1. A trait or feature that originally evolved for one function but is now used for a different function; a characteristic that has been repurposed by natural selection.
Usage: biology; evolutionary biology; technical term

Examples

• Feathers are a classic example of exaptation: they originally evolved for insulation or display, but birds later co-opted them for flight.
• The swim bladder in fish is thought to be an exaptation of a lung-like structure used for buoyancy control.
• Scientists study exaptation to understand how organisms adapt existing structures to new purposes.
• The evolution of the middle ear bones in mammals involved exaptation of jaw structures from reptilian ancestors.
• Exaptation explains how some traits can be useful for survival even if they did not originally evolve for that reason.