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

• A. Predation rates increase with population size.
• B. Density-dependent disease outbreaks depend on density.
• C. Weather patterns affecting survival regardless of population size.
• D. Competition for resources increases with population size.

Answer: (C)

Density-independent factors affect a population regardless of how many individuals are present. They are typically abiotic influences like weather, climate, or natural disasters that change survival or reproduction independent of population size.

Weather patterns affecting survival regardless of population size are a classic density-independent example because a drought, flood, or severe winter can reduce survival whether the population is small or large.

The other scenarios involve effects that scale with how crowded the population is: predation rates that rise with more individuals, disease outbreaks that spread more when densities are higher, and competition for resources that intensifies as population size grows. These are all density-dependent factors.