Heterotopia (medicine)

[1] In her book Developmental Plasticity and Evolution, Mary-Jane West Eberhard has a cover art of the sulphur crested cockatoo and comments on the back cover "Did it's [sic] long crest[head] feathers evolve by gradual modification of ancestral head feathers?

It can also be further expanded to a subtle form of exaptation where a gene product used for one underlying purpose in a diverse group of organisms can re-emerge repeatedly to produce seemingly paraphyletic distributions of traits.

[4] It is thought that because so many organisms share such a profound degree of genetic and molecular similarity that shifts in the location of expression might be a regular occurrence throughout time.

Molecular analysis shows that proteins that seem to have a single specific function are instead found in many different tissue types.

One example of this phenomenon is crystallin, a clear protein that makes up the lens of the eye; it is also has structural functions in the heart.