Predator Scavenger Research Articles

Complex Dynamic Behavior of a Discrete Prey–Predator–Scavenger Model with Fractional Order

This present work, we discuss the complex dynamical nature of the three species prey–predator system in presence of scavenger with fractional order. A discretization process is applied to obtain its discrete version and the impact of the scavenger on the ecosystem is discussed. Firstly, existence and local stability of the equilibria state of the model are addressed. The presences of Flip bifurcation and Neimark-Sacker bifurcation around boundary and coexistence equilibrium states are studied by using bifurcation theory. The trajectories and phase plane diagrams are plotted for biologically meaningful sets of parameter values. Numerical simulations for the effect of step size and fractional order parameters of the system are performed, on the first part to demonstrate the analytical results and on the second part revealing new motivating the dynamics behaviors of the scavenger model including period-doubling cascades (flip), periods—2, 3, 4, 5, 6, 8, 10, 12, 16, 20, 24 and 32 orbits, invariant cycles, a chaotic attractors, and the rich dynamic behaviors of the discretized model is exhibited.

Stability and bifurcation analysis for a fractional prey–predator scavenger model

In this study, we consider a fractional prey–predator scavenger model as well as harvesting by a predator and scavenger. We prove the positivity and boundedness of the solutions in this system. The model undergoes a Hopf bifurcation around one of the existing equilibria where the conditions are met for the occurrence of a Hopf bifurcation. The results show that chaos disappears in this biological model. We conclude that the fractional system is more stable compared with the classical case and the stability domain can be extended under fractional order. In addition, a suitable amount of prey harvesting and a fractional order derivative can control the chaotic dynamics and stabilize them. We also present an extended numerical simulation to validate the results.

Prey–predator–scavenger model with Monod–Haldane type functional response

In this paper, we have developed a prey, predator and scavenger interaction dynamical model. The positivity, boundedness and stability conditions of our proposed system have been derived. Hopf bifurcation analysis has been done theoretically with respect to half saturation constant in the absence of direct measure of inhibitory effects $$(\phi _1)$$ . Also, we have numerically studied Hopf bifurcation with respect to direct effects of inhibitory effects $$(\phi _2)$$ related to Monod–Haldane type functional response, carrying capacity of prey $$(\gamma )$$ , death rate of scavenger $$(\mu )$$ , conservation rate of prey $$(\alpha )$$ and harvesting rate of predator $$(\eta )$$ . It is observed that the intra-species competition can lead our proposed system towards stability. It is also found that the harvesting of predator can control the chaotic dynamics of our proposed system. The increase of death rate of scavenger species can be stabilized our proposed system. Finally, some numerical simulation results have been presented for better understanding the dynamics of our proposed model.

Stability and Bifurcation in a Prey–Predator–Scavenger System with Michaelis–Menten Type of Harvesting Function

In this paper an ecological model consisting of prey–predator–scavenger involving Michaelis–Menten type of harvesting function is proposed and studied. The existence, uniqueness and uniformly bounded of the solution of the proposed model are discussed. The stability and persistence conditions of the model are established. Lyapunov functions are used to study the global stability of all equilibrium points. The possibility of occurrence of local bifurcation around the equilibrium points is investigated. Finally an extensive numerical simulation is carried out to validate the obtained analytical results and understand the effects of scavenger and harvesting on the model dynamics. It is observed that the proposed model is very sensitive for varying in their parameters values especially those related with scavenger and undergoes different types of local bifurcation.

Modeling and dynamical analysis of a triple delayed prey–predator–scavenger system with Lévy jumps

In this paper, a hybrid triple delayed prey–predator–scavenger system with commercial harvesting and Lévy jumps is established, where both maturation delay for prey population and gestation delays for predator and scavenger population are considered. For deterministic system, positivity and uniform permanence of solution are discussed. Local stability analysis of deterministic system around interior equilibrium is investigated due to variations of triple time delays. For stochastic system without time delay, sufficient conditions for stochastically ultimate boundedness and stochastic permanence are discussed. For stochastic system with triple time delays, existence and uniqueness of global positive solution are studied. By constructing appropriate Lyapunov functions, asymptotic behavior of the hybrid stochastic system with triple time delays and Lévy jumps is discussed. Numerical simulations are supported to illustrate theoretical results.

A large carnivorous mammal from the Late Cretaceous and the North American origin of marsupials.

Marsupial mammal relatives (stem metatherians) from the Mesozoic Era (252–66 million years ago) are mostly known from isolated teeth and fragmentary jaws. Here we report on the first near-complete skull remains of a North American Late Cretaceous metatherian, the stagodontid Didelphodon vorax. Our phylogenetic analysis indicates that marsupials or their closest relatives evolved in North America, as part of a Late Cretaceous diversification of metatherians, and later dispersed to South America. In addition to being the largest known Mesozoic therian mammal (node-based clade of eutherians and metatherians), Didelphodon vorax has a high estimated bite force and other craniomandibular and dental features that suggest it is the earliest known therian to invade a durophagous predator–scavenger niche. Our results broaden the scope of the ecomorphological diversification of Mesozoic mammals to include therian lineages that, in this case, were linked to the origin and evolution of marsupials.

High variability in spatial and temporal size-based trophodynamics of deep-sea fishes from the Mid-Atlantic Ridge elucidated by stable isotopes

Demersal fish play an important role in the deep-sea ecosystem by acting as a link to mobile food in the water column, consuming benthic fauna, breaking down large food parcels and dispersing organic matter over large areas. Poor diet resolution from stomach content analysis often impairs the ability to assess differences in inter- and intra-population trophodynamics and therefore understand resource partitioning among deep-sea fishes. Antimora rostrata (predator–scavenger), Coryphaenoides armatus (predator–scavenger), Coryphaenoides brevibarbis (predator) and Halosauropsis macrochir (predator) were collected from 3 stations on the Mid-Atlantic Ridge (MAR) in 2007 and 2009 to investigate trophic ecology using δ13C and δ15N. Variability in lipid-normalised δ13C (δ13Cn) and δ15N was explained by body length in all species but slope and significance of the isotope–length relationships varied both temporally and spatially. δ15N increases with length were observed in A. rostrata at all stations, C. brevibarbis and H. macrochir at one or more stations but were absent in C. armatus. δ13Cn increased with length in A. rostrata but the slope of δ13Cn–length relationships varied spatially and temporally in C. armatus and C. brevibarbis. The co-occurring δ13Cn and δ15N size-based trends in A. rostrata and H. macrochir suggested that size-based trends were a result of increasing trophic position. In C. armatus and C. brevibarbis the isotope-length trends were difficult to distinguish among trophic position increases, shifts in resource use i.e. benthic to pelagic or internal physiology. However, the overall strength, direction and significance of isotope-length trends varied temporally and spatially which suggested varying degrees of overlap in trophic ecology and feeding plasticity among these species.

Quantifying associations of large vertebrates with salmon in riparian areas of British Columbia streams by means of camera-traps, bait stations, and hair samples

The importance of transfers of marine derived nutrients (MDN) in salmon between stream ecosystems and terrestrial riparian systems is a subject of much recent research which has established that MDN subsidies support populations of many animal species, affect riparian zone productivity and may control the biodiversity of riparian plant communities. Numerous biophysical processes are involved in the transfer of MDN between aquatic and riparian zones of streams but, the largest proportion of MDN transport across the aquatic-terrestrial interface appears to depend on the actions of a predator–scavenger complex (PSC) that in British Columbia includes at least 23 species of mammals and birds. Consequently, the role of salmon in maintaining riparian ecosystem integrity depends not only on spatial and temporal variations in salmon abundance but also on variations in the composition and strength of linkages between salmon and other PSC species. Measuring these linkages with traditional methods using direct observation would be prohibitively expensive and time consuming. In the current paper laser activated camera systems, salmon carcass manipulation and deoxyribonucleic acid (DNA) analysis of hair samples were employed to (1) identify large vertebrate members of the PSC of riparian zone ecosystems and (2) quantify the strength of linkages of these PSC vertebrates to spatial and temporal changes in salmon abundance. Techniques developed and applied here to gain insights into the salmon PSC have several advantages over traditional survey methods. These include semi-automated capture of large volumes of data, identification of diurnally and nocturnally active PSC members, ready inclusion of experiments in field survey design, reduced impacts of unintentional human interference on survey results, and greatly reduced cost relative to direct observational studies. Results reported here confirm black bears (Ursus americanus), pine marten (Martes americana), cougar (Felis concolor), wolverine (Gulo luscus), eagles (Haliaeetus leucocephalus), ravens (Corvus corox), and vultures (Cathartes aura) as large vertebrate members of the regional salmon PSC. However, the composition and strength of linkages between salmon and these PSC members vary so much in space and time that most appear unsuitable as generally useful indicators of the potential magnitude of salmon-dependent, MDN-transport from aquatic to riparian-zone ecosystems. Black bears however, given their high relative abundance, broad geographic distribution, and strong linkages to salmon represent a superior candidate for further development in combination with salmon, as indicators of the maintenance of MDN transport potential in future assessments of riparian ecosystem integrity of salmon bearing streams.

Elucidating trophic pathways in benthic deep-sea assemblages of the Mid-Atlantic Ridge north and south of the Charlie-Gibbs Fracture Zone

The Mid-Atlantic Ridge (MAR) is a topographically complex feature in the North Atlantic Ocean with little exploration of benthic fauna except in association with hydrothermal venting, resulting in the biodiversity and ecosystem functioning of the MAR benthos away from these sites remaining largely unknown. Stable isotope analysis of carbon, nitrogen and sulphur were undertaken on fauna collected north and south of the Charlie-Gibbs Fracture Zone, in areas believed to be devoid of hydrothermal venting, to investigate the trophodynamics of the benthic assemblage. δ13C and δ34S values of the benthic and bentho-pelagic fauna indicated a dependence on photosynthetic primary production, with no influence from an unknown chemosynthetic source. A large trophic discrimination in δ13C between consumers and potential food sources (particulate organic matter and surficial sediments) suggested reworking of organic carbon before assimilation by benthic fauna. Interpretation of sediment δ15N values was difficult as these ranged between −0.74 and 23.14‰, suggesting further work is required to understand nitrogen utilisation by benthic deposit feeders. Differences in trophic guilds (predators, predator–scavenger, surface deposit feeders, subsurface deposit feeders and suspension feeders) were evident for δ13C and δ15N, with the main difference between the mobile predators–scavengers and the benthic deposit feeders. Dividing the assemblage based on trophic guilds into food chains dependent on phytodetritus (deposit and suspension feeders) and predation–scavenging (fishes and crustaceans) resulted in strong positive correlations between δ15N and δ13C at both stations. These reflected the 2 dominant trophic pathways organic matter passed through deposit feeders and predatory and scavenging deep-sea fishes and crustaceans.

Co-evolution and ecosystem based problem solving

Emergent cooperative relations in ecosystems are ill understood, but have the potential to strongly improve evolutionary computing. On the other hand, eco-evolutionary computation has the potential to provide new insights in the structuring and functioning of ecosystems. Here we study ecosystem based problem solving in a co-evolutionary framework of predators (solvers) and prey (problems), extended with a population of scavengers, which can eat the remains of prey (that is, cooperate with the predators in solving the problems). We show that such an artificial ecosystem of predators, prey and scavengers, with a selection and fitness regime favoring specialization, self-organizes in space and time such that (1) problems are automatically decomposed in easier to solve parts, (2) the predator, prey and scavenger populations differentiate in sub-populations according to this decomposition, and (3) predators and scavengers automatically co-localize in space such that the problems are indeed solved by predator–scavenger combinations which together correctly approximate the target function. That is, the use of a spatial co-evolutionary ecosystem as information processing unit for evolutionary computation gives rise to an emergent structure of niches, each consisting of complementary partial solutions. As a result, ecosystem based solutions are preferred over individual-based solutions in solving the studied function approximation task.

Forb‐Arthropod Food Chains in a One‐Year Experimental Field

Phosphorous—32 tracer studies of plant—arthropod food chains showed a significant difference in both consumer diversity and grazing pressure between the two dominant plant species on a first—year weed field in South Carolina. Where Heterotheca subaxillaris was the labeled plant 32P was transferred readily to a number of phytophagous insects and secondarily to the predator fauna. Where only Erigeron canadensis was tagged, there was little transfer of the isotope to the consumer populations, with the exceptions of the ant Dorymyrmex and the tree cricket Oceanthus. Dorymyrmex is a predator—scavenger, but also tends the aphids present on Erigeron; this latter habit accounted for the high uptake and unusual retention pattern of 32P by this ant where Erigeron was tagged. Oecanthus was primarily an herbivore, but the data suggest some predation on aphids from Erigeron plants. Very little 32P was transferred to the detritus eaters during the 43 day period of the study. Further support is given for the use of radioisotope to study trophic position of organisms as well as grazing pressure and food chain diversity associated with single species of terrestrial primary producers.