Like inmates on Alcatraz, Iceland's arctic foxes (Vulpes lagopus) live their lives surrounded by freezing water. But unlike those prisoners, Iceland's foxes have had periodic contact with the outside world. DNA evidence shows that they share several genetic markers with arctic foxes from around the world. But how they managed to mingle with arctic foxes from as far away as North America and Norway puzzled researchers until now. Around 100 to 300 years ago, during the Little Ice Age, sea ice bridges formed between landmasses and gave foreign foxes the means to move into Iceland, say scientists in a study published online today in the Proceedings of the Royal Society B. The researchers compared 1000- to 700-year-old arctic fox DNA from archeological sites in Iceland to modern-day arctic fox populations. The ancient and modern Icelandic foxes share one DNA variation, called I2, which arctic foxes from other parts of the world don't have. But the modern Icelandic foxes also have four DNA variations that their ancient relatives didn't have—three of which also show up in arctic fox populations elsewhere around the world. That suggests that migration must have occurred at some point—probably over sea ice bridges that connected Iceland to Greenland for several months each year, the researchers say. But with declining sea ice due to climate change, the team notes, Iceland's arctic foxes will become more isolated, and more genetically distinct.
See more ScienceShots.