sentences:  Keystone predators are responsible for the control of prey densities, and their removal can result in an increase in one or a number of predators, consumers, or competitors elsewhere in the food web.Several prey or competitor species can consequently suffer a population decline and potentially be extirpated; the result of this would be a decrease in community diversity.Without the keystone species, prey populations can grow indefinitely and will, ultimately, be limited by resources such as food and shelter.