50 generation ago, was a population of rabbits some traits were white,gray, & brown. Predators were not common. Adaptive traits were thick fur, and white fur causing them to blend.
many generations later, the environment changed rabbits with white fur were not really blended in. This made it easier for predarators, and thick fur caused them to overheat. The adaptive traits are brown,gray,& black fur, good eyes, strong legs
More generations later, the population was only dark furs, with thin layers. White fur & thick fur is not common