They’d interbreed into mutts; dogs always do. However, the various populations of mutts would eventually speciate (if they didn’t die out), since they’d be on multiple landmasses with no way to continue interbreeding.
This. The dogs that didn’t initially starve due to being chained up, or enclosed in a house or fenced yard they couldn’t escape from, would interbreed indiscriminately, and after a few dozen generations, you’d get a fairly homogeneous population of dogs within any region bounded by sufficiently challenging geographical limits (oceans, wide rivers, deserts, mountain ranges, etc.).
Over the millennia, dogs would probably find different ecological niches, but like John Mace said, it takes hundreds of thousands of years for speciation to take place.
And lets not forget, without human intervention, most of the dogs that have been bred for specific human-desireable traits will not survive long enough to contribute to the breeding gene pool.
While my neighbor may think his pug is the cutest thing ever, I have serious doubts about it surviving on it’s on. My current ball of hair, a cockapoo, while showing some hunting ability here in my backyard (her kill count is at 4 birds, 3 chipmunks, a squirrel, and hundreds of bugs), I doubt she could really sustain herself very long before a coyote, bigger dog, or some other wild critter eats HER.
Here in the south, I figure the “without human intervention” mongrelization of dogs would turn out something like this.
Also, this Youtube link is pretty interesting.
Yeah, somewhere here someone with some knowledge (Blake, maybe? Colibri?) speculated that feral populations end up producing smaller, yellow dogs with very curly tails. How much that applies worldwide I couldn’t tell.
Yes, both Blake and I have brought that up. Worldwide, dogs that live in loose contact with human communities have converged on a similar look. Carolina dogs in North America, pariah dogs in India, dingoes is Australia, and so on.
I’m less sure these dogs would survive long-term without humans, though, as they are adapted to living in proximity to us. Truly wild species might outcompete them.
I read an article a few years back about dogs on a pacific island and elsewhere that end up with similar features when left to their own devices.
Perhaps you’ll end up with something like the Carolina Dog.
The wiki on Carolina dogs describes how they hunt and states that many of them live out in the woods. So it sounds like they have a shot at successfully going completely wild.
If I can ask a somewhat stupid biology nomenclature question, what differentiates a breed from a subspecies?
According to the book, What Evolution Is by Ernst Mayr I just read, they are basically interchangeable.
As said, that wasn’t speculation - it’s observation. I seem to remember that fact throws the idea that all domesticated dogs came from the Gray Wolf into some doubt.
I’m not sure it will take that long, since the dogs are starting out with a lot more diversity in the genome than you’d find in a species that we hadn’t messed with.
I’d think that speciation would come from size differences which would prohibit either mating or successful births of hybrid dogs larger than their mothers.
There are lots of little dogs interested in my dog, but they wouldn’t be able to do anything without a stepladder.
There might be some geographical isolation which would help in speciation, but I don’t think we know which breeds would occupy each niche.
Actually dogs have a lot LESS diversity in their genome than wolves or coyotes do. The various genes that control coat color and texture, floppy ears, smooshed faces, short legs, and so on are only a tiny fraction of the dog genome. Most of these characteristics would be highly undesirable in a wild dog and almost none of these types of dogs would make it into the founder population.
It seems to me highly unlikely that any breed of domestic dog would become the founder of a new species. I imagine the OP was thinking that a pack of Jack Russell Terriers might found a fox-like species, a pack of Greyhounds might found a cheetah-like species, a pack of Retrievers might found a water-loving species, and so on. But this is very unlikely because although Jack Russell Terriers and Labradors look different, there are no physical or genetic or behavioral barriers to interbreeding between the populations, or with native coyotes or wolves. So even if for a couple of generations the founder population of terriers still retains some terrier-like characters, that population is not going to maintain reproductive isolation and will soon be submerged into the main Canis population.
I thought about that, but I’m not sure it works. Sure, the Great Dane and the Chihuahua aren’t going to hook up. But there are a lot of dogs that are just a bit smaller than the Dane, and a lot of dogs that are just a bit bigger than the Chihuahua. Next generation, your biggest dogs are going to be a bit smaller than a purebred Dane, and your smallest dogs are going to be a bit bigger than a purebred Chihuahua. And the generation after that, the extremes are going to close up even more. Inside of ten generations, I suspect that any individual population of dogs is going to end up a roughly uniform size, long before they split into different species.
On the other hand, the main driver behind evolutionary change is environment, and what sort of environments are these dogs going to be living in after humans are gone? Ruined cities aren’t an issue - they’ll be completely reclaimed by nature within a few centuries. But some environments might end up selecting for traits that were artificially introduced into dogs in the first place. Terriers and other dogs bred for hunting rodents and burrowing animals might find themselves flourishing in a post-human environment, while larger dogs find more success as wolfish pack hunters, eventually leading to two distinct species.
Everything I have to say has already been said, but to sum up:
Short term: Natural selection weeds out the existing variety. Useless breeds like Pomeranians are wiped out quickly, while more generalized breeds, like Labradors or whatever, are relatively successful. Lots and lots of dogs die without humans to care for them, but the survivors survive.
Medium term: Lots of interbreeding and mixing between dog breeds, and, depending on geography and local conditions, with coyotes and possibly wolves. You’d be likely to see a regression toward the mean, so that much of the phenotypic variety we see now is lost, while underlying genetic diversity slowly begins to increase and populations rise.
Long term: Canid populations in different areas of the world could possibly speciate. Specialized forms might emerge that are adapted to particular ways of life or particular food sources - semi-aquatic dogs in swampy areas, etc.
The above is exactly what I was thinking of. St. Bernards and Chihuahuas will never hybridize.
And this.
Nitpick: You mean “helpless”; with no humans around, “useless” no longer applies.
My St. Bernard-Boxer mix might disagree with that statement