Within biological communities, some species are important in determining the ability of a large number of other species to persist in the community. Such species are called

The species described — those whose presence or absence disproportionately affects the ability of many other species to persist in a community — are referred to as keystone species. Keystone species are defined by their large, often disproportionate influence on community structure: their addition to or loss from an ecosystem produces major changes in the abundance or occurrence of other species, and their loss can lead to ecosystem degradation [1]. Examples often include top predators and ecosystem engineers whose regulatory roles maintain diversity and stability. The keystone concept is distinct from related terms like “umbrella species,” which are chosen for conservation because protecting them incidentally protects many others by virtue of shared habitat requirements [2].

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 8: Biodiversity > Kqystone specigs > p. 149
2. [2] https://education.nationalgeographic.org/resource/role-keystone-species-ecosystem/