What is a density-dependent factor that affects population growth?

Predation is a density-dependent factor that affects population growth because its impact on a population varies based on the population's density. As the population of a species increases, the likelihood of encounters with predators also increases. This can lead to higher rates of predation, which can reduce the prey population. In contrast, if the prey population is low, there may not be enough predators to significantly impact the population growth of the prey. Therefore, in higher-density populations, predator interactions become more pronounced, leading to a regulation of the population size due to increased predation pressure. This concept is an important aspect of population ecology, where interactions among species, such as predator-prey dynamics, play a critical role in population regulation.

Other factors, like environmental pollution or natural disasters, do not change in impact based on the population density, while climate change influences populations globally but is generally considered a density-independent factor, as its effects are felt uniformly regardless of the local population sizes.