Predator-induced collapse of niche structure and species coexistence
Biological invasions are a pressing environmental challenge and an opportunity to investigate the role of top predators in regulating biodiversity and food-web structure.
On small Caribbean islands where brown anole lizards were the native top predator, we staged invasions by competitors (green anoles) and/or new top predators (curly-tailed lizards). We show that predators destabilized prey coexistence, contrary to the classic idea of keystone predation.
Fear-driven avoidance of predators collapsed the spatial and dietary niche structure that otherwise stabilized coexistence, contributing to the extinction of green-anole populations on two islands. Also, whereas adding one lizard species lengthened food chains, adding both species reversed this effect.
We realized that diversity-enhancing effects of top predators cannot be assumed, and non-consumptive effects of predation risk may be a widespread constraint on species coexistence.
Watch this Nature film about the project:
A tale of three lizards: The problem with predators
Introducing a new top-predator onto islands in the Caribbean turned out to be bad news for some small tree-dwelling lizards. Ecologists spent six years running a series of evolutionary experiments, observing the lives of brown anoles, green anoles and predatory curly-tailed lizards. These results could impact how ecologists manage introduced and invasive predators around the world.
Read about our findings at Pringle et al. 2019, Nature
For similar work on the ‘landscape of fear’, see
Special thanks to our collaborators
This project graciously supported by
