A Wolf Is a Dog Is a Coyote Is a Jackal Is a Dingo
New genetic studies show the closeness of canids.
Posted Aug 09, 2016
It is well known among Latin scholars, taxonomists, evolutionary biologists, natural historians, dog buffs, and other people familiar with the vagaries of taxonomy that the genus, or family, Canis takes its name from the Latin word for dog, meaning that all members thereof are technically dogs, “whether called dogs or wolves or coyotes or jackals or dingoes,” says Paul Errington in his book Of Wilderness and Wolves.
More than 50 years ago—well before the advent of comparative genomics—Errington observed: "In view of the original wild sources of domestic dogs, it should not be remarkable that some domestic dogs may show inclinations toward wildness; in view of the taming if not partial domestication of wild dogs that has repeatedly occurred during historical times, it should not be remarkable that some of the wild dogs should continue to show inclinations toward tameness" (p. 45, Kindle Edition). He then cited examples of wolves and coyotes, living in close proximity and friendship with people they had grown to trust, whom they did not fear, as well as examples of domestic dogs turned “wild” and vicious. The wild dogs he discussed were usually adult wolves and coyotes who made a decision to befriend welcoming humans. Theirs is a friendship of equals not of beggary, although certainly a confused human observer could misconstrue the animal’s motive if the human provided food to the visiting wolf or coyote.
Sometimes those adult canid friendships were stronger than those that wolf puppies formed with women who nursed them, apparently not an uncommon occurrence among hunters and gatherers, who would adopt all manner of animal. Although some of those wolves, sociable, curious, and inclined to fearlessness, even boldness when approaching strangers, would have stayed near the homes in which they were raised; others would have returned to more wolfish society.
As I have noted previously in this blog, the great cynologist, John Paul Scott observed decades ago that wolves exist on a continuum of dogs in terms of size, temperament, boldness, fear, sociability, and other physical, emotional, and mental traits. Put plainly, dogs are wolves and wolves are dogs.
That is the conclusion, too, of a little noticed paper in Genome Research [published online in December 2015; paywall] by Zhenxin Fan, of the Key Laboratory of Bioresources and Ecoenvironment at Sichuan University, China, and an international group of collaborators, including Robert Wayne, an evolutionary biologist at UCLA. Fan, Wayne, and their colleagues were examining worldwide genomic variation in modern wolves and dogs, using 34 dogs and wolves, as well as a golden jackal and coyote for comparison. Their findings confirmed among other things that the Eurasian wolf progenitor of modern dogs is extinct and that the genomes of wolves and dogs are thoroughly admixed—both ways—wolf to dog and dog to wolf. The researchers report that up to 25 percent of Eurasian wolf genomes show “signs of dog ancestry.”
They found that the first divergence of modern wolves from their common ancestor came about 52,000 years ago, following the divergence of New World wolves and coyotes. Dogs split next, meaning that they originated in Eurasia, just as most researchers have suspected. Furthermore, as Earth passed through the Last Glacial Maximum, and humans began to move across the planet some 25,000 to 8,000 years ago, virtually all modern wolves fell into genetic bottlenecks that the authors attribute to the colonization of Eurasia by anatomically modern hunters and gatherers with new weapons that allowed them to kill efficiently at a distance. They “domesticated” some wolves and killed others for their pelts. They may well have formed mixed packs with their new dogs to outcompete wolves for the large game all three favored. Dogs and wolves would have bred freely or with human encouragement, as people moved into “wild” new lands, using their dogs for transport and as guards, companions, and emergency food supplies. As a result wolf numbers declined while dogs increased.
Much of that is speculative, for now, and the dates are proximate rather than fixed, the result of making assumptions about generation times and mutation rates in ancient dogs and wolves, as well as behavior and location of wolves, dogs, and people at certain times and places. The researchers assert that “studies [of dog origins] that do not take admixture into account with specific demographic models are problematic.”
Fan, Wayne and their colleagues report that among their results was one suggesting that the time of divergence of wolves from coyotes set at one-million years ago and used to calibrate molecular clocks for studying canid evolution was off by a factor of 20 or more. Indeed, Wayne joined Bridgett vonHoldt of Princeton and other colleagues, including Fan, on a paper published last July 27 in Science Advances in fixing the time when coyotes and North American wolves diverged from a common ancestor at around 50.8 to 52 thousand years ago. Writing for the group, vonHoldt says:
Thus, the amount of genetic differentiation between gray wolves and coyotes is low and not much greater than the amount of differentiation within each species… This result contradicts molecular clock calculations based on short mitochondrial control region sequences, which were calibrated using a 1-Ma (million years ago) divergence time between gray wolves and coyotes. Despite body size and other phenotypic differences between the two species ,for example, and a long history of coyote- and wolf-like forms in North America, the genomic data suggest that modern coyotes and gray wolves are very close relatives with a recent common ancestry.
As that proposed correction indicates, dates from prehistory are constantly being revised. That is why it is necessary for people studying the evolution of anything, but especially dogs in all their variety, to understand what happened and where, and that cannot be done unless one understands the relation between early man and wolves, the essence of their partnership and its transformation. The dates will follow and probably will vary from place to place, as humans and dogs spread across the land—unless one day we “discover” that our cousins in Europe and Asia—Neanderthal and Denisovans consorted with wolves.
Dogs, wolves, and other canids are closer genetically than some populations of people and should, by rights be considered one species. That means the configuration that says a wolf is a dog is a coyote is a dingo is the correct one. They are thoroughly admixed and in some places continue to hybridize whether by design or chance encounter matters little. For hybridize we should by rights substitute miscegenate, as in a mixing of races.
Wayne, vonHoldt, and their colleagues were looking to see whether Canis rufus, the red wolf of the Southeastern U.S. and Canis lycaon, the so called “eastern” wolf, said by the U.S. Fish and Wildlife Service to have inhabited the eastern U.S. through the Great Lakes region[GM1] . Recently the Fish and Wildlife Service attempted to use these putatively unique species of wolves to delist the gray wolf, minus the Mexican wolf subspecies, thereby removing its protection under the Endangered Species Act. The courts rejected the scheme, and vonHoldt and Wayne’s work shows through exhaustive analysis of the whole genomes of 28 wolves and coyotes, as well as other canines for comparison, that neither the red wolf nor the eastern wolf is currently more than a gray wolf X coyote hybrid.
These arguments are not new: Wayne has been making them for a quarter of a century. But the US F&WS has previously rejected or ignored them, partly out of a reluctance to admit that the red wolf—one of the first species covered by the ESA and subject of one of the first captive breeding programs—is a hybrid. That program was started before modern genomics, when judgments of purity were based on physical measurements. The ESA was written to preserve species as the fundamental unit, the driving force of evolution, at a time when hybridization was dismissed as having no role—certainly not a positive one—in evolution. ESA made no provision for hybrids. They were believed to die upon birth if they made it that far, and if they were born, to be sterile, like mules; because by definition, species were unique breeding units.
What is new here is the degree of genetic mixing of North American wolves and coyotes. There is no genetic purity among them—even those outside hybrid zones are not free of some admixture—and that seems the point. vonHoldt, Wayne, and their colleagues modestly suggest that the ESA needs to be more flexible in recognizing hybrids and managing their habitat in ways that might encourage the hybrid offspring to become more wolf-like in genotype and phenotype over time. Given the current political climate, it seems unlikely that the ESA will be modified to benefit animals of any sort for any reason, much less wolves or other predators. In recent years, F&WS has repeatedly sided with rabid anti-wolf and anti-grizzly bear forces in defiance of its mandate to follow the best available science in decision making, not politics.
But the real question seems to me, are these animals hybrids, and the answer should be yes and no, not really. They have a mixed ethnic heritage, if one wants to use a human metaphor, but they remain dogs. Certainly, they exist in a human-made world because of human actions, but that is their reality, and they should be allowed to adapt to it, the way their ancestors adapted to their world. That’s one reason I find the eastern canid/coyote so fascinating. The animal is evolution in action, its mixed heritage of wolf/coyote/dog producing an animal who can move through the varied habitats of humans and apparently flourish. We don’t know what it is; it is still becoming, and we need to let it evolve.
Some years ago we spent a year on the headwaters of the Battenkill in Vermont, a beautiful marsh with resident beavers, otters, deer, and deer hunters who in the fall skulked the boarders of the marsh, shotguns in hand. I never saw one of he eastern canids there, but it would have been safer than a human hunter with a gun because the odds of it harming a person were much less than the human shooting someone by mistake, an annual occurrence in those parts it seemed. The year we were there, for example, a man accidentally shot and killed his son and then, despondent, shot himself. It is long past time to recognize that the predator most likely to kill not to eat, not to survive, is, as Pogo knew, us.