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arXiv 1111.1674q-bio.PEcond-mat.stat-mech
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三种群捕食-食饵循环系统与两种群洛特卡-沃尔泰拉模型的关系

On the relationship between cyclic and hierarchical three-species predator-prey systems and the two-species Lotka-Volterra model

Qian He, Uwe C. Tauber, R. K. P. Zia

摘要:

我们的目的是澄清相互作用的三种群模型和两种群Lotka-Volterra(LV)模型之间的关系。利用平均场理论和二维正方格子上的Monte Carlo模拟,研究了两种不同的三种群捕食-食饵相互作用系统的时间演化特征:(1)总粒子数守恒但反应速率强烈不对称的循环石头剪刀布(RPS)模型,该模型使系统向构型空间的一角演化;(2)在LV模型中,在捕食者和被捕食者之间插入一个中间种群的分层食物链〈动〉<动>。对于模型变体(1),我们证明了LV系统很好地近似了这个随机空间三种群角RPS模型稳态下两个少数种群的进化特性,其新兴的特征是局部种群聚集,持续振荡动力学,相关的时空模式,以及通过捕食率中的淬灭空间无序增强适应度。相比之下,我们不能确定任何制度的层次模型(2)将减少到两个物种的LV系统。在存在对交换过程的情况下,系统基本上保持良好的混合,我们通常发现空间扩展模型(2)的Monte Carlo模拟结果与相应的平均场速率方程的预测一致。如果传播只发生通过最近的邻居跳,小人口集群出现,但中间物种集群的要求显然破坏捕食者和猎物之间的时空相关性,并相应地消除了许多有趣的波动现象的特点随机空间LV系统。

英文摘要:

We aim to clarify the relationship between interacting three-species models and the two-species Lotka-Volterra (LV) model. We utilize mean-field theory and Monte Carlo simulations on two-dimensional square lattices to explore the temporal evolution characteristics of two different interacting three-species predator-prey systems: (1) a cyclic rock-paper-scissors (RPS) model with conserved total particle number but strongly asymmetric reaction rates that lets the system evolve towards one corner of configuration space; (2) a hierarchical food chain where an additional intermediate species is inserted between the predator and prey in the LV model. For model variant (1), we demonstrate that the evolutionary properties of both minority species in the steady state of this stochastic spatial three-species corner RPS model are well approximated by the LV system, with its emerging characteristic features of localized population clustering, persistent oscillatory dynamics, correlated spatio-temporal patterns, and fitness enhancement through quenched spatial disorder in the predation rates. In contrast, we could not identify any regime where the hierarchical model (2) would reduce to the two-species LV system. In the presence of pair exchange processes, the system remains essentially well-mixed, and we generally find the Monte Carlo simulation results for the spatially extended model (2) to be consistent with the predictions from the corresponding mean-field rate equations. If spreading occurs only through nearest-neighbor hopping, small population clusters emerge; yet the requirement of an intermediate species cluster obviously disrupts spatio-temporal correlations between predator and prey, and correspondingly eliminates many of the intriguing fluctuation phenomena that characterize the stochastic spatial LV system.

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