Wildlife experts at the Smithsonian Institution say the migrations eastward -- via two main routes -- have been driven by changes in North American ecosystems over the past 150 years.
One route was through the northern United States, and the other went through the south, and DNA samples have shown that along the way the coyotes often interbred with native wolves, a Smithsonian release said Tuesday.
In a study of coyotes in Virginia, DNA shows they were most closely related to coyote populations in western New York and Pennsylvania, suggesting coyotes migrating along northern routes encountered Great Lakes wolves and interbred before converging again on the East Coast.
"The Mid-Atlantic region is a particularly interesting place because it appears to mark a convergence in northern and southern waves of coyote expansion," Smithsonian researcher Christine Bozarth said. "I like to call it the Mid-Atlantic melting pot."
With expanding coyote populations, wolf populations have become endangered, and hybridization with coyotes is a major threat to the recovery of wolves, researchers said.
"The admixed coyotes have also been found further south, into North Carolina, which brings the hybridized coyote into the range of the critically endangered red wolf, further complicating the issue," Smithsonian research geneticist Jesus Maldonado said.
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