© Jim MartellAmerican hunter Jim Martell shot this hybrid polar-grizzly bear near Nelson Head on southern Banks Island on April 16, 2006.
The two grizzly-polar bear hybrids discovered in Canada's North in recent years may be the tip of the iceberg, warn a trio of U.S. scientists who say the bears are a sign that Arctic biodiversity is at risk.
Pointing to other Arctic hybrids - an apparent bowhead-right whale photographed in the Bering Sea in 2009, a suspected narwhal-beluga found west of Greenland in the late 1980s, as well as various confirmed hybrid porpoises and seals - they argue governments must manage hybrids before interbreeding leads to the extinction of rare species.
In a commentary published in Wednesday's peer-reviewed journal
Nature, National Oceanic and Atmospheric Administration marine biologist Brendan Kelly and his co-authors say rapidly disappearing sea ice means the barrier that once kept Arctic species apart is literally melting away.
"In addition to that, marine mammals are particularly infamous for hybridizing," says Kelly. "It turns out their genes haven't changed so much that they can't interbreed."
Co-author David Tallmon, a marine biologist with the University of Alaska, says while it's unlikely hybridization is widespread in the Arctic, no one has looked systemically at the issue. He and Kelly, along with Andrew Whiteley, a conservation geneticist at the University of Massachusetts, say the question of whether to try to stop animals from crossbreeding needs immediate attention.
Comment: There seems to be a good deal of activity in this area. See USGS Records 53 Quakes In Week In Arkansas County