well it has taken Science a long time to admit that random mutations are not the way aniamls change. Many, in fact are still hanging on to this notion. They are called "selectionists"....they believe that the only way animals can change is by going through the selection process. On the otherhand you have "strucuralists". These people belive that each organism has an intrinsic ability to adapt to the environment. Indeed you see this all over the world. For example, arctic foxes' coats change from white in the winter to brown in the spring and summer. Fish can change colors according to backgrounds. Same with moths. Reindeer can can change from brown to white over time:
But see, evolutionists believe that coat color change is due to an accidental mutation...and this mutation is passed around the population via sexual reproduction. This is why they rely on gradualism. But in reality, "evolution" happens quickly, sometimes during the lifetime of the animal.