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Articles 1 - 25 of 25
Full-Text Articles in Physical Sciences and Mathematics
Population Dynamics And Bifurcations In Predator-Prey Systems With Allee Effect, Yanni Zeng
Population Dynamics And Bifurcations In Predator-Prey Systems With Allee Effect, Yanni Zeng
Electronic Thesis and Dissertation Repository
This thesis investigates a series of nonlinear predator-prey systems incorporating the Allee effect using differential equations. The main goal is to determine how the Allee effect affects population dynamics. The stability and bifurcations of the systems are studied with a hierarchical parametric analysis, providing insights into the behavioral changes of the population within the systems. In particular, we focus on the study of the number and distribution of limit cycles (oscillating solutions) and the existence of multiple stable states, which cause complex dynamical behaviors. Moreover, including the prey refuge, we examine how our method benefits the low-density animals and affects …
Effects Of A Protection Zone In A Reaction-Diffusion Model With Strong Allee Effect., Isaac Johnson
Effects Of A Protection Zone In A Reaction-Diffusion Model With Strong Allee Effect., Isaac Johnson
Electronic Theses and Dissertations
A protection zone model represents a patchy environment with positive growth over the protection zone and strong Allee effect growth outside the protection zone. Generally, these models are considered through the corresponding eigenvalue problem, but that has certain limitations. In this thesis, a general protection zone model is considered. This model makes no assumption on the direction of the traveling wave solution over the Strong Allee effect patch. We use phase portrait analysis of this protection zone model to draw conclusions about the existence of equilibrium solutions. We establish the existence of three types of equilibrium solutions and the necessary …
Dynamical Complexity Of A Predator-Prey Model With A Prey Refuge And Allee Effect, Jianping Gao, Jianghong Zhang, Wenyan Lian
Dynamical Complexity Of A Predator-Prey Model With A Prey Refuge And Allee Effect, Jianping Gao, Jianghong Zhang, Wenyan Lian
Turkish Journal of Mathematics
We consider a predator-prey model with a non-monotonic functional response encompassing a prey refuge and a strong Allee effect on the prey. The multiple existence and stability of interior equilibria are investigated. The bifurcation analysis shows this model can exhibit numerous kinds of bifurcations (e.g., saddle-node, Hopf-Andronov and Bogdanov-Takens bifurcations). It is found that there exist diverse parameter values for which the model exhibits a limit cycle, a homoclinic orbit, and even many heteroclinic curves. The results obtained reveal the prey refuge in the model brings rich dynamics and makes the system more sensitive to parameter values. The main purpose …
Analyzing Bifurcation, Stability, And Chaos Control For A Discrete-Time Prey-Predator Model With Allee Effect, Fi̇gen Kangalgi̇l, Ni̇lüfer Topsakal, Ni̇hal Öztürk
Analyzing Bifurcation, Stability, And Chaos Control For A Discrete-Time Prey-Predator Model With Allee Effect, Fi̇gen Kangalgi̇l, Ni̇lüfer Topsakal, Ni̇hal Öztürk
Turkish Journal of Mathematics
In this paper, the qualitative behavior of a discrete-time prey-predator model with Allee effect in prey population is discussed. Firstly, the existence of the fixed points and their topological classification are analyzed algebraically. Then, the conditions of existence for both period-doubling and Neimark--Sacker bifurcations arising from coexistence fixed point with the help of the center manifold theorem and bifurcation theory are investigated. OGY feedback control method is implemented to control chaos in the proposed model due to the emergence of bifurcations. Finally, numerical simulations are performed to support the theoretical findings.
Qualitative Analysis Of A Modified Leslie-Gower Predator-Prey Model With Weak Allee Effect Ii, Manoj K. Singh, B. S. Bhadauria
Qualitative Analysis Of A Modified Leslie-Gower Predator-Prey Model With Weak Allee Effect Ii, Manoj K. Singh, B. S. Bhadauria
Applications and Applied Mathematics: An International Journal (AAM)
The article aims to study a modified Leslie-Gower predator-prey model with Allee effect II, affecting the functional response with the assumption that the extent to which the environment provides protection to both predator and prey is the same. The model has been studied analytically as well as numerically, including stability and bifurcation analysis. Compared with the predator-prey model without Allee effect, it is found that the weak Allee effect II can bring rich and complicated dynamics, such as the model undergoes to a series of bifurcations (Homoclinic, Hopf, Saddle-node and Bogdanov-Takens). The existence of Hopf bifurcation has been shown for …
Stability Of Modified Host-Parasitoid Model With Allee Effect, Özlem A. Gümüs, A. G. Maria Selvam, R. Janagaraj
Stability Of Modified Host-Parasitoid Model With Allee Effect, Özlem A. Gümüs, A. G. Maria Selvam, R. Janagaraj
Applications and Applied Mathematics: An International Journal (AAM)
This paper deals with a host-parasitoid model subject to Allee effect and its dynamical behavior. Steady state points of the proposed host-parasitoid model are computed. Stability properties are analyzed with eigen values of Jacobian matrix which are determined at the steady states. Theoretical findings are supported by numerical illustrations and enhanced by pictorial representations such as bifurcation diagrams, phase portraits and local amplifications for different parameter values. Existence of chaotic behavior in the system is established via bifurcation and sensitivity analysis of the system at the initial conditions. Various phase portraits are simulated for a better understanding of the qualitative …
Stochastic Delay Differential Equations With Applications In Ecology And Epidemics, Hebatallah Jamil Alsakaji
Stochastic Delay Differential Equations With Applications In Ecology And Epidemics, Hebatallah Jamil Alsakaji
Dissertations
Mathematical modeling with delay differential equations (DDEs) is widely used for analysis and predictions in various areas of life sciences, such as population dynamics, epidemiology, immunology, physiology, and neural networks. The memory or time-delays, in these models, are related to the duration of certain hidden processes like the stages of the life cycle, the time between infection of a cell and the production of new viruses, the duration of the infectious period, the immune period, and so on. In ordinary differential equations (ODEs), the unknown state and its derivatives are evaluated at the same time instant. In DDEs, however, the …
The Long Time Behavior Of The Predator-Prey Model With Holling Type Iii, Regen S. Mcgee
The Long Time Behavior Of The Predator-Prey Model With Holling Type Iii, Regen S. Mcgee
Honors Theses
In this paper, the classical Lotka-Volterra model is expanded based on functional response of Holling type III to analyze a dynamical predator-prey relationship with hunting cooperation (a) and the Allee effect among predators. The stability of equilibrium solutions was first analyzed by deriving a Jacobian matrix from partial derivatives of our model. Newly derived eigenvalues are then used to determine the stability. The viability of the model is then demonstrated by using MATLAB. The numerical results show a clear Allee effect and a variety of possible phenomena related to stability when carrying capacity (k) is varied. Two different types of …
Qualitative Analysis Of A Modified Leslie-Gower Predator-Prey Model With Weak Allee Effect Ii, Manoj K. Singh, B. S. Bhadauria
Qualitative Analysis Of A Modified Leslie-Gower Predator-Prey Model With Weak Allee Effect Ii, Manoj K. Singh, B. S. Bhadauria
Applications and Applied Mathematics: An International Journal (AAM)
The article aims to study a modified Leslie-Gower predator-prey model with Allee effect II, affecting the functional response with the assumption that the extent to which the environment provides protection to both predator and prey is the same. The model has been studied analytically as well as numerically, including stability and bifurcation analysis. Compared with the predator-prey model without Allee effect, it is found that the weak Allee effect II can bring rich and complicated dynamics, such as the model undergoes to a series of bifurcations (Homoclinic, Hopf, Saddle-node and Bogdanov-Takens). The existence of Hopf bifurcation has been shown for …
Uncovering The Role Of Propagule Pressure In Determining Establishment Success Using A Synthetic Biology Approach, Michael D. Dressler
Uncovering The Role Of Propagule Pressure In Determining Establishment Success Using A Synthetic Biology Approach, Michael D. Dressler
HCNSO Student Theses and Dissertations
The spread of invasive species poses a major ecological and economical threat. Consequently there are ongoing efforts to develop a generalizable mechanism to predict establishment success of non-native species. One proposed mechanism to predict establishment success is propagule pressure, which is defined as the number of individuals introduced at a given time. Although some studies have demonstrated a positive correlation between propagule pressure and establishment success, others have not, and the effect of propagule pressure on establishment success remains unclear. To address this challenge, a strain of bacteria engineered with an Allee effect, a growth dynamic that is often associated …
Nonspreading Solutions In Integro-Difference Models With Allee And Overcompensation Effects., Garrett Luther Otto
Nonspreading Solutions In Integro-Difference Models With Allee And Overcompensation Effects., Garrett Luther Otto
Electronic Theses and Dissertations
Previous work in Integro-Difference models have generally considered Allee effects and over-compensation separately, and have either focused on bounded domain problems or asymptotic spreading results. Some recent results by Sullivan et al. (2017 PNAS 114(19), 5053-5058) combining Allee and over-compensation in an Integro-Difference framework have shown chaotic fluctuating spreading speeds. In this thesis, using a tractable parameterized growth function, we analytically demonstrate that when Allee and over-compensation are present solutions which persist but essentially remain in a compact domain exist. We investigate the stability of these solutions numerically. We also numerically demonstrate the existence of such solutions for more general …
Translocation As A Population Restoration Technique For Northern Bobwhites: A Review And Synthesis, James A. Martin, Roger D. Applegate, Thomas V. Dailey, Michelle Downey, Beth Emmerich, Fidel Hernández, Mark M. Mcconnell, Kelly S. Reyna, Dale Rollins, Rebekah E. Ruzicka, Theron M. Terhune Ii
Translocation As A Population Restoration Technique For Northern Bobwhites: A Review And Synthesis, James A. Martin, Roger D. Applegate, Thomas V. Dailey, Michelle Downey, Beth Emmerich, Fidel Hernández, Mark M. Mcconnell, Kelly S. Reyna, Dale Rollins, Rebekah E. Ruzicka, Theron M. Terhune Ii
National Quail Symposium Proceedings
Northern bobwhite (Colinus virginianus) abundance has declined precipitously for decades across much of the species range, to the point of widespread local, regional, and statewide extirpation. Because of successful translocations of other gallinaceous birds, bobwhite enthusiasts increasingly call for use of the approach. Consequently, the National Bobwhite Technical Committee (NBTC), on behalf of state agencies, requested a review and recommendation by the NBTC Science Subcommittee. Thus, our paper is co-authored by invited experts and includes reviews of peer-reviewed publications, manuscripts in these proceedings, state agency reports, experience by co-authors, and a survey of perspectives on translocations by state …
An Analysis Of Gulf Of Maine Cod Metapopulation Structure And Localized Stability, With Application To Area-Based Fisheries Management, Derek Olson
Electronic Theses and Dissertations
The complex metapopulation structure of groundfish stocks in the Gulf of Maine, particularly Atlantic cod (Gadus morhua), is largely ignored under the current system of broad-scale stock assessment and management. This mismatch of biological and administrative scales has contributed to severe overall stock decline and localized serial depletion of Gulf of Maine cod. Such chronic management failure has led to growing calls for a more area-based, finer-scale approach to managing groundfish in the Gulf of Maine. A primary difficulty hindering the development of finer-scale groundfish management has been the challenge of estimating fishing mortality upon local stock components. …
Spreading Speeds And Traveling Waves In Some Population Models., Quancheng Meng
Spreading Speeds And Traveling Waves In Some Population Models., Quancheng Meng
Electronic Theses and Dissertations
Virtually every ecosystem has been invaded by exotic organisms with potentially drastic consequences for the native fauna or flora. Studying the forms and rates of invading species has been an important topic in spatial ecology. We investigate two two-species competition models with Allee effects in the forms of reaction-diffusion equations and integro-difference equations. We discuss the spatial transitions from a mono-culture equilibrium to a coexistence equilibrium or a different mono-culture equilibrium in these models. We provide formulas for the spreading speeds based on the linear determinacy and show the results on the existence of traveling waves. We also study a …
An Economical Model With Allee Effect, Rafael Luis, Saber Elaydi, Henrique Oliveira
An Economical Model With Allee Effect, Rafael Luis, Saber Elaydi, Henrique Oliveira
Saber Elaydi
The Marx model for the profit rate r depending on the exploitation rate e and on the organic composition of the capital k is studied using a dynamical approach. Supposing both e(t) and k(t) are continuous functions of time we derive a law for r(t) in the long term. Depending upon the hypothesis set on the growth of k(t) and e(t) in the long term, r(t) can fall to zero or remain constant. This last case contradicts the classical hypothesis of Marx stating that the profit rate must decrease in the long term. Introducing a discrete dynamical system in the …
Population Models With Allee Effect: A New Model, Saber Elaydi, Robert J. Sacker
Population Models With Allee Effect: A New Model, Saber Elaydi, Robert J. Sacker
Saber Elaydi
In this paper we develop several mathematical models of Allee effects. We start by defining the Allee effect as a phenomenon in which individual fitness increases with increasing density. Based on this biological assumption, we develop several fitness functions that produce corresponding models with Allee effects. In particular, a rational fitness function yields a new mathematical model that is our focus of study. Then we study the dynamics of 2-periodic systems with Allee effects and show the existence of an asymptotically stable 2-periodic carrying capacity.
General Allee Effect In Two-Species Population Biology, G Livadiotis, Saber Elaydi
General Allee Effect In Two-Species Population Biology, G Livadiotis, Saber Elaydi
Saber Elaydi
The main objective of this work is to present a general framework for the notion of the strong Allee effect in population models, including competition, mutualistic, and predator–prey models. The study is restricted to the strong Allee effect caused by an inter-specific interaction. The main feature of the strong Allee effect is that the extinction equilibrium is an attractor. We show how a ‘phase space core’ of three or four equilibria is sufficient to describe the essential dynamics of the interaction between two species that are prone to the Allee effect. We will introduce the notion of semistability in planar …
Recolonizing Wolves And Mesopredator Suppression Of Coyotes:Impacts On Pronghorn Population Dynamics, Kim Murray Berger, Mary M. Conner
Recolonizing Wolves And Mesopredator Suppression Of Coyotes:Impacts On Pronghorn Population Dynamics, Kim Murray Berger, Mary M. Conner
Wildland Resources Faculty Publications
Food web theory predicts that the loss of large carnivores may contribute toelevated predation rates and, hence, declining prey populations, through the process ofmesopredator release. However, opportunities to test predictions of the mesopredator releasehypothesis are rare, and the extent to which changes in predation rates influence preypopulation dynamics may not be clear due to a lack of demographic information on the preypopulation of interest. We utilized spatial and seasonal heterogeneity in wolf distribution andabundance to evaluate whether mesopredator release of coyotes (Canis latrans), resulting fromthe extirpation of wolves (Canis lupus) throughout much of the United States, contributes tohigh rates of …
Pronghorn (Antilocapra Americana) Offspring Recruitment On The Carrizo Plain National Monument: Evaluating The Effects Of Low Population Density And Marginal Habitat Quality., Diego Ramirez Johnson
Pronghorn (Antilocapra Americana) Offspring Recruitment On The Carrizo Plain National Monument: Evaluating The Effects Of Low Population Density And Marginal Habitat Quality., Diego Ramirez Johnson
UNLV Theses, Dissertations, Professional Papers, and Capstones
Demographic fluctuation among ungulate populations is strongly linked to variability in recruitment. Rates of recruitment are subject to various forms of density-dependent and density-independent regulation. For species which benefit from the presence of conspecifics, reduced population density can decrease rates of recruitment and trigger a decline in per capita growth. Termed the Allee effect, this scenario can cause demographic collapse and population extinction. For many ungulate species, predation on juveniles is reduced when the timing and distribution of births is synchronized within a local population. Because birth synchrony is density-dependent, it may act as a mechanism for the Allee effect …
General Allee Effect In Two-Species Population Biology, G Livadiotis, Saber Elaydi
General Allee Effect In Two-Species Population Biology, G Livadiotis, Saber Elaydi
Mathematics Faculty Research
The main objective of this work is to present a general framework for the notion of the strong Allee effect in population models, including competition, mutualistic, and predator–prey models. The study is restricted to the strong Allee effect caused by an inter-specific interaction. The main feature of the strong Allee effect is that the extinction equilibrium is an attractor. We show how a ‘phase space core’ of three or four equilibria is sufficient to describe the essential dynamics of the interaction between two species that are prone to the Allee effect. We will introduce the notion of semistability in planar …
An Economical Model With Allee Effect, Rafael Luis, Saber Elaydi, Henrique Oliveira
An Economical Model With Allee Effect, Rafael Luis, Saber Elaydi, Henrique Oliveira
Saber Elaydi
The Marx model for the profit rate r depending on the exploitation rate e and on the organic composition of the capital k is studied using a dynamical approach. Supposing both e(t) and k(t) are continuous functions of time we derive a law for r(t) in the long term. Depending upon the hypothesis set on the growth of k(t) and e(t) in the long term, r(t) can fall to zero or remain constant. This last case contradicts the classical hypothesis of Marx stating that the profit rate must decrease in the long term. Introducing a discrete dynamical system in the …
Population Models With Allee Effect: A New Model, Saber Elaydi, Robert J. Sacker
Population Models With Allee Effect: A New Model, Saber Elaydi, Robert J. Sacker
Saber Elaydi
In this paper we develop several mathematical models of Allee effects. We start by defining the Allee effect as a phenomenon in which individual fitness increases with increasing density. Based on this biological assumption, we develop several fitness functions that produce corresponding models with Allee effects. In particular, a rational fitness function yields a new mathematical model that is our focus of study. Then we study the dynamics of 2-periodic systems with Allee effects and show the existence of an asymptotically stable 2-periodic carrying capacity.
General Allee Effect In Two-Species Population Biology, Saber Elaydi
General Allee Effect In Two-Species Population Biology, Saber Elaydi
Saber Elaydi
The main objective of this work is to present a general framework for the notion of the strong Allee effect in population models, including competition, mutualistic, and predator-prey models. The study is restricted to the strong Allee effect caused by an interspecific interaction. The main feature of the strong Allee effect is that the extinction equilibrium is an attractor. We show how a "phase space core" of three or four equilibria is sufficient to describe the essential dynamics of the interaction between two species that are prone to the Allee effect. We will introduce the notion of semistability in planar …
Population Models With Allee Effect: A New Model, Saber Elaydi, Robert J. Sacker
Population Models With Allee Effect: A New Model, Saber Elaydi, Robert J. Sacker
Mathematics Faculty Research
In this paper we develop several mathematical models of Allee effects. We start by defining the Allee effect as a phenomenon in which individual fitness increases with increasing density. Based on this biological assumption, we develop several fitness functions that produce corresponding models with Allee effects. In particular, a rational fitness function yields a new mathematical model that is our focus of study. Then we study the dynamics of 2-periodic systems with Allee effects and show the existence of an asymptotically stable 2-periodic carrying capacity.
An Economical Model With Allee Effect, Rafael Luís, Saber Elaydi, Henrique Oliveira
An Economical Model With Allee Effect, Rafael Luís, Saber Elaydi, Henrique Oliveira
Mathematics Faculty Research
The Marx model for the profit rate r depending on the exploitation rate e and on the organic composition of the capital k is studied using a dynamical approach. Supposing both e(t) and k(t) are continuous functions of time we derive a law for r(t) in the long term. Depending upon the hypothesis set on the growth of k(t) and e(t) in the long term, r(t) can fall to zero or remain constant. This last case contradicts the classical hypothesis of Marx …