Previously, the gentoo penguin was believed to be a singular species of penguin, with three subspecies: northern, southern, and eastern gentoos. But following extensive study of the genetic variation between them, scientists have identified that the gentoo is actually four distinct species of penguin.
Southeastern gentoos live in the Kerguelen Islands, an archipelago of the coast of Antarctica, described as one of the most remote places on Earth. This means they are separate from the other species of gentoo penguin, which live in South America (northern gentoos), the Antarctic Peninsula (southern gentoos), and islands in the Indian Ocean (eastern gentoos) respectively.
The adaptation rate of birds is faster than that of other vertebrates. This means that when populations spread out and isolate, their evolutionary trajectories quickly diverge. In this case, gentoo penguins seem to have spread from areas they could survive in the islands north of the Antarctic Circle, to the polar waters of Antarctica to the south, and the warmer regions further north.
Gentoo penguins are opportunistic hunters who have diverse diets, which made this spreading out possible. At the same, their philopatric tendencies mean that breeding colonies put down roots in particular regions, returning to the same spots annually instead of continuously migrating, which is one of the reasons scientists gave for the emergence of the new species.
With the knowledge that these species are each independently evolving units which have their own demographic trends and threat profiles, there is a need for each species to have its own conservation assessments conducted. The IUCN Red List previously placed gentoo penguins at least concern with a stable population trend when assessing them as a singular species. However there has been rapid decline in particular areas which may mean that some species of gentoo penguins are be at greater risk than others — but this remains uncertain and greater investigation is needed.
The definition of a species and how to demarcate them is a long-debated topic of evolutionary biology. The scientists behind this discovery from UC Berkeley and the University of Chile in Santiago used the General Lineage Concept as a framework to define species when distinguishing between the numerous penguin types. However it is worth pointing out that this discovery is still subject to debate and consensus seems a long way away.
“Gentoo Penguins” by D-Stanley is licensed under CC BY 2.0.
