Final answer:
Populations in ecosystems are limited by factors such as resource availability and environmental conditions, which lead to logistic growth patterns and determine the environment's carrying capacity. Density-dependent factors and predator-prey dynamics further influence population sizes. Human societies must consider Earth's carrying capacity in discussions about sustainable growth.
Step-by-step explanation:
Populations do not grow infinitely larger in ecosystems due to a variety of limiting factors. These include the availability of resources, such as food and water, and environmental factors like space to live in, light, nutrients, oxygen, and the ability of the ecosystem to recycle nutrients and waste. Other important limiting factors are disease, parasites, and predation. When these resources are scarce or when negative factors increase, they can limit the growth of populations, leading to a logistic growth pattern where the population size eventually levels off at the carrying capacity of the environment. The carrying capacity is the maximum population size that a given environment can sustain without being degraded.
Density-dependent factors also play a significant role in population regulation when the population size becomes large. Increased competition for limited resources can cause the growth rate to slow down. In terms of predator-prey dynamics, an increase in the prey population can lead to a rise in the predator population, but when the prey population decreases, the predator population will decrease as well, showing a direct relationship where one serves as a limiting factor for the other.
In the context of human societies, questions about the Earth's carrying capacity are pivotal as they relate to the sustainability of population growth and resource consumption globally.