The graph below shows the population fluctuations of a predator species (e.g., foxes) and its prey species (e.g., rabbits) in an ecosystem over 10 years. Both populations exhibit cyclical patterns.
[Imagine a line graph with two oscillating lines, one for prey and one for predator. The prey population peaks first, then the predator population peaks, followed by a decline in both, then the cycle repeats. Prey population numbers are consistently higher than predator numbers.]
Based on the observed cyclical relationship, if the predator population has just reached its peak, what is the most likely trend for the prey species population in the immediate next phase?
Correct: B
In typical predator-prey cycles, an increase in the prey population provides more food for predators, leading to an increase in the predator population. However, an increased predator population then leads to a higher predation rate, causing the prey population to decline. Once the prey population declines, the predator population, facing food scarcity, also begins to decline. Therefore, if the predator population has just peaked, it indicates that the prey population had peaked some time earlier and has already begun to decline, providing less food for the peak predator population. The immediate next phase for the prey population would be a continued decline.