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Posts Tagged ‘gray wolves’

hooded vs carrion crow

In Europe, there are crows. The most famous of which is the carrion crow, which looks and behaves quite like the American crow.  It is usually black, fairly omnivorous, and it often regarded as an agricultural pest.

At one point, it was believed that carrion crows existed in two distinct phases, the common all black form, which is common in Western Europe, and the phase that is marked with gray on the neck and body.  This form exists in the northern parts of the British Isles, where it has been called the grey grow, the hoodie crow, or the hooded crow. This form is found in Northern Europe, Central Europe, and the Middle East.

However, ornithologists began to notice that where their ranges overlapped, it was quite unusual to see hooded crows paired off with black carrion crows, but the traditional taxonomy still thought of the hooded and black forms as being distinct phases of the same species.

Because the two forms were rarely seen mating or paired off, it was decided to call the carrion crow and hooded crow distinct species, and this is the current understanding. The hooded crow is Corvus cornix and the carrion crow is Corvus corone. But the two birds are otherwise quite similar in terms of ecology, vocalizations, and general phenotype. All that really separates them is the coloration.

Scientists that surely there was a rather deep genetic divergence between the two species, which is why there is a species barrier between the two forms of similar crow.

However, when the genomes of carrion and hooded crows were sequenced, it was revealed that they were almost identical.

Less than .28 percent of the genome varied.  That variance was related to the fact that carrion crows have gray plumage on their neck and torso.

But that little variance is enough to create a species barrier between the carrion and hooded crows. Birds are highly visual, and when young crows imprint upon their parents, they imprint heavily upon what they see. If a young crow is raised by parents that are gray hooded, they will look for mates that are gray hooded. IF their parents are all black, they will look for mates that are all black.

However, it has also been suggested that these crows look for mates that appear not to have aberrant mutations, and this keeps the crows looking for mates that generally look like those belonging to their general family group and social circle.

Whatever the case, we have two very closely related species that do not hybridize. They probably became distinct during the heavily glaciation cycles of the late Pleistocene. One form evolved a gray hood and one evolved an all-black form. Maybe founder effect is the only real reason for this difference in plumage, for this difference in plumage is awfully random.

But that difference in plumage color is enough to create a species barrier, which, if it holds, will lead to greater and greater speciation between hooded and carrion crows.

This discovery about crows is quite interesting for what it tells us about dog taxonomy. Domestic dogs and wolves live together over a broad swathe of Eurasia, and for many centuries, dogs and wolves were regarded as distinct species. However, we have recently found that there is an extensive gene flow between Eurasian gray wolves and domestic dogs across Eurasia, and this gene flow is so significant that the majority of Eurasian gray wolves are estimated to have some relatively close dog ancestry.

Carrion and hooded crows have a clear species barrier that is likely only going to intensify as the two lineages continue to diverge with very limited gene flow. Dogs and gray wolves are not experiencing such a species barrier. Indeed, it looks like the gene flow between dogs and wolves is only going to increase as wolves move into human-dominated lands in Western Europe, and the Eurasian dog population continues to increase along with the human population.

So here we have two crows that are diverging, and the wild and domestic forms of Canis lupus that are continuing their gene flow.  Closing down gene flow is a major part of speciation, and the crows are clearly on their way.

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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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Charles Darwin was an early proponent of humans belonging to a single species. The concept was not popular in Darwin’s imperialist nation, where many of the best and brightest were dead certain that “lesser peoples” of the empire were entirely different species. Monogenists versus the polygenists this was the debate by even those who accepted Darwin’s controversial thesis that species evolved through natural selection and that humans evolved from African great apes.

We know now that the monogenists won out. Only the basest racist frauds believe that humans represent multiple species deriving from distinct evolutionary lineages. The only exceptions are that we do have evidence that humans have trace amounts of other extinct humans in their DNA, such as Neanderthals and the Denisovan hominin.

The monophyly of a species is a concept that should be axiomatic. Much of the “rewriting” of taxonomy and systematics comes from us discovering that a clade is either paraphyletic or polyphyletic, but what does sometimes happen is we do run into situations where we have thought species were really distinct but now we think of them as being subspecies. Black-tailed and mule deer come to mind, as do Cape and African forest buffalo. We have to combine them in a single species to retain its monophyly.

I think something now must be done with gray wolves and their closest kin. In recent years, it has become difficult to retain that domestic dogs and dingoes remain distinct species from the Holarctic gray wolf, especially if we wish to keep the species monophyletic. But I think now a good case can be made that coyotes belong to the same species as Canis lupus. They diverged from a common ancestor only recently, around 50,000 years ago, and the much debated Eastern and red wolf “species,” which appear to be hybrids between coyotes and gray wolves can also similarly be folded into Canis lupus. Whether there was a coyote sister population in the Eastern forest that gave rise to red and Eastern wolves is a moot point. That “forest coyote” population is no more distinct from gray wolves than those of the West are.

Further, we do have evidence of continued gene flow between gray wolves and coyotes. Eastern coyotes have wolf ancestry, and many also have wolf ancestry that comes from domestic dogs.

This new way of describing Canis lupus forms has some benefits. One is that we can come up with a strong legal foundation for the protection of red and Eastern wolves without them being distinct species. Their hybrid status is no longer problematic. We no longer must strain credibility talking about them being ancient North American wolves. Instead, we just go the Endangered Species Act’s statute language which defines an “endangered species” as being a “subspecies” that requires conservation action. We currently protect the Florida panther as an endangered species using this definition, and what is more, the Florida panther was given genetic rescue when Texas cougars were released into its range. The Florida panther exists as a hybrid that holds onto alleles of a population that no longer exists in its pure form, and in the case of red and Eastern wolves, one can very easily make this case.

The problem with going this route is that coyotes themselves do not experience many protections in the United States or Canada. Most states have a very open hunting season on them year-round, and some places have bounties on them. Eastern coyotes are hard to tell apart from what are called Eastern wolves and are even harder to tell apart from red wolves. There is an overlap in phenotype that comes from both forms having similar hybrid origins.

Further, because red wolves living in the North Carolina recovery range are all derived from 19 individuals, and wild wolf-like canids have inbreeding avoidance behavior, it is quite common for red wolves to pair up with Eastern coyotes. Much energy has been devoted to killing off and removing coyotes in red wolf recovery zones, including the euthanasia of crossbred puppies, but it seems that this won’t work long-term.

Recently, researchers at Princeton discovered that the coyotes of Galveston Island are quite closely related to the red wolves in the recovery program. The authors think that many southeastern coyotes might hold the alleles of these red wolves, but I think a better explanation is that we simply under-estimated what the coyote’s range was in the United States at the time of contact. John Smith described the “wolues” of Jamestown as not being much larger than English foxes, and I initially thought he was talking about gray foxes. But then I read original text, and the gray fox is described in complete detail, including the fact that it lacks the red fox’s odor. Henry Wharton Shoemaker, the naturalist and folklorist who chronicled much of the lore of Pennsylvania’s wildlife, wrote about a “small brown wolf” that lived along the Susquehanna River, which made a yipping howl that resembled that of the prairie wolf or coyote. Shoemaker postulated that these small brown wolves were the same species as the coyote, but very few scholars have taken his speculations seriously.

Perhaps, there were coyotes living in the forest alongside Eastern wolves and a endemic Southeastern form of wolf that was very often melanistic. All three exchanged genes, and all three were killed off for their furs and for bounties without any regard to what they were. It was only when settlers in Indiana noticed that some of the wolves in their area were quite small that they began to wonder if they were a distinct species. Later explorers into the West began to call them prairie wolves, which was their name until Americans adopted the Nahuatl-derived name for them.

The most important bit of text I’ve read in any of these North American wolf taxonomy papers is one in a response paper to another one that still argues for multiple species of wolf in North America. The authors write that “[the] genetic differentiation between red wolves and other North American [wolf-like] canids is comparable to the amount of genetic differentiation found between different continental human groups, which of course are not considered to be distinct evolutionary lineages.”

And at that moment, we are back to Mr. Darwin’s debate with the polygenists. He was right to oppose their claims back then, and maybe when it comes to North American and Eurasians wolves, dogs, dingoes, and coyotes, one should be a monogenists.

That’s where I am planting my flag. I think that is where it will all end up once we’ve sorted it all out.

I find the idea of gray wolves representing a phenotypically and behaviorally diverse species awfully intriguing. This diversity is greatly exaggerated in the domestic form, but this diversity is also reflected in the wild, where we have 15-pound coyotes and wolves that weigh 130 pounds.

It may even be that the African golden wolf, which is derived from the ancestor of the gray wolf and coyote mating with the ancestor of the Ethiopian wolf, may be close enough to extant gray wolves that we might also regard it as part of this very diverse species. It would be a coyote-evolved in parallel out of the gray wolf lineage, for the coyote likely evolved in its smaller and more generalist form from the ancestral Eurasian gray wolf because it could not compete as a pack hunter in a North America dominated by dire wolves. African wild dogs once ranged over almost the whole continent of Africa, and they could have provided competition for that niche that would force these ancestral gray wolves to evolve in something like an African coyote.

The recalibration of the evolution of Canis needs to be done with light of the knowledge that gray wolves and coyotes aren’t so genetically distinct from each other. We need new papers that look at he full genomes of golden and Himalayan wolves to get an idea of when they may have split from the rest of the gray wolf swarm. It may be very well be that they all belong to this wide-ranging phenotypically diverse species that over parts of four continents

Yes, this is controversial, but I think it is parsimonious. So many scientists now have no problem thinking that pugs and Yorkshire terriers are Canis lupus familiaris, so why is it so difficult to think of coyotes as being Canis lupus latrans?

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