Demographic stochasticity and Allee effect on a scale with isotropic noise
Demographic stochasticity and Allee effect on a scale with isotropic noise
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DOI：
10.2307/3546849
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发表时间：
1998-11-01
期刊：
影响因子：
3.4
通讯作者：
Lande, R
中科院分区：
文献类型：
--
作者：
Lande, R
随机种群动力学的扩散模型，包括人口随机性和环境随机性，可以转换为具有各向同性噪声的尺度。在这个尺度上，人口随机性对人口轨迹的净下降分量与人口规模成反比，产生了一种阿尔利效应。在具有明显的人口随机性和小的长期增长率的种群中，例如许多受威胁和濒危物种，可能存在一个随机不稳定的平衡，在这个平衡之下，大多数种群轨迹倾向于下降到灭绝。在变换后的尺度上，可以直接得到与随机均衡相对应的种群大小，而不需要进行变换。在具有随机密度无关增长（包括人口和环境随机性）和确定性密度依赖的模型中，导出了显式变换及其逆变换。
Diffusion models of stochastic population dynamics, including both demographic and environmental stochasticity, can be transformed to a scale with isotropic noise. On this scale, demographic stochasticity contributes a net downward component to population trajectories that is inversely proportional to population size, creating a type of Allee effect. In populations with appreciable demographic stochasticity and a small long-run growth rate, such as many threatened and endangered species, there may be a stochastically unstable equilibrium below which most population trajectories tend to decline toward extinction. Population sizes corresponding to stochastic equilibria on the transformed scale can be obtained directly, without transformation. An explicit transformation and its inverse are derived for illustration in a model with stochastic density-independent growth (including demographic and environmental stochasticity) and deterministic density-dependence.