Meaning & use

keystone species

noun·Academic

A species that has a disproportionately large effect on its ecosystem relative to its abundance.

See it in a sentence

Sea otters are a keystone species because they control the sea urchins that destroy kelp forests.

Removing the keystone species from the reserve caused several other populations to collapse.

A note on using this word

The term describes ecological importance, not necessarily the most numerous or largest species present.

Words with a similar meaning

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