Exactly....dog wasn’t changed. What changed was the expression of dog DNA for the significantly different environments.
Are you upset that I’m not buying into mutations???
As for mutations being the source of new, useful information...
Take this sentence and insert, delete, or swap any letter and then tell me that the amount of information contained therein has increased.
If you think selective breeding is proof of evolution, then you need to go back to the drawing board.
Dogs are still dogs, different ? yes, but most early attempts left them either dead or the inability to reproduce.
And BTW, these experiments were conducted, not in nature but by human intervention.