Density-Dependent
Factors whose effects on population growth vary with population density. Competition, predation, and disease typically have stronger effects at higher densities.
Used in the Books
This term appears in 4 chapters:
"...g toxins, or coordinating bioluminescence - only when population density makes collective action worthwhile. This chapter explores how organisms use density-dependent signaling to coordinate group behavior through a process we call social crystallization: the rapid transition from disordered individual action t..."
"...andom demographic fluctuations (all individuals happen to die in one bad year, or all offspring happen to be the same sex). Background extinction is density-dependent: rare species are more vulnerable than common species because small populations face higher extinction risk from stochasticity, inbreeding, and Allee..."
"...include physical refuges like burrows, crevices, and dense vegetation, or temporal refuges like nocturnal vs. diurnal activity patterns. This creates density-dependent predation. Low-density prey hide in refuges and escape most predation. High-density prey must venture into risky areas, experiencing higher predation..."
"...s all populations proportionally - no keystone effect. Keystone predators preferentially target abundant or competitively dominant species, creating density-dependent predation - the more common a prey species becomes, the more heavily it's hunted - which prevents any single species from dominating. The sea otter..."
Biological Context
At high density, individuals compete more intensely for food, making starvation more likely. Disease spreads faster in crowded populations. Predators focus on common prey. Density-dependent factors regulate populations, preventing unlimited growth but also preventing extinction.