Answer:
All dogs are domesticated wolves. Canis lupus familiaris (dog) are smaller than Canis lupus (wolf) and are also different in their behavior.
The pattern of adaptation changed because some of the docile wolves started moving around ancient hunter-gatherers to snack on their garbage and hunter-gatherers started feeding them with extra food scraps. Thus, these friendly wolves were probably domesticated by accident and evolved into dogs.
Hence, the pattern of adaptation is toward smaller animals is due to the domestication of Canis lupus familiaris (dog).