Density-independent factors influence the number of animals in
a population without regard to the number of individuals per unit
space (density). For example, weather conditions often limit populations.
An extremely cold winter with little snow cover may
devastate a population of lizards sequestered beneath the litter of
the forest floor. Regardless of the size of the population, a certain
percentage of individuals will freeze to death. Human activities,
such as construction and deforestation, often affect animal populations
in a similar fashion.
Density-dependent factors are more severe when population density is high (or sometimes very low) than they are at other densities. Animals often use territorial behavior, song, and scent marking to tell others to look elsewhere for reproductive space. These actions become more pronounced as population density increases and are thus density dependent. Other density-dependent factors include competition for resources, disease, predation, and parasitism.
Density-dependent factors are more severe when population density is high (or sometimes very low) than they are at other densities. Animals often use territorial behavior, song, and scent marking to tell others to look elsewhere for reproductive space. These actions become more pronounced as population density increases and are thus density dependent. Other density-dependent factors include competition for resources, disease, predation, and parasitism.
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