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arXiv 2103.10976q-bio.PEcond-mat.stat-mechphysics.bio-ph
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两物种合作中的固定与涨落

Fixation and Fluctuations in Two-Species Cooperation

Jordi Piñero, S. Redner, Ricard Solé

AI总结:

本文研究两对等合作物种在孤立与迁移条件下的固定及涨落动力学,揭示低迁移率下稳态分布的单峰—三峰转变和近固定态间的长时间切换。

摘要:

合作相互作用广泛存在于众多多体种群中,例如生态群落、社会组织和经济网络。我们研究了由两个对等物种 A 和 B 构成的种群动力学,该过程受到两物种之间合作且对称的相互作用驱动。对于孤立种群,我们确定了达到固定(即仅剩下一个物种)的概率与两物种初始浓度之间的函数关系,同时给出了达到固定所需的时间;后者随种群规模呈指数尺度变化。当每个物种的个体以速率 λ 迁入种群并替换一个随机选择的个体时,会出现出人意料的丰富动力学。表面上看,种群达到了稳态,但随着迁移率降低至临界值 λ_c 以下,稳态种群分布会经历从单峰到三峰的转变。在低迁移率区间 λ<λ_c,该稳态并非真正稳定,而是在近固定状态之间强烈涨落,此时种群主要由 A 或主要由 B 组成。这些涨落的特征时间尺度按 λ^{-1} 发散。因此,尽管存在合作相互作用,种群的典型快照仍将包含几乎全部 A 或几乎全部 B。

英文摘要:

Cooperative interactions pervade in a broad range of many-body populations, such as ecological communities, social organizations, and economic webs. We investigate the dynamics of a population of two equivalent species A and B that are driven by cooperative and symmetric interactions between these species. For an isolated population, we determine the probability to reach fixation, where only one species remains, as a function of the initial concentrations of the two species, as well as the time to reach fixation. The latter scales exponentially with the population size. When members of each species migrate into the population at rate $λ$ and replace a randomly selected individual, surprisingly rich dynamics ensues. Ostensibly, the population reaches a steady state, but the steady-state population distribution undergoes a unimodal to trimodal transition as the migration rate decreases below a critical value $λ_c$. In the low-migration regime, $λ<λ_c$, the steady state is not truly steady, but instead strongly fluctuates between near-fixation states, where the population consists of mostly A's or of mostly B's. The characteristic time scale of these fluctuations diverges as $λ^{-1}$. Thus in spite of the cooperative interaction, a typical snapshot of the population will contain almost all A's or almost all B's.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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