Natural History

One of the real problems in determining the exact taxonomy of the dog family is the interfertility that exist between certain species in the genus Canis.  The dog/dingo/New Guinea singing dog/Holarctic wolf species (Canis lupus) can interbreed with the coyote (Canis latrans), the golden jackal (Canis aureus), and the Ethiopian wolf (Canis simensis) and produce fertile offspring.  Coyotes and golden jackals have been interbred in captivity and have also produced fertile offspring, so it is likely that all of these animals can hybridize with each other. According to the phylogenetic tree drawn from sequencing the dog genome, the Ethiopian wolf was the earliest offshoot of the interfertile Canis lineage , diverging 3 to 4 million years ago. And of the  “interfertile four,” it  is the most distantly related to the Canis lupus species, which strongly suggests that all four species can produce hybrids.

Potential interfetility alone is not the test for determining species, so one should not make the error of claiming that all of these interfertile dogs represent a single species.

They don’t.

Each of these animals has a unique evolutionary history, and they don’t normally hybridize in the wild.  Wolves and coyotes only cross when wolf populations are very low, and the male wolves mate with female coyotes. It is very difficult to get a dogs and golden jackals to crossbreed, though there may be be some evidence of dog genes in golden jackal population. Only the Bale Mountains National Park Ethiopian wolves have been found to cross with domestic dogs.

But various historical records, show that dogs and wolves got it on regularly when wolf populations were much higher and dogs were given more liberty. In the Old West, the best way to kill a wolf was to use a bitch in heat to draw in the male wolves. While the two were tied, it was very easy to come in with an ax or club and dispatch the male wolf, who was literally caught with his pants down. Male dogs were often known to go running off during wolf mating season, and they often returned– usually quite worn out. Wolves have been known to kill and eat other wolves that come into their territories, which is often how they will respond if a dog shows up. But there are historical accounts that show that wolf and dog interactions are much more complex than one might assume. The wolf and dog are now regarded as conspecifics. The dog is now believed to have derived from Eurasian wolves, with Middle Eastern wolf subspecies provided most of their current genetic diversity.

Dingoes and New Guinea singing dogs are derived from domestic dogs that went feral in their respective countries. Some natives of Papua New Guinea have hunting dogs that are derived from “wild” stock, and different groups of Indigenous Australians used dingoes as hunting dogs. So we now consider these animals to be derivatives of the wolf, but their most recent ancestors were domestic dogs. which were derive from wolves.

That’s why I say the Canis lupus is the Holarctic wolf/dingo/New Guinea singing dog/domestic dog species.

The existence of domestic dogs worldwide has caused a lot of confusion in classifying these species. Domestic dogs vary widely in appearance, and if an usual wolfish creature was spotted, it was assumed to be something unique. In reality, these creaturesmay have been nothing more than an aberrant domestic dog or a hybrid with a domestic dog.

Domestic dogs have contributed some genes to wild populations. Black wolves and coyotes received their melanism through hybridization with black domestic dogs.   Modern wild dog species do not have dewclaws on their hind legs, but domestic dogs do. Italian researchers found that if they found any wolf with dewclaws on the hind legs, they could be certain that it had some dog ancestry.

Now, the notion that dogs and wolves could be the same species isn’t as hard to fathom as another concept that stems from the interfertility between species in the genus Canis.

In North America, there has been some amount of gene flow between the dog and wolf species and the coyote.

Although Canis lupus and Canis latrans don’t regularly hybridize, they have done so enough to fundamentally change the genetic composition of each other.

Perhaps the first study to reveal the importance of this hybridization was Robert Wayne’s study of wolf and coyote mtDNA, which suggested that some wolves were actually coyote hybrids.  This study revealed an extensive hybrid zone between wolves and coyotes in North America, which likely resulted when wolf populations were decimated and the remaining wolves were forced to chose coyotes  for their mates.  Wayne’s research also pointed to the distinct possibility that the much ballyhooed red wolf was probably a hybrid, and this finding was confrimed in a microsatellite analysis.

In the early 90’s, this finding was not necessarily well-received. Supposed red wolves had been captured in Louisiana and East Texas, and these animals had been bred for decades in order to be released into the wild. In 1987, some red wolves from this breeding program was released into the Alligator National Wildlife Refuge in Eastern North Carolina.  By the early 90’s, this program was one of the more successful attempts at restoring endangered species under the Endangered Species Act.

Further, another microsatellite analysis revealed that the wolves of Algonquin Park in Ontario, which had been thought of as being derived from wolf/coyote hybrids, were actually a unique species. Proposed as the Eastern wolf species (Canis lycaon), it was believed to the same species as the red wolf. If these findings were true, then the only wolves to live in the temperate regions of North America were a unique species. The only survivors of this species were the wolves that lived in parts of Ontario and Quebec and the red wolf.

Microsatellite and mtDNA analysis are biased samples. They examine only a tiny part of the genome, and it is possible for these studies to produce really bad results.

What was needed was a study of nuclear DNA.

Unfortunately, studies of nuclear DNA were quite expensive and labor intensive.

It has been only in the last two years that really good analysis of dog and wolf genome has happened.

This spring, a study that examined 48,000 genetic markers within the genome of different populations of wolves, coyotes, and domestic dogs revealed that the so called Eastern wolf and red wolf are simply not valid species. This was the most in depth analysis of the genetic material of any wild species and unlike the previous studies, included a broad sample of the genome.

They wolves of Algonquin Park are fairly close to 50/50 wolf and coyote hybrids, averaging 58 percent wolf and the rest coyote. The red wolf was found to be almost entirely coyote. On average, it was found to be 76 percent coyote and only 24 percent wolf.

It was also revealed that most Eastern coyotes have both wolf and dog ancestry, and it is from wolves that Eastern coyotes have inherited several wolf-like characteristics and adaptations. They have larger size and more powerful jaws than their Western counterparts, which makes preying upon deer much easier.

The so-called red wolf has only slightly more wolf ancestry than many Eastern coyotes, so it makes very little sense to go on and on about it.

But even if these studies have cast real doubt on the validity of the red wolf and Eastern wolf as valid species, they have revealed something else.

In North America, wolves and coyotes don’t merely exist as two potentially interbreeding yet clearly distinct species.

They actually exist within what is called a species complex.

In a species complex, it is somewhat difficult to determine where one species begins and another ends. The two species are exchanging genes, if not regularly then regularly enough to cause a great deal of blurring between the two. This hybridization also winds up affecting the evolution of both species.

The  so-called red wolf, the so-called Eastern wolf, and the Eastern coyote subspecies are examples of  how the gene flow between these two species wind up blurring the edges.

The species complex should called the Canis lupus/Canis latrans species complex.

Thus far, it is the only one that has been discovered within large terrestrial carnivores, but one likely existed between polar and brown/grizzly bears. One may exist between bobcats and Canada lynx, and one existed between modern humans and Neanderthals– and perhaps the Denisovan hominins, if they actually existed.

Golden jackals might have something similar going on in the Old World. Golden jackals are widespread animals, and they can hybridize with the Canis lupus species. Wild jackal-dog hybrids have been spotted– almost always the result of a male dog mating with a female jackal. Because they are raised by the wild parent, the pups will imprint upon the golden jackal, and if they survive to reproduce, they will likely contribute to the golden jackal population. In this way, dogs could have contributed genes to the golden jackal in the same way that dogs and wolves have contributed genes to coyotes.

I know of no examples of wild wolves interbreeding with golden jackals. However, there was canid that was thought of as a subspecies of golden jackal living in East and North Africa, but analysis of its mtDNA revealed it was actually a wolf. Nuclear DNA studies need to be performed to see exactly what it is, but in its mtDNA, it was found to be similar to the Indian and Himalayan wolf subspecies, which both possess the most ancient of modern wolf lineages. This “African wolf” (Canis lupus lupaster) is often quite small, so it could interbreed with golden jackals. In fact, I had initially thought the Egyptian population of these wolves, which had initially been believed to be the only wolf in Africa, was the result of hybridization with a relict North African population of Arabian wolves and the golden jackal. In dog and golden jackal hybrids, the father is usually the dog. In a wolf/golden jackal hybrid, the parentage is probably similar.  If the African wolf were a hybrid in the same way the red wolf is, the mtDNA– which is inherited maternally– would be unequivocally be that of the golden jackal, not some form of wolf.

The golden jackal has not been examined in the same way that the coyote, wolf, and dog have been. The African wolf subspecies has also not been examined in this depth.

It is possible if these animals were included in these studies that it might reveal a Canis lupus/Canis latrans/Canis aureus species complex.

Even though species complexes exist, the species in them are still distinct.

They are just less distinct than the differences between a wolf and an Ethiopian wolf and even less distinct than the differences between a wolf and a red fox.

The edges between wolves and coyotes are blurred through their interfertility.

Amazing, eh?

See related posts:

• The creature formerly known as the red wolf
• No unique “Eastern wolf” species