Final answer:
Predators, food and water shortages, light shortages, human activities, and the carrying capacity of the environment are the key factors that limit population increases.
Step-by-step explanation:
There are several factors that limit population increases, including both natural and human-related factors. The first factor is predators. As the prey population increases, the predator population also increases, causing a decrease in the prey population. This is an example of the predator-prey population dynamics.
Next are food and water shortages. When there are insufficient resources to support a population, it can result in decreased birth rates, increased death rates, or emigration. For instance, if there are 12 hamburgers at a table and 24 people sit down, not everyone will be able to eat. This example illustrates how food supply can dramatically influence population.
Light shortages can also cause population decrease. Light is needed for photosynthesis, which is essential for the growth and development of many organisms. Other limiting factors include disease, parasites, oxygen, the ability of an ecosystem to recycle nutrients and/or waste, and space.
Human activities such as use of pesticides, habitat destruction, and pollution can limit population growth as well. Lastly, the concept of carrying capacity also plays a part - that is the maximum population size that the environment can sustain indefinitely. Factors keeping populations from reaching their carrying capacity include resource scarcity, changes in climate, warfare, deforestation, and disease.
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