A female fly, full of fertilised eggs, is swept by high winds to an island far out to sea. She is the first fly to arrive on this island and the only fly to arrive in this way. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species, each of which eats only a certain type of food. 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. The ranges of all of the daughter species overlap.
Which of these fly organs, as they exist in the description, best illustrates an exaptation?

Question

Quizplus · Accepted Answer

The halteres are the best example of an exaptation because they were originally used for balancing during flight but have been modified for use in courtship displays in the daughter species. The vestigial halteres, mouthparts, and eggs do not demonstrate a significant change in function from their original purpose to their current form and function.

A Female Fly, Full of Fertilised Eggs, Is Swept by High