell them apart based just on how they look. These are called cryptic species, and we must use special scientific methods to tell them apart, like taking very precise measurements of their bodies or by comparing their DNA [1, 2]. Recognizing species is very important for protecting wildlife, because scientists, governments, charities, and the public are all focused on saving species [3].

Gentoo Penguins

Gentoo penguins are one type of penguin that lives in the Southern Ocean, which is the body of water surrounding Antarctica.

You can recognize a gentoo penguin from its bright red bill, black head, and striking white patches on its face (Figure 1). They live across the whole Southern Ocean, from South Georgia and the Falkland Islands in the north, all the way down to Antarctica. The environment on the islands is quite different than that of Antarctica. On the islands there is less ice and more plant life, while in Antarctica there is far more ice and snow.

We know from other scientific studies that the number of gentoo penguins in Antarctica is growing every year. But that is not the case in other areas, like the sub-Antarctic islands, where the number of gentoo penguins is falling. This means that individual populations vary in their levels of success at getting food and increasing their populations. Eventually, some of those populations might go extinct if conservation efforts are not increased. Conservation usually applies at the species level, and we do not usually protect specific populations of the same species. Therefore, if the gentoo penguin is more than one species, we would be better able to protect them. Other scientists have already looked at gentoo penguins and found that groups were more distinct than they expected. We wanted to go a step further and use the latest science to find out if the differences meant gentoo penguins were actually more than one species.

In this study, we looked at gentoo penguins from four areas in the Southern Ocean, to see if they might be more than one species: the island of South Georgia, the Falkland Islands, Kerguelen Island, and the Antarctic Peninsula.

Evidence From Gentoo DNA

DNA is the material inside the cells of all living creatures (including you!) that carries all the information about how that creature will look and function. You can think of DNA as a tiny blueprint for making a living thing. By comparing their DNA, we can tell how similar or different creatures are, as well as how closely related they are. Your DNA is very similar to the DNA of your siblings, quite similar to the DNA of other humans that are not in your family, and very different from the DNA of a tree frog or a penguin.

In our study, we compared the DNA of gentoo penguins living in the four areas of the Southern Ocean using a small drop of their blood. We found that the penguins that live together in the same area have DNA that is very similar to each other, but between areas, we found that the penguins’ DNA is very different [4].

Evidence From Gentoo Measurements

Because the DNA of the gentoo penguins is different between locations, we also looked closely at their bodies to see if there are any differences in how they look. If you were on a boat in the Southern Ocean and a gentoo penguin jumped out of the water and landed at your feet, it would be extremely difficult to know which area it came from just by looking at it. That is because penguins from separate areas have very similar colors and overall shapes. However, it is possible that there are smaller differences that we do not notice at first glance.

We visited museum collections that have lots of preserved gentoo penguins and used a pair of calipers and a ruler to carefully measure their bodies. By measuring the heads, legs, and flippers and comparing measurements between penguins in the four areas, we found that penguins from each area have slightly different sizes. Gentoo penguins from Antarctica are the smallest, followed by Kerguelen, then South Georgia, and the gentoos from the Falkland Islands were the biggest.

New Species Alert

All the evidence points to gentoo penguins being four separate species: Pygoscelis papua for the Falklands Islands gentoos, Pygoscelis taeniata for the Kerguelen Island gentoos, Pygoscelis ellsworthi for the gentoos from Antarctica, and finally Pygoscelis poncetii from South Georgia. One of the most exciting things about finding new species is that we get to name them. Pygoscelis poncetii is named after Sally Poncet, a marine biologist who works in South Georgia where the new species is found. Figure 2 shows where each of the four species live and Figure 3 shows each of the new species in their habitats.

Conclusion

Discovering new species is an incredibly exciting part of biology. In our study, we used DNA and body measurements of gentoo penguins to look for cryptic species, and we found that gentoo penguins are actually four separate species. By using the latest tools in biology, we can find new diversity in the most surprising of places, including in very well-known animals like penguins. There are many other penguin species beyond the gentoo penguin, each facing challenges in the face of climate change. By understanding their biology and how many species there are, we can learn how to best protect penguins—as well as many other types of creatures—so that generations of people can enjoy them.

Glossary

Species: ↑ A group of closely related organisms that can reproduce with each other and produce offspring that can reproduce with other similar individuals.

Cryptic Species: ↑ Groups of organisms that look nearly identical but are actually different species that cannot reproduce with each other.

DNA: ↑ The material inside cells that provides instructions on what an organism will look like and how parts of the body will work.

Conservation: ↑ The act of protecting species from extinction and actively maintaining or restoring habitats.

Museum Collections: ↑ Collections found in museums that contain many specimens (bones, teeth, stuffed skins, etc.) of various species. Scientists use these collections to study species without having to find them in nature.

Calipers: ↑ Used to measure lengths like a ruler, Calipers allow scientists to get exact measurements of objects that are often odd shapes.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.