Idea or model
Food chains and webs
Who eats whom in an ecosystem. Energy and nutrients pass from producers to the animals that eat them.
Trophic cascade
Effects that ripple down a food chain, as when predators hold herbivores in check and plants flourish.Source: Estes & Palmisano, 1974Source: Ripple & Beschta, 2012Source: Hobbs et al., 2024
Process
How Trophic cascade connects
Trophic cascade involves
Trophic cascade can be caused by
Idea or model
Keystone species
A species, often a predator, that strongly shapes its whole community. Robert Paine introduced the term in 1969.
Studied in
Your progress
Sources & further reading
The explanations on this page are our own summaries of these sources. Follow a link to read the original; if anything here disagrees with it, the original wins. How we choose and check sources.
Sea otters: their role in structuring nearshore communities (opens the original in a new tab)
Estes JA, Palmisano JF (1974). Science 185:1058-1060.
Historical paperPrimary researchTrophic cascades in Yellowstone: the first 15 years after wolf reintroduction (opens the original in a new tab)
Ripple WJ, Beschta RL (2012). Biological Conservation 145:205-213.
Peer-reviewedReviewDoes restoring apex predators to food webs restore ecosystems? Large carnivores in Yellowstone as a model system (opens the original in a new tab)
Hobbs NT, Johnston DB, Marshall KN, et al. (2024). Ecological Monographs 94.
Field experiments questioning how fully wolf reintroduction restored Yellowstone's streamside vegetation.
Peer-reviewedPrimary research