While current climate conditions may be optimal, genetic analysis of emperor penguins has suggested that parts of Antarctica were too harsh for large populations to survive during the last ice age

ROSS SEA – Only three species of emperor penguins may have survived the last ice age and the Ross Sea in Antarctica was probably the refuge for one of them, research published in the journal Global Change Biology has claimed.

The research was led by scientists from the universities of Southampton, Oxford, Tasmania and the Australian Antarctic Division and was supported in Antarctica by Adventure Network International. The study, which assessed how climate change has affected emperor penguins over the last 30,000 years, suggests that previous environmental conditions during the last ice age—about 19,500 to 16,000 years ago—in Antarctica were actually too hostile for large populations of emperor penguins to survive.

Emperor penguins are renowned for their genetic adaptations to their icy surroundings; they can, for example, breed on sea ice when temperatures plummet to below minus 30C (minus 22F) during the Antarctic winter. However, while examining the genetic diversity of modern and ancient emperor penguin populations, the research team discovered that, as a result of the previous ice age, the population was seven times smaller than today and divided into three refugial populations.

Gemma Clucas, a PhD student from Ocean and Earth Science at the University of Southampton and one of the lead authors of the paper, explained: “Due to there being about twice as much sea ice during the last ice age, the penguins were unable to breed in more than a few locations around Antarctica. The distances from the open ocean, where the penguins feed, to the stable sea ice, where they breed, was probably too far. The three populations that did manage to survive may have done so by breeding near to polynyas—areas of ocean that are kept free of sea ice by wind and currents.”

The study revealed that one polynya capable of having supported one refugial emperor penguin population during the previous ice age may have been the Ross Sea. Emperor penguins from the Ross Sea are genetically distinct from others in Antarctica.

Jane Younger, a PhD student from the Australian Institute for Marine and Antarctic Sciences and the other lead author of the paper, commented: “Our research suggests that the populations became isolated during the last ice age, pointing to the fact that the Ross Sea could have been an important refuge for emperor penguins and possibly other species too.”

“It is interesting that the Ross Sea emerges as a distinct population and a refuge for the species. It adds to the argument that the Ross Sea might need special protection” Dr Tom Hart, from Oxford University’s Department of Zoology and one of the organisers of this study, added.

Antonio Sousa, Correspondent (Antarctica)

Image Courtesy: US Embassy (https://www.flickr.com/photos/us_embassy_newzealand/5245341604), Licensed under the Creative Commons Attribution-NoDerivs 2.0 Generic | Flickr