Dilemma: Protect Mutts or Just Purebreds

The Endangered Species Act currently lacks provisions for genetically mixed populations. Should that change?

Many North American wolves are coyote-wolf hybrids, according to a new study that could lead to an important Endangered Species Act (ESA) change that may set a precedent affecting not only wolves, but also other animals.

The ESA currently lacks provisions for genetically mixed populations, aka hybrids or mutts, but DNA analysis studies like this new one reveal that such animals are sometimes already included in the Act as unique species.

An example is the red wolf, which the new study -- published in the journal Science Advances -- finds is a hybrid of about 25 percent now-extinct gray wolf and 75 percent coyote. The red wolf was listed as an endangered species in 1973, initiating a captive breeding program by the U.S. Fish and Wildlife Service (USFWS).

"The program began with 12 of 14 founding individuals selected because they lacked apparent coyote-like traits," senior author Robert Wayne, a professor of Ecology and Evolutionary Biology at UCLA, told Discovery News. "The descendants of these founders have led to several hundred red wolves that now form a reintroduced population in eastern North Carolina."

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The study conducted by Wayne, lead author Bridgett vonHoldt and their colleagues identified the red wolf's substantial coyote ancestry that likely resulted from another round of human activity.

"In the mid 1800s, federal, state and local governments extirpated wolves in the southeast by trapping, poisoning and by other means," Wayne said, explaining that coyotes then became more prevalent in the region. As the wolf population there diminished, they must have had trouble finding their own kind to mate with, resulting in the hybrids.

Coyotes do well, he said, "because the more we kill them, the more they amp up their reproduction. They are even in New York's Central Park now."

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The now-extinct population of southeastern gray wolves appears to be in the red wolf's genome, similar to the way that Neanderthals, which went extinct some 30,000 years ago, left their DNA mark in the genomes of people with Asian and European heritage.

Wayne and his team additionally found that the so-called "eastern wolf," which inhabits the Great Lakes region and the eastern U.S., is yet another hybrid that is about 50–75% gray wolf and 25% coyote. This is significant, as the USFWS has accepted the eastern wolf as a distinct species and has argued that the presence of eastern wolves in an area previously thought to be included in the geographic range of only the gray wolf is grounds for removing (de-listing) the gray wolf's ESA protection.

According to a USFWS fact sheet, "The gray wolf has rebounded from the brink of extinction to exceed population targets by as much as 300 percent. Today, there are at least 5,510 gray wolves in the contiguous United States. Wolf numbers continue to be robust, stable and self-sustaining."

Wayne and his colleagues, along with other animal experts, conversely believe that today's gray wolf populations in the U.S. are, as a whole, much smaller than what they were in the past.

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"We have not restored wolves to their past geographic ranges," Wayne said. "Based on genetic analyses, there were hundreds of thousands of wolves in the American West, for example, before their authorized mass extinction."

He added, "There is always pressure to de-list wolves, with some saying that they hurt livestock. The 'big bad wolf' image is still very much with us, even though grizzlies, black bears and mountain lions can have a greater impact on livestock."

He and his team propose a new ESA rule change that would address hybrids like the eastern and red wolves, in addition to purebreds such as the Holarctic gray wolf (Canis lupus). There was an attempt to create an "intercross policy" in the ESA in 1991, but that effort subsequently fizzled.

In the meantime, high tech genetic analysis methods have improved and are revealing that other animals protected by the Act -- such as Florida panthers and the northern spotted owl -- are often, in fact, hybrids.

Hybrids can, at times, pose problems. As an example, Wayne mentioned that native California tiger salamander individuals have bred with another, larger species to produce a hybrid that is bigger and "survives better," essentially becoming an invasive new species that is pushing out the native one.

The researchers propose a balanced conservation approach that focuses on historical patterns of genetic variation. In the case of wolves, that would mean restoring habitats to favor their original species, if still alive.

Roland Kays, a wildlife biologist at North Carolina State University, told Discovery News that the "data is adding up" that red and eastern wolves are hybrids. He agrees that the ESA should be changed to protect such animals, in addition to purebreds.

"It is important to protect hybrids," Kays said. "They are really common now throughout the world. There are many fish hybrids, for example, such as certain trout. Each hybrid population would have to be evaluated on a case by case basis."

Wayne is not very hopeful that the ESA will make the change, which could take up to a year to implement. Kays, on the other hand, believes that the future inclusion of hybrids in the ESA is "quite likely."

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