density-independent factor


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density-independent factor

any factor, such as climate, that is not dependent on the density of population. Compare DENSITY-DEPENDENT FACTOR.
References in periodicals archive ?
We define a "density-independent factor," such as exceptionally unfavorable snow or ice conditions, as one that negatively influences a caribou population, but that is independent of the existing population's density and its absolute forage supply.
Density-independent factors have also been suggested to affect the population fluctuations of herons and egrets.
Populations can be affected by simple density-dependent factors (Nicholson 1933, Lack 1954; see references in Dennis and Taper 1994), density-independent factors (Andrewartha and Birch 1954, see references in Martinat 1987), and time-delayed or nonlinear density-dependent forces (sometimes leading to chaotic fluctuations; May 1976, Hastings et al.
The Kalman filter provides a powerful mechanism for estimating the parameters and detecting various sources of noise, such as parameter and system noise from density-dependent and density-independent factors, if the model is clearly specified.
Second, we now see that even if density-independent factors are not regulatory, they may nevertheless cause populations to switch back and forth between one type of density-dependent regulation (e.g., food limitation) and another (e.g., predator control).