Why do island chains provide ideal conditions for adaptive radiation to occur?

The comparatively fast evolution of various species from a single common ancestor is known as adaptive radiation. It usually takes place when an organism enters a novel region and distinct traits influence its survival. The island chain offers suitable conditions for adaptive radiation to take place as when an organism of a certain species comes to an island together and get disperse all through the chain, and each of these organisms getting settle into distinct niches and exploiting various food resources in order to minimize the competition, thus, resulting into adaptive radiation.

b is dominant over the allele for the white fur.