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brush wolf

It cannot be overstated how much the discovery that coyotes are not as distantly related to wolves as we believed ultimately questions our entire understanding of the evolution of the Canis species.

The traditional understanding Canis species evolved from some form of Eucyon dog some six million years ago. Wang and Tedford, who wrote the most important book on the paleontology of the dog family, believe this was Eucyon davisi, which was the first of its genus to enter Eurasia. The genus Eucyon is where the common ancestor of the Canis dogs (including Lycaon and Cuon) and the South American wild dogs would be located. Eucyon dogs were small. Imagine them as being something like a black-backed jackal or a Hoary fox rather than a coyote.

Then, 5 million years later in the Southwestern US and northern Mexico, a coyote-like Canis evolved, which was called Canis lepophagus. This animal is sometimes considered the common ancestor of wolves and coyotes. It may be, but considering how close we now know wolves and coyotes are now, it’s not the most recent common ancestor. Canis lepophagus did migrate into Eurasia, where it either founded or is identical to Canis arnensis.

In Eurasia, several smaller jackal-to-coyote forms evolved. One of these was Canis estruscus,  which then evolved into Canis mosbachensis (which is called Canis variabilis in China).

Ron Nowak believed the red wolf was an offshoot of this wolf that wound up colonizing North America and then becoming isolated from the rest of Canis mobachensis when the ice sheets expanded. There was also a competing view that the red wolf was actually a remnant version of Canis edwardii or Canis priscolatrans (which were probably the same animal). This animal was roughly the size of a red wolf, but Nowak rejected it as a red wolf ancestor because it lived too early for what he thought were red wolf fossils.

The Eurasian wolf species evolved mosbachensis-variabilis, but the two forms of wolf shared habitat and likely exchanged genes, making it very difficult

The coyote’s evolution was never clear. It was thought to have evolved out of Canis lepophagus. It was thought that lepophagus evolved into edwardii, and then it began to become more gracile and smaller, eventually becoming the now coyote.  It’s now pretty clear that it evolved out of the Eurasian Canis lupus and not these endemic North American “wolves.”

It either evolved from the modern wolf, which evolved into roughly its current form 800,000 years ago, or it came from a late surviving mosbachensis-type wolves that were regularly crossing with modern wolves before they came into this continent. Maybe the remains that Nowak had been considering “red wolves,” were actually these ancestral wolves that were evolving into the modern coyote.

Maybe when this wave of wolves came back across from Eurasia, perhaps 50,000-100,000 years ago, it came into a world already dominated by a dire wolves, which already occupied the niche for large, pack hunting canids and this wave of Canis lupus evolved as the American jackal.  After all, the bobcat is just a diminutive Eurasian lynx that found itself in a very similar position when it came into this continent, and it evolved to be a smaller animal that generally hunts smaller quarry than its larger ancestor. Of course, the modern bobcat didn’t reach its current form until about 20,000 years ago, but it still was forced to adapt to a slightly different niche than its Eurasian ancestor.

In literature on the paleontology of Canis, there is a heated debate as to how these animals all fit. The conventional view is that the wolf evolved from Canis mosbachensis/variabilis through Canis etruscus, which may be the same thing as Canis edwardii/ Canis priscolatrans. Wang and Tedford contend that the coyote and wolf split from Eucyon.  The modern wolf evolved from Canis chihliensis, which was a large wolf-like canid. It spread into North America to found Canis armbrusteri, which then evolved into the dire wolf (Canis dirus) in North America and Canis gezi and Canis nehringi in South America.  In the Old World, another offshoot of chihliensis gave rise to Canis falconeri, which the supposedly gave rise to the Xencyon, which is supposed ancestor of the dhole and African wild dog. Another view holds that the Armbruster’s wolf (C armbrusteri) is descended from edwardii/priscolatrans (which may be the same as etruscus). This lineage then gave rise to the dire wolf and the two sister species in South America, thus descending solely from North America wolves.

All of these ideas come from paleontology, and they pretty much are done without looking very deeply into the studies that are examining the DNA of these species. It is pretty obvious from that literature that the notion that coyotes and wolves split at the time of the Eucyon ancestor is quite wrong. For that hypothesis to work, African of  wild dogs and dholes would have to be genetically closer to wolves than coyotes and golden jackals are. They aren’t.

But if the genome-wide analysis shows that coyotes are so much more closely related to wolves is true, then all these fossil and subfossil canids that are said to be the most recent common ancestor of wolves and coyotes simply aren’t.  Instead, all of these species that are classified in Canis are likely a mix of evolutionary dead ends, like the dire and Armbruster’s wolf, or could be hidden ancestors of extant canids that aren’t wolves or coyotes.

For example, black-backed and side-striped jackals diverged from the rest of Canis and its allies at about the same time that Eucyon was diverging from Canis. It is possible that there are many relatives of these particular dogs that are hidden in this vast sea of Canis fossils.

The new discovery about the coyote’s split from the wolf also means that any remains of North American canid that are listed as coyote that date to 1 million years before present are not coyotes. What they actually were is a very good question.

We’ve spent a lot of time assuming that coyotes and wolves were quite divergent. We know now that they really aren’t, but when we look into the past at all the “wolves” and “coyotes” that came before, we see how this genus became so successful. It can easily evolve into big game-hunting forms, but the real success is in its ability to assume the size and shape of the generalist predator. Phenotypic plasticity is a wonderful thing for a lineage to possess.

But the real message of the new discovery about wolves and coyotes should be is a cautionary tale about paleontology. Paleontology is a wonderful science, and it makes amazing discoveries every day, but when its faced with a lineage of animals where phenotypic plasticity and tendencies toward parallel and convergent evolution are commonplace, it is bound to make errors. Paleontologists aren’t examining flesh and blood that can have its molecules tested for relationships. They are measuring anatomical characters and determining phylogenetic relationships based upon the similarities of these characters.

Which works well.

Until you get something like wolves and coyotes, where there are many ancient fossil and subfossil remains that look like they could be ancestors of either.

But the DNA says they aren’t.

And paleontology would have problem catching the inverse. There are many species that we’ve discovered only through DNA testing. African butterfly fish in the Congo and Niger basins look identical to each other, but they have been isolated from each other for 57 million years. I have yet to see this species split into two, but if they were mammals, you could bet they would be placed in distinct species in heartbeat.

Paleontology is missing some really important things we’ve since found out through molecular analyses.

And paleontologists know this.

They are working with the data they have, and by definition, it’s going to be more incomplete than genetic studies.

Science is provisional. Different disciplines and methodologies are going to come up with different answers. It’s pretty amazing that one genome-wide assay study can wipe out so much literature in paleontology.

These debates have been raging for years.

And it turns out that everyone was actually wrong.

Update 21 August 2016:  It turns out that I missed a paper that actually did some limited DNA analysis and found that Canis nehringi was pretty much a South American dire wolf, as in it was likely the same species as the North American dire wolf. Canis gezi, however, was  more closely related to the modern maned wolf and had been incorrectly identified as a wolf. So let this stand as a correction to the error above.

 

gray fox west

A few weeks ago, we lost at least two canid species. Analysis of whole genome sequences indicated that the red and Eastern wolves are recent hybrids between wolves and coyotes. Indeed, this study also showed that the genetic variance between coyotes and wolves is equivalent to the variance between wolf populations, which actually calls into question whether coyotes are a valid species as well.

But this finding does not mean that there aren’t new cryptic species to be found in North America’s endemic canids.

I was just perusing some of the literature on gray foxes, when I came across this study in PLOS ONE. The authors sequenced mitochondrial DNA from 169 gray foxes from California and Georgia, as well as 11 “island foxes”  and added in a sample from an aberrant gray fox that wound up in Washington State.

The authors were trying to figure out if California and the American Southeast represented a kind of “glacial refugia” for the species during the Last Glacial Maximum.

What they found was a deep divide between Eastern and Western populations. The California and Washington samples and those from the “island foxes”  were estimated to have separated from the Georgia samples some 500,000 years ago. That’s actually greater than current genetic distance between Old World and North American red foxes, which separated 400,000 years ago, and are currently being proposed as distinct species.

We know from previous studies on Eastern gray fox mitochondrial DNA studies that the gray foxes of the Northeast are relatively recent colonizers from the Southeast.  So my guess is that we’d find a similar divergence between gray foxes from New York and Ohio and those from California as was seen in this study with Georgia and Western gray fox samples.

Now, this study looked at only mitochondrial DNA, and this is only a tiny part of the genome. More detailed genetic studies are needed to determine the exact time of divergence between the two gray fox populations. Further, because this study included foxes from only California, Washington, and Georgia, it doesn’t really show us where the divide between these two lineages exists on the North American continent.  More samples from across the range of gray foxes could give us that answer. My guess is there is a hybrid zone between the two lineages either in the Southwest or in the South-Central US.

But this assumes that there really this genetic divergence is confirmed with nuclear DNA sampling. It could be that the Western population just has an old mitochondrial DNA sequence that wound up surviving, even though the majority of the gray fox genome comes from same source as the Eastern gray fox.

It could be, but there is still a very strong possibility that Western gray foxes do represent a distinct species from the Eastern gray fox, and this question can be answered. We just need analysis from a bigger part of the genome from a broader cross section of gray foxes.

If there actually is a distinct species of Western gray fox, then it would be obvious that the island foxes, which have only been on the Channel Islands for 7,100-9,200 years, should be classified as part  of that species. The authors found that no extant population of gray fox in California actually gave rise to the island fox, but there are similarities between island foxes and those in Northern California. But they were still part of this Western gray fox division.

I’ve thought it very odd that gray foxes live in Minnesota quite well, but in the West, they don’t come as far north as western Oregon. The Washington sample in this study was the first gray fox found north of the Columbia River, and western Washington has a much, much milder climate than Minnesota.

Maybe the differences in range reflect a difference between species. Maybe the gray fox of Minnesota is the same as the gray fox of Georgia, and this species has evolved more cold tolerance than the Western species.

There are just so many questions that arise from one study that has largely been overlooked.

And if there are two species of gray fox on the North American mainland, there could be several cryptic species of gray fox in Mexico and Central America. Maybe the isolated populations of gray fox in Colombia and Venezuela are also different species.

The Urocyon foxes are really interesting animals. They are the most basal of all canids, and among North American canids, they are the only one without any connection to Eurasia.

Most taxonomists divide the genus into two species: the gray fox and the island fox. The island fox was recently removed from the Endangered Species List, but I’ve always been very doubtful that it actually is a species. Most of the evidence now shows that it was actually introduced by people. Something very similar could happen with red foxes in Australia, which are now reproductively isolated from the rest of the Old World red foxes. Maybe in 9,000, they will be morphologically distinct enough for someone to declare them the “Australian fox” and work to preserve them as a distinct species.

But in focusing so much on this odd insular population, could we have missed the really big story about the urocyon?  Maybe there were two species after all, but we never bothered to look into it.

Maybe one day, we’ll have Urocyon cinereoargenteus and Urocyon occidentalis as the two species of gray fox native to the United States.

So there is only one wolf species in North America.

But there could be two gray foxes on the mainland.

And that is pretty cool.

 

 

 

 

 

From the BBC’s The Hunt:

 

These two are aggressive nursers.

Coyotes are supposedly killing all the fawns, but they didn’t get these two.

 

 

Damaged antler

A buck with a damaged antler is the first to visit this year’s feeding station:

The antler could very well continue to grow out at this weird angle. The antler is still in velvet and will be for the next month or so.

Turkey bunch

A big flock of wild turkeys (hens and this year’s poults) cam by the Moultrie 1100i.

Canis cedazoensis

Canis cedazoensis was an early species of the wolf-coyote-jackal tribe. It lived what is now the American Southwest and Northern Mexico until 300,000 years ago. It probably scavenged kills of bigger predators and lifted off the fawns of the various species of pronghorn.

Conventionally, we believed that the lineage from which this jackal-like canid gave rise to the wolf, the coyote, and the golden jackal. We based these assessments on comparative morphology from fossil and subfossil remains, and it all made sense.

These jackal-like forms entered Eurasia and Africa. They gave rise to the Xenocyon, the first wolf-like canid to evolve of this lineage.  The Xenocyon gave rise to the dhole and the African wild dog. Then the actual wolves evolved in Eurasia, and they walked back into North America to found the Armbruster’s wolf and the Dire wolf. They spread to South America, and endemic North American wolves, Canis edwardii and the putative red wolf evolved out of an unrelated jackal-like line.

The coyote descended from some sort of jackal-like canid in North America and a least a million years of evolution separates the coyote from the modern gray wolf.

The most recent study that examined full genomes of various wolves, dogs, and coyotes revealed that the separation between coyotes and gray wolves happened only 50,000 years ago. This finding pretty much destroys all this thinking.

We’ve conventionally thought of the lineage starting out with jackal-like forms that evolve into wolf-like forms, but the truth is we have a lineage that started out with jackal-like forms. Wolf-like forms evolved at least twice from this lineage, and jackal-like forms have evolved from wolf-like forms as well.

What we’ve missed that just as the Xenocyon and the dhole and African wild dog have evolved into wolf-like forms in parallel to actual wolves, the real story of Canis is that there has been a constant tension between selection for wolf-like traits and jackal-like traits. The coyote is a wolf that has re-adapted itself to the jackal-like form. To become a jackal is to become a generalist again. To evolve towards the wolf is become an apex predator and be forced to hunt for large game to survive.

What we know from the fossil record is the story of wolves and dogs and coyotes and their kin is that it began with “jackals.”  Paleontology says that North America is where this story got started, but the oldest species in this lineage of dogs lives in Africa.

I would love to know the full story.

Canis cedazoensis is a creature lost to time. If we could see one, maybe we know some answers. Maybe we would see something very much like a black-backed jackal. Maybe it would answer some questions.

And it would probably raise more.

Yet more of the mystery to which we should humble ourselves.

It began with jackals, and in the Anthropocene, it may end with them as well. The coyote and Eurasian jackal have continued to spread their range. The coyote is from from Alaska and Newfoundland to Panama– on its way to Colombia. The Eurasian jackal (the “golden jackal,” as it is normally called) spreads north and west through Europe. Both are generalists of the jackal type.

Phenotypic plasticity and convergent evolution have played quite a game with this part of the dog family.

Science is always provisional, and often takes just one profound discovery to turn over the apple cart.

And oh, has it been turned!

 

 

 

 

 

 

 

 

 

 

 

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