Protected: In search of the Ur-Mastiff (Premium Members Only)

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The Thylacine was more a marsupial coyote than a marsupial wolf

One of the most common memes in our popular understanding of zoology is that the thylacine of Tasmania was the marsupial equivalent of the gray wolf.  This idea comes from a rather superficial understanding of its morphology, and lots of speculation about its behavior have stemmed from this popular understanding. One idea is that they were pack-hunters like wolves and dingoes, and they would have been murder on Tasmania’s sheep industry. Therefore, the final extinction of the thylacine was largely predicated upon a rational fear that the creatures would have been detrimental to sheep husbandry.

A lot of these speculations come from a belief that the thylacine was quite large. As I have discussed before on this space, larger carnivores are largely forced to hunt larger prey to survive. Otherwise, the larger size is of no benefit to the animal. Ecologists have found that the mass of 21 kg (about 46 pounds) is the size at which a carnivorous mammal can no longer subsist on smaller prey alone.

Thylacines were estimated to have weighed 29. 5 kg (about 65 pounds), which meant that their diet would have been larger prey. However, really big prey species are almost absent from Tasmania. The largest kangaroo in Tasmania is the Tasmanian Eastern gray kangaroo, which weighs is roughly the size of the smaller forms of white-tailed deer in the US.  Further, analysis of Thylacine skulls revealed that they could not withstand very much force. So the thylacine would not have been a very effective predator of prey the size of an Eastern gray kangroo, and it would have had a lot of trouble grappling with a fully grown sheep.

The fact that thylacines would have had problems killing large prey creates a contradiction in their supposed larger size.  If thylacines really did weigh 65 pounds on average, then they would be a major exception to the rule that larger predators must hunt larger prey to survive.

Well, a new analysis by researchers at Monash University has revealed that traditional estimates of thylacine size were greatly exaggerated.  Using complex morphometric analyses on various preserved specimens, the researchers revealed that the mean weight of a male thylacine was 19.7 kilograms (43 pounds). The mean weight of a female was 13. 7 kilograms (30 pounds).

These animals would have been roughly the same size of an Eastern coyote. Now, Eastern coyotes can live on large prey or small prey, and they can scavenge quite well. But they have skulls that can withstand blunt force from a sheep or a deer that a pack of them has run down. The Eastern coyote can live as a fox or a wolf, depending upon the conditions of the ecosystem in which it lives.

A thylacine would have been a smaller prey specialist, and because its weight did not exceed 21 kilograms, its subsistence on smaller prey did not violate the “costs of carnivory” rule.

Indeed, the only predatory mammal I can think of that does come close to violating this rule is the maned wolf, which sometimes weighs 22 or 23 kg. It lives almost entirely on small prey and fruit. This species has been persecuted for its attacks on livestock, but like the thylacine, it is not much of a threat to them.

Of course, there will be debate about this finding. Many historical accounts of thylacines suggest or imply or even outright claim that they were killing sheep and dogs left and right.

But the truth is that Europeans had their own concept of what a creature like this could do or was likely to do, and they merely transposed these ideas onto a creature that had the superficial appearance of a wolf or hyena.

We should by now stop trying to pigeonhole the thylacine into a marsupial wolf and should try to appreciate it for what it was.

Or might still be.*

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*I don’t believe they still exist, but I certainly wish they did!

 

 

 

 

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Protected: History of Bulldogs, Part 2

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What is a German Shepherd? The answer from the genomic data

If you were to ask the average person how to classify a German shepherd in terms of dog breed taxonomy, most would say it’s guard dog, putting it somewhere with the Rottweiler and the boxer. Others might think it’s a primitive breed and might classify it with the Siberian husky and the malamute.

Those with a bit more dog knowledge would p lace it with the Belgian and Dutch shepherds.

Indeed, if you were going to ask me where I’d classify German shepherds ten years ago, I would have placed them as the German variant of what became distilled from a German-Belgian-Dutch prick-eared, black-masked herding dog landrace.

DNA studies have changed quite a bit of our understanding of dog breeds and their origins. In the initial attempts to classify dog breeds using only mitochondrial DNA found that German shepherds clustered with the mastiff breeds.

However, more recent genome-wide analyses have revealed something rather unusual. German shepherds are not directly related to the Belgian herding dogs at all. Instead,  one study found that they they are most closely related to the Berger Picard, the Chinook, and the Peruvian and Mexican hairless dogs.

Initial studies of regional Italian herding dogs using microsatellites suggested a close relationship between those dogs and border collies.  However, more recent genome-wide analyses have placed the Italian herders much closer to the German shepherd dog. Indeed, the German shepherd is very closely related to Italian prick-eared herding types, such as the Lupo Italiano and the Cane Paratore. These Italian herders and the Berger Picard all fit in a single clade with the German shepherd.

These findings upturn our assumption that the Belgian and Dutch shepherds are that closely related to German shepherds– at least in the bulk of their DNA.

However, the initial genome-wide study that found a relationship between the Berger Picard and the GSD also found that there was some GSD in the various Belgian herders, including the Bouvier des Flandres.

That means that at some point in the development of those breeds, German shepherds or proto-German shepherds were crossed into them. Crossing German shepherds with the Malinois isn’t an uncommon practice in some working dog circles even now. Apparently, this practice was done more frequently when the breeds were not so defined as they are now.

And it should be noted that only tiny ancestry blocks from German shepherds into the Belgian breeds. The bulk of their DNA derives from very distinct dog stocks. The Belgian herding breeds are more closely related to British herders and Western sighthounds than they are to German shepherds.

These genome-wide studies have lots of interesting findings, including that xoloitzcuintli and Peruvian hairless dogs are almost entirely derived from European herding dogs and that their sister breed is the Catahoula. Because of this relationship to these Latin American dogs, the Catahoula is probably more derived from Iberian herding breeds than from French ones. It is likely that the hairless dogs of the New World are the originators of their hairless trait, but because it is conferred via a semi-dominant allele it was easily transferred onto a population that consists of dog of European origin.

The relationship between German shepherds and Italian herders is easily understood. German shepherds are heavily derived from Bavarian and Swabian sheepdogs, and Bavarian shepherds were often grazing their sheep in the Alps during the summer, as were the Italian shepherds. The dogs exchanged genes in those high country meadows, and their pups went onto found populations on both sides of the mountains.

This story fits the genomic data, but it make the Berger Picard a bit of an anomaly. Picardy is in the northeastern France, a long distance from the Alps. It would make more sense for this breed to be more closely related to the Belgian shepherds and the Bouvier, but it is not. The North European Plain is easier for dogs and their genes to flow across, but the Berger Picard is very close the German shepherd breeds and its Italian cousins.

I do not have a good answer for why this anomaly exists. I don’t know much about the Berger Picard or its history. Maybe it became a very rare breed and was interbred heavily with German shepherds, or maybe the region is very connected through markets to the Alps or Bavaria or Northern Italy.

Maybe someone can answer these questions for me.  It seems weird that the Berger Picard is so closely related to dogs that have origins in Southern and Central Europe rather than adjacent Belgium.

The evolution of herding breeds is complex. Apparently, having a dog with a wolf-like phenotype is useful for herding flocks. The Belgian shepherds apparently evolved their type independently of the German shepherd, the Berger Picard, and the Italian prick-eared herders. Perhaps sheep just respect that look more, and it has some advantage in their management.

As we have seen, dogs can evolve very similar physical traits in parallel with each other, which is why we must always be careful when creating an umbrella classification for different breeds.

Just because they look alike and have similar functions does not mean they are that closely related.

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