Keystone Species Notes – Trophic Cascades & Ecosystem Stability (Biology)

Keystone Species
Keystone Species

Keystone species plays a critical role in maintaining the structure and functioning of the ecosystem in
which they live.
o It is not necessarily the most abundant species in the ecosystem.
o If a keystone species is removed from an ecosystem, the community can become less stable
and susceptible to structure changes.

Trophic Cascade

Trophic cascade is triggered by the addition or removal of a species from an ecosystem.
o This can affect the population of predatory and prey organisms through a food chain.
o A trophic cascade can lead to dramatic changes in the structure of an ecosystem and
recycling of nutrients.




Keystone Species

maintain the balance of organisms
o If lost it affects a number of other species in the community
o Often only identified after an ecosystem has been impacted
indicating features include:
a. Ability to eat a variety of organisms in the ecosystem (keep all populations under control)
(interactions)
b. Influence on other organisms is out of proportion to its biomass or abundance