Emperor penguins migrate throughout the frozen Antarctic continent, creating a single interbreeding population. And being one big circumpolar population ensures evolutionary unity in the species, according to findings published in Nature Communications last week.
Robin Cristofari of Université de Strasbourg and colleagues sequenced the genomes of 110 emperor penguins (Aptenodytes forsteri) from six colonies spanning the entire range of the species. Some of these colonies are separated by 8,000 kilometers (5,000 miles) of coastline. To study small- and large-scale movement and migration, the team sampled three colonies around Adélie Land in eastern Antarctica, two colonies from across the continent in the Weddell Sea area, and one colony from the Ross Sea region.
They discovered that emperor penguins are one single population. Despite their fragmented distribution, emperor penguins have a remarkable degree of what’s called genetic homogeneity: The entire species shares a common gene pool thanks to their continent-wide dispersal. Most juvenile emperor penguins will leave their natal colony for about two to three years for a life at sea before attempting to breed. The majority of penguins return to mate and raise chicks in the colony they were born in. However, every generation, each colony receives, on average, between 0.7 and 4.2 percent of its population size in migrants. Based on their estimates, a colony like eastern Antarctica’s Pointe Géologie – with 7,000 breeding adults – would exchange between 260 and 300 migrants per generation with the rest of the continent.
As a single genetic population, emperor penguins will follow a shared evolutionary trajectory with global climate change. They’ll be similarly resilient and similarly vulnerable. But that also means that each colony of this near-threatened species has a much larger reservoir of genetic diversity than researchers previously thought. “Diversity is the raw material of evolution,” according to study author Emiliano Trucchi of University of Oslo in a statement. “So the more the better.”
