Watch out, Rudolph: Climate change endangers reindeer games
Reindeer habitats are shrinking in the face of global climate change. While some pockets will survive, their genetic diversity and ability to withstand change is vulnerable, say scientists.
Reindeer may or may not be able to fly – that's a matter of belief – but they definitely need room to roam and lichen to eat, and global climate change is threatening that, say scientists.Skip to next paragraph
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"We want to know how reindeer and caribou will cope with climate change," says Glenn Yannic of Université Laval in Quebec, lead author on an article in the current issue of Nature Climate Change. "These animals have already faced two climate changes: We're now in a warming period, but ten to twenty thousand years ago, the Northern Hemisphere was very cold."
By genetically mapping the migrating population during the dramatic climate change since the last Ice Age, the researchers are able to predict both where the herds will move as the planet warms, and how diverse their herds will be.
The idea that climate change is reducing wildlife habitat is nothing new, but this international team of researchers took it a step further.
"We've tied habitat stability to reservoirs of genetic diversity," says Kris Hundertmark, a wildlife ecologist at the University of Alaska – Fairbanks and a co-author on the paper. "We've always thought that this would be the case, but ... we finally have that link now."
Genetic diversity strengthens a species, making it better able to withstand changes and challenges. "Genetic diversity is a bit like a Swiss (Army) knife," says Dr. Yannic, a native French speaker. "In a Swiss knife, you have a lot of tools that allow you to cope with different situations in your life. Genetic diversity is the same for a species... The more genetically diverse, the more a population has tools to cope with new or abnormal situations."
The researchers mapped out the genetic variation within reindeer and caribou populations in North America, Europe, and Asia. ("Reindeer" and "caribou" are the European and North American labels, respectively, for members of the same species, Rangifer tarandus.) This included gathering DNA samples from 1,297 animals. The scientists found two subspecies of Rangifer, indistinguishable to the eye but genetically very different.
The "Euro-Beringia" subspecies is found throughout the northern reaches of Europe, Asia, and the western two-thirds of North America, while the other subspecies lives only in northeastern North America, south and east of the Hudson Bay.
"The caribou from the western part of the Hudson Bay are more related to caribou in Europe – to 'reindeer' – than to caribou from the eastern part of the Hudson Bay," says Yannic.
Survivors of the Ice Age
These giant members of the deer family make up one of only a handful of species left over from the "Beringia megafauna," the group of massive creatures from the last Ice Age that includes mammoths and mastadons, saber-toothed tigers, musk oxen, moose, and steppe bison, the ancestor to the American bison and the wood bison, still found in Canada but extinct in Alaska for about 200 years.
"Actually, the wood bison is a poster child for what we don't want to happen to caribou," says Dr. Hundertmark. The wood bison were driven locally extinct both because of overhunting and because of ecological factors, he says. "The types of habitat they were adapted to – grasslands – there just weren't many of them left in Alaska. The boreal forest had more or less taken over, so the suitable areas of habitat for them were very small. And then, that allowed them to be hunted out very easily, because they had such small populations.... When you have that isolation, things can go badly wrong."