What does the term "keystone species" describe?

The term "keystone species" specifically refers to a species that plays a crucial role in maintaining the structure of an ecological community, and its impact on the environment is disproportionate to its abundance. This means that a keystone species can have a significant influence on many other organisms within the ecosystem and can affect the diversity and health of that ecosystem.

For instance, a well-known example of a keystone species is the sea otter, which helps maintain kelp forest ecosystems by preying on sea urchins that can otherwise overgraze kelp. The otters are not the most numerous species in these environments, but their predation significantly shapes the community structure and biodiversity.

In contrast, a species that is the most abundant in an ecosystem does not necessarily alter its environment in such a critical way; it may simply dominate due to high population numbers. Similarly, a species that is endangered or threatened may not play a unique role in the ecosystem relative to others. Lastly, while a species that feeds at multiple trophic levels may have diverse interactions within the ecosystem, this characteristic alone does not define it as a keystone species unless its removal would lead to significant changes in the community dynamics. Hence, the correct understanding of keystone species emphasizes their disproportion