Endemics

species, genera, families, and other taxonomic units (systematic categories) of plants and animals whose range is limited to a relatively small region.

The range of some endemics is particularly limited. For example, the colubrid Oreotrochilus chimboraso is found only on Mount Chimborazo (South America) at an elevation of 4,000–5,000 m above sea level. The snail Limnaea convoluta occurs only in one small lake in Ireland. Among plants, the Sequoiadendron are found only on the slopes of the Sierra Nevada in California (USA); Pinus eldarica occupies an area of 25–50 sq km on the northern and northeastern slopes of Mount Eyliar-Bug in Soviet Georgia.

Areas that are isolated geographically or ecologically (deep lakes, mountains, islands) are rich in endemics. For example, endemics constitute 75 percent of the fauna of Lake Tanganyika (East Africa), 76 percent of the fauna of Lake Baikal, and 72 percent of the flora of New Zealand. On the Hawaiian Islands endemics constitute 82 percent of the plant species, all of the terrestrial mollusks (400 to 500 species), most beetle species, and almost all of the land-dwelling birds (55 species).

Endemics are divided into two groups—paleoendemics and neo-endemics. (See alsoCOSMOPOLITE, PALEOENDEMIC, and NEO-ENDEMIC.)