Final answer:
A preadaptation is a trait that initially serves one function but later evolves to serve a different function, leading to the evolution of an adaptive structure. An example of this is the development of feathers in birds.
Step-by-step explanation:
A preadaptation is a trait in an organism that initially serves one function but later evolves to serve a different function. It provides the foundation for the evolution of an adaptive structure. An example of a preadaptation that led to the evolution of an adaptive structure is the development of feathers in birds.