[John H K]

Here's one. Dogs.

Now, of course, they're all the same species, and all can interbreed, so it's not technically "speciation." And they're all essentially wolves at root.

It's now believed that humans didn't run out and domesticate wild Wolves, but that some Wolves began hanging around humans for scraps on their own (basically evolving naturally) and VERY quickly became more docile and accepting for humans. AFTER that humans began actively selecting for certain types of dogs.

And in ONLY 10,000 years we've gone from Wolves to Dachsunds, poodles, Chihuahas, Newfoundlands, etc., by a combination of NATURAL selection, and active organized breeding (but only in the last couple thousand years of that.)

[Truth666]

Thanks for your contribution (the third case) - dogs, that in only 10,000 years have changed/evoluted from WOLVES to CHIHUAHUAS.

[Virginia-American]

Dogs... Now, of course, they're all the same species, and all can interbreed...

Great Danes and chihuahuas?!

I've used this example before:

Consider an island with plenty of game, water, etc., but no canids. Introduce 100 male great Danes and 100 female chihuahuas. Come back in 100 years. I predict there will be no canids. Ditto if we use 100 f. Danes and 100 m. chihuahuas.

If we introduce 100 m + f Danes and 100 m + f chihuahuas, I predict that in 100 years there will be two populations of dogs that breed true.

So it's not precisely true that dogs are all one species - they're actually a ring species where the non-breeding extremes are separated by sized rather than geography.