A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from the air-breathing organ (a simple lung) of an ancestral fish is an example of ________.
A) exaptation
B) changes in Hox gene expression
C) paedomorphosis
D) adaptive radiation

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. The swim bladder is an example of exaptation, as it evolved from the air-breathing organ of an ancestral fish and was co-opted for buoyancy control.

A Swim Bladder Is a Gas-Filled Sac That Helps Fish