Final answer:
In the case of the squirrel population, the light and dark squirrels are selected for due to diversifying selection, which increases genetic variance by favoring these extreme color variants, while the medium-colored squirrels are selected against as they do not blend in as well with the environment, making them more prone to predation.
Step-by-step explanation:
The light- and dark-colored squirrels may be selected for and the medium-colored squirrels selected against because of diversifying selection. This type of natural selection favors the extremes of a trait within a population while selecting against the intermediate forms. In the case of squirrels inhabiting a large park area with numerous predators, the light-colored squirrels may blend in with lighter areas, like footpaths and clearings, while dark-colored squirrels may be more camouflaged in shady areas or darker foliage. Medium-colored squirrels, on the other hand, may not blend well with either extreme and thus are more vulnerable to predation.
Since this scenario favors two distinct phenotypes - light and dark colored squirrels - and selects against the intermediate, it is an example of diversifying selection. Over time, this type of selection can increase the genetic variance in the population as both the light and dark-colored traits are favored. Therefore, the population may become more diverse in color.