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Posts Tagged ‘Tibetan fox’

tibetan fox vs. marmot

The 2019 winner of the London Museum of Natural History’s “Wildlife Photographer of the Year” is Bao Yongqing, who took this amazing predator-prey action shot on the Qinghai-Tibetan Plateau. It shows a Tibetan fox (Vulpes ferrilata) trying to catch a Himalayan marmot (Marmota himalayana).

In an interview with the photographer, it was revealed that the fox was a vixen with young that needed meat. Even after a long stalk on the marmot, the prey was not easily subdued. Other marmots came to its defense, which is something that our groundhogs would never do. The fox had do dive around the defensive marmot to get at its prey, but eventually, the targeted individual collapsed and fell to the fox’s jaws.

Tibetan foxes have only recently become well-known. The initial descriptions of them were based upon pelts, and it is only now that we have a popular concept of these foxes with their oddly-shaped, squared-off heads.

I was surprised that this species of marmot would engage in altruistic behavior. The marmot species I know best, the groundhog (Marmota monax) does not do this. They are way more solitary than those marmot species of Central Asia, though, and this social behavior can be of great benefit for life on the exposed ground.

This is a pretty cool photograph that reminds me of another winner. In 2015, a photograph of a red fox killing and eating an arctic fox in Canada won earned the photographer this same award.

So foxes killing things– well, that’s an award winner these days.

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tibetan fox corsac

L: Tibetan fox (Vulpes ferrilata) R: Corsac fox (Vulpes corsac)

I’m sure that just about everyone has seen the footage of the Tibetan fox. Its blocky head is really unique among canids, and one theory about why it has such an unusual head is that the head actually makes the fox more camouflaged around rocks as it stalks its prey.

If you’ve not seen the footage, here it is:

The Tibetan fox is found in the Tibetan and Ladakh Plateaus, and it pretty much found only in high grasslands. It is a specialist of this environment.

The mitochondrial genome of this species was sequenced recently. Preliminary studies had indicated that its closest relative is the corsac fox, which ranges in the steppe country that runs from the eastern edge of the Caucasus to northeastern China.  It lives in arid, semi-arid, and grassland habitats to the north of the core range of the Tibetan fox.

The corsac is the basic fox. It is smaller than most red foxes, and it comes in gray or reddish brown.

And to be completely honest with you, I have a very hard time telling corsac foxes from North American swift foxes (Vulpes velox). I should note that even though the two look alike, the corsac is more closely related to the red fox, while the swift fox* is very close to the arctic fox (Vulpes lagogpus). Both swift and corsac foxes are adapted to grassland ecosystems, so their similarities can be chalked up to simple convergent evolution.

The researchers who sequenced the Tibetan fox mitochondrial genome also looked at other dog species and found that modern dog species radiated very rapidly. The authors estimate less than 5 million years separates Canis species from the maned wolf, which is actually quite about half the time that has been estimated for the divergence between Canis and its allies and the South American wild dogs through the sequencing of the dog genome.

Mitochondrial DNA studies can lead us astray, but this is still an interesting find.

The researchers found that the corsac and Tibetan foxes split from each other about 1 million years ago.  Although they don’t say so in the paper, it’s pretty likely that the corsac is the ancestor of the Tibetan fox. Maybe it happened like this:

A population of corsac foxes, whose range had been pushed south during the Pleistocene, were able to roam into the Tibetan Plateau during a warming period. They were then cut off by glaciers and began their journey toward speciation, adapting the high grassland habitat in ways that made them quite different from their ancestors. The squared off heads gave the foxes marginal advantages in hunting in the high, rocky  grasslands.

The authors didn’t find any genetic evidence of any sort of adaptations in the mitochondrial genome for higher altitude living among Tibetan foxes. Those genes probably do exist, but they don’t exist in the mitochondrial genome.

So what the researchers found is that Tibetan fox is very closely related to the corsac fox. This is not a surprising find, but I have wondered where this fox really does fit in the dog family. It’s from such an isolated area that virtually no studies have been done on it.

The squareness of its head makes the Tibetan fox a bit of a celebrity in the digital age. If BBC cameras hadn’t filmed it (twice!), it wouldn’t really be known. I’d only ever heard of it from a children’s book, which included a bad painting of one. It was just a nondescript fox as far as I was concerned.

So the Tibetan fox is a modification on the basic fox.

It evolved from the banal to the bizarre.

Bizarre enough to be on the BBC.

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*The study looked at kit foxes. Kit foxes are closely related to swift foxes. Both are very closely related to the arctic fox.

 

 

 

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The Tibetan fox (Vulpes ferrilata) is endemic to the Tibetan Plateau. Its exact position within vulpine phylogeny isn’t clear.

One of the more famous clips from the Planet Earth series is the sequence that shows the unusual-looking Tibetan fox hunting pika.

The fox’s square-muzzled features have intrigued many people, and on the internet, it is often used as a meme to convey messages in much the same way as the corgis and the so-called “LOL cats.” (I don’t find cats particularly funny, but then I’m an extreme ailurophobe.)

This fox is a pika-hunting specialist.

Yes.  You heard me correctly. It hunts pikas.

Pikas are not just found in western North America.  North America has only two species of these adorable little lagomorphs, but there are many more species in Eurasia.

They are particularly numerous in the Tibetan Plateau, and the Tibetan fox has evolved to be an efficient predator of pikas.

However, the exact function of the fox’s weird looking head isn’t exactly clear. One hypothesis goes that the Tibetan fox evolved its squared off head to make it easier for the fox to jam it into squared off crevices in rocks where a pika might be hiding. Another hypothesis is the fox evolved the head shape as a way of matching the angles of the rock formations in the Tibetan Plateau, which provides the fox greater camouflage when stalking pikas. Still another  hypothesis suggests that the head shape is nothing more than an  adaptation for retaining heat during the region’s frigid winters. (Arctic foxes, however, don’t have heads that are anything like those of Tibetan foxes, and they live in a much colder climates.)

The truth is none of these hypotheses have been tested.

We just know that the Tibetan fox has a weird head.

And  the head shape is not the only mystery behind this fox.

We don’t know where this fox fits in the canid phylogenetic tree.

The only genetic data I’ve been able to find on this species is a study that developed a genetic test for determining whether a fox scat had been left by a red fox or a Tibetan fox, and another study that analyzed the cytochrome-b gene from various carnivoran scats in the region, which found that sequences from Tibetan and Corsac foxes  (V. corsac) were virtually indistinguishable. Cytochrome-b gene is found in found in the mitochondria DNA, so what we have is a very narrow mtDNA study that suggests a relationship between the Tibetan fox and the corsac fox.

Corsac foxes are found in the steppe country of Central Asia. They are very much equivalent to our kit and swift foxes.

I don’t know of any other genetic studies on Tibetan foxes and where they might fit in the canid phylogenetic tree.

Tibetan foxes do have some features in common with red foxes.

If you look closely at the photo at the top of this post, you can see that Tibetan foxes have a red base color that is somewhat lighter than the typical red fox. However, in this part of the world, the only two reddish colored foxes are Tibetan and red foxes.

Reds and Tibetans also share a white tail tip, and some red foxes also lack the black legs we typically associate with this species.

This might mean that, despite what the narrow mtDNA studies suggest, the red and Tibetan foxes are close relatives.

In fact, the Tibetan fox might be nothing more than a specialized offshoot of the red fox lineage, in the same way that the arctic fox is a specialized offshoot of the swift fox lineage.

Of course, these two hypotheses are not necessarily mutually exclusive. The corsac fox is actually more closely related to the red fox than to the swift fox that it resembles in both morphology and ecological niche. It may be that the corsac and Tibetan fox may both be offshoots of the red fox lineage, and the corsac lost its red coat as it adapted to living in the steppes.

The truth is we need better genetic studies to see exactly where the Tibetan fox fits.

Its coloration suggests that its a close relative of the red fox, and the cytochrome-b gene analysis says they are related to corsacs.

And as a general rule, one needs to be skeptical of studies that look at mtDNA, especially those that  just a narrow sector of that DNA.

At the very least, a microsatellite  study is warranted to figure out where this very unusual fox fits.

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