Categorized | ESA, Imperiled Wildlife

Conservation Implications for Delimiting Species

Historically, wolves roamed across North America, from coast to coast and Alaska to Mexico. But an aggressive campaign of hunting and trapping in the early 1900s left wolves in very few places where they once lived. Conservationists, scientists, and managers working to recover wolves today face a difficult task: combining historical records, the present-day distribution of wolves, and genetic analyses to determine the kinds of wolves that once lived in different parts of the U.S. This problem is particularly evident in places like New England where wolves were once abundant but are not found today. Occasional interbreeding between wolves, coyotes, and even dogs blurs the boundaries between species and only adds to the challenge.

Biologists now recognize several distinct subspecies of gray wolf (Canis lupus), each of which is adapted to life in a different region of North America. For example there is the lobo of the southwest (C. l. baileyi) and the snow wolf (C. l. arctos) of the arctic tundra. The assortment of gray wolf subspecies also includes a northeastern variety – the so-called “eastern wolf” or Canis lupus lycaon – that was once found throughout the forests of eastern Canada and New England. These eastern wolves are smaller than their western and northern cousins, likely enabling them to efficiently hunt small prey. But not everyone agrees with this assessment. Recently the U.S. Fish and Wildlife Service (Service) argued that the eastern wolf is instead a unique wolf species, dubbed Canis lycaon. The Service contends that eastern wolves are actually more akin to coyotes than to gray wolves, and that gray wolves never lived in the east. But a recent peer review of this science showed that this is not the majority view among biologists.

Are eastern wolves a full species or just a distinct population or subspecies of one of these other canids? Several genetic studies have tried to tackle this question, but the results so far are conflicting. Studies based on DNA that wolf pups inherit from only their mother (and not their father) suggested that eastern wolves may be a distinct species. However, other evidence including an excellent study based on over 48,000 different “markers” (parts of the genome used to tell individuals apart) found that eastern wolves are the result of gray wolf and coyote interbreeding. This hybridization between wolves and coyotes likely began about 600 to 900 years ago and resulted in eastern canids that are about 85% gray wolf and 15% coyote today. Therefore eastern wolves could be a distinct subspecies, a distinct species, or even a group of gray wolf and coyote hybrids. Although the science remains unsettled, most wolf taxonomists and the American Society of Mammalogists disagree with the Service’s position that the eastern wolves and gray wolves are different species.

While the identity of eastern wolves may seem like a mere disagreement among biologists, the issue turns out to have major conservation ramifications. The Service currently plans to strip gray wolves of their endangered species protections throughout most of the country, including in New England. Although no wolves have been found in New England recently, large areas of excellent wolf habitat remain, especially in Maine. But the Service claims that gray wolves (C. lupus) never lived in New England; they say it was eastern wolves (C. lycaon), a new species with no current legal protections. With some taxonomic sleight of hand, the Service cut out the northeast from the historical range of gray wolves, and made it easier for endangered species protections to be removed everywhere. Divide – then conquer.

As you might imagine, the Service’s plan has received considerable criticism. The delisting plan ignores much of the available science and is not the consensus of biologists. As the peer review panel pointed out, even if eastern wolves are a distinct species, gray wolves may have once roamed New England too. Therefore more time is needed – for scientists to sort out the taxonomy of wolves, and for gray wolf populations to recover across their former range – before protections for wolves are removed.


Dan Thornhill, Ph.D.

Conservation Scientist

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Dan Thornhill is a Conservation Scientist at Defenders of Wildlife. He conducts original basic and applied research at Defenders while providing science-based advice for conservation and education programs. His focus is on the conservation of coral reef ecosystems and large carnivores. He works closely with the staff at Defenders, colleagues in academia, and staff at other conservation organizations with a similar interest in the protection and sustainability of threatened and imperiled species.

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