Oscillation of Predator and Prey Populations

Question

Source: Oxford Designers & Illustrators Ltd/Pearson Education Ltd



On the graph (above), a healthy, stable predator-prey oscillation is shown. The blue line represents the population of a prey species, while the red line represents the population of a predator species. Assume that this specific predator eats this specific prey.

3. Use the graph above to determine if each statement (below) is accurate or inaccurate.

Scoring: Earn 1 point by getting 2 or 3 correct responses. Earn 2 points by getting 4 correct responses.

(2 points)
Accurate Inaccurate
An increase in the prey population causes a subsequent increase in the predator population because there is more food available for the predators.

There must always be a higher population of predators than prey in order for both populations to survive.

A decrease in the prey population causes a subsequent decrease in the predator population because competition for food becomes more difficult.

The two populations have no affect on each other. The fluctuations are just random.

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Answer 1

Let's analyze each statement regarding predator-prey oscillations based on the dynamics typically seen in ecological models like the Lotka-Volterra equations:

1. An increase in the prey population causes a subsequent increase in the predator population because there is more food available for the predators.

   • Accurate. This statement reflects the classic predator-prey relationship where a rise in prey leads to more food for predators, which can support a larger predator population.

2. There must always be a higher population of predators than prey in order for both populations to survive.

   • Inaccurate. This statement is not necessarily true. While both populations affect each other, it is not required for predators to outnumber prey for their populations to coexist. In fact, a stable ecosystem often has a balance where prey outnumbers predators.

3. A decrease in the prey population causes a subsequent decrease in the predator population because competition for food becomes more difficult.

   • Accurate. When the prey population decreases, there is less food available for the predators, which can lead to a decline in the predator population as they struggle to find enough resources.

4. The two populations have no effect on each other. The fluctuations are just random.

   • Inaccurate. This statement contradicts ecological principles; predator and prey populations are deeply interconnected, and their fluctuations are not random but rather dependent on each other's populations.

Based on the analysis:

• Accurate statements: 1 and 3
• Inaccurate statements: 2 and 4

You have 2 accurate responses, which means you earn 1 point according to the scoring system provided.