California
Ecology

California is one of the ecologically richest and most diverse parts of the world, and includes some of the most endangered ecological communities. California is part of the Nearctic realm and spans a number of terrestrial ecoregions.

California's large number of endemic species includes relict species, which have died out elsewhere, such as the Catalina ironwood (Lyonothamnus floribundus). Many other endemics originated through differentiation or adaptive radiation, whereby multiple species develop from a common ancestor to take advantage of diverse ecological conditions such as the California lilac (Ceanothus). Many California endemics have become endangered, as urbanization, logging, overgrazing, and the introduction of exotic species have encroached on their habitat.
keywords:existence