Natural History

Coyotes and anything that is called a wolf in North America are as genetically close to each other as we humans are to each other.

This is the most radical thing I’ve ever learned from a scientific paper.

The paper is about whether red wolves and Eastern wolves are hybrids, which is a controversial topic. They probably are hybrids, but what are they hybrids between?

Are they crosses between two really distinct species or are they hybrids between two lineages of what one might rather radically and boldly declare subspecies?

The really radical discovery of these genome-wide studies on wolves and coyotes in North America isn’t that red wolves and Eastern wolves are hybrids.  The really radical discovery is that wolves and coyotes are much closer to each other than we assumed. The initial calculation suggested a divergence that happened only around 50,000 years ago.

Wolves in Yellowstone and Alaska have coyote genes, and coyotes in the Eastern US have wolf genes. That’s not a hybrid zone, which is what you get with bobcats and Canada lynx and with kit and swift foxes, where only a narrow hybrid zone has been identified.

Coyote and wolf genes have traveled across this continent, entering into what we have classically thought of as two distinct species but really aren’t.

My take is that coyote are nothing more than a diminutive wolf. Its ancestor was an archaic form of Eurasian Canis lupus, the Holarctic wolf.  It wandered across the Bering Land Bridge during a warming period that happened roughly 50,000 years ago. It came into a continent that was already dominated by dire wolves, dholes, and archaic jackal-like canids, as well as a whole suite of large cats, including jaguars, American lions, sabertooths, and dirk-toothed cats.

The way to survive was not to be a large pack-hunter. That niche was already occupied by dire wolves and dholes, so they became convergently-evolved jackals.

A jackal evolved out of the wolf-lineage is a pretty durable animal, and it played second fiddle to the modern Holarctic wolves that invaded some 20,000 years ago. The wolves that came across were large wolves that were adapted to hunting larger prey, and as the dire wolf became extinct, the larger Holarctic wolf replaced the endemic North American wolf.

The behaviors of coyotes and wolves generally keeps them from interbreeding. Coyotes are much more strictly monogamous, a trait that would be of great importance for an animal that had to live on smaller prey species and carrion for survival.

Wolves are far less monogamous, and if prey populations are high, it is not impossible for wolf packs to have several females produce litters. These extra litters come from the female wolves that have not yet left their mother’s packs but have bred with wandering males that slip around at the edges of the established pack territories. These matings happen all the time in wolf societies, but generally, these females don’t get to raise their pups. They die of exposure or are killed by the main breeding female.

Western and Northern wolf packs kill interlopers. A coyote is nothing more than interloper and gets killed. The two animals could mate and produce fertile offspring, but they usually don’t.

But the wolves that colonized the Eastern forests developed differently.  These Eastern forests had far more deer per square mile than the West, and greater social tolerance may have been a trait of these wolves, even when they were driven to near extinction. There is evidence that these wolves have mated with coyotes before European contact, but after European contact, they mated with the coyotes that came east.

The coyotes that came into the East were descendants of those little wolves that scrapped around the big predators of old. They could pack up as wolves to hunt deer, or they could remain in mated pairs to hunt only mice and rabbits. They could scavenge at the edges of human civilization, and they could thrive.

Most of North America is now under the reign of the little wolf, a remarkable feat of evolution.

Dr. Ian Malcolm’s most famous line from Jurassic Park is that “Life finds a way.” The context of the line is that he was rejecting the claim that the genetically engineered dinosaurs would never reproduce simply because they had chosen to engineer these creatures as solely female.

In our context, I would argue that “Wolves find a way.” Right now, the most successful wolf lineage in the world is the one that includes domestic dogs and dingoes. They are found on every continent, except Antarctica, and were found there until very recently. This lineage does well because it has become part of humanity. Populations go feral or go stray. Others become so humanized that they almost cease to be an entity separate from our species. It has largely given up hunting big game for survival and thrives on the fat of human civilization.

In North America, the second most successful wolf lineage is this coyote lineage.  It thrives because it can much more easily exploit life in the civilized world than the larger, more specialized wolves. They can scavenge. They can mouse and rabbit. They can run deer. They can eat apples and pears in orchards. But they do not depend upon the large ungulates for survival.

It is a wolf that cane become a jackal, then a fox, and then, should the deer numbers be high enough, return to a more lupine existence as a pack hunter.

Yes, my concept of the coyote and the North American wolf means rejecting some fossils. There are fossils that have been described as “coyotes” that date to 1 million years before present.

But the full-genome comparisons are so compelling that I have to reject these fossils. The full genome comparisons are exactly like the ones that have been used to compare humans to chimps, humans to gorillas, and domestic cats to tigers (and cats). 

The findings of these studies aren’t as controversial as the wolf and coyote genome comparisons have been, but that’s because they haven’t found that certain endangered species are likely hybrids.

The red wolf and Eastern wolf exponents can debate as to whether these animals are hybrids or not, but the real problem is the discovery of recent divergence between the wolf and coyote.

This recent divergence allows for a hybrid origin for the red wolf and Eastern wolf, but it also shows that this hybrid origin is most a debate of semantics. They might be hybrids, but they are hybrids between two different forms of the same species. And the resulting hybrids are much better adapted to living in the new North America.

That’s the best case red wolves and Eastern wolves have in light of the genetic data.

Paleontology is often the study of bones and teeth and comparing bones and teeth. Except for instances in which ancient DNA has been extracted and compared, most of these studies will miss very important parts of an organism’s natural history. Because of recombination, DNA studies can also be flawed, but they are a much more complete record of an organism’s evolution than we might get from measuring bones.

And we know now that canids are particularly prone to parallel evolution. The golden jackal species as classically defined has had to be split into two. African golden jackals are much more closely related to Eurasian wolves, while Eurasian golden jackals are much more distinct lineage. Their similarities are the result of parallel evolution, which was also at work in producing the jackal-like coyote out of the wolf lineage.

Had their bones been found in some ancient layer of sediment, paleontologists using comparative morphology methods would have declared them all one species, an error that is likely been repeated thousands of times with any number of specimens from a variety of lineages.

I like paleontology, but every time I read a paper from that discipline, I wonder if this is the full story.

And pretty sure virtually every paleontologist does too.

If the full-genome comparisons are correct– and I have little reason to think they are wrong–then we are living in the reign of the little wolves. They press on deeper into Alaska and Canada. They push east until they hit every state. They pushed deep into Central America, now running the right at the edge of the Darien Gap. Once they cross that great swamp, they will arrive in Colombia and will be the first wild Canis species to cross into South America since the dire wolf.

It’s just a matter of time. They will make it.

And South America’s guild of unique canid species are in for some disruption.

I hope they can handle our little renegade, for the reign of the little wolf could also displace the fruit-eating wolf with a mane and the short-legged convergent dhole.

Those problems are a way off, but they are worth thinking about, as the coyote completes its conquest of one continent and reaches for another.