By Dr. Becker
The red wolf is said to be the rarest wolf species. Historically found in the southeastern U.S., the wolves were hunted nearly to extinction in the mid-1900s. Compounding matters was their propensity to mating with coyotes, leading to wolf-coyote hybrids.
In 1973, the U.S. Fish and Wildlife service (FWS) put the red wolf on the endangered species list and started a captive breeding program, which supposedly began with about a dozen “pure” individuals.
Two other wolf species are also recognized in North America, gray wolves, which once roamed across much of the U.S., and eastern wolves, which range from the Great Lakes into Eastern Canada.1
The designations are not nearly as straightforward as they may appear on the surface, however, as much controversy exists about whether red wolves and eastern wolves are, in fact, pure wolves or if they’d be better described as coyote-wolf hybrids.
Genomic Testing Reveals Wolves and Coyotes Are Very Close Relatives
In a study published in Science Advances, researchers sequenced the genomes of 28 large canids, including wolves from Asia, Mexico, Canada and the U.S. along with coyotes, dogs and one golden jackal.2 The purpose was to determine the ancestry of the different types of wolves (or wolf-coyote hybrids) roaming the U.S.
The data yielded some surprises, including that coyotes and gray wolves split into two distinct lineages from the Eurasian wolf far more recently than had been believed.
While this split was previously dated to about 1 million years ago (based on fossil records), the genomic analysis revealed the split occurred just 6,000 to 117,000 years ago, leading researchers to say, “They are very close relatives.”3
Further, red wolves and eastern wolves were also found to contain a lot of coyote genes — in some cases more than 50 percent.
The researchers concluded that red wolves and eastern wolves are not separate species but rather are hybrid wolf-coyote populations that flourished after gray wolves were hunted to near extinction and survived as a species by mating with coyotes.
Study co-author Robert Wayne, an evolutionary biologist at the University of California, Los Angeles, told Science, “There’s nothing in their genome that’s not gray wolf or coyote.”4
Why Aren’t Hybrids Protected Under the Endangered Species Act?
The study findings could have ramifications for the future protection of U.S. wolves. Red wolves are currently protected under the U.S. Endangered Species Act (ESA) and some argue the eastern wolf should also be protected, as it is in Canada.
FWS hasn’t listed eastern wolves under the ESA because they’re known to mate with coyotes and hybrids are not eligible for protection under ESA.
The findings that red wolves are also likely a hybrid could technically mean they could lose their ESA protections, but the researchers pointed out that this highlights an antiquated system that should account for mixed ancestry among animals.
Lead study author Bridgett vonHoldt, Ph.D., an evolutionary biologist at Princeton University, told Science:5
“People think that species should be genetically pure, that there should be tidy categories for ‘wolf’ and ‘coyote.’ That’s not what we found …
The study shows that mixed ancestry is common, even in animals [in the western United States] we’ve traditionally identified as ‘pure’ … It shows how outdated the endangered species policy is with respect to hybrids.”
The researchers also noted that “a strict designation of a species under the ESA … does not consider admixture [hybridization] can threaten the protection of endangered entities.”6 It’s also worth noting that several hybrid species, including the Florida puma and western spotted owl, have already been protected by the ESA.7
Coyote-Wolf Hybrids Are Incredibly Adapted to 21st-Century Living
Oftentimes breeding between animal species results in offspring that is less robust than its non-interbred peers, and in some cases the offspring may not survive at all. But in the case of coyotes and wolves, the combination has proven to be an exception.
Coywolves, a name used to describe some modern coyote-wolf hybrids, have adapted to survive well in both rural and urban environments, taking traits from either side — such as wolves’ preference of finding prey in forests and coyotes’ preference of hunting in open spaces — and combining them to their advantage. Coywolves, for instance, can catch prey in both open areas and forests.8
When researchers analyzed DNA from 437 so-called coywolves, they found coyote DNA was dominant while wolf DNA made up about one-quarter of the animals’ genetic material — and dog DNA actually made up one-tenth (primarily from larger breeds like Doberman Pinschers and German Shepherds).
Their wolf and coyote genes prepare them for life in the wild, but their dog DNA makes them remarkably suited to living in urban areas. Unlike wolves, which generally prefer to live away from humans, coywolves are not as bothered by people and noise.
Interestingly, researchers found differing “blends” of species in coywolves from different locales. In the Northeast U.S. the animals were primarily coyote followed by wolf and dog. In Virginia, in contrast, the animals were mostly coyote followed by dog and then wolf.9
Rather than an entirely new species, the coywolf may simply be an example of natural selection at its finest. The new genetic mixture — larger size, stronger jaws, a more varied diet and a penchant for urban living –— likely offers a significant survival advantage, which means the traits are bound to stick around for some time.
Simply the fact that they’re hybrids shouldn’t disqualify them from protection under the ESA, however. As the researchers concluded, “We argue for a more balanced approach that focuses on the ecological context of admixture and allows for evolutionary processes to potentially restore historical patterns of genetic variation.”10