Archive for the ‘evolution’ Category


Our brains like simple answers. We love to see the cause and then the effect, and we constantly look for them in nature.  At one time, we believed that the appearance of comets in the sky would be harbingers of great doom. And even in the past century in my home state, it has long been claimed that the appearance of Mothman in the area around Pt. Pleasant corresponded with the Silver Bridge collapse.

Correlation does not equal causation. Chanticleer, that old rooster of English Medieval lore, believed that his crowing at dawn made the sun rise.  When two variables occur at the same time but don’t have any causal relationship, they are called stochastic. Stochastic is one of my favorite words from graduate school, and even today when someone posits a bogus relationship between two variables, I say “Those are stochastic variables.”  I get some odd looks, but that was the point.

In trying to understand the complex phenomena that comprise evolution, we are constantly looking for these relationships. Some of them make some good sense and are well-supported with the data. We know that predators are the driving force behind making the prey swift and nimble, and we also know that plant-eating animals are the driving force behind the development of thorns and toxic plants.

But sometimes, our desire to see patterns leads us astray.  One example of what may be an erroneous positing of stochastic variables involves one of North America’s most unusual animals.

If one were to go to Wyoming on a hunting trip, there is a good chance that the outfitter will tell you to buy “antelope tags.”  Tags, of course, are licenses that give permission to the hunter to take a particular species, and in Wyoming, there is great interest in the pursuit of antelope.

But the little secret is there are no antelope in Wyoming. Indeed, the only true antelope in the United States are gemsbok that have been introduced to specific part of New Mexico, and Texas game ranches are full of various species of Old World antelope.

But no true antelope is native to the Americas. The animal we call an “antelope” should be more appropriately called “the pronghorn.”  It is not an antelope at all, but it is the last survivor of a lineage of creatures that are much more closely related to the various giraffe species and the okapi.  The pronghorn and its extinct kin are placed in a superfamily of Artiodactyla called Giraffoidea. These animals have bony processes that stick off their heads. In the giraffe and okapi, these are called ossicones and are covered in hair. In the pronghorn, a sheath of keratin grows over the bone. This sheath is shed every year, which leads to the claim that the pronghorn is the only animal that loses its horns every year.

The animal we call a pronghorn is superficially quite similar to what we would call an antelope or gazelle in the Old World.  But these similarities arose through parallel evolution. Both gazelles and pronghorns evolved in the open land where all sorts of cursorial predators hunted them. Predation forced these animals into swiftness and nimbleness.

That part is not much up for debate.

The problem comes with a specific claim about pronghorns.  One odd feature of this species is its speed. The top speed of an adult pronghorn is 55 mph (88.5 km/h). This speed far exceeds any of its predators that were around in historical times. A pronghorn can smoke a pack of wolves or coyotes and can easily outrun a cougar or a bear.

This high speed has vexed science for quite some time, but there has been an attempt to explain how it could evolved using predation as the driving force.

The hypothesis even points to a specific predator.

At one time the cougar lineage was much more diverse than it is now.  Right now, only three cats still exist in this lineage:  the cougar/mountain lion/puma/catamount/painter/panther (all names for one species), the jaguarundi, and the cheetah of Africa and Iran.

But during the Pleistocene, there were long-limbed cats that superficially resembled the cheetahs of the Old World. They were called “American cheetahs,” but analysis of mitochondrial DNA extracted from their fossils revealed they were much more closely related to cougars. Indeed, they were more closely related to cougars than cougars are to jaguarundi, which complicates the whole move to place jaguarundis in the same genus as the cougar. The two extinct American cheetahs are currently classified in the genus Miracinonyx, while the cougar is in Puma and the jaguarundi is in Herpailurus. Because these two American “cheetahs” are closer to the cougar, placing the jaguarundi in Puma creates a paraphyletic genus. This problem could all be solved if we just placed the two American “cheetahs” into Puma, but not everyone agrees with the mitochondrial DNA assessment of their phylogeny.

Let’s just say that the current pronghorn species lived at the same time as these lithe cougars, and it has been suggested that these cheetahs are the driving force behind the evolution of the extreme speed. The person who came up with this suggestion was a pronghorn expert named John Byers. Byers does not claim that these “cheetahs” were the sole force behind the development of speed in pronghorns. Instead, he lists them among a whole guild of running predators that could have placed selection pressures on pronghorns to force them into the evolution of speed.

The claim that these “cheetahs” were the driving force behind pronghorn speed has been picked up on the popular press though. Wildlife writer Dan Flores even made this claim recently on the Joe Rogan Podcast, and one can find countless pieces on the internet (including this blog when I was a lot more naive) that the extinct North American cheetahs are the “but for” cause of the pronghorn’s fleetness.

The problem with this claim is that it leaves out the nuance of the original hypothesis, and what we’re left with is a sort of cartoon version of evolution.

On the blog Laelaps, a great amount of skepticism is leveled at this hypothesis, largely because the popular understanding of how North American cheetahs might have affected pronghorn evolution.

One problem is that no one really knows how the two species of North America cheetah lived:

We don’t know very much about the natural history of either Miracinonyx species. Their skeletons are cheetah-ish, but that’s not nearly enough to pin these carnivores as the inspiration for artiodactyl agility. In fact, the ecological context of Miracinonyx bones hints that these cats were not simply speedy specialists who prowled open grasslands.

In their 1990 study, Van Valkenburgh and collaborators noted that later Miracinonyx bones have been found from Nebraska to Pennsylvania and Florida in deposits which accumulated under varying conditions. These cats were apparently just as at home among coastal savannahs as mountain stream valleys. More recently, at the 2010 Society of Vertebrate Paleontology meeting, John-Paul Hodnett and coauthors presented a poster about Miracinonyx that frequented caves in prehistoric Grand Canyon, Arizona. There was a distinct lack of fast-running, open-savannah prey animals during the same time period – the researchers noted that the extinct mountain goat Oreamos harringtoni was the most common possibly prey animal in the area. Rather than speeding over the grasslands, Hodnett and colleagues reported, the Grand Canyon Miracinonyx may have lived like snow leopards, bounding down sheer rock faces in pursuit of mountain goats.

This isn’t to say that Miracinonyx never bolted after equally-swift prey. It’s only to point out that we don’t know much about the cat’s ecology, feeding habits, or hunting strategy. There are a few ways we could find out a bit more, though.

Coprolites attributable to Miracinonyx might contain identifiable bone fragments of the cat’s prey. And while such a find is a longshot, perhaps a trackway made by a Miracinonyx running or launching itself into pursuit could tell us about how these cats actually moved. Both lines of evidence suffer from the complexities of accurately attributing a particular trace fossil to a trace-maker, though. Another route may be to compare the isotopic clues in the teeth of Miracinonyx to those of their potential prey, as was recently done for two sabercats and a bear dog found in Spain. By ascertaining where herbivores were feeding, and how geochemical signatures of prey became locked in carnivore teeth, paleontologists could narrow down the preferred habitats and prey of Miracinonyx. Furthermore, a poster presented by Natalia Kennedy and coauthors at the 2012 SVP meeting outlined a new attempt to compare the spine of the modern cheetah to that of Miracinonyx and other extinct cats to see how skeletal anatomy influenced flexibility and lifestyle.

Miracinonyx might have been the reason for the swiftness of pronghorn. False cheetahs and archaic pronghorn overlapped in time, if not habitat, for as much as three million years. But saying Miracinonyx was certainly a speed demon that gave pronghorn a reason to run is only supported by the barest amount of evidence. If we’re going to understand the evolution and natural history of these animals, we must first untangle their histories and the specific details of their ecology. The Just-So story of how the pronghorn got its speed has yet to be tested by the evidence which resides in the fossil record.

So we really don’t know enough about the extinct North American “cheetahs” at all, and we certainly don’t know enough to make claims that they were the driving force behind the evolution of speed in pronghorns.

Further, if one reads Byers’s text on these predators, he does say that these cheetahs were “the principal agents of selection” behind the pronghorn’s speed, but the author does point out that things like dholes, wolves, and various species of Borophaginae could have been part of the mix as well.

Pronghorn don’t just have speed. They have endurance.  Endurance is one way that Old World antelope elude the speed of cheetahs, but the main way they elude them is through agile running maneuvers. Pronghorn are fast, but they don’t have the quick turns of a Thomson’s or dorcas gazelle.

If these North American “cheetahs” ran down their prey in the same way the Old World true cheetahs do, then one would expect the pronghorn to have evolved some of these tricks.

Instead, pronghorn are running machines. They can take off and go and go and go. An animal that evolved to do such a thing likely didn’t evolve to outpace a sprinting cheetah. It likely evolved to outrun endurance runners.

Dholes are known in North America’s fossil record largely from Beringia, but we do have remains of dholes from Mexico. So their distribution in North America was probably more extensive than we might have assumed, but their fossil record is still quite spotty. Dholes run down their prey in long endurance chases, and dhole predation could have been a pretty strong selection pressure on pronghorns to make them fast endurance runners.

But another species could have also provided this pressure, and its presence in North America is well-established. What’s more, it lived in roughly the same areas where pronghorn were common.

This animal was North America’s only hyena, Chasmaporthetes ossifragus. These hyenas were far less like the modern bone-crushing species of hyena. Indeed, they were quite dog-like and are part of a grouping of hyenas that were called “dog-like hyenas.” The only dog-like hyena still in existence is the aardwolf,  which eats almost nothing but termites.  Its extinct relatives, though, were pretty adept predators of ungulates. They are thought to have run down their prey in much the same way dholes and African wild dogs do today.

So it seems that the pronghorn’s speed and endurance are much more likely to have evolved in response to predation from these long-distance running predators.

Further, we really don’t know how early North American wolves hunted their quarry.  Edward’s wolf and Armbruster’s wolf were both pretty common in North America until 300,000 years ago. They may have also hunted in much the same way dholes and African wild dogs do.  We don’t know enough about their natural history either, so we can only speculate.

The truth is we really don’t know why pronghorns are so fast.  It is possible that the North American “cheetahs” were the principal driving force behind the pronghorn’s speed. It is possible, but the evidence still is wanting. Further, there are more likely candidates that should be explored as having some influence on evolution pronghorn predation avoidance behavior.

So it is possible, but right now, it looks like we have two stochastic variables. We need much more evidence for a causal relationship.

And like everything else in evolution, we need to be careful about looking for patterns where they might not exist.








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Reeves’s muntjac is native to China and Taiwan. It is not native any place in Europe, but one of the places where it has been introduced is England. The epicenter of their population in that country is Bedfordshire, where this hunt takes place.  The Dukes of Bedford were into promoting deer on their estate, Woburn Abbey, and they were instrumental in saving the Pere David’s deer from extinction. One suggestion is that the muntjac in England derived from Reeves’s muntjac that escaped Woburn Abbey, but they also could have derived from escapees from the Whipsnade Zoo.

Whatever their origin, Reeves’s muntjac have established themselves a long way from their native territory, and they do quite a bit of damage to trees.

And what usually happens is that people are encouraged to hunt the invasives, but as you can see from the selective shooting that goes on this video, the species is now being managed as a sort of game species on many estates. This development should be of no surprise, and it should be noted that island of Great Britain has only two native deer species, the red and the roe. The very common fallow deer was introduced by the Romans and then again the Normans from the European continent.

But the fallow deer is essentially managed as a native game species. The exact same thing is done with Sika deer that have been introduced to Maryland. White-tailed deer are treated the same way in the Czech Republic, as are all the deer that have been introduced to New Zealand.

Whatever their treatment as a game or invasive species, this video does provide a nice closeup of the male Reeves’s muntjac as a specimen. Of particular note are the tusks, which they use for fighting and display.  It is mentioned in this clip that they are “musk deer, ” but this is in error.

This error comes from the tusks that both muntjac and musk deer possess, but musk deer are placed in their own family (Moschidae).  True deer are Cervidae, and all the muntjac species are true deer that fall into the Cervinae subfamily (which includes red deer, fallow deer, and North American elk).  However, they are primitive Cervinae.

Musk deer differ in some morphological characters from true deer in that they don’t have facial glands, possess only a single pair of teats, and have a gallbladder.  They also never have antlers, and all species possess a scent gland on their tail.

The common ancestor of musk and true deer, though, had prominent tusks. The modern muntjac species is unique in that it still has those fangs of the earliest Cervinae.

The other true deer that is known for its tusks is the Asian water deer, which was definitely introduced to Britain thanks to escapees from Woburn Abbey. But it is not closely related to the muntjac at all.

It is also not a musk deer, even though it has much more prominent tusks than the muntjac and never has antlers. Instead, it fits within Capreolinae, the subfamily of deer that includes roe deer, moose, reindeer/caribou, and all the New World deer but the wapiti. Its prominent tusks and lack of antlers are a also primitive trait in this lineage of deer.

That muntjac and water deer are both fanged shows that more primitive animals will resemble each other more the derived forms of their respective lineages.

These cnine teeth are celebrated in North America elk lore. Their “ivory” is taken as almost as much a trophy as the antlers, and indigenous people in Canada and the US used them as jewelry. They aren’t sharp daggers like those found on muntjac and water deer, though. They are just vestigial teeth that show that the ancestor of the great bugling bull were once little fanged creatures.

These upper canines also appear in white-tailed deer on occasion as an atavism.

Beyond these little fangs, North American deer lack these primitive traits, so I find fangs on these Asian species totally fascinating.

They are windows into the past, when deer were just little beasts of the undergrowth.


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coyote  eastern

I cannot tell you how many times I’ve been seen this article from The Economist, claiming that we’re seeing the evolution of a new species of canid that is a hybrid coyote and wolf.

It’s interesting, but I don’t think that just because we have a coyote that has hybridized with wolves and domestic dogs means that a new species is suddenly evolving. Rather, it’s a good example of how some introgression with a related species can provide some potential benefits to a species as it enters new ecosystems.

But the popular naming of this animal is coywolf. To me that suggests that the animals is a 50/50 mix, but the closest we have to 50/50 animals that are 50/50 coyote and wolf crosses are those in parts of Ontario, especially Algonquin Park. Those wolves are around 60 percent wolf and 40 percent coyote .

Most Eastern coyotes are still overwhelmingly coyote in ancestry.

This has led Roland Kays, one of the world’s leading authorities on coyote and wolf genetics (and one of the discoverers of the olinguito), to write this piece in The ConservationHe writes:

Coyotes in the Northeast are mostly (60%-84%) coyote, with lesser amounts of wolf (8%-25%) and dog (8%-11%). Start moving south or east and this mixture slowly changes. Virginia animals average more dog than wolf (85%:2%:13% coyote:wolf:dog) while coyotes from the Deep South had just a dash of wolf and dog genes mixed in (91%:4%:5% coyote:wolf:dog). Tests show that there are no animals that are just coyote and wolf (that is, a coywolf), and some eastern coyotes that have almost no wolf at all.

My little quibble, which is more a gentlemen’s disagreement, is that dogs are part of Canis lupus in the same way that Pekin duck is part of Anas platyrhynchos. They are just domestic variants of a widespread wild species.  Pekin ducks have lost most of their brooding instincts, which means they don’t exist anywhere but captivity. One could say the same thing about bulldogs, which usually cannot free-whelp. They simply wouldn’t exist in the wild, but I think that doesn’t give them a distinct species status.

However, even if we count the dog content in Eastern coyotes as wolves, they are still overwhelmingly coyote in their genetic makeup. If that’s the case, then I think it’s much more fair to call them Eastern coyotes.

If you’re going to call this a coywolf, then you’re going to have call yourself (if you’re not of Sub-Saharan African ancestry) a “humadenisothal.” That’s because modern humans who have origins out of Sub-Saharan Africa have Neanderthal in them, and those who have ancestry in Melanesia and Australia have genes from the now extinct Denisova hominin. All of us are still overwhelmingly Homo sapiens in ancestry, but some humans have the genes of other extinct hominins. It doesn’t mean that we’re all different species. It’s just that different populations have experienced introgression.

Kays is very cognizant of the issues around calling this animal a “coywolf”:

There are many examples of bad animal names that cause a lot of confusion.

The fisher is a large type of weasel that does not eat fish (it prefers porcupines). The mountain beaver of the Pacific Northwest is not a beaver and does not live in the mountains. And then there’s the sperm whale…

We don’t get many opportunities to name new animals in the 21st century. We shouldn’t let the media mess up this one by declaring it a new species called the coywolf. Yes, there are wolf genes in some populations, but there are also eastern coyotes with almost no wolf genes, and others that have as much dog mixed in as they do wolf. “Coywolf” is an inaccurate name that causes confusion.

The coyote has not evolved into a new species over the last century. Hybridization and expansion have created a host of new coyote variations in the east, and evolution is still sorting these out. Gene flow continues in all directions, keeping things mixed up, and leading to continual variation over their range, with no discrete boundaries.

Could evolution eventually lead to a coyote so specialized for eastern forests that they would be considered a unique species? Yes, but for this to happen, they would have to cut off gene flow with nonhybrid animals, leading to distinct types of coyotes that (almost) never interbreed. I think we are a long way from this possibility.

For now, we have the eastern coyote, an exciting new type of coyote in the midst of an amazing evolutionary transition. Call it a distinct “subspecies,” call it an “ecomorph,” or call it by its scientific name Canis latrans var. But don’t call it a new species, and please, don’t call it the coywolf.


However, if we want to make things more confusing. We’ve gone down this path of naming all sorts of wild dogs “wolves” for quite some time now. The Falklands wolf or warrah was actually closely related to the maned or “red” wolf. “Red wolf” is the direct translation from the Russian for the animal we call a dhole, and one way to interpret the scientific name of the African wild dog (Lycaon pictus) is “painted wolf.”

Coyotes are very closely related to wolves and dogs. They are something like 99.3 percent genetically similar.

And now that we’ve started to use molecular data to classify the dog family, we’ve generated several new “wolves” that aren’t part of Canis lupus. For example, when I was a child, Canis simensis was the Simien jackal.  Mitochondrial DNA analysis suggested it was closer to wolves than other African canids, so we started calling it the Ethiopian wolf.  Now we know it’s not that closely related to Canis lupus, but we still call it by that name.  My guess is that it is easier to get people interested in conserving a unique form of wolf than it is to get people to want to conserve a uniqiue form of jackal.

We also now know that African golden jackals are more closely related to wolves and coyotes than to Eurasian golden jackals, and we’re now moving to calling African golden jackals “golden wolves” (Canis anthus).

However, if we start calling the African canids “golden wolves,” why aren’t we calling the coyote something like “the lesser North American wolf.” A coyote is much more closely related to Canis lupus than the golden wolves of Africa are.

So you can see that it’s not that trivial what we call this animal.

Of course, calling the Eastern coyote a “coywolf” just adds to the mystique of this animal, and it certainly has plenty of mystique.

Most people in the US don’t live near any wolves. The last wolf in West Virginia was killed around the year 1900. The nearest wolves to me are in Michigan’s lower Peninsula, where they were discovered just a few months ago.

Yet we’ve come to think of wolves as a symbol of the wilderness we’ve lost.

So when the media says that we have “coywolves” running around, then it makes us feel that some of that wild mystery is running about.

Well, it certainly is, but using this term doesn’t help our understanding of what is happening.


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velvet claw

If you probably couldn’t tell from reading this blog, carnivoran evolution and natural history is one of my passions.

Where did all of this get started? I’d say sometime in the mid-90s. I used to watch A&E’s old Wildlife Mysteries series on Thursday nights. These were mostly very high quality wildlife documentaries and a lot of them were BBC productions.

Some of these films were shown in a series called “Carnivores.” It was about the evolution of the order Carnivora, minus the pinnipeds. And I loved it.

The series was based upon the work of David MacDonald, a carnivoran specialist and conservation biologist at Oxford.

In the UK, it was shown as “The Velvet Claw,” which is one reason I’ve had a few problems finding even clips of it online.

And for a long time, all that we could see are short clips, but now, well, it’s been uploaded in full.  Here is the entire series on Youtube.

I don’t know how long it’s going to be up, so you’d better watch it soon.


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sumatran rhino

A few days ago, I had a discussion on Facebook with someone about Sumatran rhinoceroses and why they were still hairy. I had posted one of Frans de Waal’s photos of a Sumatra rhino calf, and as calves go, it was very shaggy.

The discussion got to a really interesting question, which I think points out to a misunderstanding of the mechanisms by which evolution happens. The discussion went something like this:

“Sumatran rhinos are hairy. Therefore, there must be some reason they are hairy. Otherwise, there would be selection against having lots of hair in jungles of Southeast Asia, Borneo, and Sumatra.”

The answer I had was that the Sumatran rhino is the closest living relative to the extinct woolly rhino. Woolly rhinos were quite well-furred out, and it’s possible even now for animals to retain primitive traits. You hear people talking all the time about living fossils, but there is usually no understanding that a 20 million-year-old shark that looks very similar to living species most likely is incapable of reproducing with that living species (if the two were made to live contemporaneously with each other.)

The error is in assuming that a trait an animal possesses is always a benefit to it. This is a corollary of thinking the evolutions happens through natural selection alone, when it is actually only one way that it happens. (And it’s actually not the main way).

The truth is the Sumatran rhino is nothing more– or less– than the last survivor a lineage of rhinos that retained their furry bodies of their tapir-like ancestors. (And Sumatran rhinos aren’t even that hairy!).

And it should be noted that there are plenty of mammals in the Sumatran rhino’s range that have much furrier bodies.

Evolution isn’t planned out. It can only work with what genetic material is available in the population. Assuming that Sumatran rhinos retain their excessive fur only because it has some advantage to them is putting the cart before the horse.

Now, there is a possibility that there is some advantage for these rhinos to retain the very furred up bodies. I’ve not seen any literature that explores this possibility, but the fact that this animal is so closely related to the woolly rhino kind of provides the best explanation. This animal retains a primitive trait solely because that’s what its ancestors were. It just can’t magically evolve a relatively hairless body.

So always be careful in assuming that a trait exists solely because there is some advantage to it. That’s a real problem in our popular understanding of evolution.

Be very careful of putting the cart before the horse. Sometimes a trait is advantageous. It’s often just neutral.


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pygmy three-toed sloth

Defining species and subspecies is a complex task. Lot of ink gets used in peer-reviewed journals debating if a population is a true species, a subspecies, an ecomorph, or a mere local variant. There is no cut-and-dry definition for any of these classifications, which is actually one of the strongest pieces of evidence for evolution. If all things were specially created, it would be very easy to determine species statuses. You wouldn’t have all this debate at all. It would be very easy to settle.

Long-term readers know that I’m skeptical of considering dogs a separate species from the wolf, even if it is not politically correct in some dog training circles to say so. I’m also skeptical of species status of the red wolf and the “Eastern wolf,” which are almost certainly just hybrids with wolves and coyotes. I’m skeptical that the Island fox of the California’s Channel Islands is separate species from the mainland gray fox, but I don’t deny that it is a very unique subspecies.

Part of my reasoning for being skeptical of the Island fox’s species status is that it only recently derived from the mainland species. These two populations have split from a common ancestor only within the last 9,200 years and may have been introduced to the islands by humans only about 7,000 years ago. For those of you keeping score, dogs split from their most recent common ancestor with wolves at least 15,000 years ago, and when you realize that there are some populations of wolves, especially in the New World, that are even more distantly related to dogs than the common subspecies of Eurasian wolves are, you can see where this gets really tricky.

So if I’m not calling a dog a species, then I really shouldn’t be calling an Island fox one.

If you call an Island fox is a species, then it is perhaps the youngest mammal species on earth.

The only other species that comes close to it is the pygmy three-toed sloth. That species derived the Panamanian brown-throated three-toed sloth about 8,900 years ago, when the island of Isla Escudo de Veraguas became separate from the mainland. Unlike their more generalist ancestor on the mainland, the pygmy sloth lives solely on mangrove leaves, and it spends a lot of time swimming from mangrove to mangrove.  It is 40 percent smaller than its mainland ancestor.

And there are only about 70 of them left.

This sloth and the Island fox are good examples of how rapidly simple barriers to gene flow can result in phenotypic divisions between related populations.

It is at this stage I realize that I have contradictions in my own concept of species. I think everyone who has looked at the issue does at some point.

I’m less willing to think of the Island fox as a species than the pygmy three-toed sloth. But the truth is they are both kind of in that nebulous area.

I’m pretty sure that if you caught a gray fox here in West Virginia and turned it out on the island of San Nicolas, it would mate with the island foxes. If it were a dog fox, I’m pretty sure it would dominate the island, not only because a mainland gray fox is quite a bit bigger than an island but also because these foxes are known for their very tight genetic bottleneck. These foxes have been able to keep their MHC haplotypes diverse and heterozygous because they have a way of picking up on these differences when they choose their mates. My guess is a big mainland gray would be in demand with just about any vixen on the island. Monogamy be damned.

But somehow, I think adding a brown-throated three-toed sloth to Isla Escudo de Veraguas would mess up the uniqueness of the pygmy three-toed sloth. Maybe the hybrids would be unable to live so well on mangrove leaves. Maybe.

Or maybe I’m just finding a way to rationalize it.

This isn’t an easy question. It’s not an easy answer.

We talk a lot about conserving endangered species, but the truth is we don’t have a very good concept of what a species is. We have a lot of different concepts for defining species– all of them good. But every single one of them leads to contradictions like these.

These contradictions are wonderful in science.  They give us things to question, debate, and explore.

But when we come up with something called an Endangered Species Act, what exactly do we mean?

The law cannot handle such nebulous and contradictory definitions. Science explores natural phenomena. The law derives requires clear definitions, or lacking such clear definitions, case law that fleshes out the nebulousness. (At least in common law countries…)

I don’t have any good answers to these questions, and the truth is that no one really does.

That’s because at the core of it, evolution isn’t just something that happened. It is something that is happening, and our human brains, which try to make clear distinctions so that we can understand, intuitively cannot handle the gray area.

We know that the Urocyon genus of wild dogs is a very distant offshoot from all other canids.  We know that three-toed sloths are not that closely related to two-toed sloths, which are the last survivors of the lineage that included those giant ground sloths that once roamed much of North America.

When we get to the finer distinctions between really closely related populations, we really don’t have good answers.

But it’s pretty clear that if we call the Island fox and the pygmy three-toed sloth species, they are very new ones.

Evolution can happen rapidly, but it usually doesn’t.

And islands have a way of making it happen fast.

Those concepts are fascinating in themselves– much more so on which Latin or Latinized binomial we use.


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pekin duck

One of the more bizarre fights that happens in the world of dogs is how to classify them. Within these debate is always a background of what it actually means to care for a dog “naturally” and what their “natural” life should be.

It actually shouldn’t be this way. Whether one considers a dog to be its own species or a subspecies of Canis lupus, there is no natural way to care for them or natural life for them. That’s because a dog is a domestic animal, the oldest of domestic animals, and there is very little that is natural about them. Over the thousands of years that have been part of human societies, they have adapted very nicely to our needs. Dogs have even developed cognitive short-cuts that have made them better readers of human body language than virtually any other animal, wild or domestic.

The natural way of keeping a dog is that a dog lives with people. It’s an oddball among domestic animals in that is derived from a very old domestication, and it is also the only large carnivoran that has ever been domesticated. Almost all other domestic animals are herbivores, and the other domestic carnivorans–the Near Eastern wildcat, the European ferret, and the red fox– are all small species. Most large carnivorans consider humans to be prey, so there is something very unusual about domestic dogs.

I get that.

But I am not among those who thinks that there is a species called Canis familiaris. I think dogs are most correctly classified as a subspecies of Canis lupus. 

As soon as I say this, people just lose it. That’s because when you say this, it is almost like justifying abusive dog training methods that are based upon dominance. It also might be justifying raw feeding, which is also contentious issue in the world of dogs.

Those are implications that I soundly reject. There is nothing inherent in a classification of an organism that tells you how to feed it or train it, especially when you’re dealing with the real oddball among domestic animals.

Note that it is never controversial to say that a pekin duck is a mallard. In the photo at the top of the page, you can see the old pekin drake that used to rule the pond. His mate was that Rouen-cross hen, which was sold at a feed store as a mallard. They were both of the same species. Her ancestors were some kind of Western Europe mallard, while his were wild mallards living around Nanjing that were later transplanted to the area around Beijing, where they were selected for larger size and white plumage.

Both of these animals were quite different from the true wild mallard that I see swimming in rivers here in West Virginia. She was twice the size of a wild mallard hen and much darker in color, and he was three times the size of wild drake. Neither of them could fly very well. The Khaki Campbell crosses in the photo were actually much better fliers than either of them.

Performance-strain Rouens are not far removed from the wild mallard. Although they are larger and cannot fly, they still produce the large amounts of oil in their plumage that keep them warm and dry even when they swim the coldest water. Female Rouens also retain the brooding instinct and can hatch out their offspring.

Pekins don’t produce as much oil and aren’t as cold tolerant, and if incubators didn’t exist, there would be far fewer pekin ducks in this world. Most pekin hens have no broody instinct. Further, they also grow so much more rapidly the either Rouens or wild mallards that they are prone to growth disorders.

Even though it is so far removed from the wild mallard, the pekin duck is still a mallard. It is as much a modification on a mallard as a St. Bernard is on a wolf.

The only difference is that no one is going to launch into a culture war tirade over the classification of a pekin duck, but if you say a St. Bernard is a wolf, then you will be asking for it.

It is certainly true that dog domestication happened a lot longer than mallard duck domestication. I cannot find any good literature on dates for mallard domestication, but it’s pretty clear that ducks have been kept in Southeast Asia for thousands of years.  Dog domestication dates and locations are still quite contentious, but the best evidence I’ve seen suggests that they were domesticated from an extinct wolf population between 15,000 and 32,000 years ago.

Some will argue that this extinct wolf population actually is a different species from modern Canis lupus, but I’m quite skeptical. Wolves themselves are among the most varied species in the wild. If we were to go back in time  see that ancestral wolf population that gave rise to domestic dogs, I think it would be hard to say that they weren’t within the diversity of phenotype that we see in current Canis lupus populations.

I think the big difference is that these wolves had far fewer reasons to fear people and were actually quite curious about our kind and were actually fairly easy to habituate to living near us. Over time, these wolves became incorporated into our society.

Much has been made that dogs and wolves have different reproductive strategies, but the truth is wolves actually have two reproductive strategies. One of these is the pair bond, where a male and female become partners and their grown offspring help care for the puppies. This is the most successful strategy for wolf reproduction because all the resources and attention of the pack can be devoted to a single litter. Another strategy goes on in parallel. Young male wolves leave their natal packs, but they often cannot find a mate or suitable territory. So they often try to mate with the grown daughters that are part of an established pack. These daughters cannot mate with their father, who is pair-bonded to their mother, who will attack them if she catches them in the act. So these females do often mate with these roaming male wolves. They often become pregnant and even have puppies, but in the wild, they almost never get a chance to raise those pups.  In the early years of wolf reintroduction to Yellowstone, prey was so abundant that many packs raised multiple litters every year. One would be born to the mated pair, while others would be born to these unpaired daughters and the roaming males. The way dog genes get into wolf populations is almost always when one of these non-paired females in a pack hooks up with a roaming male dog, which is why dog hybridization in European wolves went unnoticed. Most studies on wolf DNA looked at mitochondrial DNA alone, and if a wolf had dog ancestry coming from a male dog, it simply never would have been noticed.

The pair bond strategy exists because it about the only way to raise wolf pups. It is very common in all other dog species. In fact, a study of Chicago coyotes revealed that they are almost 100 percent monogamous, and similar findings have been discovered in golden jackals. However, in a wolf pack, preference toward the bonded pair during the mating season means lots of stress. They mated pair has to spend lots of time making sure no one mates with the wrong wolf, and they also will try to kill any of the roaming males that come near the unpaired females, which is also why the roaming male strategy isn’t as successful with wolves.  Natural selection would favor pair-bonding over roaming male mating strategies.

Domestication changed this equation. When wolves began to hook up with people, people began to provide food.  These wolves may have pair-bonded and mated in that fashion, but the chances of these secondary females to raise litters to maturity were much greater. Over time, pups born to roamers and unpaired females would start to outnumber those that were born to the pair-bonded wolves, and thus, a relaxation of selection pressures for pair bonding would become ubiquitous in these wolves. When pair-bonding became broken, then it became easier to selectively breed them. One could have a stud that mates with many females, and this promiscuous behavior could have been heavily selected for. Dogs are able to reproduce at much faster rates than wolves do, and one of the weird effects of domestication has been that female dogs are no longer monestrus and become sexually mature at younger ages than wolves or virtually any other wild dog.

Dogs and wolves have continued to exchange genes since the initial split. Black wolves in North America derive from domestic dogs that mated with wolves, as do black Italian wolves.  Wolves in Italy also can have dewclaws on their hind legs, which also originated from dog and wolf matings. Historians ranging form Pliny the Elder to the Plott hound historian Bob Plott have documented cases of hunters breeding their dogs with wolves, a practice that still goes in parts of Russia. It was just recently revealed that the livestock guardian dogs of Georgia have a rather significant amount of gene flow with the wolves of the same region.

So yes, I do recognize there are differences between wolves and dogs, but dog is a modification on the original wolf template.

The final important reason why I classify dogs as being part of the wolf species is that evolution has within it a nested law. This is the law of common descent. One can never evolve out of one’s ancestry. Humans are always going to be great apes, and humans are always going to be primates, not matter how different we become from our ancestors. A whale will always be a mammal, even if it somehow evolved gills.

A dog is always going to be a wolf. We change them through selective breeding, as we have with all our other domestic animals, but we are never going to change their fundamental ancestry.

All that I’m doing when I use Canis lupus familiaris is that I’m putting dogs where they fit on the tree of life. I’m showing my respect to their evolutionary heritage. I am paying homage to their phylogeny.

I’m not making excuses for Cesar Millan or anyone else.

Many people who promote science in our understanding of dogs are actually engaging in what I call “phylogeny denial.”  Many people bend over backwards to show how dogs aren’t like wolves, which I supposed is harmless, but I think it gives people a false impression of what a dog actually is in terms of its evolutionary history. It’s not a domesticated golden jackal or coyote or African wild dog. It is a domesticated ancient wolf, but that wolf was just an older form of the modern Canis lupus.

When you classify an animal according to its phylogeny, you aren’t doing anything else but classifying it. If a whale is a mammal, it does not automatically follow that it is a land mammal, does it? And classifying a dog a subspecies of wolf doesn’t mean that it evolved to hunt moose in Alaska.

I really wish people were taught to think about natural history in this fashion more often. It clarifies a lot of misconceptions people have about evolution. If I had a nickel for every time I get asked about humans evolving from modern chimpanzees, then I’d be a pretty wealthy individual. The last common ancestor between humans and chimps was not a chimpanzee. It may have looked more like a chimpanzee, because chimpanzees retain a lot more of the original African ape’s features than humans do, but it was not a chimpanzee like we have today.

By contrast, the wolves that gave rise to domestic dogs were probably indistinguishable from Eurasian wolves living today. Further, dogs and wolves continue to affect each other’s evolution through a rather significant gene flow. Humans affect chimpanzee evolution only through hunting them for bushmeat, destroying their forest habitats, and spreading disease. There is no gene flow between the two species, and because we have a different chromosome number, any “humanzees” would likely be sterile.

Finally, Canis familiaris creates a stumbling block in understanding the natural history of dogs, which is why you still run into people who think dogs derive from any number of different species of wild dog. Canis lupus familiaris neatens up that confusion very nicely.

Classifying a dog as a wolf shouldn’t be any more controversial than classifying a pekin as a mallard, but dog people just have a much harder time thinking in this way. I have never seen an internet flame war erupt between pekin duck owners over the classification of their ducks. In fact, I don’t think many pekin duck owners actually know that their ducks are mallards and do not actually occur anywhere in the wild.

But with dogs, charlatans have used the dog as wolf idea to justify all sorts of bad human behavior towards dog, but scientific facts remain scientific facts, whether charlatans misuse them or not. In terms of their ancestry, as has been revealed through copious analyses of their DNA, dogs are in the Canis lupus lineage.

They simply aren’t anywhere else in the tree of life. This is where they belong. Accept it, and move on.






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