The causes are essentially irrelevant. The entire point is that YOU still call them dogs but by what line do you delineate that? You call them dogs because there is no amount of differences that would make you call them otherwise. The fact that they cannot breed seems irrelevant in that they are still dogs yet the fact that tigers and lions can breed shows that they are MORE SIMILAR THAN IRISH SETTERS AND BEAGLES. Essentially, you have demanded that ANYTHING that comes from breeding dogs is a dog - period. Then demand that I need to supply you with a species that has produced another species through drift.It is happening right now and right in front of you and you are still trying to deny that it is even possible.
What is "happening right now?" Dogs have been intensively bred for 5,000 years, yet they are all still dogs. The causes of your alleged Beagle/Setter reproductive anomaly are not known, so this example has no direct relevance to genetic evolution. More relevant is that a Great Dane and a Chihauhua have remained genetically compatible despite the fact that dogs represent the greatest variation in size and appearance of any animal that ever existed on Earth.
As to your word games about "species," it seems that you want to eat your cake and have it, too. Since this term doesn't always suit your purposes, why don't YOU come up with an alternative term that addresses genetic incompatibility or whatever else YOU mean by Evolution?
Do you not see how nonsensical that is. Your starting presumption makes such evidence impossible because it is already rejected before it is even presented.