More than wolves: researchers uncover the striking variety of Keystones Species, challenging our view of which animals make ecosystems tick

New research on the planet’s ‘Keystone Species’ has revealed a staggering and unappreciated diversity in what kind of animal fits this distinguished label.  Defined as those species that have enormous influence on ecosystems relative to their abundance, the stereotypical Keystone Species that frequently come to mind are large predatory mammals, like the recolonizing wolves that changed the Yellowstone area. 

But a new peer-reviewed paper in Ecology and Evolution challenges this stereotype. Presenting the first evidence-based list of animal keystones, a team of scientists from Canada and the US reveals a wide diversity of the planet’s keystone species in terms of their size, shape, and functional role. The prominence of many smaller species on the list, like cabbage butterflies and pocket mice, challenges the prominent belief that all keystones are large carnivores. 

“We’ve all heard of the Yellowstone wolves, but they’re just part of the story. Many keystones are much smaller, and instead of influencing ecosystems via predation, they perform important ecosystem services such as churning up soil or filtering water”, says Ishana Shukla of the University of Victoria and Raincoast Conservation. Shukla and her team identified 230 keystone animals from 1800 scientific papers. Their analysis found that large carnivores are just one of five keystone ’archetypes ’, with other archetypes comprising small marine invertebrate modifiers, insects consumers, fish consumers and rodents modifiers.

This new Keystone Species list has applied value. While large carnivores have played center stage in conservation debate for decades, many smaller keystones have been overlooked. Investing resources to protect the broader range of keystones reduces risks that overlooked keystones are lost from ecosystems, which can impose devastating effects on nature and, eventually, humans. ‘While we might tend to forget about these less charismatic species, targeting them for conservation helps the entire system, giving those who invest in conservation great bang for their buck!’