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key concept

55.2

Predation Is a Trophic Interaction in which Predators Benefit and Prey Are Harmed

Predator–prey interactions are probably the most familiar, and perhaps the most dramatic, type of species interaction. Even though carnivory, herbivory, and parasitism all involve the simple interaction of one species eating another species, they often defy categorization. For example, a carnivore might sometimes function like an herbivore by eating berries and roots, or an insect might be considered an herbivore or a parasite if it spends its entire life feeding on a single tree. In addition, predators can differ considerably in the ways they affect their prey’s population dynamics if the prey species is not killed in the process. Despite these complications, we will explore predation by considering carnivory, herbivory, and parasitism separately. We will end by drawing on some generalities regarding population and community consequences of predation.

focus your learning

  • Prey have evolved many strategies to avoid being captured, including escape, avoiding detection, chemical defenses, warning signals, and mimicry.

  • Plants and herbivores have developed reciprocal adaptations to counter their effects on one another.

  • Parasites are abundant and have highly varied effects on their hosts.

  • Coupled predator–prey cycles greatly influence the populations of both species and the communities in which they reside.