Mountain tapirs are also important seed dispersers within their environments, and have been identified as a keystone species of the high Andes. A relatively high proportion of plant seeds eaten by mountain tapirs successfully germinate in their dung, probably due to a relatively inefficient digestive system and a tendency to defecate near water. Although a wide range of seeds are dispersed in this manner, those of the endangered wax palm seem to rely almost exclusively on mountain tapirs for dispersal, and this plant, along with the highland lupine, declines dramatically whenever the animal is extirpated from an area.