Which of the following is an example of a density-independent limiting factor?

• A. Disease outbreaks
• B. Floods
• C. Competition for resources
• D. Predation by predators

Answer: (B)

Density-independent limiting factors affect a population regardless of how many individuals are present. An environmental event like a flood illustrates this because its impact depends on the occurrence of the flood itself, not on how crowded the population is. A flood can kill or displace wildlife whether the population is small or large, making its effect scale independently of density.

In contrast, the other factors are tied to how many individuals are in the population. Diseases spread more readily when hosts are in close contact, so their impact increases with higher population density. Competition for resources becomes tougher as density rises, squeezing growth and survival when more organisms compete for the same limited supplies. Predation rates often rise with prey density, since more prey available can lead to more encounters with predators, linking the effect to density.