Coyotes vs. Wolves as species

Nature Talk
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Recently I got into a huge (but good-spirited) argument with someone about coyotes and wolves. They claimed that wolves and coyotes were essentially the same species, and that the taxonomic field has needlessly complicated itself over the last few decades by splitting genera into more and more species based on seemingly arbitrary standards. I argued that there are factors besides genetics that differentiate species, and I cited coyotes’ smaller size, antisocial tendencies, and instinctive animosity between them and wolves as evidence that they are distinct. They countered by saying that coyotes and wolves share a very significant amount of DNA to begin with, and that since their offspring are fertile it separates them from other species whose offspring are infertile.

For the record this person is in their 50s and I’m in my early 20s so the way we both learned biology in school is undoubtedly different. I learned that there were “barriers” that separated species such as behavioral and temporal barriers that extended beyond just gametes; he says that stuff wasn’t around when he was my age.

I’d love to hear this community’s thoughts on this debate.

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I agree whole-heartedly. Having taken a Bioinformatics course, although it is introductory, one key takeaway was that different sources of information give different phylogenetics. With respect to DNA difference, it depends on which DNA one uses to differentiate species; the DNA difference based on Mitochondrial Cytochrome Oxidase, Subunit 1 will be dissimilar to that of genomic DNA. Same thing with Protein families, RNA transcripts, and Metabolites.

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It’s true that members of the genus Canis have been mixing it up genetically for some time, as evidenced by the presence of timber wolf and domestic dog genes in eastern Coyote populations, as an example. There are behavioral, anatomical, physiological differences between “pure” coyote, wolf, and dog although they can be subtle. There’s good reason why the genus is sometimes called “Canis soup.” And yes this ability to hybridize can complicate taxonomic decisions. In my corner of the NA continent (Southwest) you can be fairly confident in identifying something as a coyote, a wolf, or a dog. But that’s not necessarily true elsewhere.

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Some places have coyotes mixed up with wolves and dogs, but I doubt 40 or 30 years ago people in schools were learning that coyotes and wolves are the same. In fact I had an hour long argument with self-proclaimed canine expert that said wolves will never hybridize with anyone. So no, nothing changed in science recently the way this person says, in fact it is becoming more complicated with more blurred edges as Canis are sometimes mixed very much, but those populations are not one of parent species, they’re separate, there’s so many differences between them, you’re right they’re valid.

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Of course, in my area (New England) there are hardly any ‘pure’ wolves or coyotes, but intermixed genetics of both species, who are often referred to as eastern coyotes or coywolves; I prefer the latter, personally, as it reflects their genetic history more accurately than stating that they are an ‘eastern’ form (or whatever else you want to call it) of one of them. I have no clue how they should be classified taxonomically however. They certainly remind me a lot more of wolves than coyotes, and they seem to fulfil a similar, though lesser, ecological role here; they may not often hunt large mammals successfully, but they do appear to be quite important for other scavengers. They clearly have traits of both species.

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That’s an argument falling back on the old Biological Species Concept that is often still taught, but not really used in professional circles much any more because it has too may exceptions and problems.

The issue of what constitutes a species was addressed just a few days ago, and I linked some resources to highlight the difficulty of coming up with a universally agreed upon definition of a species.

A major point is that the amount of genetic difference is sometimes not as important as where that genetic difference takes place.

The genetic difference between coyotes and gray wolves is larger than that between domestic dogs and gray wolves and is enough that genetically coyotes and gray wolves can be easily distinguished from each other. Their ancestors split around 2 million years ago, although other studies put the divergence closer to 50 thousand years ago. Determining the exact splitting date is difficult because of repeated hybridization between wolves and coyotes over time.

In addition to genetic differences, there are a host of behavioral differences that set coyotes and wolves apart.

The basic point is that just because two creatures can produce viable, fertile hybrid offspring doesn’t make them members of the same species according to most modern species definitions. Arguments that it does are based on an outdated concept of how to differentiate species.

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All species concepts are man-made constructs. I remember first learning about ring species back in high school, and I that pretty quickly started to erode at my confidence in these ideas. And the older I get, the more I’ve come to realize that it doesn’t really matter at all without context. The context where it seem most important is in the legal/conservation realm, but even there things have shifted to address subspecies, evolutionarily significant units, and genetic biodiversity as a whole. Taxonomies definitely help us understand how life forms are organized and interrelate, but none always conform to what we see out there. Delineations either have utility, or they don’t, but either way, life is gonna do its thing (including introgressive hybridization), taxonomists will argue, and the current status at any given time is merely a snapshot.

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:) According to this site, Humans share a significant portion ( 60%) of their DNA with bananas.

https://thednatests.com/how-much-dna-do-humans-share-with-other-animals/

I don’t know how authoritative it is; still, I am surprisingly happy to claim kinship with bananas!

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If it makes anyone feel better, the term semi-species has been applied to two or more organisms that are very closely related, can readily interbreed under some circumstances, but might still be on separate evolutionary trajectories and recognized as separate species taxonomically (even if they don’t really fit well).Basically they are incompletely separated species.

Linnaean taxonomy tries to be tidy but nature is messy.

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A small number of regulatory genes can produce organisms that are distinctly different due to their substantial effects on development. The overall percentage of similarity in the genome isn’t always the best indicator of how differentiated two species are from each other.

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yes but how many genes do coywolves share with Taraxacum microspecies?

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That helps explain why bananas do not look much like my side of the family.

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Hmmm… extrapolating on that chart posted above, I might hazard a guess of 40% with the Taraxacum micro species? Not as close as me and my banana.

To get back (or at least closer) to the topic, I might similarly surmise that both coyotes and wolves are as closely related to bananas as bananas are to me.

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You raised such a fascinating question. I’ve been reading about wolves, coyotes, and dogs for a couple of hours now.

This article says that wolves and coyotes are two different lines of descent from a common ancestor. (Perhaps, not too unlike Homo Sapiens and Neanderthals.)

“ That ancestor gave rise to two species — the predecessor of today’s gray wolves and that of today’s coyotes — somewhere in Eurasia. Dr. vonHoldt said that the two species then migrated into North America.

There, coyotes evolved into small predators that specialize in taking down smaller prey. Wolves took a different path, relying on their larger size and great speed to prey on moose and other big mammals.”

https://www.nytimes.com/2016/07/28/science/red-eastern-gray-wolves.html

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There is no ‘right’ answer when it comes to drawing species boundaries. There are so many definitions out there (thousands, with at least some dozens in active use) of what exactly a species is, and not one of them can usefully be applied in all cases. The biological processes behind all that diversity are themselves too diverse and wonderful to allow any consistent system of pigeon-holing.

I met Ernst Mayr, the (approximate) originator of the Biological Species Concept, when he was close to 100 years old. He had been fighting for the BSC for several decades by this point. He gave a talk at a field station where I was working, during which he mostly bashed phylogenetic thinking and those who employ it, especially botanists. I was a student, knew very little about it at the time, and asked quite innocently why he thought botanists didn’t adopt his BSC if it was so much simpler and more sensible than the methods they were using. He replied without pause, “because none of them are smart enough to figure out how to apply it to their organisms.” Ernst and his enemies have now mostly passed away, and most biologists I know agree that the species concept you use depends on what you are working on.

So a coyote and a wolf are clearly the same species, and also clearly different species. The important thing is that if there is a question, say what taxonomy or definition is being used.

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This is my favorite topic, what defines a species? I guess Canis is part of the reason why the Biological Species Concept (BSC) doesn’t work. To recap, it’s when a species is a population that can and will only breed with that of it’s open species. Big problem with that idea is, hybrids don’t exist? What about a mule? So we say that BSC accepts hybrids as long as those offspring are infertile? Now what about a Fiesta Macaw? It’s family tree looks like this:

Offspring: Fiesta Macaw
Parents: Camelot Macaw (hybrid) and Harlequin Macaw (hybrid)
Grandparents: Scarlet Macaw, Catalina Macaw (hybrid), Blue-and-gold Macaw and Green-winged Macaw
Great Grandparents: Scarlet Macaw, Scarlet Macaw, Blue-and-gold Macaw, Scarlet Macaw, Blue-and-gold Macaw, Blue-and-gold Macaw, Green-winged Macaw and Green-winged Macaw – or in other words 3/8 Scarlet, 3/8 Blue-and-gold and 1/4 Green-winged.

Now for those unfamiliar with these species, just google them. Clearly they are very different but they can breed freely with each other, right? So under the BSC, does that make these splashes of red, green, blue and yellow feathers under the same species? Not necessarily because the Fiesta, Camelot and Harlequin Macaws are captivity hybrids. They do not occur in the wild and in fact, the Catalina Macaw is the only known wild occurring macaw hybrid. And the lack of hybrids are the not the result of range as Blue-and-gold and Green-winged share practically the same range. It’s because they breed only with their species.

This situation also applies to the Canis situation. As of this comment, I have not heard a convincing report of a Coyote interbreeding with a wolf. I know here in Oregon, they are ecologically separated as coyotes tend to stay in the lowland valleys closer to people while wolves live in the deepest, most remote forests. I would think this would mean they are reproductively isolated and therefore different species. In captivity, they can probably interbred but not in the wild. Same thing goes to the Gray Wolf and the Domestic Dog, except they do interbred quite often in captivity, my own dog being approximately 3/8 wolf. However, if a stray dog encounters a wild wolf pack, it’s more than likely it’s the last thing that dog is going to do.

In summary, my opinion is the distinction between the Gray Wolf and the Domestic Dog is more arbitrary than Gray Wolf and Coyote.

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my understanding is the mixing between coyotes and wolves did not likely happen out west where as you say the size and ecology differences are great. But as wolves were removed and the landscape changed in the eastern part of North America, coyotes spread east to fill these new or changed or opened niches. There was a sort of evolution towards bigger, more social coyotes even before interbreeding occurred, because it made more sense in an often colder, wetter environment than the older coyote range in the West. When the larger coyotes came way out into the Upper Midwest they encountered individual or small groups of wolves, the ‘survivor’ wolves that had learned to survive under persecution and consequentially were a bit smaller and did not have the ‘cultural’ pack coherency to remain distinct from the coyotes, and that is when coyote and wolf mixing occurred. I think after that point evolution has favored coywolves in the east because they have more of the versitality in habits and diet and ability to withstand and even thrive around modern human disturbance, but also the larger size and more complex social structure of wolves. The coyotes here in Vermont literally sound very different when they sing than the ones I knew in the deserts of California and Nevada. Much less yipping, more howling. I don’t know why, and it may not have much to do with genetics, but they sound much, much more like wolves for whatever reason.

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Local museum folks have looked at this issue some. http://rolandkays.com/coyote/

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Incidentally, just to add to the taxonomic fun, the wolves that contributed genes to coyotes in eastern North American are now no longer recognized by most specialists as conspecific with Canis lupus (Gray Wolf), they are themselves a distinct species, Canis lycaon (Timber Wolf, Eastern Wolf).

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Now consider the golden jackal – by appearances, seemingly the African and Asian version of a coyote. Do these same issues exist where wolves and golden jackals meet? Are there known wolf-jackal hybrids, or jackal-domestic dog hybrids?

Another thought: if domestic dogs are essentially domesticated wolves, why is it that when domestic dogs revert to the wild, they do not revert to a wolf-like appearance, but instead become the dingo, New Guinea singing dog, and Carolina dog?

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