Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
An engineer keystone species is a type of organism that creates or modifies habitats, affecting other organisms within the ecosystem. Their impact on the environment is significant and disproportionate to their population size.
Beavers are a classic example of an engineer keystone species. They build dams on rivers which create wetlands - beneficial for many plant and animal species.
Coral Reefs: Corals are another example of an engineer keystone species. They build large underwater structures (reefs) that provide habitat for a multitude of marine life.
Trophic Cascade: This term refers to changes in an ecosystem caused by the addition or removal of top predators (like wolves) or key engineers (like beavers). These changes can affect multiple levels of the food web.