论文标题

由α稳定征噪者诱导的单物种模型中的随机分叉

Stochastic Bifurcation in Single-Species Model Induced by α-Stable Levy Noise

论文作者

Tesfay, Almaz, Tesfay, Daniel, Yuan, Shenglan, Brannan, James, Duan, Jinqiao

论文摘要

分叉分析在不同的科学领域中有许多应用,例如电子,生物学,生态学和经济学。在种群生物学中,通常使用确定性分叉方法。相反,很少使用随机分叉技术。在这里,我们建立了(i)具有状态依赖性出生率和恒定死亡率的增长模型的随机P分类行为,以及(ii)具有依赖状态载能能力的逻辑生长模型,这两者都是由乘法对称性稳定稳定征费噪声驱动的。跨临界分叉发生在第一个模型的确定性对应物中,而马鞍节分叉发生在逻辑生长模型中。我们专注于增长率的变化,人均每日死亡率,稳定性指数以及噪声强度对相关非本地Fokker-Planck方程的固定概率密度函数的影响。在第一个模型中,分叉参数是人口出生率与人口死亡率的比率。在第二个模型中,分叉参数对应于承载能力在平衡附近的人口大小变化的敏感性。在每种情况下,我们都表明,随着分叉参数的值增加,稳态概率密度函数的形状会发生变化,并且两个随机模型都表现出随机的p-构造。随着稳定性指数的增加,周围的单峰密度函数在确定性平衡点周围变得更加峰值。虽然其他任何参数中的任何一个都会影响固定概率密度函数。这意味着密度函数的几何形状从单峰变为平坦,其峰出现在域的中间,这意味着发生了过渡。

Bifurcation analysis has many applications in different scientific fields, such as electronics, biology, ecology, and economics. In population biology, deterministic methods of bifurcation are commonly used. In contrast, stochastic bifurcation techniques are infrequently employed. Here we establish stochastic P-bifurcation behavior of (i) a growth model with state-dependent birth rate and constant death rate, and (ii) a logistic growth model with state-dependent carrying capacity, both of which are driven by multiplicative symmetric stable Levy noise. Transcritical bifurcation occurs in the deterministic counterpart of the first model, while saddle-node bifurcation takes place in the logistic growth model. We focus on the impact of the variations of the growth rate, the per capita daily adult mortality rate, the stability index, and the noise intensity on the stationary probability density functions of the associated non-local Fokker-Planck equation. In the first model, the bifurcation parameter is the ratio of the population birth rate to the population death rate. In the second model, the bifurcation parameter corresponds to the sensitivity of carrying capacity to change in the size of the population near equilibrium. In each case, we show that as the value of the bifurcation parameter increases, the shape of the steady-state probability density function changes and that both stochastic models exhibit stochastic P-bifurcation. The unimodal density functions become more peaked around deterministic equilibrium points as the stability index increases. While an increase in any one of the other parameters has an effect on the stationary probability density function. That means the geometry of the density function changes from unimodal to flat, and its peak appears in the middle of the domain, which means a transition occurs.

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