June 1, 2011

Genetics Show Eastern Wolves Are Coyote Hybrids

A new genetic study finds that wolves in the eastern United States and Canada are actually hybrids of gray wolves and coyotes, while the area's coyotes are wolf-coyote-dog hybrids, according to a recent Associated Press (AP) report.

The research advances a long-standing debate over the origins of two endangered species -- the red wolf, Canis rufus, in North Carolina and the eastern Canadian wolf, Canis lycaon, in Ontario.  

The author's of the current study concluded that these hybrid wolves developed relatively recently, over the last few hundred years.

However, some scientists believe the wolves evolved from an ancient eastern wolf species distinct from the larger gray wolf, Canis lupus, found in western North America.  They say the current study is interesting, but does not explain why hybrids appear only in some places.  Furthermore, western wolves don't hybridize with coyotes, but often kill them, they say.

In the current study, a team of 16 international scientists, led by Robert Wayne of the University of California-Los Angeles, used data from the dog genome to assess the genetic diversity in dogs, wolves and coyotes.

The research was the most intensive genetic study of any wild vertebrate species to date, using sophisticated molecular genetic techniques to examine more than 48,000 markers throughout the entire genome, study co-author Roland Kays, curator of mammals at the New York State Museum, told the AP.

In a previous study of the dog genome published last year in the journal Nature, an international team of researchers, also led by Wayne, reported that domestic dogs likely originated in the Middle East.  These animals were more genetically similarity to Middle Eastern gray wolves than any other wolf population, the researchers said.

However, the current study showed a gradient of hybridization in wolves.  In the West, wolves were pure wolf, while in the western Great Lakes, they were 85 percent wolf and 15 percent coyote, on average.  Wolves in Algonquin Park in eastern Ontario averaged 58 percent wolf, the study found.  The endangered red wolf in North Carolina was found to be 24 percent wolf and 76 percent coyote. Northeastern coyotes, which only colonized the region in the past 60 years, were found to be 82 percent coyote, 9 percent dog and 9 percent wolf.

In a separate study co-authored last year by Kays in the journal Biology Letters, an analysis of genetic samples and museum specimens revealed that coyotes migrating eastward bred with wolves to evolve into a larger form.  The animals became the top predator in the Northeast, filling the void left when native eastern wolves were hunted out of existence.

The hybridization enabled the coyotes to evolve from the scraggy mouse-eaters of western grasslands to strong deer-hunters in eastern forests.

The genetic techniques used in the current study allowed the researchers to estimate that the hybridization happened when humans were hunting eastern wolves to extinction, Kays explained.

"The few remaining animals could find no proper mates so took the best option they could get," Kays told the AP.

Some scientists are skeptical of the theory that eastern wolves are hybrids.

"How do you reconcile this with the fact that gray wolves typically don't breed with coyotes, but kill them?" said L. David Mech, senior research scientist at the U.S. Geological Survey's Northern Prairie Research Center in St. Paul, Minnesota.

"We have no records in the West of wolves hybridizing with coyotes, even in areas where single wolves looking for mates have dispersed into the middle of coyote country," said Mech, founder of the International Wolf Center in Ely, Minnesota, during an interview with the AP.

Mech also has doubts about whether the researchers tested enough Canadian and North Carolina wolves, and whether the specimens were truly representative of those populations.

Mech said the 48,000 genetic markers examined in the study are only a relatively small part of the entire genetic code.  Therefore, the evidence of a unique eastern wolf ancestor could simply be in another part of the code that wasn't analyzed, he said.

The study was published online earlier this month in the peer-reviewed journal Genome Research. 


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