Endemic (ecology)

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This article is about the ecological meaning of "endemic". See also endemic (epidemiology).

In biology and ecology endemic means exclusively native to a place or biota, in contrast to cosmopolitan or introduced. However, it is also differentiated from indigenous: A species that is endemic is unique to a defined place or region (in other words only found in that place or region) and not naturally found anywhere else, whereas a species that is indigenous to somewhere may be native to other locations as well. Usually the term is applied to a discrete geographical unit, often an island or island group, but sometimes a country, habitat type, or other defined area or zone. For example, we can say that the Orange-breasted Sunbird, Anthobaphes violacea, is a Fynbos endemic (i.e. exclusively found in the Fynbos vegetation type of southwestern South Africa), or that the Socotra Sparrow, Passer insularis, is endemic to Socotra (only found in the Socotra island group). The Bermuda cedar, Juniperus bermudiana, and the, Bermuda Petrel, Pterodroma cahow, are both endemic to Bermuda. Although the petrel is pelagic, spending most of its life roaming far over the Atlantic, and only comes ashore to nest, Bermuda is the only place in which it does so.

Islands are especially likely to develop endemic types or species because of their geographical isolation. This includes remote island groups, such as Hawaii, the Galápagos Islands and Socotra. The restricted area and vulnerability to the depredations of man and introduced species mean that endemics all too easily can become endangered or extinct. There were several millions of both petrels and 'cedars' (actually junipers) in Bermuda, when settled at the start of the 17th Century. By the end of the century, the petrels were thought extinct, and cedars were very nearly driven to extinction by centuries of shipbuilding, then an introduced parasite. Both are very rare, today, as are other species endemic or native to Bermuda.

Endemism can also develop in other biologically isolated areas, such as the highlands of Ethiopia or large bodies of water like Lake Baikal.