Exaptation

Under an exaptation is understood in evolutionary biology, the utilization of a property to a function for which it was not originally created - in other words, it is a " creative " misappropriation. The distinction of purpose-bound adaptation ( adaptation) and an original purpose estranged failover ( exaptation ) by a previously otherwise used feature goes back to the treatise " exaptation - a missing term in the science of form" by Stephen Jay Gould and Elisabeth Vrba. From the concept of " exaptation " Gould also distinguished the concept of " preadaptation " ( synonym: Präadaption ), which describes a property that has been developed by chance ( with no apparent function) and proves useful as environmental conditions change.

An example is the follicular atresia, which may be an adaptation to maintain the required hormonal balance during pregnancy. Menopause would therefore be a consequence of this adaptation, without itself being a selected conformity.

The term exaptation was later applied in genetics by Jürgen Brosius and Stephen Jay Gould for the recruitment formerly non-functional regions of the genome in a function.

Due to the content close to the concepts of " exaptation " and " Präadaption " has been controversial whether a specific concept was necessary " exaptation " to describe the evolutionary processes. The scientific reality is that the terms " exaptation " and " preadaptation " are often used interchangeably. It is in any case the merit of Gould to have stressed the term " exaptation " the importance undirected incurred structures for evolution. Many evolutionary biologists today share the view that new structures never develop targeted for something specific and rather randomly arise as byproducts in the faulty transmission of the genetic material. Because the selection itself does not create new structures, but also tackle the existing variants, all new variants must have arisen as Exaptationen. This also fits the realization that not only such structures are preserved, which prove to be beneficial, but also those who simply do not bother further.