A female fly, carrying fertilized eggs, is hypothetically swept by high winds to an island far out to sea. She is the first and only fly to arrive on this island. Thousands of years later, her numerous descendents occupy the island and have overlapping geographic ranges. They are separated into several different species with different foods, mouthparts, egg-laying sites, and egg shapes. None of the species can fly and their balancing organs (halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. Which of these fly organs, as they exist in the description, best illustrates an exaptation?
A) the wings in the ancestral species
B) the halteres
C) the mouthparts
D) the eggs

Question

Quizplus · Accepted Answer

Exaptation refers to a trait that has been co-opted for a use other than the one for which natural selection has built it. In this scenario, the halteres, originally used for balance during flight, have been repurposed for use in courtship displays, making them an example of exaptation.

A Female Fly, Carrying Fertilized Eggs, Is Hypothetically Swept by High