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pale fox

One of the least studied of all canids is the pale fox (Vulpes pallida). It is native to the Sahel, a region in North Africa that lies between the Sahara and the savannas.

It was always assumed that the pale fox was a true vulpine fox, perhaps closely related to the fennec, which lives just to its north in the Sahara proper.

However, a new study out of the Russian Institute for Cytology has revealed something truly shocking.  Not only is the pale fox not a true fox, it actually is much more closely related to the black-backed and side-striped jackals than to any other canid.

Researchers traveled to Senegal and Mali and spent eighteen months live trapping the little foxes.  Initially, the researchers thought it would be quite difficult to capture enough specimens for the study, but it turns out that pale foxes are very easy to trap. All it took was just a bit of sheep fat and marten glands to lure the foxes into live cage traps.

The researchers were able to capture 21 in Senegal and 17 in Mali. They took blood samples from the foxes, which were sent to St. Petersburg.

At St. Petersburg, the researchers were able to extract good quality samples of mitochondrial DNA, which were then compared to the mitochondrial DNA of other extant canids. Mitochondrial DNA is inherited from the mother’s line, and it can be used to determine evolutionary relationships among various species.

The studies found that the samples of mitochondrial DNA of pale foxes most closely matched the black-backed and side-striped jackals than any of the fennecs, red foxes, and Rüppell’s foxes in the study. They were also similar to wolves, domestic dogs, and golden jackals.

Dr. Igor Iljin, head researcher on the study, says that the findings are truly a surprise.

“What we have found is that the pale fox is actually a jackal that has evolved into roughly the same niche as a desert fox. Our analysis of the mutation rates suggest that the pale fox only split off from the black-backed/side-striped jackal clade about 3.5-4 million years ago.”

Because black-backed jackals have been around in their present form for around 2-3 milion years, Iljin thinks that the pale fox evolved from jackals that became stranded in the Sahel around that same time period. Over time, they adapted to a more specialized diet of insects and small rodents. They also became significantly smaller to adapt to such a nutrient-poor diet.

Because the pale fox resembles the fennec in its ecology and morphology, it was assumed that these two species would be the most closely related.

However, this study shows that the pale fox’s similarity to the fennec are the result of convergent evolution.

“Just as convergent evolution produced a placental wolf in Eurasia and a marsupial wolf in Australia,  it has also produced two very similar arid-zone “foxes” in Africa,” Dr. Iljin concludes.

Further, Dr. Iljin strongly suggests that we stop calling the pale fox by that name:

“From now on, it should be referred to as the ‘pale jackal,’ and its scientific name should be updated to Canis pallida. Of course, we are aware that that the exact position of this endemic African clade of canids may or may not be properly classified within Canis, and if that were to change, we would expect the pale jackal to be placed with its closest relatives.”

So there we have it.  What was once thought to have been a fox is actually a jackal.

DNA has found stranger things before!

So we have a new species in Canis, which was once Vulpes.

Convergent evolution hid a dog in fox’s clothing.

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Important note.

 

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Rüppell's fox (Vulpes rueppelli) is the closest relative of the common red fox. This particular specimen, photographed in Egypt, really looks like its more widespread relative.

Although this particular fox looks very similar to the red foxes with which we are so familiar, this animal is actually something a bit different.

This fox is a Rüppell’s fox (Vulpes ruepelli). It is found in arid and semi-arid regions from Morocco to Southwestern Pakistan. And although it is a widely distributed species, it has not been widely studied.

It is a close relative of the red fox, but it is much smaller, weighing about 3.5 to 4 pound son average.

It looks like a hybrid between the fennec fox and the red fox, but that is the wrong way to think about them.

Instead, it is better to think of them as a descent from the ancestral red fox that evolved fennec fox adaptations in parallel in response to selection pressures that come from living in desert environment.

Smaller size means the animal can get by on very little food. Larger ears means the fox can better cool itself.

Now, if you really want to make things confusing, there are foxes native  to parts of North Africa, the Middle East, and South Asia.

They are typically on the smaller side, and they also tend to lack the black legs of the red foxes we know so well. Further, they have also evolved the larger ears that virtually all wild canids living in desert environments possess. Female red foxes of the Egyptian or Nile species are about the same size as the Rüppell’s fox.

So it can be a bit confusing tell the two species apart.

Egyptian or Nile red fox (Vulpes vulpes aegyptiaca). Not the larger ears and the lack of black legs.

Red foxes can live in arid environments, but they aren’t as well-adapted as Rüppell’s fox. So one is more likely to find red foxes areas with better access to water than Rüppell’s foxes. If it’s relatively large, it definitely a red fox, but unless one gets a good look at head, one might have a hard time telling them apart. Red foxes have longer, narrower muzzles, while Rüppell’s fox has more, apple-headed Chihuahua-esque appearance.

These desert foxes are actually quite hard to tell apart. In addition to the Rüppell’s fox, there are pale foxes (Vulpes pallida) of Africa’s Sahel region,  the well-known fennec fox (Vulpes zerda) ofNorth Africa and Egypt’s Sinai,  and Blanford’s fox (Vulpes cana) of Central and South Asia, Egypt’s Sinai, and the Arabian Peninsula.  Because they often share traits with other species, these foxes can be hard to tell apart. I think one of the reasons why people once thought that Fennecs were found throughout the Middle East is that people were confusing pale-colored Rüppell’s and native Blanford’s foxes with Fennecs. Blanford’s foxes are closely related to Fennecs, but they are quite a bit larger.

Here’s a pale colored Rüppell’s that might be mistaken for a Fennec:

The black marks under the eye give its identity away. If you could see the white tail tip, it would also tell you that you’re looking at a Rüppell’s . Fennecs have tawny streaks under their eyes. Fennes are still much smaller than this species, but a really large fennec might approach the size of a Rüppell’s vixen.

If one is south of Sahara in the Sahel, region and one comes across a small cream-colored fox. It probably isn’t a fennec,  If the ears are smaller and it’s somewhat larger than a fennec, it’s a pale fox.

Pale fox

This fox actually reminds me a lot of the San Joaquin kit foxes that are currently a protected subspecies in the US.

And then there is the Blanford’s fox, the closest relative of the fennec. Unlike the Fennec, this particular fox prefers to live in mountainous areas where it uses its superior climbing  and jumping talents to negotiate the sheerest cliffs. This fox is also found in Egypt’s Sinai and is also to  be found in other areas around Egypt’s Red Sea coast. It also exists in isolated populations on the Arabian Peninsula, but it is much more common in Pakistan, Afghanistan, Iran, and Turkestan. These two distinct populations are disjointed, and they may have been separated for a long enough time for the Blanford’s fox actually to be two distinct species. No one has performed genetic studies to compare the two populations.

Blanford's fox.

This species, like all desert foxes from Africa and Middle East, are really quite poorly studied. We know Fennecs pretty well, but what we know about them comes from captive populations.   Fennecs are commonly bred as pets, but as far as I know, no one is keeping larger numbers of other desert foxes in captivity. So the exact nature of their populations in terms of genetics and behavior has not been explored with any detail.

Oh and remember how I said that one way you could tell a pale Rüppell’s fox from fennec is the white tail tip?  It doesn’t work for telling a Rüppell’s from a Blanford’s.  And yes, their populations do overlap in range. I don’t think Blanford’s foxes can be found outside of areas where one might encounter a Rüppell’s. Most Blanford’s foxes have black-tipped tails, and they are so heavily sabled that the local in some areas call them black foxes. But a certain percentage of Blanford’s  foxes are going to have white-tipped tails, though they aren’t as fully white as one might find on a Rüppell’s.

Blanford's fox with a white-tipped tail.

The way to tell these foxes apart is a bit harder. Generally, Rüppell’s foxes are going to be found in sandy desert environment, while Blanford’s foxes tend be in mountainous regions. But that’s still hit or miss. Blanford’s foxes are usually darker sabled and even grayish in color when compared to Rüppell’s foxes, and Blanford’s foxes have a dark stripe of hair that runs down their backs in much the same way one will find on a Urocyon “fox” in North America and Colombia and Venezuela. Blanford’s foxes also have shorter legs than Rüppell’s foxes, another trait they share with Urocyon.  Both Urocyon and Blanford’s foxes have adapted to climbing. It’s just the Urocyon climbs trees, and the Blanford’s fox climbs cliffs.

Rüppell’s and fennec foxes have fur covering their pads. Blanford’s fox does not. I can’t find any information on the pale fox’s foot pads at this time, but these fur-covered pads actually protect the fox’s feet from burning sands. Even though all of these foxes come out at night, the sun can make the sand particularly hot, and it may take a while for it to cool in the night.

The exact taxonomy of these foxes is still not clear.  It was commonly asserted that Rüppell’s foxes, Fennecs, and pale foxes were all closely related. But recent genetic evidence shows that Rüppell’s foxes are closely related to red foxes, and Blanford’s foxes are closely related to fennecs. No one knows where the pale fox fits– at all.

These foxes don’t live in the most stable countries in the world, so they are pretty hard to study. Blanford’s, Rüppell’s, and fennec foxes are not considered endangered, although they might be threatened regionally.  So there is no really big push to study them.

Pale foxes are a great unknown. We don’t know where they fit in terms of dog taxonomy. We don’t know if their numbers are stable or not. As far as most people are concerned, they are fennecs with short ears that happen to live in the Sahel.

That’s not what they are, of course.

Of course, the black hole that is fox biology isn’t limited to these species. The only foxes that have been widely studied in the literature are red and arctic foxes.  That’s probably because they have always been an important fur-bearers, and they have been bred in captivity so much that there are now hundreds of thousands them in captivity. Red foxes also live in developed countries, and one of the leading red fox researchers, David MacDonald, studied them near Oxford.  If only a major university existed in the Sahel, maybe we might know more about pale foxes.

Swift and kit foxes are also pretty well understood– although their taxonomic status is still being debated. The Urocyon “foxes” aren’t as well understood at all, except the island fox, which is often considered a distinct species, is pretty heavily studied.  They island fox is considered endangered on its native Channel Islands, and there have been many studies to determine its exact genetic make-up and behavioral ecology. Urocyon on the mainland hasn’t been studied very much at all. It’s never been a major fur-bearer, and because it usually lives in very dense forests, it is much harder to observe than red foxes.

Of course, the Urocyon isn’t actually a fox. It’s derives from a lineage that split off from the other living dogs 9-10 million years ago, and because it is so unique, it needs a lot more attention that it is currently getting. Urocyon would be pretty easy to study. They are found throughout the United States, but it’s just not a major priority in canid biology.

The other foxes have been studied even less. You don’t see many papers on corsac, Tibetan, corsac, or Bengal foxes.

Foxes just aren’t as charismatic as wolves and their close relatives are.

And they aren’t as amazingly bizarre as South American canids are. There is no fox that is quite as unique as a maned wolf or short-eared dog.

So we’ve have very little knowledge about the little desert foxes of the Middle East and North Africa. All we do know is that their taxonomic relationships are more complex than we might have assumed. The dog family has had a lot of parallel evolution, and classifying species based upon morphology is often a dubious undertaking.

The fact that  Rüppell’s foxes were once classified with fennecs really shows the limits of using comparative morphology to determine taxonomy within this family. And one should be careful of studies that use this methodology to determine taxonomy. Morphology must be compared with genetic data if it is ever to be accurate. Remember, it was  upon this methodology that red wolves wered claimed to have derived from the ancient Canis edwardii species, but it is now regarded as a recent hybrid between modern wolves and coyotes.  And at one time, it was once accepted that the bush dog of South America was actually a species of dwarf dhole. Dholes and bush dogs have similar dental features, so it was assumed that there was some relationship between them. Genetic evidence has shown that the bush dog’s closest relative is the maned wolf, which is looks nothing like a bush dog.

So if the taxonomy of these more charismatic canids is actually wrong, you can bet that our current classification of these more poorly understood species is probably erroneous.

These little foxes need more attention.  Wolves are known entities.

We need a David Mech of the sand foxes!

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