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bush dog

We often talk about the South American wild dogs. The South American wild dogs are a sister group to Canis and its allies, and in South America, evolution allowed dogs to go many unusual directions.

When the dog family phylogenetic tree was drawn from sequencing the genome of a boxer, I was amazed that it put the bush dog, which is sort of a wild version of the dachshund, as being a sister species to the maned wolf, which has very long legs.

There was actually a big debate as to where the bush dog actually fit. When I was learning about dog evolution as a child, I had books that told me that the dhole, African wild dog, and the bush dog were all closely related because of their trenchant heel dentition. One of their carnassials has a single, blade-like cusp that increases their ability to bolt shear meat.

The phylogenetic tree that was created from the dog genome sequence pretty much ended this discussion. The dhole and African wild dog were both found to be closely related to Canis, more so than the side-striped and black-backed jackals. The bush dog was with the maned wolf and the other South American canids, and the trenchant heel dentition was the result of convergent evolution.

End of story.

Or so I thought.

In 2012, a study was released that that was meant to update the divergence times with all extant carnivora. The researchers used large samples of DNA and other characters to determine when these animals diverged from each other. Some of these “other characters were things like vocalization and scent gland similarities.

Its phylogenetic tree for Canidae is similar to that in the aforementioned paper on the domestic dog genome, except that it greatly increases the divergence time between species. For example, it has the Urocyon foxes diverging from the rest of Canidae 15-16 million years ago, instead of the 9-10 million years that the dog genome paper found.  It also has the golden jackal and the coyote being sister species, and the wolf is not the closest relative of the coyote. We now know this is very much in error, and it probably comes from the non-genetic “source trees” that were used in the analysis. It has has the Tibetan fox as being related to the extinct Falkland Islands wolf, which happened because there are almost no genetic studies on the Tibetan fox. Both the Tibetan fox and the Falkland Islands wolf had kind of weird squared off bodies, though, and this type of analysis does use morphology.

It has the dhole as being closely related to the wolf, golden jackal, and coyote.

But it has the African wild dog splitting off much sooner from this clade, and what’s more, it has the bush dog as its sister species!

One should be skeptical of this finding, because of its use of so many non-genetic “source trees,” it is going to miss the problem that occurs so much with dog species. Convergent evolution and phenotypic plasticity run riot in the family, and it is really hard to figure out relationships between species using just morphology and behavior alone.

This would make a lot of sense if it were confirmed with better genetic studies. Bush dogs are very weird animals. They are the only South American canids that hunt in packs. They really don’t have a rich fossil record, and it is pretty hard to connect them to other South American wild dogs.

It is tempting that they might be something that weird, but we need more evidence.

If they really did turn out not to be part of the South American clade of wild dogs and to be closer to the African wild dog, it would be a real shocker.

But not entirely.

The questions that would arise from it would be how it evolved.  We have evidence of Xenocyon coming into North America. Xenocyon is traditionally thought of as the ancestor of the African wild dog and the dhole, but it may not be. But there is also evidence of dholes or dhole-like dogs that are actually closer to the AWD coming into North America and making it as far south as Mexico.

So maybe there is something to it.

But this sort of study does have its limits. It’s trying to morph both classical and molecular techniques for taxonomy, and those tend not to hold up very well.

But I still think it’s worth examining.

 

 

 

 

 

 

 

 

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The bush dog

Photo by Nicola Williscroft at Twycross Zoo, UK.

Photo by Nicola Williscroft at Twycross Zoo, UK.

Only two species of wild dog are found in both North America and South America.

The Urocyon gray fox that yaps in the night from the dense brush near my home ranges all the way down to Colombia and Venezuela. It’s an unusual animal, derived from an evolutionary lineage that split off from the rest of the dog family 9 or 10 million years ago.

The other species that is found on both continents is the bush dog (Speothos venaticus). When I say that it ranges on both continents, I mean that it does range into extreme southernmost Panama. Panama used to be part of Colombia, and there actually is some debate as to which continent it actually belongs.

The bush dog is the smallest wild dog to hunt in packs, a trait that it has evolved in parallel with the wolves, the dholes, and African wild dogs. At one time, it was believed to have been a type of dwarf New World dhole. Like the dhole and African wild dog,  the bush dog has the “trenchant heel” dentition that allows the dog a sharper cutting surface when it eats meat.

Besides the unusually smug expression on this bush dog, one can see another feature prominently displayed in the photo– truly webbed feet.  Retriever and Newfoundland dog people like to brag about how webbed their dogs’ feet are, but they are nothing like a bush dog’s. Bush dogs and the little studied short-eared dog have this feature, which assists them in maneuvering around in flooded forests and through large rivers.

The closest living relative to the bush dog is the maned wolf, as known as the “real red wolf,” but the two species do not resemble each other in the least. The maned wolf is a long-legged, rather ostentatious creature that looks something like what would happen if one tried to make a wolf out of a red fox. It is a creature of the savannas and open marshland, while the bush dog is more of a habitat generalist.

The bush dog is like a naturally-occurring basset. Some native people of South America have tried to tame them, but no one has been able to establish a domestic population.

South America is currently home to the most diverse genera of wild dogs currently in existence. It also has some of the most bizarre.

The dog family first evolved in North America around 40 million years ago, but over time, the Northern Hemisphere and Sub-Saharan Africa became dominated by two basic types:  Canis and the genera that should be in Canis (dhole and African wild dog) and the true foxes (the genus Vulpes). Currently, if we adhere to cladistic classification, there are only three species outside of Canis/should be-Canis  and Vulpes:  the bat-eared fox (Otocyon megalotis), the raccoon dog (Nyctereutes procyonoides), and the aforementioned Urocyon gray foxes.

In South America, there are five different genera. They are all more closely related to the Canis/should be Canis species, but they are all quite distinct. These lineages evolved in North America alongside the ancestors of the Canis/should be Canis species, but for whatever reason became found exclusively in South America, where they wandered down over the past 3 million years.

Outside of South America, no one knows much about these animals, and because most of these animals are quite elusive, very few people in those countries know much about them either.

South America’s canids are a good place to play around with speculative evolution. This is what happens when the diverse endemic North American canids wind up invading the tropics and then wander down to the Southern Hemisphere.

If you look at all the wild dogs of the Old World and North America, the body type is really conservative.

You don’t see anything like a bush dog, a short-eared dog, or a maned wolf.

(Unless you’re looking at domestic dogs, which are the most bizarre animals in the whole order Carnivora!)

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Love in the bush

 

These two bush dogs trying to increase the numbers of their species, which is considered near threatened in the wild.

These little dogs form packs of up to 10-12 individuals, and although they weigh only 10 to 18 pounds, they’ve been known to bring down tapirs and peccaries.

Bush dogs, dholes, and African wild dogs have an extra long “blade” on their lower carnassials that allows these wild dogs to more efficiently slice through flesh. These blade is called the “trenchant heel.”

Dholes and bush dogs were once thought to be close relatives. Not only do they share the trenchant heel, they also are unique among canids in that they have only 40 teeth. All other dogs have 42.   However, dholes are also relatively small, weighing only 22 to 55 pounds, and bush dogs are the smallest of all pack hunting canids.  But both the dholes and bush dogs have reputations for killing prey much larger than themselves. There is a common legend that dholes kill tigers, even though it’s much more likely that the tiger would stalk dholes.  Amur tigers keep the northernmost dholes at relatively low densities, but Amur tigers are known for their penchant for eating both wolves and dogs. A dhole would just be a wolf of another flavor.

But when you combine the dentition with the legendary behavior of both species bringing down large prey, it is easy to see why people put the two together.

But now we know that the bush dog, despite its short legs, is actually most closely related the rangy maned wolf of South America– which is not a true wolf at all but a member of the South American canids clade.  The dhole is very closely related to the genus Canis, and it probably should be classified within it. Its exact relationship to the African wild dog is still debated, as is the exact natural history of the dhole.

But it’s obvious from the genetic studies, that dholes are not related to bush dogs at all. (See this phylogenetic tree, which was drawn from sequencing the dog genome to see where the various dog species.)

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This post is working up to something else, so be ready for it.

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Click here to see the video.

Bush dogs (Speothos venaticus) are the smallest of the pack-hunting canids.

They live in South America at pretty low densities. They are widespread on that continent, but they are not that common anywhere

Yes, I know they look like the cross between an otter and a fox.

And they are famous for doing handstands to mark their territory.

But beyond that,  they also have been kept as semi-domesticated animals by several indigenous groups. They have never reached the level of the domesticated culpeo, but they have been kept as pets.

It’s not something I recommend, but it is worth considering when we talk about dog domestication.

It is likely that any number of wild dog species have been kept as pets, but only one (C. lupus) has managed to be so successful.

The vast range of C. lupus may have played some role in it, and the fact that C. lupus is a large carnivore that can both hunt the same prey that people were hunting and protect against intruders, including  other large predators that might prey upon humans.

However, we have to consider these potential domestications in order to understand how man and C. lupus became attached to each other in this way.

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Bush or vinegar dog In wild dogs, a general rule exists: pack hunters are generally larger wild dogs–dholes, wolves, and Lycaon pictus. These animals live in packs to bring down large prey. Smaller wild dogs tend to be solitary hunters or scavengers, even if they do live in family groups.

Two exceptions to this rule exist:

One of these is the Ethiopian wolf, which is a relatively large wild dog that is closely related to Canis lupus. It lives in packs, but its diet is mostly rodents. Its pack behavior has nothing to do with its size or diet.

Then there is the bush dog or vinegar dog (Speothos venaticus). It generally weighs only 11 to 15 pounds.

It lives in packs of 10 to 12 individuals, which communicate with each other with high pitched whines as they charge through the undergrowth.

Its typical prey is the lowland paca. Although not a large species, it does exceed the bush dog in size, often weighing as much as 25 pounds.

If the bush dogs were not pack hunters, they would probably have trouble bringing down this large rodent. After all, bush dogs are not much larger than foxes, and foxes typically don’t bring down prey much larger than rabbits.

So here, we have an exception to the rule that all pack hunting wild dogs are large.

Oh, and I couldn’t do post on bush dogs without showing you the rather strange way they mark their territories:

http://www.arkive.org/bush-dog/speothos-venaticus/video-12.html

These dogs actually do “hand stands” to place urine higher up the tree.

This behavior is actually not unknown among small domestic dogs that think that have very high opinions of themselves.

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