The following question refers to this hypothetical situation.
A female fly, full of fertilized 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?
A) the vestigial halteres
B) the halteres
C) the mouthparts
D) the eggs

Question

Quizplus · Accepted Answer

The halteres, which were originally used for balancing during flight, have been repurposed for courtship displays in the daughter species. This is an example of an exaptation, where a structure or trait evolves for a new function, different from its original function. The vestigial halteres also show evolutionary change, but they do not illustrate an exaptation as they have lost their original function without evolving a new one. The mouthparts and eggs have not been mentioned in the description as undergoing any significant evolutionary change or repurposing.

The Following Question Refers to This Hypothetical Situation