- a process in which a feature acquires a function that was not acquired through natural selection.
- a feature having a function for which it was not originally adapted or selected.
- a morphological or physiological feature that predisposes an organism to adapt to a different environment or lifestyle.
- predisposition toward adaptation.
"Scientists speculate that the repeated evolution of blue skin in birds may be due to the inherent nature of collagen. In their role of supporting skin, collagen fibers are organized parallel to the surface in the facial region and spaced closely enough to be near the distance to interfere with wavelengths of visual light... The repeated exaptation of collagen for generating blue makes the unique nature of the beta-keratin nanofibers in penguins all the more interesting... Perhaps other methods of creating blue await discovery even now."
- Daniel T. Ksepka, "The Penguin's Palette—More Than Black and White", January-February 2016 American Scientist (http://www.americanscientist.org/issues/feature/2016/1/the-penguins-palette-more-than-black-and-white)