16: Antagonistic Interactions

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Page ID: 78225

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Learning Objectives

Differentiate between the various types of antagonistic interactions
Understand how antagonistic interactions drive evolution in the positively impacts species (predator, parasite, herbivore) and in the negatively impacted species (prey, host, plant)
Predict fluctuations in populations of predators and prey (or parasites and hosts) using a modification of the exponential growth model, the Lotka-Volterra predator-prey model.

Summary

Antagonistic interactions involve interactions in which one individual or species benefits, while the other individual or species is harmed. These interactions include predation, herbivory, and parasitism. These type of interactions exert immense evolutionary pressure on the individuals involved as they are required to obtain energy (predators, parasites, herbivores) for one of the species involved and to avoid loss of energy or death (prey, host, plant) for the second species involved. As a result, antagonistic interactions often drive an "evolutionary arms race", a cycle of adaptations and counter-adaptations. Ecologists model interactions among predators and their prey using the Lotka-Volterra model, which builds on the exponential growth model to link predator population growth and prey population decline.