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Archive for the ‘wolves’ Category

red wolf

So I’ve been sent this story a couple of times: apparently, a genetic analysis of Galveston Island coyotes found a relationship between these coyotes and what are called red wolves that are part of the US Fish and Wildlife Service’s endangered species recovery program.

I found it interesting that Bridgett vonHoldt was part of the study that found this genetic link between Galveston Island coyotes and red wolves. VonHoldt is one of the leading canid molecular geneticists who was part of a team of researchers that have found that the red wolf is of hybrid origin. She was also an author of the paper that shows the biggest problem that the red wolf has in claiming species status.

This problem is that it really doesn’t matter whether red wolves are hybrids or not. The question is whether they are hybrids between two entities that are best described as distinct species or not.

A comparisons of full genomes of gray wolves, Eastern wolves, red wolves, and coyotes revealed that Eastern wolves and red wolves are hybrids between coyotes and gray wolves. This finding has been revealed in three papers, one in 2011, one in 2016, and one in 2018. This hybrid discussion is tiresome, though, because we can get into a sea-lioning contest about how there might very well be a hidden unique red wolf species hidden somewhere in the coyote.

This paper would appear to have found such a thing, but it needs to be understood within the full context of the literature.

Yes, the genome-wide and full genome comparisons reveal a hybrid origin of red and Eastern wolves, but the problem that no one seems to be willing to deal with is how recently gray wolves and coyotes split.

When it seemed like gray wolves and coyotes had a common ancestor 800,000 to a million years ago, debates about hybrid origin made some sense. But in the 2016 study, the authors did some comparisons of gray wolf and coyote DNA to see if they could find when the two forms of canid split. The most statistically valid date for that common ancestor was alive around 50,000 years ago:

If we assume a generation time of 3 years, and an effective population size of 45,000 (24, 25), then this corresponds to a divergence time of 50.8 to 52.1 thousand years ago (ka), roughly the same as previous estimates of the divergence time of extant gray wolves (26–28). 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 (for example, Eurasian versus North American gray wolf, FST = 0.099; Table 2 and fig. S1).  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 (10). Despite body size and other phenotypic differences between the two species [for example, (1)] and a long history of coyote- and wolf-like forms in North America (1, 29), the genomic data suggest that modern coyotes and gray wolves are very close relatives with a recent common ancestry. (Italics mine).

This paper shows that what we call a coyote could best be described as a form of gray wolf, a smaller and more jackal-like form of gray wolf to be sure but a gray wolf nonetheless. I don’t know why the authors didn’t make this suggestion, because a similar way of thinking clearly puts pugs and Newfoundlands in the gray wolf species as well. This classification is controversial, but it’s not that controversial if you understand systematics based upon clade-based thinking.

So what the researchers found Galveston Island is a population of coyotes that share some genetics with the red wolf. The population that founded the red wolf population that receives conservation attention came from the East Texas and Louisiana mainland, and if this population is isolated, then you can see how this unique population could have retain its genetics as more coyotes spread through the mainland on their way East.

Even if we were to find that there were once large wolves in Prehistoric North America that had coyote-like mitochondrial DNA, we would still have that problem of the recent coyote origins. The only way that problem might be solved is if these large wolves are significantly older than the date suggested from the gray wolf-coyote split. Because we know that anatomically modern gray wolves already existed in Eurasia well before the coyote-gray wolf split, one would expect to find large wolves with coyote-like DNA in North America. We also should expect to find wolves with coyote-like DNA in the Old World as well.

The real debate should be about the validity of Canis latrans as a species. The problem with going down this road is more political than scientific. Coyotes are the most successful relatively large canid in North America. They are found in 49 states, and the only reason they aren’t in Hawaii is they can’t swim that wall.  They are working their way down through Panama, and I would not be surprised if I read some morning that they had crossed the swamps of Darien into Colombia.  Coyotes receive almost no protections anywhere in their range, while wolves generally are protected via the ESA where their populations have been reduced or extirpated.

But we don’t regard domestic dogs as a species either. One can easily see them as a divergent form of gray wolf without losing perspective that there really ecological distinction between a domestic animal and a top-level predator. We are currently grappling with the evidence that dog genes are introgressed heavily into Eurasian wolf populations, but almost exactly the same thing has been observed with North American wolves and coyotes. Even the wolves of Alaska and Yellowstone have coyote ancestry.  

So one should have a bit of skepticism about what was actually discovered on Galveston Island.  At the very least, we should be very careful about thinking of gray wolves, dogs, and coyotes as hard and fast entities and that all three continue to exchange genes across their respective ranges.

We do have a species problem, a species problem that would make sense only if Darwininan precepts are true. With this clade in Canidae, we have also have the Ethiopian wolf, the African golden wolf, and the Eurasian golden jackal that are capable of exchanging genes with each other and with dogs and Holarctic gray wolves. Indeed, the African golden wolf is derived from either a gray wolf or a gray wolf ancestor interbreeding with the ancestral Ethiopian wolf, which was probably much more widespread in the past. 

I don’t have as much of problem thinking of coyotes as a form a gray wolf, probably because I’ve long since accepted that domestic dogs are also a form of gray wolf, but thinking in this way is disruptive to our concept of hard and fast species. However, we should never think that such thing as a hard and fast species exists in the first place. Evolution is fundamentally about change, but it’s also about fuzziness and questions that harry our concepts of essentialism.  

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One of the great exercises on the internet among those who wish to be taken seriously as “dog people” is to say that dogs are not wolves. In one sense, they are quite right. Dogs are not wild canids, and they are certainly not the mostly fearful and reactive wolves of the middle latitudes of Eurasia and North America.

But in another broader sense, they are dead wrong. I’ve been following this debate for some time. At one time, there was a great emphasis on the so-called Canis variabilis that were contemporaries with Homo erectus at the Zhoukoudian cave system in China. The remains date to 500,000 years ago, and it’s quite a leap to say that Homo erectus began dog domestication.

It should be noted now that Canis variabilis is no longer an accepted scientific name for these early wolves. They have since been reclassified as a subspecies of the Mosbach wolf (Canis mosbachensis). Their new name is Canis mosbachensis variabilis, and although the Mosbach wolf is ancestral to the modern gray wolf, the Chinese subspecies is now not regarded as leading to the modern one.

So this idea that these Chinese specimens are ancestral to the domestic dog is quite faulty. Even if we were to say that Canis mosbachensis were the ancestor of dogs, we would have a real problem on our hands. The Mosbach wolf disappears from the Eurasian fossil record no later than 300,000 years ago, when it was replaced by modern gray wolves. The earliest domestic dog that has been proposed dates to 33,000 years ago in the Altai Mountains.

Somehow, you have to get a species that went extinct hundreds of thousands of years before the formation of the earliest domestic dog to become its ancestor. The chronology makes no sense.

Now, we do have some ancient mitochondrial DNA of a Siberian Canis cf. variabilis that appeared to show a connection with the origins of the domestic dog. This specimen is probably a ate surviving Siberian variant of the Mosbach wolf, and it is possible that the reason for this mitochondrial DNA similarity is that domestic dogs have a mitochondrial DNA lineage that very close to this extinct wolf. The real problem with this study is it is a mitochondrial DNA study, and if we could somehow get a full genome comparison from these remain, which would not be easy, then we could get a better picture of how the Mosbach wolf relates to wolves, domestic dogs, and coyotes. Yes, the discovery that gray wolves and coyotes shared a common ancestor only around 50,000 years ago means that coyotes descend from the Mosbach wolf as well.

So when you see someone claiming that Canis variabilis is wild Canis familiaris, just understand that this person hasn’t looked at the most recent literature on these Middle Pleistocene wolves. But I’ve seen this repeated enough that I do think I need a place on this blog where I can easily link to the problems with this assertion

The real problem with all of this is that in dogs, at least in the English speaking world, there is a real problem with phylogeny denial. So many people are caught up in this “dogs are not wolves” idea that they invest lots of mental gymnastics in trying to create another wild ancestor for the domestic dog.

So many people got worked up with the discovery that no extant population of gray wolf is ancestral to the domestic dog that they had to make it about how dogs were not derived from wolves.

Again, the gray wolf species is at least 300,000 years old, and no one has found a relationship between dogs and wolves that posits their divergence as being greater than 33,000 years. There is an old mitochondrial DNA estimate that is largely not accepted that puts their split between dogs and wolves at something like 135,000 years ago, but that’s still after the gray wolf existed as a species.

So let’s talk about why saying dogs are not wolves is an exercise in phylogeny denial:

One of the implications of our modern Darwinian synthesis is monophyletic descent. All organisms derive from ancestors, and it is impossible to evolve outside one’s ancestry. If we were to go back in time to see when the most recent common ancestor of dogs and gray wolves, you would have a hard time describing that ancestor as anything other than a form of Canis lupus.

Dogs have evolved through their Canis lupus ancestor, just as modern wolves have evolved through theirs. It is accurate to say that domestic dogs are not derived from extant wolves, but it is not accurate to say that dogs did not derive from wolves. It is also not accurate to say that dogs are a different species from Canis lupus, because dogs are still part of a Canis lupus lineage.

Further, we have lots of data about the extensive gene flow between dogs and wolves in Eurasia. We know that livestock guardian dogs in the Republic of Georgia have exchanged genes fairly extensively with wolves. But we now have data that shows an extensive gene flow between domestic dogs and wolves across Eurasia.

So dogs and wolves are continuing to exchange genes. They are not becoming reproductively isolated from each other in a way that would lead to speciation, even now.

I’ve never understood why this line of thinking has ever been popular, except that wolves people have indeed abused dogs under the assumption that their social systems are much like those of captive wolves. Further, it is quackery of the worst order to assume that dogs should be fed only full raw carcasses of meat because that is what wolves eat.

But those problems are not adequately addressed by promoting another scientifically dubious prospect. Dogs do behave somewhat differently from wolves, but that is because dogs are domesticated. Wolves behave differently because they are a wild form, and as a wild form, they have undergone a selection for extreme timidity and wariness as we have tried to wipe wolves off the face of the earth.

The argument that dogs are part of Canis lupus is well-supported by science. Indeed, an analysis of gray wolf, domestic dog, and dingo genomes revealed that creating a separate species for the dog, the dingo, or for both would make the entire species polyphyletic and thus not in keeping with Neo-Darwinian principles.

So it is scientifically correct to say that dogs are wolves, but one should say that dogs are domesticated wolves. And just leave it at that.

And drop the phylogeny denial.

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Coyotes, nature’s sighthounds

Built a lot like a lurcher.

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Collie and wolf cross

From The Wolves of North America (1944) by Stanley Young and Edward Goldman.

And that’s how they made German shepherds. LOL.

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Great Lakes gray wolf on Wisconsin’s Stockton Island.

An extensive camera trap survey of the Apostle Islands in Lake Superior has revealed a great diversity of carnivorans, including gray wolves and American martens. These islands, located just off Wisconsin’s Bayfield Peninsula, are among the few places left in the Eastern and Midwestern US that still retain an intact predator guild, and because all but one of the islands is protected as a national lakeshore, these islands will be protected from most exploitative development.

I love living in a country that still has room for wolves and wild places. Our natural heritage is every bit as important to us as a nation as our constitution and rule of law, and it should be protected with the same ferocity that we use to protect our republicanism.

Also of importance is the Great Lakes wolf in the trail camera capture that was part of the survey. This wolf looks to be one of wolves with some amount of coyote introgression. Great Lakes wolves can have quite a high amount of coyote ancestry, and the earliest estimated introgression of coyote genes into gray wolves that has been documented is from these Great Lakes wolves. This introgression happened as early as 963 years ago.

Coyotes and gray wolves are found on the islands now, and one wonders if they still occasionally interbreed. The Great Lakes are also the region that experienced the beginnings of the hybrid swarm we call the Eastern coyotes.

So these islands could be a new Isle Royale from which to study the new and evolving wolf and coyote of North America.

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Why coyotes are not basal Canis

The traditional understanding of coyote evolution is that coyotes are basal wolf-like canids. This understanding comes from the hypothesis that coyotes directly evolved from Canis lepophagus in North America alone. Coyotes look and behave a lot like jackals of the Old World, and because we know that the larger wolf-like canids evolved from jackal-like ones, we just assumed that the coyote was a primitive form.

One problem with this positioning has always bothered me. Jackals tend to have proportionally smaller brains than wolves, but coyotes have proportionally larger brains than wolves. Domestic dogs have evolved smaller brains from wolves, although wolf and dog brain size comparisons aren’t as cut and dry as people think. 

No one thinks of dogs as basal forms of Canis, so it is possible for animals in this lineage to lose brain size, just as it is possible for a primitive lineage of canids known as coyotes to evolve a larger brain.

Please note that my discussion on brain size here isn’t really a discussion about intelligence, because the literature on which form is most intelligent is quite all over the map. Domestic dogs kept in Western countries in the modern way do appear to have social cognitive abilities that virtually all other species lack, while wolves are much better at working with each other to complete tasks.

But coyotes have proportionally larger brains than either wolves or dog do, and in this lineage, larger brains are generally a derived characteristic.

However, the really important data about coyote evolution is the discovery that they shared a common ancestor with gray wolves much more recently than commonly suggested. A genome-comparison study of various North American canids found that the common ancestor of both gray wolves and coyotes lived around 50,000 years ago. Because anatomically modern gray wolves replace the Mosbach wolf in the fossil record between 300,000 and 500,000 years ago, the ancestor of both had to have been a form of gray wolf from Eurasia.

The coyote is thus a jackal that has evolved in parallel out of the gray wolf lineage, which means it is not a primitive canid at all. It likely evolved this jackal -like morphology and behavior because the form of gray wolf that it derives from was unable to compete with the dire wolf, the American lion, the short-faced bear and the machairodonts as a top-level predator. It was forced to evolve a smaller body that could be fed on carrion and small prey.

We know now that there is a big difference in what prey predators target once they exceed 20 kg. Predators that weigh more than that mass target large vertebrates, while those that are smaller than that weight target smaller prey. Although coyotes do cooperatively hunt deer, they primarily feed on rabbits and mice. So by becoming smaller, coyotes were not directly in conflict with dire wolves or the other large predators of Pleistocene North America.

Only through analyzing full genomes of coyotes and gray wolves did we realize that our assumptions about their evolution were wrong. Earlier studies that looked at mitochondrial DNA alone found that coyotes fit within a basal position of the wolf-like canid lineage. However, recent full genome comparison of various wolf-like canids that looked at the role hybridization played in their evolution found something interesting. The lineage that leads to wolves, dogs, and coyotes experienced some introgression from a ghost species that was closely related to the dhole. The authors think that the reason why coyotes turn up so basal in these mitochondrial DNA studies but appear so wolf-like when their full genomes are compared is coyotes have retained a mitochondrial line that comes from that ghost species.

So the generalist coyote is a re-invention out of the gray wolf lineage. It is not basal to the wolf-like canids. It just merely resembles the basal forms in some of their ecology, in some of their behavior, and in their odd mitochondrial inheritance.

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Long-time readers of this blog know that I am quite critical of Dan Flores’s Coyote America, a book that has been hailed as a sort of definitive source for the natural and cultural history of the animal. The good parts are where the author talks about native peoples and their relationship and understanding of the animal. The bad parts are where he misrepresents the molecular research on coyote evolution, most notably where he contends the genetic difference between a gray wolf and a coyote is equivalent to that of humans and orangutans (page 27, if you’re looking for it). I’ll give Flores a pass in that he didn’t do his research for the book until after the coyote, gray wolf, Eastern wolf, and red wolf genome comparisons came out, and found that all these animals were as closely related to each other as humans from different continental origins.

But I don’t know of anyone who thought that coyotes are to wolves what humans are to orangutans. At best, we thought coyotes were to wolves what our species of human was to Neanderthals.

So that was my beginning of great distrust in Flores’s account of how coyotes evolved in North America.

I do remember one part that I thought might have been true, simply because it mirrors the way coyotes moved into the eastern parts of North America. Flores contends that coyotes did not make it into Southern Mexico and Central America until after European colonization took place. The clearing of the tropical forests and the introduction of sheep and goats made all of this possible.

This made sense to me, but then I thought, well, I should look it up.

It turns out that Flores was dead wrong about Southern Mexican and Central American coyote populations. A 2004 paper that looked at the paleontology and sixteenth century accounts of coyotes in the region found that coyotes were in the region before European conquest.

So coyotes have lived in Guatemala and El Salvador long before Europeans felled the forests and turned out sheep and goats. Their recent range expansion into southern Panama may eventually lead to their arrival in Colombia, and they will have the Southern Continent to colonize.

This book gets so many facts wrong about the evolution and natural history of coyotes that I do worry a lot about its impact. It is written as a popular natural history, so it needs to be understood in that vein. However, the author seemed to choose which scientific facts he wanted to present without looking deeper into the fullness of the literature that exists on them.

And as a natural history writer, I find such errors to be problematic, but I always find some way to make sure you know that I am not the final authority on any subject. Because I blog, I can show you my evolution in thought more easily. Books are far more permanent inscriptions. That’s why you will see me hedge about certain subjects where I know more research is being done, such as what the African golden wolf actually is or where dog domestication happened.

The challenge is to make natural history subjects interest and to make your interpretations fit the literature, both of science and of prose.

And yes, it took me a month to read Flores’s coyote book. I had that many problems with it.

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