Answer:
Adaptation is correct
Explanation:
Remember all the species changes little by little because of the genetic changes (like in this case) or because need to adapt the quantity of food (in some seasons like camels) or because they need to adapt to environmental conditions (like in hotter summers or colder winters in some regions).
In all these cases, the changes occurred through the pass of time and could be a result in changes in their morphology or physiology.
