The phenomenon where rare traits are found in abundance in a new or recently isolated location is called

This phenomenon is known as Exaptation.  

Explanation:

This phenomenon occurs in both anatomy and behavior and serves to provide an advantage to the organism or specie that undergoes exaptation. It is a process that can be considered as an opposite to adaptation.

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for example, no new evidence will demonstrate that the earth does not orbit around the sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the earth is not divided into solid plates that have moved over geological timescales .