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Few people have ever seen a wolf in the wild. Most of our knowledge about wolves comes from the movies, where the animals depicted are often gray members of the gray wolf (timber wolf) species. However, a recent study published in Science by a global team of biologists and molecular geneticists explains that up to 62% of wolves living in wooded areas are actually black.
Lineage of Black Wolves
Black wolves are most often found in North America while most wolves in Europe and Asia are either gray or white. In fact, the black wolves in Europe belong to a recently-hybridized group in Italy. How did black-colored wolves come to be? To find out, the DNA from 41 wolves in the Canadian Arctic and 224 more in Yellowstone National Park was compared with that of domestic dogs and coyotes.
Based on this research, scientists determined that wolves first started appearing in black about 10,000 to 15,000 years ago – some time after people began migrating to North America. These people brought their dogs with them, and it is believed that the offspring of domesticated dogs and wolves came with a genetic mutation. This mutation is what causes black coloration in wolves.
Genetic Questions
Some wildlife biologists claim that wolves vary by color depending on their hunting territory. Other scientists disagree. It doesn't seem that the animals need camouflage to protect themselves from predators or to aid in hunting. Wolves are faster than most of their prey and have the advantage of hunting in a pack.
Interestingly, the gene for black fur is part of a gene family that aids in fighting infection. Some scientists think that there may be an underlying cause for more black wolves in certain areas – the gene could help strengthen the immune system. Since black wolves are more prevalent in wooded areas (62% of populations in those locations) compared to on the open tundra (7%), it could be that the black gene helps to protect wolves from pathogens found in forests. Or, perhaps individual wolves just prefer to mate with wolves of the same color coat.
Black Fades
Black wolves do not remain black forever. They turn gray with age, just like many domesticated dogs (and humans!). This could be another indication that the gene does not exist to help with camouflage. Otherwise, the wolves would probably remain black throughout their lives.
Where are the Wolves?
The Northern Rockies (including the population in Yellowstone National Park) have about 1,300 wolves. Packs in Yellowstone usually consist of about 10 members and can be seen most frequently in the winter. Alaska is estimated to have about 7,500 to 11,000 wolves in packs ranging in size from six to 30.
Resources:
http://www.nytimes.com/2009/02/06/science/06wolves.html?_r=2
http://www.google.com/hostednews/afp/article/ALeqM5jv1yXsW5zF8jDpJlNPRZqJ7R9hDg
http://www.eurekalert.org/pub_releases/2009-02/uoc--bsm020509.php
http://blog.wired.com/wiredscience/2009/02/blackwolves.html
http://www.foxnews.com/story/0,2933,488704,00.html
http://en.wikipedia.org/wiki/Mackenzie_Valley_Wolf
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