集合种群空间混沌的模拟研究以及Allee效应、拥挤效应与捕食效应对空间模式的影响

集合种群的空间模式研究是当今生态学的核心问题之一。本研究利用常微分动力系统以及基于网格模型的元胞自动机模型对Allee效应、拥挤效应以及捕食作用集合种群的空间分布模式做了全面的模拟研究。Allee效应描述当种群水平低于某一阈值时会发生由生殖成功几率下降造成的种群负增长率，而拥挤效应是指当种群密度过高时引起的个体性为异常从而达到调节种群增长率的作用。文章组建了3个空间确定性模型：局部作用模型(CIM)、距离敏感模型(DSM)和集合种群捕食模型(MMP)。局部作用模型显示在一维生境中空斑块形成金字塔状，二维模型显示出明显的动态拟周期性以及由空间混沌所形成的异质性。距离敏感模型可导致由迁移个体中密度制约强度决定的集合种群大小复杂动态与种群密度的双峰分布。这些结果说明动态行为的复杂性，不仅可用于表征研究物种的特性，而且可以表明该物种的续存能力与灭绝风险。集合种群捕食模型是概率转换空间模型，利用该模型得出了依赖于模型参数和生境尺度的白组织种群概率空间分布模式。模拟的结果表明，系统的内在机制和这种白组织模式导致捕食者形成集团型不明显的“捕食小组”或“杀手小组”，并具有较高扩散力．但却包括侵占率低、灭绝率高的特点。而使猎物种群形成高集团性、高侵占率、低灭绝率、低扩散力的种群集团。这种特点又使捕食者种群在生境中处于中心地带，而使猎物种群形成在捕食者和生境边缘间的环状分布。这些结果还说明了尺度对于生态学的研究是至关重要的，不同的尺度将产生不同的系统模式。

Spatial chaos of metapopulation incurred by Allee effect,overcrowding effect and predation effect

Spatial pattern of metapopulation is one of the focuses of modem ecology.In this paper,I discuss and simulate the influences of Allee effect,overcrowding effect and predation effect on the spatial distribution of metapopulation by cellular automata based on lattice model and ordinary differential equations.The Allee effect indicates scarcity in reproductive opportunities that cause negative growth rates below a critical density threshold,which may arise from a number of sources such as difficulties in finding mates,social dysfunction and inbreeding depression.The overcrowding effect is a regulation of population growth by behavioral abnormalities caused by malfunction of the endocrine glands,which themselves occur in response to overcrowding.I constructed three spatially explicit models:local interaction model (CIM),distance-sensitive model (DSM) and metapopulation model with predation (MMP).The empty patches of CIM are pyramid-like in one-dimensional habitat;two-dimensional CIM shows a periodic phenomenon and the heterogeneity incurred by spatial chaos.Results of DSM show the overcrowding effect can lead to complex dynamics and bimodal distribution determined by the intensity of density dependence in immigrants.These results illustrate the complexity of dynamics can indicate not only the character of focal specie,but also the ability of persistence and the risk to extinction.MMP is a spatial probability transitional model and obtains a self-organization pattern of probability distribution.In order to comprehend the change of distribution pattern with parameters and scales,I simulated the model under different parameters and scales.The results show that the systematical internal mechanisms and the self-organization patterns lead to "predator group" or "killer group",with unobvious congeries and high diffusivity and low-level colonization and high-level extinction.In addition,this character makes the predator inhabit in the central zone,with prey population distributed between the edge and the center circularly.It also illustrates the important significance of scale in ecological researches,in which different scales can result in distinctive system patterns.