Predators may increase the biodiversity of communities by preventing a single species from becoming dominant. Such predators are known as keystone species and may have a profound influence on the balance of organisms in a particular ecosystem. <answer>Introduction or removal of this predator, or changes in its population density</answer>, can have drastic cascading effects on the equilibrium of many other populations in the ecosystem. For example, grazers of a grassland may prevent a single dominant species from taking over.
What changes to a keystone predator can seriously affect an ecosystem's equilibrium?
Introduction or removal of this predator, or changes in its population density