endemisk

Endemism is the ecological state in which a species, or other taxon, is restricted to a defined geographic area. The term is used in biology, biogeography and epidemiology to describe organisms that occur naturally only in that area and nowhere else.

Endemic species are confined to a particular location, such as an island, a mountain range, or a country. Examples include Madagascar’s lemurs, the Galápagos finches, and many plant species in the Cape Floristic Region of South Africa. Some regions harbor many endemics, making them priority areas for conservation.

Causes and patterns: Endemism arises through geographic isolation, ecological specialization, and historical factors such as plate tectonics and climate change. Endemism can be categorized as neoendemism (recently evolved endemics) or paleoendemism (ancient lineages that persist in restricted areas). Endemics can be narrowly distributed (restricted to a single site) or more widespread within a limited region.

Conservation: Because endemic species have restricted ranges, they are often more vulnerable to habitat loss, invasive species, and environmental change. Protecting their habitats, controlling introductions, and sometimes ex-situ breeding programs are used to conserve endemics. Regions with high levels of endemism are often biodiversity hotspots.

In medicine, an endemic disease is one that is continuously present in a population or region at relatively stable levels. By contrast with outbreaks or epidemics, endemic diseases show a steady baseline incidence, as seen historically with malaria in parts of the tropics or tuberculosis in many areas.

Endemism differs from being native or introduced: a native species occurs naturally in a region but may also occur elsewhere, while an endemic species is limited to that region; introduced species originate elsewhere and have colonized the area.