The correct answer is: E. Keystone species.
A keystone species is a species that has a disproportionately large effect on its environment relative to its abundance. Keystone species are essential to the stability of an ecosystem and the survival of other species in the community.
Edge species are species that are found at the edges of two or more communities. They are often adapted to the conditions found at the edge, such as increased light or wind exposure.
Link species are species that connect two or more communities. They often do this by providing a food source or habitat for species that live in both communities.
Pioneer species are the first species to colonize an area that has been disturbed, such as a new volcanic island or a clear-cut forest. They are often fast-growing and tolerant of harsh conditions.
Successional species are species that replace pioneer species as an ecosystem matures. They are often slower-growing and more specialized than pioneer species.
Here are some examples of keystone species:
- The sea otter is a keystone species in the kelp forests of the Pacific Northwest. Sea otters eat sea urchins, which graze on kelp. When sea otters are removed from an ecosystem, sea urchin populations explode and kelp forests collapse.
- The American bison is a keystone species on the North American prairie. Bison graze on grasses, which helps to prevent the spread of wildfires. When bison are removed from an ecosystem, wildfires become more common and the prairie ecosystem changes.
- The bald eagle is a keystone species in the coastal forests of the Pacific Northwest. Bald eagles eat salmon, which are an important food source for many other species. When bald eagles are removed from an ecosystem, salmon populations decline and other species that rely on salmon suffer.