keystone species

American  

[kee-stohn spee-sheez, spee-seez] / ˈkiˌstoʊn ˈspi ʃiz, ˈspi siz /

noun

plural

keystone species

1. Ecology. a species, especially a plant or animal, that is critical to the health of the ecosystem it is part of.

---

keystone species Scientific  

/ kē′stōn′ /

1. A species whose presence and role within an ecosystem has a disproportionate effect on other organisms within the system. A keystone species is often a dominant predator whose removal allows a prey population to explode and often decreases overall diversity. Other kinds of keystone species are those, such as coral or beavers, that significantly alter the habitat around them and thus affect large numbers of other organisms.

2. Compare indicator species

---

Example Sentences

They "play a central role in the food web, consuming fish and invertebrates and recycling nutrients" and are one of the "keystone species" of their ecosystem.

From Barron's • Oct. 10, 2025

“While there’s no silver bullet solutions to environmental restoration, beavers are a keystone species, and an important part of the puzzle to restore our ecosystems in California.”

From Los Angeles Times • Jan. 7, 2025

Considered "keystone species" by many, crayfish play an outsized role as food sources for other animals and as ecosystem engineers, creating burrows that act as habitat for many species in semi-terrestrial environments.

From Science Daily • Nov. 25, 2024

"We have been able to pinpoint the origin of baobabs, which are an iconic keystone species supporting a wide diversity of animals and plants as well as humans," she told the BBC.

From BBC • May 15, 2024

Until Columbus, Indians were a keystone species in most of the hemisphere.

From "1491" by Charles C. Mann