Endemism
Endemism means that something is unique to a geographical area. An endemic species of Ibiza (or of the Balearic Islands) is one that lives nowhere else on Earth. For example the Balearic Saint John's-wort only lives in the Balearics, the Ibicencan broom (Genista dorycnifolia) only on Ibiza.
Endemics are particularly vulnerable to changes in their environment.