In AP Bio, predation is an interaction where one organism (the predator) kills and eats another (the prey). It's a density-dependent factor that helps cap population growth and a major driver of community structure and natural selection.
Predation is the relationship where a predator kills and eats its prey. It's one of the negative-effect interactions in Community Ecology (Topic 8.5), alongside competition and parasitism, that shape how populations grow and how energy and matter move through a community.
Here's the part that trips people up: predation isn't just "who eats whom." It's a feedback loop. When prey are dense, predators have an easy buffet, so predator numbers climb. More predators then knock the prey population back down, which starves out some predators, and the cycle repeats. That makes predation a density-dependent factor, meaning its effect gets stronger as the population gets crowded. This is exactly the kind of pressure that bends an exponential growth curve into the leveling-off shape of logistic growth (Topic 8.4).
Predation lives in Unit 8: Ecology and ties together four learning objectives. It's a density-dependent brake under AP Bio 8.4.A (how density and resources cap population size), one of the named population interactions under AP Bio 8.5.B (predator/prey interactions, trophic cascades, niche partitioning), a factor in growth dynamics under AP Bio 8.3.A (death rate), and a selective force under AP Bio 8.7.A (adaptations like camouflage or speed get favored by selection). It also shows up in AP Bio 8.7.B, where invasive species explode partly because they land in a new niche free of predators. So predation is a thread that runs from single-population math all the way up to evolution and ecosystem disruption.
Keep studying AP Biology Unit 8
Carrying Capacity & Logistic Growth (Unit 8)
Predation is one of the density-dependent forces that pulls a population toward its carrying capacity (K). As prey get crowded, predators eat more of them, raising the death rate and flattening the logistic curve at K instead of letting growth run forever.
Competition (Unit 8)
Both are negative-effect interactions, but they push in different ways. Competition is two species fighting over the same resource, while predation is one species eating another. A top predator can actually boost diversity by eating the strongest competitor and freeing up space for everyone else.
Invasive Species (Unit 8)
Under EK 8.7.B.1, an invasive species often booms because it escaped its natural predators. Kudzu and zebra mussels show what happens when predation is removed from the equation, the population grows almost unchecked.
Adaptation & Natural Selection (Unit 8)
Predation is a selection pressure (AP Bio 8.7.A). Traits that help prey avoid being eaten, like camouflage or warning coloration, get favored, and predator traits that improve hunting get favored too. This back-and-forth is a classic example of coevolution.
Predation almost never appears as its own vocabulary question. Instead, it shows up as the reason behind a pattern. On MCQs, you'll see it labeled as a density-dependent mortality factor, often contrasted with a density-independent factor like a drought or severe weather, and you'll need to predict how it bends a logistic growth curve. In community questions, predation is the interaction that drives diversity changes, like the recovery of a coral reef after a bleaching event. You may also need to read predator-prey cycle graphs and explain why predator peaks lag behind prey peaks. The skill being tested is connecting predation to a quantitative model (dN/dt = B - D, or the logistic equation) or to a change in Simpson's Diversity Index, not just defining the word.
Both are negative interactions, but predation is one organism eating another, while competition is two organisms fighting over the same limited resource (food, space, light) without one eating the other. Quick check: if energy flows directly from one organism's body into another's, it's predation. If they're just both reaching for the same supply, it's competition.
Predation is a density-dependent factor, so its impact on the population gets stronger as the population becomes more crowded.
Predation raises the prey's death rate, which is what bends an exponential growth curve into the leveling-off shape of logistic growth at carrying capacity.
Predator and prey populations cycle together, with the predator peak lagging behind the prey peak because predators need prey to be abundant first.
Predation can increase community diversity when a predator eats a dominant competitor and frees up resources for other species.
Removing natural predators is a key reason invasive species like kudzu and zebra mussels grow out of control.
Predation acts as a selection pressure, favoring prey adaptations like camouflage and predator adaptations like speed.
Predation is an interaction where one organism (the predator) kills and eats another (the prey). On the AP exam it's treated as a density-dependent factor that raises death rates and a key driver of community structure under Topic 8.5.
Density-dependent. Its effect grows stronger as the population gets denser, because crowded prey are easier for predators to find. Compare that to a drought or cold snap, which kills the same fraction of a population no matter how dense it is.
Both are negative interactions, but predation is one organism eating another, while competition is two organisms fighting over the same resource without one consuming the other. If energy flows directly from one body into another, it's predation.
No. Predation can actually raise diversity if a predator eats the dominant competitor, which frees up resources and space for weaker species to survive. This is a common twist on community ecology questions.
Often because they escaped their natural predators. Under EK 8.7.B.1, an invasive species like kudzu or zebra mussels can exploit a new niche with no predators to keep its numbers in check, so its population explodes.