To borrow again from conservation biology, maintainers can be thought of as a keystone species. A keystone species is small in population size but has an outsize impact on its ecosystem. If we were to imagine a forest, for example, while there may not be many wolves in absolute numbers, if the wolves disappeared there would be cascading effects on the rest of the forest. The deer population, lacking a natural predator, would grow out of control, the plants would start to disappear because there would be too many deer, and so on.
