Over many generations darker fur color becomes more common in a population of squirrels living shady area this is example of?

Here's why:

* Variation: There is naturally occurring variation in fur color within the squirrel population. Some squirrels have lighter fur, and some have darker fur.

* Environmental pressure: The shady environment provides an advantage for squirrels with darker fur. They are better camouflaged from predators and may be able to find food more easily.

* Survival and Reproduction: Squirrels with darker fur are more likely to survive and reproduce, passing on their genes for darker fur to their offspring.

* Adaptation: Over many generations, the frequency of the genes for darker fur increases in the population, leading to a shift in the overall fur color of the squirrels.

This process demonstrates how natural selection acts on existing variations to favor traits that increase an organism's chances of survival and reproduction in a specific environment.