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Fri April 4, 2014
So You Think It's a Wolfdog: What Can DNA Tests Tell Us?
Connecticut’s Department of Energy and Environmental Protection has ordered genetic testing for seven hybrid “wolfdogs” found in the state. But if all dogs come from wolves, can a DNA test actually tell us how much “wolf” and how much “dog” is in a hybrid?
To find out, I emailed Becky Ewalt-Evans at the UC Davis Veterinary Genetics Laboratory. They’re the lab running the test for DEEP. She said proving an exact percentage of a hybrid’s wolf ancestry is basically impossible. "Wolves and dogs are fairly closely related," Ewalt-Evans wrote. "Fixed genetic differences (that allow determination of origin) between wolves and dogs are relatively few."
But here’s what scientists can figure out: whether a domesticated dog has a wild wolf in its family tree within the last three generations.
To do that, scientists compare genetic data from known dog breeds to genetic data collected from wolf populations in the wild. They focus on a number of known genetic variations between the two — things like Y chromosome differentiation (in males) and DNA STR (short tandem repeat) markers that have variants specific to wolves. Results are then reported back as “dog,” “wolf” or “hybrid.”
Jessica Addams is the author of Between Dog and Wolf: Understanding the Connection and the Confusion, one of the few books published on this topic. In an email, she said DNA tests on hybrids aren’t yet terribly reliable.
"They don’t actually test for ‘wolf’ DNA," Addams said. "They’ll just report, ‘This dog does not match any breeds,’ which could mean it’s one of the breeds they don’t have samples for, an unusual mutt, a mutant, or a wolf, who knows? It’s possible to send a DNA sample out to a research laboratory for testing, I’m sure, but the research labs don’t (yet) have a really wide database of many, many wolves — usually they have a few individuals from local populations."
Here’s another question: what if hybridization extends beyond three to five generations of back-crossing to dog?
Ewalt-Evans said that means test results are unreliable. "Within each generation of back-crossing to dog," she wrote, "after the original wolf x dog breeding, there is random shuffling of genetic material such that a subject may end up with more or less wolf content. The biggest challenge to wolf-hybrid genetic analyses are for hybrids with high ‘dog’ content. The analyses easily detect higher ‘wolf’ content."
DEEP expects to receive the results of the UC Davis wolfdog test in the coming weeks.