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Posts Tagged ‘red wolves’

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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As far as I know, no red wolf has ever had a white-tipped tail.

As far as I know, no red wolf has ever had a white-tipped tail.

A few days ago, a video of a female canid and her puppies began making the rounds in the blogosphere. The footage was taken in Walton County, Florida, which is in the Florida Panhandle. It has been suggested that these animals are red wolves.

Now, I don’t doubt that the animals are large wild dogs, but they most likely aren’t red wolves.

Now, there are red wolves in Florida,  and more specifically, there are red wolves living not very far from where this footage was taken. However, the nearest red wolves are at the St. Vincent Island National Wildlife Refuge. In case you didn’t notice, they live on an island, and not only that, their movements are very closely monitored. A similar population is found on Cape St. George Island. Both of these islands are in the general same region as the animals in the footage. If these animals were living in the Rockies or Minnesota, I definitely would believe the theory that they dispersed that distance. However, these are closely monitored island populations. I don’t think they would have the opportunity to disperse to the mainland.

After all, red wolves have a real threat to their continued existence. Red wolves seem to like having relations with coyotes.  The only way to keep red wolves pure is to closely monitor them. Introducing them to islands is one very good way to keep coyotes out and the bloodline pure.

My other problem with the suggestion that these are red wolves is the amount of white on their tails. Half of the animals in the video, including the adult, have white tail tips. Indeed, one third to one half of their tails are white. Now this feature is not something I’ve heard of on any wolf native to North America.

Coyotes sometimes have a small amount of white on the tips of their tails, but they normally have only a tiny little tuft of white at the end of their tails.

I think this video is some interesting footage of some coyotes with some distant dog ancestry. Wild coyote-dog crosses are not common in the wild. One of the main ways that coyotes remain largely pure of cross-breeding with dogs is that female coyotes come in season during a very narrow window of just a few weeks a  year. Male coyotes are also not fertile the whole year, so hybridization in the wild is far less common than one would think. Most wild coyotes are pure coyote– although they can have traces of wolf or dog ancestry.

However, in subtropical and tropical climates, the female coyotes come in season over a longer period of time. It doesn’t matter when a coyote bitch has her pups. In cooler climates, a coyote must have unfrozen ground to dig her den, and to feed her pups, she must have them at a time in which the rabbits and other small game are producing young. Those young rabbits are a good supplement to the bitch’s nursing diet, and then they become good weaning food for the pups. As the pups mature, learning to hunt naive little rabbits is a good way to hone hunting skills. In colder climates, both of these necessities are strictly determined by the season. In subtropical and tropical climates, neither of these problems is as much an issue. The ground is never frozen, and the small game species produce offspring more months out of the year.

Because the breeding season occurs over a longer period of time, hybridization becomes much more likely, and in this part of the country, there is some evidence of genetic pollution from domestic dogs. A study of Southeastern coyote MtDNA found that there were some coyotes with dog MtDNA sequences. It is not known exactly when this hybridization occurred. It may have happened in the early days of coyote colonization of the Eastern US or happened to Western coyotes before they migrated east. Further, coyotes with dog MtDNA sequences don’t look look like dogs or behave like them. They look and act like normal Eastern coyotes.

Maybe the white tail tip on these coyotes is the last vestige of their  distant dog ancestry. Other than those characteristics, the animals look like Eastern coyotes, which are often mistaken for wolves of all sorts. They are a bit larger than one might expect coyotes to be.

But these are not red wolves. If they were red wolves, it is very likely that US Fish and Wildlife Service would know about them.

It’s nice to think that red wolves could be living wild in the subtropical South free of any human interference. The truth of the matter is they really don’t– not even the large population at the Alligator River National Wildlife Refuge exists without trappers culling out the coyotes and FWS scientists closely monitoring their movements.

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