Despite popular metaphors and cartoons depicting straightforward “food chains,” ecologists such as Brown University Professor Jon Witman typically doubt that they’ll see predators in diverse tropical ecosystems have meaningful impacts on species even just two links down the line. But after six years of meticulous experimentation and observation off the coast of the famed Galápagos Islands, Witman and two colleagues have amassed direct evidence that just such an important “trophic cascade” is happening there.