I still don't fully agree with the first argument. You just can't simply say that the gene pool of a species is decreasing when you look at dogs. According to your theory wolves existed around 7 or 8 thousand years ago and had a huge and perfect gene pool.
The earliest dog remains that have been found are dated at around 10, 15 thousand years ago. That are atomic years so that would be between 4, 5 thousands years ago on the orbital time scale according to you
That leaves around 4 thousand years or 40 thousand wolf generations before they were tamed to dogs. During these 40 thousand generations the gene pool got smaller and smaller, but somehow mankind managed to get a huge variety of dogs.
That might make sense to you, but not to me I am afraid.
I do hardly know anything about the mutations that have been seen in nature, so I won't say anything about that.