confused about dog breeds

Factual Questions
1

OK, so I understand that all dogs are the same species when it comes to the types of dogs that we keep as pets. From little terriers to Saint Bernards, they are all Canis lupus familiaris. They have the same skeletal structure, they can breed fertile offspring, blah blah blah.

I know that most dog breeds exist because the dogs were bred for certain purposes (herding, hunting, guarding, companionship, etc.). I assume that at one point there were just a bunch of plain old dogs (although it’s hard to think of what they must have looked like to me haha) and then people took a female and bred it with a male “plain old dog” that was slightly different in some way from the female. As that process continued through multiple generations of dogs, certain traits began to develop and be consistent. Am I right about this?

I don’t understand though how we started with a bunch of “plain old dogs” that I would guess were all similar in shape and size to what we have now which is chihuahuas that could fit in your pocket and mastiffs that outweigh human adults. I guess I understand (and shit, I could be wrong, genetics confuses me) that if I mate with a female that is very short and our offspring mates with someone very short, then in time, they’ll look back at the family tree and see their 6’ 2" ancestor as a beast. It’s the extreme variety in dog breeds that baffles me (super fluffy chows, spotted athletic dalmatians, long bassets with big feet, lazy snorting pugs with wrinkly skin). Does this huge variation within one animal species happen anywhere else in nature? I know there are a whole lot of different breeds in horses, cats, pigs, cows, various bird species, and so on. They all seem fairly similar though, at least a lot more than some dog variations.

Let’s say every German Shepherd or every English Cocker Spaniel were to just suddenly disappear from the earth. Would it then be impossible for this breed to exist again, or could selective breeding create more of them? I was reading earlier about “extinct dog breeds”, so that’s why I ask.

I referred earlier to “plain old dogs” that were bred in the beginning when the first human breeders started doing their thing. What would these dogs have looked like? Do we have any way of knowing?

Lastly, I know that “breed” is by no means a scientific term, and is just a superficial identification system type thing we’ve created, just in case anyone felt the need to bring that up.

Thanks all :slight_smile:

2

Plain Old Dogs are otherwise known as wolves.

Even in a large population of wolves, which all look pretty similar, there are a range of characteristics. Some will be larger than others, some will have more of a particular color fur than others, some will be better at hunting, tracking, and attracting mates as others.

This is how evolution works: with natural selection and a range of traits in a population, the individuals with the traits that make them more likely to succeed and reproduce will pass on those traits to more offspring than their competitors.

Breeding works through artificial selection. It’s the same thing, except the selective pressure is applied by humans arranging the mating instead of nature weeding out the less capable individuals.

When early humans started keeping dogs around, they chose the ones with the most useful traits, such as tracking or hunting skills, and bred those together, while killing or ignoring the less useful ones. In some cases, the genes that are associated with the desired traits may also be associated with irrelevant secondary traits, like large or small size, fur color, etc. After many generations of selecting for the desired traits, the other traits that go along with it become dominant in the local population, and gradually over many hundreds or thousands of generations, the population looks strikingly different from their ancestors.

Anywhere you find domesticated animals, you can find wide variation in breed standards. Take a look at horses; you’ve got everything from Shetland ponies to Clydesdales.

Non-domesticated animals demonstrate plenty of variation between distinct populations of the same species, but the range is more limited than with domesticated animals. Whereas domesticated animals like horses or dogs may be selected to emphasize a particular useful of aesthetic trait, wild populations will be pressured to approach an average, normal distribution of characteristics for their species.

3

Dogs are definitely about the most widely varied species on the planet.

Each “extreme” difference in dog breeds came about through inbreeding: an isolated population of dogs that were, often, selectively bred by humans to emphasize a certain trait. (I’m sure there’s a clearer way to state this. Anyone?)

Many of the traits that distinguish a dog breed from the “norm,” which is probably close to wolflike, are recessive. Think how so many captive-bred animals usually become readily available in amelanisticforms: Farms full of white turkeys, white ducks, white chickens; think of white mice and rats, etc. I worked in the reptile trade for years and any animal that became commonly bred in captivity eventually produced enough amelanistic offspring for them to become affordable in the pet trade. That’s because a breeder is not likely to have available to him as large a population of animals to bring fresh DNA into the line he’s breeding, so over time it becomes more and more inbreed, and recessive traits like amelanism begin to express themselves more frequently.

Multiply that by the centuries–if not millennia–that Homo sapiens has been directing the breeding of Canis lupus familiaris, and you get an idea of the power of inbreeding to effect major structural changes in a species over time. You get, in fact, a Chihuahua and a St. Bernard sharing a single species.

4

According to wiki, dogs have been domesticated for at least 15,000 years, but probably began to differentiate from wolves well before that.

Australian dingoes are descended from domesticated dogs (brought to the continent by the aborigines), and they have breeding wild for many millennia. I would think that by now they should have reverted to a fairly good approximation of what dogs were like before domestication.

5

Dogs are unusually variable - you’re right about that. They exhibit extremes in shape that are more diverse than pretty much any other animal out there, and until recently, it wasn’t entirely clear why, genetically. Not long ago, a gene was discovered that seems to be the start of the whole process. It looks like a mutation developed during domestication that introduced two sizes of dogs - large and small. Everything has sort of spread from that initial change.

6

I don’t think so. If dogs didn’t exist in Australia before they were introduced by humans, then there is no dingo type that they could have “reverted” to. Rather, these feral dogs would have adapted to the particularities of the Australian ecosystem, and thus would have acquired many behaviours and physical traits absent from their wild Asian ancestors.

7

What exactly is the evolutionary status of pariah dogs? My understanding was that this type of dog was understood to resemble the earliest domesticated canines.

You might also want to read about domesticated foxes to see how quickly and effective intentional breeding can be.

8

Actually, I think it’s a bit more than that. As I understand it, true breeds will breed true – e.g., two collies will always produce more collies. But crossbreeds, such as cockapoos, will not – the offspring of two cockapoos might be mainly a cocker spaniel or mainly a poodle.

9

I think the point is that other feral animals rapidly revert to wild type regardless of ancestry. So feral horses rapidly revert to a small horse/large pony type regardless of whether they are descended from Clydesdales or Shetlands. Similarly feral cats, pigs, cattle and so forth rapidly lose gross domestic traits and conform to something approaching the wild ancestor. That’s not really surprising, since the form best suited to survival in the wild is unsurprisingly the form that evolved over a million years to survive in the wild.

The problem with that is twofold.

The first, and most easily verified, is that the dingo of today is indistinguishable phenotypically from the numerous Asian wild dogs. I can’t speak for behavioral traits, but they are behaviourally indistinguishable from New Guinean Singing dogs. IOW they demonstrably haven’t acquired traits that separate them from their Asian ancestors

The second problem is that their isn’t really a peculiarity of the Australian ecosystem from the point of view of a mid sized canid. In fact there isn’t any Australian ecosystem. Dingoes inhabit tropical rainforest, deserts, alpine snowfields, coastal dunes, monsoon swamps and so forth for every ecosystem on the continent. Yet despite that ecological diversity they are all esentially identical. There is a minor decrease in size in the north, but no more than 10%, and a preponderance of the melanistic form in some regions, but never universal. So once again, we know hat dingoes haven’t acquired traits depending on teh ecosyetm in which they live. And once again, this shouldn’t be surprising. These animals are generalist predators on animals that are rarely larger than themselves. The ideal size and behaviour is pretty standard for such a creature.

Basically NJTT is correct. This is one of the main factors in the debate about the ancestry of the domestic dog. If dogs were all desended from *Canis lupus *we would expect the to all revert to that form in the absence of constrained breeding. Instead dogs all rapidly revert to the little yellow dog, nothing like the grey wolf.

10

Another interesting part of the equation is that feral dogs look different according to the environment. Without man interfering and exerting selective pressure, the environment still exerts natural selective pressure. So, the “average” stray in Cuba looks different than the average stray in Finland.

11

True. However the wolf subspecies most likely to be close to the ancestral domestic dog, the Indian Wolf Canis lupus pallipes and Arabian Wolf Canis lupus arabs are small, delicate, and have a partly yellowish coat, and thus are closer to “yellow dogs” than the big, gray northern subspecies.

12

Yes, I’ve read in several places that pariah dogs supposedly resemble the most basal dog type. Most pariah dogs have similar appearances: yellowish-tan coat, darker muzzle, black nose, curly tail. My introduction to this concept was when I met a Carolina Dog at the local dog park; some claim they are feral descendants of dogs that crossed the Bering land bridge with the first Americans. The ones I’ve met seemed like perfectly normal dogs.

13

In undergrad I was lucky enough to get to see and learn about the Carolina Dog. Look at that dingo and then the Carolina Dog, they look remarkably similar to me. The wiki page seems rather skant on the Carolina Dog. What we learned from the gentleman that brought the dog to our class was that the dogs were found at the Savannah River Nuclear Site. The SRS is basically 310 square miles of undeveloped land, which allowed the dogs to “revert” back to their most basic form and lose some of the human bred traits which typify most dogs.

Edit: I took so long in writing and finding the links that it looks like Sailboat already knew about the Carolina Dog.

14

What’s vastly weirder about our two posts is that I have received (work-related) faxes today from the Savannah River Nuclear Site. That seems like quite a coincidence!

15

Not really. Neither such population has been around long enough to have adapted too noticeably to its environment. A likelier reason they’d be distinct from one another is that initial breeding pool of strays was different. And in a relatively isolated situation like that, the only “fresh blood” that would come into the population would be other strays, also likely to be different breeds in two such disparate places as Finland and Cuba. All entirely speculative, of course, but I think the time frame is still narrow enough that the initial breeding population exerts more influence than environmental selection.

16

And there are some breeds (such as the Pyrenean Shepherd, my personal fave) that, although they are a very old breed, were not necessarily bred for looks - so the breed still has tons of visible variation. Size, movement and herding ability are rather consistant, but very few folks will believe that Corbi and her sister are littermates - folks assume they are different breeds! I’m assuming that will go by the wayside, as the AKC has picked them up.

I will try to find the studies where they have noticed very quick shifting to the ‘pariah dog’ type in war-time situations worldwide - but my google-fu is weak tonight. The basic type seems to be tannish, 30lbs, prick ears, and slightly curled tail.

17

Yep. the little yellow dog. It’s been well documented to occur worldwide where dog breeding isn’t constrained. The form is also independent of ancestry and isn’t tied to any specific genotype. All of which suggests very strongly that this is the ancestral form of the domestic dog.

Which is why it is puzzling that it doesn’t look anything like the grey wolf. Although, as Colibri notes, the Asian grey wolf subspecies tend to be somewhat more gracile and often have some yellowish markings they are still rather obviously wolves, and couldnt be mistaken for a little yellow dog even in poor light.