Endemic species are those that are found in a single defined geographic location, such as an island, state, nation, country, or other defined zone. They are restricted to a specific habitat within a given area and do not occur naturally in any other part of the world. Endemic species are crucial to the health of our planet because of the enormous variety of living beings they contribute to the environment. They are often found in isolated areas, such as on an island or on a mountain or within a mountain range, and they often have specialized adaptations that allow them to survive only in unique habitats. Endemic species can be classified in two ways, by their geographical distribution or genetics, giving rise to a series of categories:

• By location:

  • Microendemic species: are those established in a limited area.
  • Quasi-endemic: are species that go beyond the limits of their specific zone.
  • Semi-endemic: are species that spend only part of the year in a specific area.

• By genetics:

  • Apo-endemics: these are species with a long evolutionary history whose endemism is often due to geographical limitations, as is the case for islands.
  • Endemic relict species: species that in the past were found in several parts of the world but extinction has limited their existence to a single specific area.

Endemic species are the most vulnerable of all and, therefore, those in the greatest danger of extinction, which can be due to natural causes or human activity. Environmental conservation has become a major standard-bearer for protecting these species.