The writer is a science commentatorIt is fitting that a concept now regarded as somewhat slippery began life in a rock pool. In the 1960s, Bob Paine, an ecologist at the University of Washington, removed a species of purple starfish from a tidal pool on a stretch of the US Pacific coast to see what would happen.
Years later, he found that mussels, normally kept in check by the carnivorous starfish, had overrun the territory, crowding out other marine life. Paine termed the starfish a “keystone species”, reflecting its outsize effect on its environment. The moniker spread like Japanese knotweed, floating on the breeze of the budding environmentalism movement and into public consciousness.
More than 200 animal species have since been described in academic literature as “keystone”. There is little agreement, however, over the definition. And, as the magazine Quanta reported last month, ecologists are now reappraising the concept. The rethink matters: such species are central to the idea of rewilding, a modern form of conservation that promotes biodiversity by encouraging habitats to revert to a more natural state. Without a clear sense of which animal and plant species control an ecosystem’s gears, environmentalists are rewilding in the dark.