Which statement best describes a density dependent factor?

Which statement best describes a density dependent factor?

• A. A factor that limits population growth regardless of population size
• B. A factor that changes in intensity with population size
• C. A factor that always increases population
• D. A factor that only affects a single species

Answer: (B)

Density-dependent factors are forces whose effects on a population change as the population becomes more or less crowded. The idea is that the impact of the factor rises with higher population density—think of things like competition for limited food, disease transmission, and territorial or social stress. When there are many individuals, these pressures intensify and tend to slow or cap growth; with few individuals, the same pressures are weaker. This contrasts with density-independent factors, such as weather events or natural disasters, which affect populations regardless of how many individuals are present. The other options describe scenarios that don’t capture the core idea of density dependence: a factor that always limits growth regardless of density, a factor that always increases population, or a factor that only affects one species. The defining feature here is the dependence on how crowded the population is.

Density-dependent factors are forces whose effects on a population change as the population becomes more or less crowded. The idea is that the impact of the factor rises with higher population density—think of things like competition for limited food, disease transmission, and territorial or social stress. When there are many individuals, these pressures intensify and tend to slow or cap growth; with few individuals, the same pressures are weaker.

This contrasts with density-independent factors, such as weather events or natural disasters, which affect populations regardless of how many individuals are present. The other options describe scenarios that don’t capture the core idea of density dependence: a factor that always limits growth regardless of density, a factor that always increases population, or a factor that only affects one species. The defining feature here is the dependence on how crowded the population is.