Egyptian jackal or African wolf with golden jackal and wolf-like features. From “Roosevelt in Africa” (1910).
One the strange ironies about dogs is that we have set up a system in which populations are maintained without regular influxes of new blood. However, at no point in the evolutionary history was this ever the case.
Some dog fanciers maintain breeds as if they were distinct species, and in some breeds, one can find lore that they are derived from sort of wild canid that has nothing to do with wolves or the rest of dogdom. Chihuahuas are supposedly domestic variants of the fennec fox. The Japanese chin was said to be distinct species that belonged to its own genus.
But no matter how you slice it, domestic dogs are all one species, and what is even more important, the more we have found out about the genome and that of their closest relatives, the harder it becomes to think of them as a distinct species from the wolf.
And if that weren’t such a revelation, it really gets more bizarre when we have no learned that wolves, golden jackals, and coyotes are not the cut-and-dry species we assumed them to be. In Eastern Canada and the Northeastern US and Midwestern US, we have discovered that wolves and coyotes have hybridized a whole lot more than we realized. We have also found evidence that golden jackals and wolves have hybridized in Bulgaria. Both coyotes and golden jackals can cross with wolves or domestic dogs and produce fertile offspring.
To make things more complicated, it turns out that wolves and golden jackals have continued to exchange genes since the two species separated. A recent genome-wide study of modern dogs, wolves, and golden jackals revealed that Eurasian wolves and golden jackals continued to mate with each other after their initial separation. The authors found substantial gene flow between golden jackals and Israeli wolves, as well as the ancestral population to all wolves and domestic dogs.
Most North Americans are aware of the taxonomic controversies involving coyote and wolf hybrid populations, including the red wolf and the proposed “Eastern wolf” species, but it turns out that this problem also exists in the Old World.
There is now a debate as to whether certain sub-Saharan and North African golden jackals are golden jackals or wolves. A few years ago, there were several studies that suggested that the mitochondrial DNA of certain African golden jackals were actually those of a primitive wolf lineage. There is still some debate as to whether these animals are wolves or jackals, and some of the proposed wolves have been found to hybridize with golden jackals in Senegal.
In utter ignorance of the natural history of wild Canis, domestic dog fanciers have spent the past century to century and half splitting up gene pools under the delusion that this somehow preserves them. Never mind that for most of their suggested 2 or 3 million years on the planet, wild wolves have continued to exchange genes with their closest relatives. When species hybridize, it was always thought that this would be a negative, but in truth, hybridization can be source of genetic rescue. In the case of Eastern coyotes, crossing with wolves can introduce new genes for more powerful jaws and larger size, which make them better predators of deer. It can also introduce new MHC haplotypes, which can provide the animal with enhanced immunity to disease.
One way of looking at golden jackals and coyotes is they are actually themselves primitive wolves. This might sound a bit heretical, but if you were to go back into time and find the ancestor of all wolves, golden jackals, and coyotes, it would look more less like a golden jackal or coyote. I would argue that these animals represent a sort of generalized template from which larger, more specialized forms can evolve. One of the problems in sorting out wolf, coyote, and jackal lineages from the fossil record is that at various times through their history on the planet, different lineages have evolved larger wolf-like sizes or have produced coyote or jackal-like forms to fit the niche in question.
A recent comparison of golden jackals, African golden jackals that might be wolves (Canis lupus lupaster or Canis lupaster), black-backed jackals, modern wolves, and the extinct Canis etruscus and Canis arnensis revealed that those the proposed African wolves had skull morphologies that were closer to known golden jackals and black-backed jackals. If these lupaster canids are actually wolves and not jackals, then we would have never been able to guess their identity upon morphology alone.
So while the dog fancy has been splitting hairs and arbitrarily dividing up gene pools, science has revealed that the wild dogs haven’t been doing the same.
Canis is not a closed registry.
Even the boundaries between wolves and golden jackals and between wolves and coyotes are blurry, and of course, this leaves out the rather significant gene flow that has occurred between domestic dogs and wild wolves. Black wolves and wolves with dewclaws on the hind legs are the result of dogs and wolves mating “in the wild.”
Science has found all of these wonderful things out, but the dog fancy remains stuck in another era.
Maybe someday it will move beyond the closed registry system and instead of offering up the bromide of “breed preservation,” it will adopt a system of “breed management,” which strives to maintain genetic diversity within a breed and allows regular influxes of outside blood.
That is what nature has allowed with the wild Canis.
That is the actual story of the animals of this genus. It is not one of one lineage remaining pure for millions or even thousands of years.
It is about significant hybridization.
And Canis is not the only genus with this hybridization issue. Ducks in the genus Anas hybridize quite a bit, and it is well-known that many species of whales and dolphins hybridize with their close kin as well. All of these animals are fairly mobile organisms, and their mobility is likely why they retain so much interfertility. They simply cannot be reproductively isolated from their closest relatives long enough for them to lose chemical interfertility.
It is not something that should be thought of as an evil. Instead, it’s actually a major strength. It is one our own species utilized when we exchanged genes with the Neanderthals and Denisovan people, and if there were another human species alive today, we would likely be able to cross with it.
But because we are so alone in this world, it is difficult for us to understand the concept of a species complex. We are the only humans left.
But dogs and wolves are not the last of their kind.
The gene flow between wild and domestic and among the these three species of Canis is something we have difficulty imagining.
But it is the story of dogkind.
Are there any statistics or studies on the fertile progeny? What happens to them? Do they stay with a wolf pack, form their own pack or are they solitary hunters?
There have been almost no studies of F-1 hybrids in the wild. I guess it would depend upon who the mother is as to which behavior the pups follow.
As for fertility issues, the literature is everywhere on this. There was an attempt to inseminate coyotes with Western North American wolf semen, and there were issues with conception. However it may have been that they were using poor quality semen to start with.
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0088861
I personally don’t believe in Canis lycaon as a species because coyote-wolf hybridization is definitely indicated in genome-wide analyses.
Thank you, this is very interesting! This obviously means that there IS fertile progeny, otherwise there would be no talk of hybridisation being beneficial, but I would like to second the first question: are there studies into this progeny? I must admit my ignorance; I used to think that cross species hybrids are usually infertile and thus have no significance.
Not only are there cross-species hybrids (some fertile), there are cross-generic hybrids. This has a lot more to do with the human propensity and need for labeling than with the natural course of things. The definition of ‘species’ is very slippery and much debated. I prefer one along the lines of: A genetically distinct population that is reproductively isolated from similar and related populations. The potential causes for isolation are manifold, and in many cases, as happened w/ coyotes and wolves, or w/ brown and polar bears, once the barriers are removed or a population is so reduced that availability of suitable mates from one’s own species is severely limited, they hybridize
I found your post informative and interesting. As noted in my book, “Humans, Dogs, and Civilization,” the whole issue of how many species are in the canine family depends on what you use as your criteria. If you use interbreeding as the measure, then wolves, dogs, jackals and coyotes are one species, but if you, instead, look at the expression of genes within the population of wolves and dogs, for instance, you find that dogs and wolves differ from each other in important ways. Wolves have 3 pads on their paws. Dogs have 5. Dogs are attentive to the human face from early puppyhood on. Wolves, even tamed ones don’t monitor human faces,, etc. This is not the place to list the different traits between these two. I confess, I don’t know much about jackals or coyotes, except I did have a coydog My book has two chapters on the question of species and what counts as determining whether they are one or two species
Actually, dogs and wolves have the same number of pads on their feet.
Five pads that touch the ground on a wolf: http://factsaboutwolvesandkitties.weebly.com/wolf-paws.html
Dog: http://en.wikipedia.org/wiki/Paw#mediaviewer/File:Paw_and_pads.jpg
Five that touch the floor.
There is also a carpal pad on the front in both wolves and dogs.
BTW, there are some studies that show that at least some wolves can respond to human body language and facial expressions.
Not all wolves reproduce in packs that are headed by a mated pair. Many wolves in Yellowstone have been born to young females that have no pair bond. The father of the pups was an outsider that did not belong to her pack. That’s basically how dogs reproduce, and their social system is based upon that form of reproduction. What domestication allowed was for wolves that did not form pair bonds to be able reproduce and have offspring. It’s also been found that virtually every female wolf within a pack will have some evidence of pregnancy at some point in her life, even while she’s not pair bonded. This suggests that there are lots of matings between these non pair-bonded females and outside males. It is only in Yellowstone where prey is really abundant that they can wind up raising pups from those breedings.
Most matings in the wild between dogs and wolves happen between male dogs and female wolves that do not have a male partner. This mimics almost exactly those types of matings which often don’t result in producing litters that survive. They just don’t get the care they need. This is also where the myth of female wolves luring male dogs to their deaths originated. What would happen is that one of these young females would come into season and start flirting with a male dog, they would run off together but as they approached her pack, her family wound up killing the dog. This also happens with these outside male wolves.
Must be a typo there? . . Both dogs and wolves have four digital pads (those on the toes) and a metacarpal (or metatarsal, on the rear foot) pad that contact the ground. In addition there is the accessory carpal pad, the “stopper pad” that can come into play iwhen turning at speed, in landing fron a jump, ot other times when the entire front pastern contacts the ground. But that doesn’t show up in the usual paw prints.
I think the reason wolves were domesticated and not golden jackals or coyotes is that wolves have a more flexible mating system than those do. Coyotes and golden jackals are unusually strictly monogamous, and if it weren’t for that strict monogamy, we’d have so much dog and coyote mixing in the US that you’d never be able to keep them straight.
Pentadactylism is found in many species. Whoever wrote that there is a difference in wolves’ and dogs’ feet should educate him- or herself…..on evolution! :-)