For decades a debate has raged over the nature of the canids colonizing the eastern United States. Are they the spawn of wolves and coyotes; of dogs, wolves, and coyotes; of dogs and coyotes; or simply coyotes grown larger from a steady diet of deer—not their usual fare.
In 1975, behavioral analysis of a litter of the New England canids by Marc Bekoff, Harriet L. Hill, and Jeffrey B. Mitton, all at the University of Colorado, revealed that they were more closely related to coyotes than to wolves or dogs (“Behavioral Taxonomy in Canids by Discriminant Function Analyses,” Science, 19 December 1975, Volume 190, pp. 1223-1225, by subscription). Other taxonomic studies led to similar conclusions about the mystery canid.
In recent years, genetic evidence has mounted they are coywolves, with some observers insisting that dogs were part of the mix.
It was called a canid soup, and the notion that these hybrids could successfully multiply and quickly expand their range was disquieting to many people, including environmental purists pushing for a reintroduction of wolves to the Adirondacks. Wolf opponents would use its existence to argue against the return of the larger, more majestic and more lethal wolf.
An environmentalist active in the reintroduction effort told me several years ago that the eastern canid, as it is sometimes known, could not be a wolf substitute because it could not bring down a moose. (Evidence has shown that it actually can.) He had wanted me to write something about bringing wolves back to the East, trotting out the moose after I told him a big carnivore already called those lands its own. As far as I was concerned the New England canid was, I told him, evolution in action, and we should welcome the opportunity to watch it unfold. That statement was heretical enough, given that everyone knew that hybrids, especially those involving wild and domestic animals could not possible be good for anything.
Now three researchers—Javier Monzón of SUNY Stony Brook, Roland Kays of the North Carolina Museum of Natural Science, and Daniel Dykhuizen also at SUNY Stony Brook have investigated the genetic ancestry of 427 canids from Ohio and the eastern states above the Mason and Dixon Line and found that all are admixtures of wolves, dogs, and coyotes, with the wolves representing eastern and western subspecies of gray wolf, and with the Great Lakes serving as a mixing/contact zone. Their article, “Assessment of wolf-coyote-dog admixture using ancestry-informative diagnostic SNPs,” appears in the January 2014 issue of the journal Molecular Ecology (subscription required).
For their analysis of what they call the eastern coyote in recognition of its predominant genetic heritage, the researchers chose 63 single nucleotide polymorphisms (SNPS) that have been proven good indicators of ancestry, meaning they are clearly associated with one species or population or another. Their results show that eastern canids are a mixtiure of coyotes (all initially from the West), eastern and western wolves, with the Algonquin wolf of Ontario representing the eastern population, and dogs. In most cases the matings seem to have been between larger males—be they wolves or dogs—and smaller female coyotes.
The researchers sorted their samples into three geographic regions—Ohio believed to host only pure coyotes; a contact, or mixing, zone around the eastern) Great Lakes for coyotes moving east, western and eastern wolves; and the Northeast region from the Mason and Dixon Line (the Maryland/Pennsylvania border) into southeastern Canada.
Coyotes south of the Line are believed to have arrived by a southern route, including escape from hunting camps, where they were being held for sport hunters. That raises the prospect of a mixing zone in Maryland and Virginia, where eastern and southern coyotes meet.
All the animals that the researchers sampled showed evidence of wolf-dog-coyote admixture although the percentages of each varied by area. The mixing was not uniform; Ohio’s canids, widely believed to be pure coyotes, were 24 percent wolf and 10 percent dog.
Those percentages are fairly constant across the study area, although they do show some variation based on geography and food supply, the researchers said. Thus, where forests and deer populations are dense, the canids are more wolflike, probably due to a steady diet of deer, not a regular part of the western coyote’s diet but standard fare for wolves. In areas more disturbed by human activities, coyote genes seem to increase.
What the dog contributes is a mystery since the researchers argue that hybridization with dogs is not continuing and thus their genetic contribution is being diluted. Still, there is some speculation that the dog genetic material might aid in the eastern coyote’s adaptation to human habitations and activities.
Not too many years ago, it was commonplace to dismiss the importance of hybridization between species as a vehicle of evolution. The biological species concept held that by definition species were reproductively isolated. Should representatives of two different species mate, their offspring would be infertile, if they were viable at all.
There is No matter whether it is called the eastern coyote or New England canid or eastern canid or some other name, this large predator should be celebrated for what it is and what it is telling us about evolution. In a real sense it is Nature’s response to a part of the world we have remade.