Biologists have found more than 500 species of fruit flies on the various hawaiian islands, all apparently descended from a single ancestor species. when this ancestor colonized the island chain, it found few competitors: many insect and fly families present in other regions are absent from the isolated hawaiian islands. this example illustrates

Adaptive radiation

Explanation:

Adaptive radiation occurs when an ancestral species move to a new environment that has various resources that are necessary for survival and also has environmental conditions that would ensure its offspring adapt well over time. In this new environment, the ancestral species would produce offspring with different traits and behaviors that will allow them to survive in this new environment while occupying their various niches. Over a relatively short time, different species arising from the common ancestor would occupy the new environment.

they may bind directly to special “promoter” regions of dna, which lie upstream of the coding region in a gene, or directly to the rna polymerase molecule.