You may not like ferocious predators like lion, tiger, cheetah etc. But these top predators are the key regulators in an ecosystem. Think of a grassland with the number of lions dwindling, what will happen? The number of ghazals (deer) may rise up that eventually results in overgrazing causing a decline in primary productivity and a complete chaos in the system. So the real problem is reduction in lion population. Such species that has profound impact in an ecosystem and removal of such species results in a complete imbalance in an ecosystem. Such vital species are termed as keystone species.
In other words, the term keystone species refers to an organism that plays a critical role in its environment, one that may become apparent only once it is removed from an ecosystem. Keystone species exerts a strong influence on the structure and function of ecosystem. Let us have a look at some of these “KEYSTONE” species.
Sea Otters are a keystone species of the kelp forest ecosystem. Kelp is home to hundreds of species like crabs, snails,sea urchins and geese etc that depend on kelp for food. Many types of fish use the huge kelp forests to hide from predators. Sea otters feed on sea urchins, controlling their population. If the Sea Otters didn't eat the urchins, the urchins would eat up the kelp. Without sea otters to control the urchin population, the entire ecosystem would collapse.
Beavers, the mammalian architect construct dams and transforming streams into ponds, create new habitats for many plants and animal species.
The keystone species concept was put forward Robert T Paine to explain the relationship between Pisaster ochraceus (Starfish) and Mytilus californianus (Mussel). The removal of a certain species of starfish was found to cause a rapid growth in the numbers and biomass of the mussel.
The flying fox is a key stone specie on tropical islands.It pollinates many of the plants, and is a key disperser of seeds. Its elimination due to hunting and habitat loss is having a devastating effect on the ecosystems of South Pacific Islands.
The prairie dog is a keystone species of the prairie ecosystem. They contribute to the lives of the other mammals by providing habitat and food. Abandoned burrows are frequently used as homes by burrowing owls, rabbits, weasels, and even snakes. Prairie dogs' churning activities aerate the soil to allow for more water penetration, while their nitrogen-rich dung improves the quality of the soil and vegetation.
African elephants are the keystone species that maintain the entire savannah ecosystem. Elephants eat acacia and even if an acacia tree grows to a height of several feet, elephants are able to knock over the tree and uproot it. This behavior keeps the savanna as a grassland and not a forest or woodland. With elephants to control the tree population, grasses thrive and sustain grazing animals such as antelopes, zebras.
Some species of hummingbird are keystone species in the Sonoran Desert of North America. Hummingbirds pollinate many varieties of native cactus and other plants.
The keystone species disappearance could affect other species that rely on it for survival.