What is a keystone species?

A keystone species is defined as one that has a disproportionately large effect on its environment relative to its abundance. This means that the presence or absence of this species can significantly influence the structure and function of the ecosystem. For example, a keystone species might control the population of other species, maintain the structure of a habitat, or facilitate the survival of multiple other species within an ecosystem.

By playing such critical roles, keystone species help to maintain biodiversity and the stability of the ecosystem. When keystone species are removed or their populations decline, the effects can ripple through the environment, leading to changes that can affect many other species and the overall health of the ecosystem. In contrast to this, species that have a minor role or those least affected by environmental changes do not exert the same level of influence over their habitats. Similarly, a species that consumes only plant life might contribute to its ecosystem but does not encapsulate the broader impact that defines a keystone species.