Summary
A species with a disproportionately large effect on its ecosystem relative to its abundance, like sea otters.
In depth
Robert Paine's starfish (Pisaster) removal experiment led to mussels excluding other species, cutting diversity. Sea otters, wolves, elephants and beavers (ecosystem engineers) are other examples.
Loss may cause cascading changes.
Keystone effects are disproportionate to abundance. They can be predators, engineers or mutualists. Identifying them requires removal or addition experiments.
Key idea: removing a keystone species changes the whole community.
Frequently asked questions
What is Keystone Species?
A species with a disproportionately large effect on its ecosystem relative to its abundance, like sea otters.
Which area of biology covers Keystone Species, and how advanced is it?
Keystone Species is one of the 54 topics in Ecology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Food Web, Species Diversity, Trophic Cascade.
Can you give an example of Keystone Species?
Prairie dogs create burrows used by many species.
What should I learn before Keystone Species?
Work through the Beginner topics in Ecology first, such as Ecology, Ecosystem, Biotic and Abiotic Factors, then return to Keystone Species. Intermediate topics assume the Beginner vocabulary.
What topics are related to Keystone Species?
The closest topics to Keystone Species are Food Web, Species Diversity, Trophic Cascade, Macroecology. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Keystone Species?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Keystone Species. To practise the whole of Ecology, use the Ecology quiz.
How is Keystone Species different from Food Web?
Keystone Species: A species with a disproportionately large effect on its ecosystem relative to its abundance, like sea otters. Food Web: An interlinked network of food chains showing feeding relationships in a community. Read both side by side and note what each one explains.
How should I study Keystone Species step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Food Web and explain the difference aloud. Finally, take the Ecology quiz and come back to this page for any question you miss.