What is a keystone species?

A keystone species is defined as an organism that plays a critical role in maintaining the structure and health of its ecosystem. Its presence or absence has a significant impact on the ecosystem's diversity and stability. Keystone species are often key predators, herbivores, or facilitators, and their activities help to regulate populations of other species, which in turn influences the overall biological community.

For example, the removal of a keystone species from an ecosystem can lead to dramatic changes, possibly resulting in a decline of biodiversity. This concept highlights the importance of certain species, which may not necessarily be the most abundant or largest in number, but whose ecological roles are fundamental to the functioning of their environment.

This understanding differentiates keystone species from organisms that might have little to no noticeable effect on their ecosystems or those that are top predators but do not play a pivotal role in structuring their environments. Invasive species, meanwhile, often disrupt native ecosystems but do not fall under the definition of a keystone species, as their primary impact tends to be detrimental rather than sustaining.