Sheesh! Haven't we been through this before?
http://www.freerepublic.com/focus/f-news/1512465/posts?page=236#236
http://www.freerepublic.com/focus/f-news/1512465/posts?page=283#283
You guys are the ones who have the theory that says life arose from non-life on its own; that all life comes from a common ancestor, and that higher order species evolved from lower order forms of life. I've never seen any of that occur. What is observable is that animals are able to adapt to their environments, but they still are the same animals. Dogs in cold weather have different body and hair than dogs in warm climates, but they still are dogs, they don't 'evolve' or bring forth offspring that aren't dogs.
So what you're really telling me is that over time you may get (and actually you would need TWO dogs on each island, male and female for your example) dogs that do not resemble the original dogs. You also assume they aren't purebreds, and you also assume they are not already adapted to their current environment. Given all of this, let's say they do adapt nad variations occur over time, and certain features become more prominent and certain things become less prominent. You still haven't added any NEW information. More fur, a smaller muzzle, longer legs is not evidence of evolution, but variation. Where is the new genetic information? It's just a modification of genetic information that was already present. Adaption doesn't create a dog with a beak, it may create a dog with different features than its predecessor - but it's still a dog, and will always be a dog.