循环竞争引起的集合种群时空波

在集合种群框架下研究了循环竞争关系.基于Tilman的多物种竞争模型和均匀场假设,建立了三物种循环竞争的Lavins型集合种群模型.在局部扩散的假设下,依据马尔科夫过程理论建立了概率转移模型.解析分析和计算机模拟的结果表明Lavins型模型表现出阶段性平衡动态,即特定的时刻只有一个物种在群落中占有绝对数量,但很快就被它的优势物种取代,这样三物种轮流处于优势地位;概率转移模型却呈现出在时间和空间上的混沌动态行为,模拟结果表现为一种螺旋生物波;这说明局部扩散可以弱化竞争引起的种群振荡,引起空间分布的异质性,同时表明Lavins型集合种群模型可能低估了物种共存的条件.

Spatiotemporal wave in cyclically competitive metapopulation

Starting from the cyclic competition, we construct the Levins-like metapopulation model (LMM) based on the mean-field assumption and the probability transition model (PTM) based on local dispersal and Markov process in homogenous patchy environment. The LMM takes on the stage equilibrium dynamics. The PTM reveals the more complex chaotic dynamics in time and space. Snapshots from simulation in two-dimensional space display spray-like distributions and spatial dynamics depending on the ratio of extinction rate to colonization rate. These spatially self-organized structures can globally weaken metapopulation fluctuation produced by competition. This result implies that local dispersal is the mechanism incurring spatially heterogeneous structure for cyclic competition and, thus, leading to competitive coexistence, and that mean-field approximation may underestimate the condition of species coexistence.