On a population growth curve, what does a plateau indicate?

On a population growth curve, what does a plateau indicate?

• A. Carrying capacity has been reached.
• B. The population is experiencing exponential growth.
• C. Predator numbers have increased.
• D. The environment has more resources.

Answer: (A)

A plateau on a population growth curve shows that the population has reached the environment’s carrying capacity—the maximum number of individuals that the available resources (like food, space, and water) can sustain over time. As resources become limited, births may balance deaths (and immigration balance emigration), so net growth slows to zero and the curve levels off. This leveling off reflects logistic growth, where growth slows as density increases and the population stabilizes at roughly that sustainable size. The other ideas describe ongoing or different dynamics (exponential growth, changes in predators, or more resources) that would not produce a sustained plateau at the current resource level.

A plateau on a population growth curve shows that the population has reached the environment’s carrying capacity—the maximum number of individuals that the available resources (like food, space, and water) can sustain over time. As resources become limited, births may balance deaths (and immigration balance emigration), so net growth slows to zero and the curve levels off. This leveling off reflects logistic growth, where growth slows as density increases and the population stabilizes at roughly that sustainable size. The other ideas describe ongoing or different dynamics (exponential growth, changes in predators, or more resources) that would not produce a sustained plateau at the current resource level.