Predator–prey Notes

What Is A Predator–Prey Relationship?

1. Predators obtain energy by feeding on other organisms.
   1. The predator benefits by gaining energy and nutrients.
   2. The prey is harmed and usually killed.
2. Predator–prey interactions link the population sizes of both species.
   1. Predator survival depends on prey availability.
   2. Prey mortality depends on predator pressure.

How Do Predator And Prey Populations Change Over Time?

1. Predator and prey populations are closely linked.
2. A change in prey population affects predator population size, and a change in predator population affects prey survival.
3. These interactions often produce population cycles:
   1. Prey population increases first when resources are available.
   2. Predator population increases after a time delay due to increased food supply.
   3. Increased predation causes prey numbers to decline.
   4. Reduced prey availability causes predator numbers to decline.
   5. With fewer predators, prey populations recover and the cycle repeats.

How Do Predators Regulate Prey Populations?

1. Predators reduce prey population size by consuming individuals.
   1. This limits unchecked prey population growth.
   2. It reduces pressure on food resources used by prey.
2. Predators often remove weaker individuals first.
   1. Sick, injured, or slower prey are more likely to be caught.
   2. This increases the average fitness of the prey population over time.

How Do Prey And Predators Adapt To Each Other?

Prey evolve traits that reduce the chance of being eaten, while predators evolve traits that improve hunting success.

1. Prey adaptations:
   1. Camouflage to avoid detection.
   2. Speed and agility to escape.
   3. Defensive structures such as shells, spines, or toxins.
   4. Behavioral strategies such as group living or alarm calls.
2. Predator adaptations:
   1. Sharp teeth or claws for capturing prey.
   2. Speed or endurance for pursuit.
   3. Stealth to approach prey unnoticed.
   4. Enhanced senses to detect prey.

Why Are Predator–Prey Relationships Important For Ecosystem Stability?

1. Predator–prey interactions help regulate population sizes.
   1. Predators prevent prey populations from growing too large.
   2. This reduces overuse of food resources.
2. Balanced predator–prey relationships support biodiversity.
   1. No single species dominates the ecosystem.
   2. Multiple species can coexist.
3. Disruption of predator–prey balance causes instability.
   1. Loss of predators can lead to prey population explosions.
   2. Excessive predation can cause prey population collapse.

What Happens When Predator–Prey Balance Is Disrupted?

1. Changes to one population affect the other.
   1. A decline in prey reduces predator survival.
   2. A decline in predators allows prey populations to increase.
2. Indirect effects often follow.
   1. Increased prey populations can overuse food resources.
   2. Reduced prey populations can cause predator starvation or migration.

How Are Predator–Prey Relationships Different From Competition?

1. Predator–prey interactions involves consumption: one organism kills and eats the other.
2. Competition doesn't involve consumption: organisms compete for shared resources but do not feed on each other.