I always learned that there were either 2 or 7 of each animal in the ark (i.e., 2 dogs, 2 cats, 2 cows, 2 lions, etc.) My question is, (using dogs as an example), where there only 2 dogs or 2 of each kind - 2 pitbulls, 2 poodles, 2 german shepards, etc, etc.? If this was the case, then there would have been hundreds or thousands of dogs on the ark!!
From the Ramban (Bereshit 6; 19) it appears that all species and subspecies gathered to the Ark. That was another miracle among the many others.