Predator Competition Research Articles

Camouflage or Coincidence? Investigating the Effects of Spatial and Temporal Environmental Features on Feral Cat Morphology in Tasmania

ABSTRACTVariations in coat morphology are well documented among felids and are theorised to aid in camouflage during stalk and ambush hunting. A diverse array of coat types has arisen in Felis catus (feral cats) through domestication and subsequent selective breeding. This species has successfully spread across Australia over the past 200 years, raising the question of whether any specific coat types offer an adaptive advantage. We used 24,657 camera‐trap images of feral cats in Tasmania, Australia, and assigned each cat observation a coat colour and pattern. We analysed these data to examine how different spatial features affect the modal coat type present at a site. We also tested if cats with differing coat types were active on different days in response to temporal features, including moon luminosity (full or new). Elevation was positively associated with the presence of orange (odds ratio = 2.5, 97.5% confidence interval = 1.5, 4.4) and tortoiseshell (odds ratio = 4.1, CI = 1.6, 10.5) cats, while blotched brown cats were negatively associated with elevation (odds ratio = 0.64, CI = 0.5, 0.9), relative to black cats. Brown mackerel cats were more common in eucalypt and rainforests (odds ratio = 1.9, CI = 1.1, 3.3), as well as sites with a higher FPAR (odds ratio = 1.3, CI = 1.1, 1.6). All coat types were 1.2–2 times more likely to be active on nights with a new moon, except for orange cats who were equally active regardless of moon luminosity (odds ratio = 0.94, CI = 0.62, 1.42). Our results indicate that coat types are equally successful across Tasmania, perhaps owing to naïve prey or limited predator competition. The high activity of orange cats irrespective of moon phase may be reflective of the male cat's tendency to patrol territory, as opposed to favouring dark nights for hunting. Future studies should consider comparing the coat types found in feral cats to adjacent domestic populations, and against a wider array of habitat types to further investigate the potential for selective pressure on feral cat coat types in Australia.

Dynamics of a non-local intraspecific competition predator–prey model with memory effect

In the paper, we investigate a diffusive predator–prey model with nonlocal intraspecific prey competition and spatial memory under Neumann boundary conditions. Through stability and bifurcation analysis, we find that the memory-based diffusion coefficient and the spatiotemporal diffusive delay have important effects on the dynamics of the model. By using the spatiotemporal diffusive delay as a bifurcation parameter, the critical values are determined for the stability of the positive constant steady state and the associated Hopf bifurcation. We find that the system may admit no stability switch, one stability switch and multiple stability switches.

Hydra effect and global dynamics of predation with strong Allee effect in prey and intraspecific competition in predator

We consider a predator-prey system with strong Allee effect in prey and intraspecific competition in predator. We divide the parameter space into several mutually exclusive regions, and for each region we give a rather complete description of the global dynamics including equilibrium stability, Hopf bifurcation and its directions, existence of a heteroclinic orbit loop, a homoclinic orbit loop and limit cycles. In comparison with systems without the Allee effect in prey and systems without the intraspecific competition in predator, we find that the Allee effect in prey and the over-exploitation of the prey by the predator may drive the extinction of two species, but the intraspecific competition in the predator can generate “hydra effect” that regulates the population size of both predator and prey by suppressing the over-exploitation of prey, improving the probability of survivals of two species.

Low predator competition indicates occupation of macro-predatory niches by giant Miocene reptiles at La Venta, Colombia

The La Venta fauna of Colombia (∼13.5–11.5 Ma) represents the most diverse Tertiary locality in the neotropics, with 75 mammal species and a highly non-analogue reptile assemblage containing at least seven testudines and six crocodyliforms. It has been widely hypothesized that the carnivore guilds of South American mammals throughout the Cenozoic were depauperate, potentially due to the continent's isolated history, and that, as a result, non-mammals acted as its dominant predators. Here we test this hypothesis using novel community composition analysis and a model of prey meat availability and competition between carnivorous taxa for prey in different size classes. We find that the carnivorous reptiles account for a very large proportion of demanded biomass, but that, even including reptiles, there was minimal competition for resources among the carnivore guild, relative to competition within modern communities. Further, we evaluate one possible impact of low predation pressure on the herbivores of La Venta through a population analysis of enamel hypoplasia in the notoungulate Pericotoxodon platignathus. At La Venta, mammalian carnivores alone exerted very little predation pressure on the terrestrial community, and our community composition analysis supports the filling of macropredatory niches by crocodyliforms, including both the terrestrial sebecid Langstonia huilensis and semi-aquatic giant crocodylians.

The introduction of African cheetahs to India was planned without considering their spatial ecology

The introduction of African cheetahs to India was planned without considering their spatial ecology

Additional Food Causes Predators to Explode — Unless the Predators Compete

The literature posits that an introduced predator population is able to drive its target pest population to extinction, if supplemented with high quality additional food of sufficient quantity. We show this approach actually leads to infinite time blow-up of the predator population, so is unpragmatic as a pest management strategy. We propose an alternate model in which the additional food induces predator competition. Analysis of this model indicates that depending on the competition parameter [Formula: see text], one can have global stability of the pest-free state, bistability dynamics, or up to three interior equilibria. As [Formula: see text] and the additional food quantity [Formula: see text] are varied standard codimension one and codimension two bifurcations are observed. We also use structural symmetries to construct several nonstandard bifurcations such as saddle-node-transcritical bifurcation (SNTC) in codimension two and a cusp-transcritical bifurcation (CPTC), also in codimension two. We further use symmetry to construct a novel pitchfork-transcritical bifurcation (PTC) in codimension two, thus explicitly characterizing a new organizing center of the model. Our findings indicate that increasing additional food in predator–pest models can hinder bio-control, contrarily to some of the literature. However, additional food that also induces predator competition, leads to rich dynamics and enhances bio-control.

Persistence and extinction of a modified LG-Holling type II predator-prey model with two competitive predators and Lévy jumps

In this paper, we study a three-species predator-prey model with modified LG-Holling type II with Lévy jumps, and we take the competition among predators into consideration. First, We use an Ornstein-Uhlenbeck process to describe the environmental stochasticity and prove that there is a unique positive solution to the system by mathematical analysis skills such as comparison theorem. Futhermore, the extinction or persistence in the mean of each species under different conditions is obtained. Finally, some numerical simulations are carried out to support our main results.

Relaxation oscillations of a piecewise-smooth slow-fast Bazykin's model with Holling type Ⅰ functional response.

In this paper, we consider the dynamics of a slow-fast Bazykin's model with piecewise-smooth Holling type Ⅰ functional response. We show that the model has Saddle-node bifurcation and Boundary equilibrium bifurcation. Furthermore, it is also proven that the model has a homoclinic cycle, a heteroclinic cycle or two relaxation oscillation cycles for different parameters conditions. These results imply the dynamical behavior of the model is sensitive to the predator competition rate and the initial densities of prey and predators. In order to support the theoretical analysis, we present some phase portraits corresponding to different values of parameters by numerical simulation. These phase portraits include two relaxation oscillation cycles, an unstable relaxation oscillation cycle surrounded by a stable homoclinic cycle; the coexistence of a heteroclinic cycle and an unstable relaxation oscillation cycle. These results reveal far richer and much more complex dynamics compared to the model without different time scale or with smooth Holling type Ⅰ functional response.

Stability and Bifurcation Analysis of Bazykin’s Model with Holling I Functional Response and Allee Effect

In this paper, we introduce Allee effect and predator competition in the Bazykin’s model with Holling I functional response. Theoretically, we analyze the existence and stability of equilibria, and derive the existence conditions of saddle-node bifurcation and Hopf bifurcation. In addition, in order to determine the stability of limit cycles, we explicitly calculate the first Lyapunov coefficient and prove that the positive equilibrium is not a center, but a weak focus with a multiplicity of at least two. Therefore, the system has Hopf bifurcation and Bautin bifurcation with two limit cycles. Our results indicate that the Allee effect and predator competition lead to a series of complex dynamic phenomena. Finally, numerical simulation verifies the effectiveness of the theoretical results.

Coexistence of chaotic and non-chaotic attractors in a three-species slow–fast system

The dynamical complexity of conceptual few-species systems has long been attracting considerable attention. In particular, significant attention has been paid to the three trophic level systems to demonstrate that even a baseline prey/predator/top-predator system can exhibit complex dynamics. However, previous studies left many open questions. In this paper, we consider a generalization of the Hastings–Powell model that include intraspecific competition among the predators and top predators. To enhance the ecological relevance of the model, we incorporate different timescales for different species. Specifically, we aim to study how the dynamics of the system is affected in the presence of multiple timescales along the trophic levels. We employ the geometric singular perturbation approach to analyze the change in species abundance over three different timescales, slow, fast, and intermediate. We analytically determine the entry and exit points from the vicinity of the critical manifold; the corresponding values act as critical thresholds for a sudden, fast transition in population density. We show that the properties of this generalized form of the Hastings–Powell model are dynamically more rich than it was observed in previous studies; particularly, the system can exhibit bi-stability or tri-stability in certain parameter intervals. The existence of a homoclinic orbit in a limiting subsystem (prey–predator) indicates period-doubling cascades to chaos in the full system (prey–predator–top predator). We further investigate the impact of the intraspecific competition of predators and top predators on the system’s dynamics. Strong intraspecific competition among the predators and top predators shows periodic coexistence of all species. In contrast, weak competition can drive the system to exhibit tri-stability, which includes the coexistence of chaotic and periodic (of different periods) attractors.

Морфобіологічна характеристика щуки звичайної (Esox lucius L.) малих водойм комплексного призначення Сумської та Київської областей

The purpose of the work was to conduct a morphobiological analysis of common pike (Esox lucius L.) from two reservoirs similar in their parameters and conditions, and to determine the difference between the populations of these species due to various anthropogenic factors. The pike from the Sumy region has a more slender body, as it is indicated by displaced dorsal (5.76) and anal fins (9.19), a larger body width (2.47) and an enlarged tail stem (9.62), a more elongated head with a snout and upper jaw (6.10, 11.37, 4.9, respectively). Such signs may indicate that the pike hunts for prey that has the maximum size ac-cording to a specimen. The indicators of the pike from the Kyiv region are somewhat different and indicate that the predator makes very rapid and fairly long-distance attacks on prey, despite obstacles such as macrophytes and other aquatic vegetation, which can be evidenced by a larger width of the forehead (13.32), head height (4.16) and head height at the nape of the neck (3.56). Also, big eyes (4.91) and an enlarged lower jaw (9.89) can indicate speed and big jerks. Based on biological indicators, we can conclude that the pike from Sumy region is more fattened, which is confirmed by measurements and coefficients of its fatness. Therefore, it is fleshier, which, first of all, affects the quality of the fish as a commodity. As for the pike from the Kyiv re-gion, it is somewhat smaller with lower fatness coefficients, which may indicate greater expenditure of energy for obtaining food. This costliness, in our opinion, is related to competition from two more predatory fish species — perch and zander, which are common in the reservoir, and possibly to the size of the reservoir itself, which is four times larger. We consider it expedient to diversify the ichthyofauna of the reservoir in the Paryshkiv village, in particular peaceful species of fish, in order to remove or reduce the trophic competition of predators.

Predicting solutions of the Lotka‐Volterra equation using hybrid deep network

Prediction of Lotka-Volterra equations has always been a complex problem due to their dynamic properties. In this paper, we present an algorithm for predicting the Lotka-Volterra equation and investigate the prediction for both the original system and the system driven by noise. This demonstrates that deep learning can be applied in dynamics of population. This is the first study that uses deep learning algorithms to predict Lotka-Volterra equations. Several numerical examples are presented to illustrate the performances of the proposed algorithm, including Predator nonlinear breeding and prey competition systems, one prey and two predator competition systems, and their respective systems. All the results suggest that the proposed algorithm is feasible and effective for predicting Lotka-Volterra equations. Furthermore, the influence of the optimizer on the algorithm is discussed in detail. These results indicate that the performance of the machine learning technique can be improved by constructing the neural networks appropriately.

STABILITY ANALYSIS OF TWO PREDATORS-ONE PREY MODEL WITH FEEDBACK CONTROL AND TIME FRACTIONAL DERIVATIVE

The interaction between prey and predator is one of the most fundamental processes in ecology. In this paper, we first consider the system incorporating a feedback control and we discuss the dynamic behavior of preypredator interaction model that includes two competitive predators and one prey with a generalized interaction functional. The primary resumption in the model construction is the effects of feedback control and the competition between two predators on the only prey which gives a strong implication of the real-world situation. By analyzing characteristic equations, we carry out detailed discussion with respect to stability of equilibrium points of the considered model. Further, we investigate the impact of the memory measured by fractional time derivative on the temporal behavior.

A Mathematical Model of Intraguild Predation with Prey Refuge and Competitive Predators

A Mathematical Model of Intraguild Predation with Prey Refuge and Competitive Predators

Bifurcation analysis of a predator–prey model with Beddington–DeAngelis functional response and predator competition

In this paper, we consider a predator–prey model with Beddington–DeAngelis functional response and predator competition, which is a five‐parameter family of planar vector field. It is shown that the model can undergo a sequence of bifurcations including focus type degenerate Bogdanov–Takens bifurcation of codimension 3 and Hopf bifurcation of codimension at least 2 as the parameters vary. Our theoretical results indicate that predator competition can cause richer dynamics such as two limit cycles enclosing one or three hyperbolic positive equilibria and three kinds of homoclinic orbits (homoclinic to hyperbolic saddle, saddle‐node, or neutral saddle). Moreover, there exists a threshold value for predator capturing rate , below or equal to which the predators always tend to extinction, above which the predators and preys will coexist in the form of multiple steady states or periodic oscillations for all positive initial populations. Numerical simulations are presented to illustrate the theoretical results.

Weak Selection and the Separation of Eco-evo Time Scales using Perturbation Analysis

We show that under the assumption of weak frequency-dependent selection a wide class of population dynamical models can be analysed using perturbation theory. The inner solution corresponds to the ecological dynamics, where to zeroth order, the genotype frequencies remain constant. The outer solution provides the evolutionary dynamics and corresponds, to zeroth order, to a generalisation of the replicator equation. We apply this method to a model of public goods dynamics and construct, using matched asymptotic expansions, a composite solution valid for all times. We also analyse a Lotka–Volterra model of predator competition and show that to zeroth order the fraction of wild-type predators follows a replicator equation with a constant selection coefficient given by the predator death rate. For both models, we investigate how the error between approximate solutions and the solution to the full model depend on the order of the approximation and show using numerical comparison, for k=1 and 2, that the error scales according to varepsilon ^{k+1}, where varepsilon is the strength of selection and k is the order of the approximation.

Hopf bifurcation analysis in a delayed diffusive predator-prey system with nonlocal competition and generalist predator

<abstract><p>A delayed diffusive predator-prey system with nonlocal competition and generalist predators is considered. The local stability of the positive equilibrium and Hopf bifurcation at positive equilibrium is studied by using time delay as a parameter. In addition, the property of Hopf bifurcation is analyzed using the center manifold theorem and normal form method. It is determined that time delays can affect the stability of the positive equilibrium and induce spatial inhomogeneous periodic oscillation of prey and predator population densities.</p></abstract>

A competitive Predator–Prey approach to enhance surveillance by UAV swarms

In this paper we present the competitive optimisation of a swarm of Unmanned Aerial Vehicles (UAV) protecting a restricted area from a number of intruders following a Predator–Prey approach. We propose a Competitive Coevolutionary Genetic Algorithm (CompCGA) which optimises the parameters of the UAVs (i.e. predators) to maximise the detection of intruders, while the parameters of the intruders (i.e. preys) are optimised to maximise their intrusion success rate. Having chosen the CACOC (Chaotic Ant Colony Optimisation for Coverage) as the base mobility model for the UAVs, we propose an improved new version, where its behaviour is modified by identifying and optimising new parameters to improve the overall success rate when detecting intruders. Six case studies have been optimised using simulations by performing 30 independent runs (180 in total) of our CompCGA. Finally, we conducted a series of master tournaments (1,800,000 evaluations) using the best specimens obtained from each run and case study to test the robustness of our proposed approach against unexpected intruders. Our surveillance system improved the average percentage of intruders detected with respect to CACOC by a maximum of 126%. More than 90% of intruders were detected on average when using a swarm of 16 UAVs while CACOC’s detection rates are always under 80% in all cases.

Dynamics of Predator-Prey Model Interaction with Intraspecific Competition

In this paper, we have formulated and studied a dynamic predator-prey model. We have formulated intraspecific competition of predators. Holling type I and Holling type II response function have been used for the consumption of prey by two predators respectively. We have analyzed the positivity of solutions, existence of equilibria, and stability of the proposed system around these equilibrium points. Condition for local stability was obtained by eigenvalue approach and Routh-Hurwitz Criterion. Finally, some numerical simulation have been presented to investigate the dynamic of the system.

Dynamical behavior of two predators\u2013one prey model with generalized functional response and time-fractional derivative

The behavior of any complex dynamic system is a natural result of the interaction between the components of that system. Important examples of these systems are biological models that describe the characteristics of complex interactions between certain organisms in a biological environment. The study of these systems requires the use of precise and advanced computational methods in mathematics. In this paper, we discuss a prey–predator interaction model that includes two competitive predators and one prey with a generalized interaction functional. The primary presumption in the model construction is the competition between two predators on the only prey, which gives a strong implication of the real-world situation. We successfully establish the existence and stability of the equilibria. Further, we investigate the impact of the memory measured by fractional time derivative on the temporal behavior. We test the obtained mathematical results numerically by a proper numerical scheme built using the Caputo fractional-derivative operator and the trapezoidal product-integration rule.