Final answer:
The picture-winged fruit flies of the Hawaiian Islands are an example of the founder effect, a form of genetic drift caused by the establishment of a new population by a small number of individuals from a larger population, leading to a reduction in genetic variation.
Step-by-step explanation:
The scenario described with the picture-winged fruit flies of the Hawaiian Islands is an example of the founder effect. The founder effect is a type of genetic drift that occurs when a new population is established by a very small number of individuals from a larger population, leading to a reduction in genetic variation and potential differences from the original population. This small group may carry only a subset of the genetic diversity found in the parent population. Thus, the genetic makeup of the new population is shaped by this subset of alleles rather than the full diversity of the original population.
In the case of the Hawaiian fruit flies, a small ancestral population from Asia likely colonized the islands, bringing with it a limited genetic pool. Over time and generations, the genetic drift amplified by the founder effect would cause these fruit flies to diverge markedly from their Asian ancestors and from each other, resulting in the several hundred species observed today, each adapted to their specific Hawaiian environment.