Endemism

Definition

The ecological condition of a taxon being restricted to a specific geographic area and naturally occurring nowhere else; the taxon itself is described as endemic. Endemism reflects historical isolation, limited dispersal ability, or specialized habitat requirements, and is a key metric in biogeography and conservation prioritization. Contrast with cosmopolitan distribution or introduced range.

Etymology

From Greek endemos 'native, dwelling within' (en- 'in' + demos 'people, district'), via New Latin endemicus.

Example

The Lord Howe Island stick insect (Dryococelus australis) exhibits extreme endemism, having persisted only on a single island in the Tasman Sea until its rediscovery on a nearby rocky islet after presumed extinction.

Synonyms

• endemicity

Related Terms

• Cosmopolitan
• disjunct distribution
• relict population
• biogeographic realm
• area of endemism
• narrow endemic

Usage Notes

Endemism is a property of populations or taxa, not individuals. The scale matters: a species may be endemic to a continent (e.g., Madagascar) or a single cave system. 'Endemic' is sometimes misused as a synonym for 'native' or 'indigenous,' but those terms carry no restriction on geographic range. In island biogeography and arthropod systematics, microendemism—restriction to tiny habitats like single springs or summits—is frequently documented for flightless insects and cave arachnids.