Carrying capacity is best defined as:

• A. The average population size over time
• B. The number of species in an area
• C. The rate of resource production
• D. The maximum population size an environment can support indefinitely

Answer: (D)

The idea being tested is that carrying capacity is the maximum number of individuals of a species an environment can support indefinitely given the available resources, space, and interactions within the ecosystem. As a population nears this limit, resources run short, competition increases, and births may slow while deaths rise, causing growth to level off and the population to stabilize. This is why populations often show logistic growth: rapid increase at first, then a plateau as the environment’s limits bind. Carrying capacity can shift when resources change, habitats are altered, or climate affects food and shelter, so it isn’t a fixed number. It isn’t the average population size over time, nor the number of species in an area, nor the rate at which resources are produced. The maximum population size an environment can support indefinitely is the best definition.