Final answer:
The carrying capacity is determined by both biotic and abiotic limiting factors and represents the maximum population size that can be sustained in an environment. It is subject to change due to environmental fluctuations and is represented by the upper flat line on a logistic growth curve.
Step-by-step explanation:
The carrying capacity of a population is determined by the limiting factors that exist in its environment, which can be both biotic, such as competition for resources like food and mates or predation, and abiotic, such as availability of water, space, and suitable climate. These factors collectively decide the maximum population size that can be sustained without leading to habitat destruction or resource depletion. The carrying capacity is the flat upper line of a logistic growth curve (S-shaped curve) and represents the population size leveling off as resources become scarcer. This contrasts with exponential growth (J-shaped curve) where the population size keeps increasing alongside the growth rate, assuming limitless resources. In reality, the carrying capacity is not fixed and can change due to various factors like seasonal changes, natural events, and interspecific competition.
An example to demonstrate this is with deer in a forest. If the forest can only sustainably provide food and habitat for 100 deer, and the population grows to 120, the extra 20 deer might lead to overgrazing. The limited food supply becomes the limiting factor, thus bringing the population down to or below the carrying capacity of 100 deer, highlighting why understanding these dynamics is important for population management and conservation efforts.