Exaptation

Common card · No. 376711

Exaptation or co-option is a shift in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common both in anatomy and in behaviour. Bird feathers provide a classic example. Initially they may have evolved for temperature regulation, but later became adapted for flight. When feathers were first used to aid in flight, that was an exaptive use. Under natural selection they subsequently evolved to improve flight, so in their current state they are best regarded as adaptations for flight. So it is with many structures that initially took on a function as an exaptation: once molded for a new function, they become further adapted for that function. Interest in exaptation relates both to the process and to the products of evolution: the process that creates complex traits and the products (functions, anatomical structures, biochemicals, etc.) that may be imperfectly developed...

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