is the ability of an organism to change internally or externally in relation to its environment.

you must remain stopped until the stop signal is retracted and the red lights are turned off. approaching traffic in the opposite roadway of a divided highway shall not be required to stop, even if the school bus has the stop-arm extended and the alternately flashing warning signal lamps on.

on island x the species needed to adapt because they were being subject to predators which didn't inhabit island y.