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Posts Tagged ‘Canis familiaris’

It’s not unusual for people who are trying to deny evolution or promote creationism or both, to come up with a common question:

“If evolution is true, then why don’t dogs have something that isn’t a dog every once in a while?”

This question would not be so much of a problem if we, who think we know better, would stop trying to create a species called Canis familiaris.

Canis familiaris made sense when we didn’t know what dogs were derived from, and it might have made sense if we thought there were hard and fast reproductive barriers between dogs and wolves.

But it turns out that they really aren’t such distinct animals. We’ve learned this when we’ve performed more complete assays of domestic dog and wolf genomes. Since then, we’ve found that the majority of Eurasian wolves have some domestic dog ancestry, and black wolves in North America got their black coloration as the result of a single cross with a black dog that mated with a wolf thousands of years ago in the Yukon or Northwest territories.

A recent genome comparison study of wolves and dogs that attempted to put together a phylogeny of the species clearly states:

[W]ithin the Old World clade, wolf and dog represent sister taxa. Therefore, suggestions that the dog or dingo are a separate species (Canis familiaris) (e.g., Crowther et al. 2014) would cause gray wolves to be a polyphetic taxon; and consequently, our results support dogs as a divergent subspecies of the wolf. This result has societal significance as legislation in some countries and regional governments consider wolves and dogs as distinct species restricting the possession, interbreeding, or the use of vaccines and medications in wolves or dog–wolf hybrids if they have only been approved for use in dogs. In this sense, analysis of evolutionary history informs law and veterinary practice, as dog lineages are nearly as distinct from one another as wolves are from dogs, and the justification for treating dogs and wolves differently is questionable.

The monophyly of the species is one thing that I think everyone should agree is worth preserving in any taxonomic system, but the genomes clearly show that if we create a special species for the dog or the dingo, we wreck the monophyly of Canis lupus.

I would also contend, perhaps a bit more controversially, that in light of a similar study of North American wolf-like canids’ genomes, that the coyote is also part of Canis lupus. This study found that gray wolves and coyotes have exchanged genes across North America and that gray wolves and coyotes last shared a common ancestor only around 50,000 years ago. That ancestor was probably an ancient Eurasian gray wolf that came into North America and evolved for a more generalist, jackal-like niche in the mid-latitudes of North America.

When someone claims that dogs are not wolves, they can only mean it in the same way that pugs are not Siberian huskies or that Great Danes are not dingoes. They are not wild Canis lupus, but they clearly are within that species, if we wish to keep the species monophyletic.

The reason why people want to claim a special species for the dog is because of Raymond Coppinger’s ideas still hold a lot of sway with people who wish to be learned about dogs. It’s not that everything that Coppinger said was wrong. It is what he was wrong about seems to be all that people know.

Coppinger argued that domestic dogs were obligate scavengers and thus must be placed as their own ecological species. An ecological species is the best argument for Canis familiaris. But it has limits for our understanding of evolution, and it can be turned into an absurd concept. For example, there are two sharp-tailed grouse subspecies that live in slightly different but adjacent habitat but do not readily interbreed. If we were to adhere to the same sort of species concept, then these two subspecies would have to be distinct species, even if it busted up the entire monophyly of the sharp-tailed grouse species.

Coppinger is ultimately quite wrong about the obligate scavenger status for domestic dogs. In India, for example, predation by feral and free-roaming domestic dogs is a major conservation issue. And Italian wolves are big time dump denizens. So both dogs and wolves can be predators or scavengers based upon available prey and refuse resources.

Because the ecological species concept is muddled when comparing wolves to dogs and keeping an arbitrary Canis familiaris species destroys the monophyly of Canis lupus, it would make more sense to drop Canis familiaris entirely.

One could raise dogs to Canis lupus familiaris, but Raymond Pierotti and Brandy Fogg have argued in their book, called The First Domestication: How Wolves and Humans Coevolved, that there is no set of behavioral, physical, or physiological traits that define all dogs as a taxonomic entity. They instead argue that we should just call them “domestic Canis lupus,” in which they also group the dingo, which is “feral domestic Canis lupus.

I remain agnostic about what we should call dogs, but Pierotti and Fogg’s quibbles are difficult to ignore. Perhaps we could have the subspecies for the dog, but there must be some acknowledgement that all we are doing is defining a domestic and feral population of a species.

If this blog post looks familiar, I wrote almost this exact same post in March, but I sometimes feel that I have to explain the very real scientific reasons why we don’t say that dogs are a unique species. It is not anti-science to do so, despite what Facebook dog experts tell you. If we want a monophyletic Canis lupus, then dogs have to be part of it.

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pekin duck

One of the more bizarre fights that happens in the world of dogs is how to classify them. Within these debate is always a background of what it actually means to care for a dog “naturally” and what their “natural” life should be.

It actually shouldn’t be this way. Whether one considers a dog to be its own species or a subspecies of Canis lupus, there is no natural way to care for them or natural life for them. That’s because a dog is a domestic animal, the oldest of domestic animals, and there is very little that is natural about them. Over the thousands of years that have been part of human societies, they have adapted very nicely to our needs. Dogs have even developed cognitive short-cuts that have made them better readers of human body language than virtually any other animal, wild or domestic.

The natural way of keeping a dog is that a dog lives with people. It’s an oddball among domestic animals in that is derived from a very old domestication, and it is also the only large carnivoran that has ever been domesticated. Almost all other domestic animals are herbivores, and the other domestic carnivorans–the Near Eastern wildcat, the European ferret, and the red fox– are all small species. Most large carnivorans consider humans to be prey, so there is something very unusual about domestic dogs.

I get that.

But I am not among those who thinks that there is a species called Canis familiaris. I think dogs are most correctly classified as a subspecies of Canis lupus. 

As soon as I say this, people just lose it. That’s because when you say this, it is almost like justifying abusive dog training methods that are based upon dominance. It also might be justifying raw feeding, which is also contentious issue in the world of dogs.

Those are implications that I soundly reject. There is nothing inherent in a classification of an organism that tells you how to feed it or train it, especially when you’re dealing with the real oddball among domestic animals.

Note that it is never controversial to say that a pekin duck is a mallard. In the photo at the top of the page, you can see the old pekin drake that used to rule the pond. His mate was that Rouen-cross hen, which was sold at a feed store as a mallard. They were both of the same species. Her ancestors were some kind of Western Europe mallard, while his were wild mallards living around Nanjing that were later transplanted to the area around Beijing, where they were selected for larger size and white plumage.

Both of these animals were quite different from the true wild mallard that I see swimming in rivers here in West Virginia. She was twice the size of a wild mallard hen and much darker in color, and he was three times the size of wild drake. Neither of them could fly very well. The Khaki Campbell crosses in the photo were actually much better fliers than either of them.

Performance-strain Rouens are not far removed from the wild mallard. Although they are larger and cannot fly, they still produce the large amounts of oil in their plumage that keep them warm and dry even when they swim the coldest water. Female Rouens also retain the brooding instinct and can hatch out their offspring.

Pekins don’t produce as much oil and aren’t as cold tolerant, and if incubators didn’t exist, there would be far fewer pekin ducks in this world. Most pekin hens have no broody instinct. Further, they also grow so much more rapidly the either Rouens or wild mallards that they are prone to growth disorders.

Even though it is so far removed from the wild mallard, the pekin duck is still a mallard. It is as much a modification on a mallard as a St. Bernard is on a wolf.

The only difference is that no one is going to launch into a culture war tirade over the classification of a pekin duck, but if you say a St. Bernard is a wolf, then you will be asking for it.

It is certainly true that dog domestication happened a lot longer than mallard duck domestication. I cannot find any good literature on dates for mallard domestication, but it’s pretty clear that ducks have been kept in Southeast Asia for thousands of years.  Dog domestication dates and locations are still quite contentious, but the best evidence I’ve seen suggests that they were domesticated from an extinct wolf population between 15,000 and 32,000 years ago.

Some will argue that this extinct wolf population actually is a different species from modern Canis lupus, but I’m quite skeptical. Wolves themselves are among the most varied species in the wild. If we were to go back in time  see that ancestral wolf population that gave rise to domestic dogs, I think it would be hard to say that they weren’t within the diversity of phenotype that we see in current Canis lupus populations.

I think the big difference is that these wolves had far fewer reasons to fear people and were actually quite curious about our kind and were actually fairly easy to habituate to living near us. Over time, these wolves became incorporated into our society.

Much has been made that dogs and wolves have different reproductive strategies, but the truth is wolves actually have two reproductive strategies. One of these is the pair bond, where a male and female become partners and their grown offspring help care for the puppies. This is the most successful strategy for wolf reproduction because all the resources and attention of the pack can be devoted to a single litter. Another strategy goes on in parallel. Young male wolves leave their natal packs, but they often cannot find a mate or suitable territory. So they often try to mate with the grown daughters that are part of an established pack. These daughters cannot mate with their father, who is pair-bonded to their mother, who will attack them if she catches them in the act. So these females do often mate with these roaming male wolves. They often become pregnant and even have puppies, but in the wild, they almost never get a chance to raise those pups.  In the early years of wolf reintroduction to Yellowstone, prey was so abundant that many packs raised multiple litters every year. One would be born to the mated pair, while others would be born to these unpaired daughters and the roaming males. The way dog genes get into wolf populations is almost always when one of these non-paired females in a pack hooks up with a roaming male dog, which is why dog hybridization in European wolves went unnoticed. Most studies on wolf DNA looked at mitochondrial DNA alone, and if a wolf had dog ancestry coming from a male dog, it simply never would have been noticed.

The pair bond strategy exists because it about the only way to raise wolf pups. It is very common in all other dog species. In fact, a study of Chicago coyotes revealed that they are almost 100 percent monogamous, and similar findings have been discovered in golden jackals. However, in a wolf pack, preference toward the bonded pair during the mating season means lots of stress. They mated pair has to spend lots of time making sure no one mates with the wrong wolf, and they also will try to kill any of the roaming males that come near the unpaired females, which is also why the roaming male strategy isn’t as successful with wolves.  Natural selection would favor pair-bonding over roaming male mating strategies.

Domestication changed this equation. When wolves began to hook up with people, people began to provide food.  These wolves may have pair-bonded and mated in that fashion, but the chances of these secondary females to raise litters to maturity were much greater. Over time, pups born to roamers and unpaired females would start to outnumber those that were born to the pair-bonded wolves, and thus, a relaxation of selection pressures for pair bonding would become ubiquitous in these wolves. When pair-bonding became broken, then it became easier to selectively breed them. One could have a stud that mates with many females, and this promiscuous behavior could have been heavily selected for. Dogs are able to reproduce at much faster rates than wolves do, and one of the weird effects of domestication has been that female dogs are no longer monestrus and become sexually mature at younger ages than wolves or virtually any other wild dog.

Dogs and wolves have continued to exchange genes since the initial split. Black wolves in North America derive from domestic dogs that mated with wolves, as do black Italian wolves.  Wolves in Italy also can have dewclaws on their hind legs, which also originated from dog and wolf matings. Historians ranging form Pliny the Elder to the Plott hound historian Bob Plott have documented cases of hunters breeding their dogs with wolves, a practice that still goes in parts of Russia. It was just recently revealed that the livestock guardian dogs of Georgia have a rather significant amount of gene flow with the wolves of the same region.

So yes, I do recognize there are differences between wolves and dogs, but dog is a modification on the original wolf template.

The final important reason why I classify dogs as being part of the wolf species is that evolution has within it a nested law. This is the law of common descent. One can never evolve out of one’s ancestry. Humans are always going to be great apes, and humans are always going to be primates, not matter how different we become from our ancestors. A whale will always be a mammal, even if it somehow evolved gills.

A dog is always going to be a wolf. We change them through selective breeding, as we have with all our other domestic animals, but we are never going to change their fundamental ancestry.

All that I’m doing when I use Canis lupus familiaris is that I’m putting dogs where they fit on the tree of life. I’m showing my respect to their evolutionary heritage. I am paying homage to their phylogeny.

I’m not making excuses for Cesar Millan or anyone else.

Many people who promote science in our understanding of dogs are actually engaging in what I call “phylogeny denial.”  Many people bend over backwards to show how dogs aren’t like wolves, which I supposed is harmless, but I think it gives people a false impression of what a dog actually is in terms of its evolutionary history. It’s not a domesticated golden jackal or coyote or African wild dog. It is a domesticated ancient wolf, but that wolf was just an older form of the modern Canis lupus.

When you classify an animal according to its phylogeny, you aren’t doing anything else but classifying it. If a whale is a mammal, it does not automatically follow that it is a land mammal, does it? And classifying a dog a subspecies of wolf doesn’t mean that it evolved to hunt moose in Alaska.

I really wish people were taught to think about natural history in this fashion more often. It clarifies a lot of misconceptions people have about evolution. If I had a nickel for every time I get asked about humans evolving from modern chimpanzees, then I’d be a pretty wealthy individual. The last common ancestor between humans and chimps was not a chimpanzee. It may have looked more like a chimpanzee, because chimpanzees retain a lot more of the original African ape’s features than humans do, but it was not a chimpanzee like we have today.

By contrast, the wolves that gave rise to domestic dogs were probably indistinguishable from Eurasian wolves living today. Further, dogs and wolves continue to affect each other’s evolution through a rather significant gene flow. Humans affect chimpanzee evolution only through hunting them for bushmeat, destroying their forest habitats, and spreading disease. There is no gene flow between the two species, and because we have a different chromosome number, any “humanzees” would likely be sterile.

Finally, Canis familiaris creates a stumbling block in understanding the natural history of dogs, which is why you still run into people who think dogs derive from any number of different species of wild dog. Canis lupus familiaris neatens up that confusion very nicely.

Classifying a dog as a wolf shouldn’t be any more controversial than classifying a pekin as a mallard, but dog people just have a much harder time thinking in this way. I have never seen an internet flame war erupt between pekin duck owners over the classification of their ducks. In fact, I don’t think many pekin duck owners actually know that their ducks are mallards and do not actually occur anywhere in the wild.

But with dogs, charlatans have used the dog as wolf idea to justify all sorts of bad human behavior towards dog, but scientific facts remain scientific facts, whether charlatans misuse them or not. In terms of their ancestry, as has been revealed through copious analyses of their DNA, dogs are in the Canis lupus lineage.

They simply aren’t anywhere else in the tree of life. This is where they belong. Accept it, and move on.

 

 

 

 

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Many people don’t like that I consider dogs to be the same species as wolves.

And usually what they’ll do is accuse me of holding views I don’t have.

For example, I don’t say that the average person should keep a pet wolf. The chances of that going wrong are just too high, but it doesn’t mean that it will never work out.  I have to point to several cases of people keeping wolves and having no problems with them, most notably Wags, the tame wolf that Adolph Murie kept while studying the wolves of Denali. Wags was taken from the den of a wild pack, and she wound up becoming something like a golden retriever in wolf form. Wolves have also been trained as hunting dogs and working dogs, and at least one turned out to be a decent bird dog and retriever.

However, the chances of a human-wolf relationship going wrong are very high, so I do not recommend that people keep pet wolves without learning as a much as they can– and of course, getting the proper licenses.

The other attack I get is that I think dogs are wolves, and therefore, I must believe that we should use compulsory, alpha-based training regimes.

That’s a position I not only don’t have, it is a position I have denounced as utterly unscientific and untenable in the modern era. (See Mark Derr’s piece in the New York Times for a good explanation of why).

Now those first two are pretty easily dealt with, but a third one requires a bit more of an explanation.

This third argument requires a bit sophistication to fully understand, but it’s one that I think can be explained if we look at other cases in nature for comparison.

This argument is one that is made by Raymond Coppinger in his book on dog domestication and behavior. There is a chapter in the book in which he denounces any attempt to represent dog phylogeny in their scientific name, which is Canis lupus familiaris. Coppinger totally defends the old scientific name Canis familiaris because dogs and wolves occupy different ecological nichees.

It’s definitely true that lap dogs have a very different ecological niche than large moose- and bison-hunting wolves in Canada.

However, what about Middle Eastern pariah dogs and Arabian wolves?  Both animals scavenge for most of their food. Neither forms large packs based upon a mated pair, but they essentially  have the same ecological niche. And they do exchange genes quite a bit, although because the wolves are far less common, this gene exchange is much more limited than it might have been.

The same goes for the wolves and stray dogs of Italy. These dogs and wolves don’t hunt prey, because there aren’t many prey species about. Instead, they hang out at garbage dumps and live on that. The wolves of Italy are much more interbred with dogs than people realize. Dog genes for black coats and dewclaws on the hindlegs are working their way into the wolf population.

If we actually take Coppinger’s argument out to its logical end, then wolves themselves represent several species, even though genetically they comprise just a single species. Wolves in the high arctic hunt muskoxen, while wolves in the Middle East hunt gazelles and hares and mainly scavenge. The newly discovered African wolf subspecies (Canis lupus lupaster) isn’t even the top predator in its ecosystem, and it subsists largely by scavenging kills and hunting small prey.

Yet they are all classified as wolves (Canis lupus).

If wolves can occupy such a wide variety of ecological niches and still be considered the same species, why on earth would we not broaden it out and allow dogs to be classified as wolves?

Just as Arabian wolves are adapted to living in the deserts and arctic wolves have adapted to living in polar regions, domestic dogs are wolves that have adapted to live with humans.

I don’t know why this is so hard to accept, but there is a lot of resistance in some quarters to considering dogs a subspecies of wolf.

But that’s exactly what they are.

Now, in other species, there are different subspecies that have different ecological niches, but no one contends that they should be separated into distinct species on the basis of their differing niches.

Let me give you one that is pretty close to home.

To me, this is a fox squirrel (Sciurus niger).

Eastern or northern fox squirrel (Sciurus niger vulpinus).

It’s a big squirrel with thick tawny gold tail and belly.  They live on the border of pastures and hardwood forests, and they are more common along river valleys in West Virginia than ridgetops. Densely forested ridges tend to have mostly Eastern gray squirrels, which are smaller and usually have gray tails with white banding. In my area, these are the two most common squirrels, although one sometimes see American red squirrels (“fairydiddles.”)  The fox squirrel is the largest tree squirrel in North America, and it is from this subspecies that they get their common name. Their tales actually look like those of a red fox, and their full scientific name reflects this similarity– Sciurus niger vulpinus. This subspecies is found from the interior Mid-Atlantic states and the Appalachians north and west to the prairie provinces.

However, this is also a fox squirrel:

Southern fox squirrel (Sciurus niger niger).

This is the Southern fox squirrel, and it is the subspecies one will find in Eastern North Carolina and most of South Carolina.

They superficially look nothing like the fox squirrels I know so well, but they are considered the same species.

However, the two subspecies are quite different from each other.

The vulpinus subspecies is quite adaptable. They have been introduced to California, where they have thrived, and if you can live from Applachia to Saskatchewan, you can do pretty well no matter what the conditions are.

The niger subspecies is in decline. They are almost entirely dependent upon the long-leaf pine forests that once covered much of the Southeast. For those of you who have not been in this part of the South, most of the land is dominated by subtropical pine forests. Historically, the long-leaf pine has been the dominant pine, but these old growth long-leaf pine forests have been cut– and the land was replanted with more commercially lucrative short-leafed and loblolly pines.  The fox squirrels prefer the more open understories that the long-leaf pines provide, and the short-leaf and loblolly forests are much better suited for Eastern gray squirrels.

In states that have both vulpinus and niger fox squirels, the vulpinus subspecies prefers to live in any available oak-hickory forests, while the niger subspecies prefers to live where there are stands of subtropical pine– especially if it’s long-leaf.  In some parts of the Piedmont, these two different kinds of forest can be relatively close to each other, but as far as I know, no transitional zones between vulpinus and niger fox squirrels have been documented. They probably do exchange genes where their ranges overlap, but because niger fox squirrels are so habitat specific, there likely isn’t much of one.

No one consideres vulpinus fox squirrels a separate species from niger fox squirrels, even though they have very different ecological niches. The niger subspecies is also quite a bit larger than the vulpinus subspecies, which is in conflict with Bergmann’s rule. In other normal situations, taxonomists would at least try to consider them to be different species.

In fact, they have a better claim to having a separate species status than dogs and wolves, but I don’t think anyone would seriously consider these fox squirrels to be different species.

After all, there are several different subspecies of fox squirrel besides these two.  The most famous is the critically endangered Delmarva fox squirrel (Sciurus niger cinereus), which looks like a giant Eastern gray squirrel, which even more habitat specific than the Southern fox squirrel. They also are specialized to living in the Mid-Atlantic pine forests from Southern New Jersey to the Virginia’s Eastern Shore. It currently is found only in Eastern Shore portions of Virginia and Maryland.

Vulpinus fox squirrels are much more habitat generalists than either the Southern or Delmarva fox squirrels. They have a different ecological niche, and if one really wants to play around with Coppinger’s adamant defense of Canis familiaris, then we have to split up the fox squirrel species.

Ecological niche can be used to determine species status, but to rely upon it alone, as Coppinger does in his defense of the usage of Canis familiaris, is to inadvertently open up whole taxons to splits that are pretty hard to justify on face value.

So if one isn’t willing to say that there are multiple species of fox squirrel, we are going to have go with Canis lupus familiaris.

Sorry, folks. Dogs are wolves.  The arguments on the contrary make no sense in the light of what we know about other species.

Update: It turns out that all these subspecies of fox squirrel have only diverged in the past 14,000 years.

 

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