31. Elephants are not the most dominant species in African grasslands, yet they influence community structure. The grasslands co
ntain scattered woody plants, but they are kept in check by the uprooting activities of the elephants. If the elephants are taken away, the grasslands convert to forests or to shrublands. The newly growing forests support fewer species than the previous grasslands. Which of the following describes why elephants are the keystone species in this scenario? A) Elephants exhibit a disproportionate influence on the structure of the community relative to their abundance. B) Grazing animals depend upon the elephants to convert forests to grassland. C) Elephants prevent drought in African grasslands. D) Elephants are the biggest herbivore in this community. E) Elephants help other populations survive by keeping out many of the large African predators.
The correct answer is C. <span>a density-independent limiting factor
When bird populations sometimes decrease in areas due to wind farms, this occurrence is known as a density-independent limiting factor because it is not related so much to density.</span>
