Final answer:
Density-dependent factors are environmental conditions that have different effects on population densities. They include predation, competition, waste accumulation, and diseases caused by parasites. Density-independent factors have the same effect at all population densities and can be weather events or human activities.
Step-by-step explanation:
Density-dependent factors are environmental conditions that have different effects on population densities. They are usually biological in nature and include predation, competition, waste accumulation, and diseases caused by parasites. These factors have a greater impact on population mortality when the population is denser. For example, during competition, the reproductive rates of individuals decrease, reducing the population's growth rate. Low prey density also increases the mortality of predators as they struggle to find food.
Density-independent factors, on the other hand, have the same effect at all population densities. They can be environmental conditions such as weather events or human activities that directly impact population numbers. These factors cause mortality in a population regardless of its density. An example is a pesticide that kills caterpillars irrespective of their population size.