Global stability and pattern formation in a nonlocal diffusive Lotka–Volterra competition model

A diffusive Lotka–Volterra competition model with nonlocal intraspecific and interspecific competition between species is formulated and analyzed. The nonlocal competition strength is assumed to be determined by a diffusion kernel function to model the movement pattern of the biological species. It is shown that when there is no nonlocal intraspecific competition, the dynamics properties of nonlocal diffusive competition problem are similar to those of classical diffusive Lotka–Volterra competition model regardless of the strength of nonlocal interspecific competition. Global stability of nonnegative constant equilibria are proved using Lyapunov or upper–lower solution methods. On the other hand, strong nonlocal intraspecific competition increases the system spatiotemporal dynamic complexity. For the weak competition case, the nonlocal diffusive competition model may possess nonconstant positive equilibria for some suitably large nonlocal intraspecific competition coefficients.     

GRAY WOLF POPULATION PROJECTION WITH INTRASPECIFIC COMPETITION

Competition effects are incorporated into a model of wolf‐population dynamics. A classic single‐state model is augmented into a dual‐state mapping of the evolution of the size of wolf packs and the number of wolf packs. This dual‐state model, unlike the single‐state density dependent model, is amenable to analyzing intraspecific competition. The single‐state, dual‐state and dual‐state with competition models are estimated using Yellowstone National Park (YNP) data on wolf populations and pack structures from 1996 to 2011. The dynamic properties of each model are examined under an array of harvesting policies. Results suggest that intraspecific competition matters when projecting wolf populations. Wolf pack removal has competition‐reducing effects from added territory availability, making populations more sensitive to pack size reduction than reduction in the number of packs. This research suggests that wildlife managers may consider monitoring the composition of wolf kills throughout a harvesting season, adaptively adjusting harvesting quotas and delineating harvesting zones over a few pack territories rather than spreading these effects evenly across all packs.     

Study on autonomous and nonautonomous version of a food chain model with intraspecific competition in top predator

In this article, a three-species food chain model with intraspecific competition in top predators has been considered. Ecological and mathematical well posedness of the model system has been established by showing that all the solutions of the model are positive and bounded. The extinction scenarios of intermediate and top predator species along with the existence and stability of all equilibrium points have been discussed. The effects of competition and conversion efficiency of top predators in the dynamics of the system have been discussed with great thrust, and it is observed that the conversion efficiency of top predators deteriorates the stability of the system, whereas intraspecific competition in top predators enhances the stable coexistence of all the populations of the system. Further, nonautonomous version of the model system has been taken into consideration to study the impact of seasonal variation in the dynamics of the model system. Sufficient conditions for the existence of a globally attractive positive periodic have been established in a periodic environment. Finally, numerical simulations have been carried out to validate our analytical findings.     

Stability and Hopf bifurcation of a delayed predator-prey system with nonlocal competition and herd behaviour

In this paper, we investigate the stability and Hopf bifurcation of a diffusive predator-prey system with herd behaviour. The model is described by introducing both time delay and nonlocal prey intraspecific competition. Compared to the model without time delay, or without nonlocal competition, thanks to the together action of time delay and nonlocal competition, we prove that the first critical value of Hopf bifurcation may be homogenous or non-homogeneous. We also show that a double-Hopf bifurcation occurs at the intersection point of the homogenous and non-homogeneous Hopf bifurcation curves. Furthermore, by the computation of normal forms for the system near equilibria, we investigate the stability and direction of Hopf bifurcation. Numerical simulations also show that the spatially homogeneous and non-homogeneous periodic patters.     

A Leslie-Gower Holling-type II ecoepidemic model

The modified Leslie-Gower and Holling-type II predator-prey model is generalized in the context of ecoepidemiology, with disease spreading only among the prey species. A new feature is introduced, the intraspecific competition of infected prey. All the equilibria are characterized and the existence of a Hopf bifurcation at the coexistence equilibrium is shown.     

Dynamical transition for S‐K‐T biological competing model with cross‐diffusion

The main objective of this paper is to study the dynamical transition for the S‐K‐T biological competition system with cross‐diffusion. Based on the spectral analysis, the principle of exchange of stabilities conditions for eigenvalues are obtained. By using the dynamical transition theory, 2 different types of dynamical transition for the S‐K‐T model are also derived. In addition, an example is given to illustrate our main results.     

A mathematical model for bovine tuberculosis among buffaloes and lions in the Kruger National Park

In this paper, a model for the spread of tuberculosis between buffaloes and lions is presented and analyzed. The most important system parameters are identified: vertical and horizontal disease transmission among the buffaloes and the influence of intraspecific competition between healthy and diseased buffaloes on the infected buffaloes population. Removal of diseased prey appears to be the most effective strategy to render the ecosystem disease free.     

基于生态竞争方程的企业竞争动态演化研究

从生态学视角来研究企业竞争的动态演化已成为一个研究热点,针对现有研究文献中只讨论二维系统的不足,以三个企业之间的竞争为例,构造了企业间竞争的三维模型,运用微分方程稳定性理论分析其稳定性,并由此揭示出企业间竞争的动力学机制.数值仿真结果表明,该三维模型能有效地模拟企业间竞争的动态演化规律.     

Global and blow-up solutions for a mutualistic model

We study the global and blow-up solutions for a strong degenerate reaction–diffusion system modeling the interactions of two biological species. The local existence and uniqueness of a classical solution are established. We further give the critical exponent for reaction and absorption terms for the existence of global and blow-up solutions. We show that the solution may blow up if the intraspecific competition is weak. This supports ecologist A.J. Nicholson’s conclusion that intraspecific competition is the main factor regulating population size.     

Backward bifurcation in a stage-structured epidemic model

A stage-structured epidemic model is proposed under the assumptions that the disease can only be transmitted among adults and that there is also intraspecific competition among them. We study the existence of equilibria and also obtain their local stability, which implies the occurrence of backward bifurcation. Moreover, sufficient conditions on the global stability of some equilibria are provided.     

Does a population with the highest turnover coefficient win competition?

We consider a discrete time competition model. Populations compete for common limited resources but they have different fertilities and mortalities rates. We compare dynamical properties of this model with its continuous counterpart. We give sufficient conditions for competitive exclusion and the existence of periodic solutions related to the classical logistic, Beverton–Holt and Ricker models.     

Complex dynamic properties of Cournot duopoly games with convex and log-concave demand function

A Cournot duopoly game is proposed where the interdependence between firms depends on convex and log-concave demand function. In this paper, a model of two rational firms that are in competition and produce homogeneous commodities is introduced. The equilibrium points of this model are obtained and their dynamical characteristics such as stability, bifurcation and chaos are investigated. Furthermore, a multi-team Cournot game is introduced. Through simulation the dynamical characteristics of the equilibrium points of this game are illustrated.     

Positive periodic solutions of nonautonomous delay competitive systems with weak Allee effect

This paper considers a nonautonomous Lotka–Volterra type multispecies competitive system with weak Allee effect and delays. The model has the intraspecific competition terms defined by sign changing functions which depend on population density monotonically and time periodically. An existence theorem of positive periodic solutions is established using the coincidence degree theory. Furthermore, for the case of constant delays, a sufficient condition for the positive periodic solution to be globally attractive is proved with the Lyapunov method so that the system attains permanence.     

Discrete May–Leonard Competition Models III

A discretization method attributed to Kahan is used to approximate the May–Leonard (M–L) competition model for three species. The local dynamics of this discrete-time M–L model are analyzed. This model differs from the discrete M–L models being studied previously. This discrete model shows dynamical consistency with the continuous M–L model. Numerically, we showed that the discrete M–L model has a degenerate Hopf-bifurcation, which is consistent with the continuous M–L model.     

Hierarchical Discrete Models of Competition for a Resource

A coupled pair of first order nonlinear discrete hierarchical age-structured models are applied to study two modes of intraspecific competitions; scramble and contest. The study focuses on several comparisons of the dynamical outcomes of the two competitions. For a constant resource, it is shown, using analytical and numerical approaches, that solutions of the contest model monotonically equilibrate, while solutions of the scramble model oscillate and become chaotic. It is also shown that the inherent net reproductive number of each population affects the comparison of equilibrium points in the two populations. By considering cases on the resource and model parameters, the local as well as the global stability of nontrivial equilibrium points are studied. The impact of a contest and a scramble consumer on a time dependent resource is considered numerically.     

一类具有种内竞争率的竞争扩散模型稳态解的存在性和稳定性

利用Lyapunov-Schmidt约化方法和扰动理论,研究了一类带有不同种内竞争率的两物种竞争扩散模型.首先给出了半平凡稳态解的存在性和稳定性的充分条件,表明在一定条件下新物种可以入侵.在此基础上进一步证实了共存态的存在性和稳定性,研究表明在适当条件下相互竞争的两物种能够共存.所得结果改进和完善了已有的工作.     

Existence and uniqueness of steady state solutions of a nonlocal diffusive logistic equation

In this paper, we consider a dynamical model of population biology which is of the classical Fisher type, but the competition interaction between individuals is nonlocal. The existence, uniqueness, and stability of the steady state solution of the nonlocal problem on a bounded interval with homogeneous Dirichlet boundary conditions are studied.     

两企业竞争与合作时标动力学模型的周期行为

研究了时标上两企业竞争与合作动力学模型的周期解的存在性.运用重合度理论中的连续性定理,得到了该模型存在正周期解的一个充分条件.     

Dynamical behaviors of a classical Lotka–Volterra competition–diffusion–advection system

This paper deals with a two-species competition model in a homogeneous advective environment, where two species are subjected to a net loss of individuals at the downstream end. Under the assumption that the advection and diffusion rates of two species are proportional, we give a basic classification on the global dynamics by employing the theory of monotone dynamical system. It turns out that bistability does not happen, but coexistence and competitive exclusion may occur. Furthermore, we present a complete classification on the global dynamics in terms of the growth rates of two species. However, once the above assumption does not hold, bistability may occur. In detail, there exists a tradeoff between growth rates of two species such that competition outcomes can shift between three possible scenarios, including competitive exclusion, bistability and coexistence. These results show that growth competence is important to determine dynamical behaviors.     

A MODIFIED TWO-DIMENSIONAL LOTKA-VOLTERRA MODEL WITH EXCHANGE BETWEEN COOPERATION AND COMPETITION

Under the assumptions that there exists exchange between cooperation and competition in some ecological systems, the paper provides a modei based on the Lotka-Volterra equations to describe the exchange in a two-dimensional system. Then dynamics of the model is studied in detail, the division of distinct regions associated with difFerent dynamics in the parameter space is obtained, and the biological significance of these dynamical properties represent is discussed.