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1.
Global bifurcation analysis of a class of general predator–prey models with a strong Allee effect in prey population is given
in details. We show the existence of a point-to-point heteroclinic orbit loop, consider the Hopf bifurcation, and prove the
existence/uniqueness and the nonexistence of limit cycle for appropriate range of parameters. For a unique parameter value,
a threshold curve separates the overexploitation and coexistence (successful invasion of predator) regions of initial conditions.
Our rigorous results justify some recent ecological observations, and practical ecological examples are used to demonstrate
our theoretical work. 相似文献
2.
We present a complete parametric analysis of a predator–prey system influenced by a top predator. We study ecosystems with abundant nutrient supply for the prey where the prey multiplication can be considered as proportional to its density. The main questions we examine are the following: (1) Can the top predator stabilize such a system at low densities of prey? (2) What possible dynamic behaviors can occur? (3) Under which conditions can the top predation result in the system stabilization? We use a system of two nonlinear ordinary differential equations with the density of the top predator as a parameter. The model is investigated with methods of qualitative theory of ODEs and the theory of bifurcations. The existence of 12 qualitatively different types of dynamics and complex structure of the parametric space are demonstrated. Our studies of phase portraits and parametric diagrams show that a top predator can be an important factor leading to stabilization of the predator-prey system with abundant nutrient supply. Although the model here is applied to the plankton communities with fish (or carnivorous zooplankton) as the top trophic level, the general form of the equations allows applications of our results to other ecological systems. 相似文献
3.
Many predator–prey systems are found in environments with a predominantly unidirectional flow such as streams and rivers. Alterations of natural flow regimes (e.g., due to human management or global warming) put biological populations at risk. The aim of this paper is to devise a simple method that links flow speeds (currents) with population retention (persistence) and wash-out (extinction). We consider systems of prey and specialist, as well as generalist, predators, for which we distinguish the following flow speed scenarios: (a) coexistence, (b) persistence of prey only or (c) predators only (provided they are generalists), and (d) extinction of both populations. The method is based on a reaction–advection–diffusion model and traveling wave speed approximations. We show that this approach matches well spread rates observed in numerical simulations. The results from this paper can provide a useful tool in the assessment of instream flow needs, estimating the flow speed necessary for preserving riverine populations. 相似文献
4.
The grouping behavior is common in nature, e.g., fish school, bird flocks and insects swarms. Indeed, numerous theoretical and empirical predator-prey models have demonstrated the impact of group-living animals on ecosystems. To examine the interactions between individuals in the same group or competition between groups, we introduced different models based on Monte Carlo simulation and mean-field theory and found that the predator group sizes follow the geometric distribution and logarithmic distribution, as in previous empirical and theoretical cases. Our models also provide an intuitive explanation for these distributions. A new distribution based on the Holling-III functional response is presented; this distribution is heavy tailed in some specific cases. 相似文献
5.
6.
Katharina C. M. Liss Laura K. Lopez Jennifer M. Donelson Marian Y. L. Wong 《Oikos》2020,129(6):842-852
Understanding the determinants and consequences of predation effort, success and prey responses is important since these factors affect the fitness of predators and prey. When predators are also invasive species, the impacts on prey can be particularly far-reaching with ultimate ecosystem-level consequences. However, predators are typically viewed as behaviourally fixed within this interaction and it is unclear how variation in predator social dynamics affects predator–prey interactions. Using the invasive eastern mosquitofish Gambusia holbrooki and a native glass shrimp Paratya australiensis in Australia, we investigated how varying levels of social conflict within predator groups influences predator–prey interactions. By experimentally manipulating group stability of G. holbrooki, we show that rates of social conflict were lower in groups with large size differences, but that routine metabolic rates were higher in groups with large size differences. Predation effort and success did not vary depending on group stability, but in stable groups predation effort by aggressive dominants was greater than subordinates. The anti-predator responses of prey to the stability of predator groups were mixed. While more prey utilized shelters when exposed to stable compared to unstable groups of predators, a greater proportion were sedentary when predator groups were unstable. Overall, this study demonstrates predator group stability is modulated by differences in body size and can influence prey responses. Further, it reveals a hidden metabolic cost of living in stable groups despite reduced overt social conflict. For invasive species management, it is therefore important to consider the behavioural and physiological plasticity of the invasive predators, whose complex social interactions and metabolic demands can modulate patterns of predator–prey interactions. 相似文献
7.
Predator–prey encounter rates in freshwater piscivores: effects of prey density and water transparency 总被引:1,自引:0,他引:1
One of the most fundamental components of predator–prey models is encounter rate, modelled as the product of prey density
and search efficiency. Encounter rates have, however, rarely been measured in empirical studies. In this study, we used a
video system approach to estimate how encounter rates between piscivorous fish that use a sit-and-wait foraging strategy and
their prey depend on prey density and environmental factors such as turbidity. We first manipulated prey density in a controlled
pool and field enclosure experiments where environmental factors were held constant. In a correlative study of 15 freshwater
lakes we then estimated encounter rates in natural habitats and related the results to both prey fish density and environmental
factors. We found the expected positive dependence of individual encounter rates on prey density in our pool and enclosure
experiments, whereas the relation between school encounter rate and prey density was less clear. In the field survey, encounter
rates did not correlate with prey density but instead correlated positively with water transparency. Water transparency decreases
with increasing prey density along the productivity gradient and will reduce prey detection distance and thus predator search
efficiency. Therefore, visual predator–prey encounter rates do not increase, and may even decrease, with increasing productivity
despite increasing prey densities. 相似文献
8.
9.
Barney Luttbeg John I. Hammond Tomas Brodin Andrew Sih 《Ethology : formerly Zeitschrift fur Tierpsychologie》2020,126(4):476-485
Predators and prey are often engaged in a game where their expected fitnesses are affected by their relative spatial distributions. Game models generally predict that when predators and prey move at similar temporal and spatial scales that predators should distribute themselves to match the distribution of the prey's resources and that prey should be relatively uniformly distributed. These predictions should better apply to sit-and-pursue and sit-and-wait predators, who must anticipate the spatial distributions of their prey, than active predators that search for their prey. We test this with an experiment observing the spatial distributions and estimating the causes of movements between patches for Pacific tree frog tadpoles (Pseudacris regilla), a sit-and-pursue dragonfly larvae predator (Rhionaeschna multicolor), and an active salamander larval predator (Ambystoma tigrinum mavortium) when a single species was in the arena and when the prey was with one of the predators. We find that the sit-and-pursue predator favors patches with more of the prey's algae resources when the prey is not in the experimental arena and that the prey, when in the arena with this predator, do not favor patches with more resources. We also find that the active predator does not favor patches with more algae and that prey, when with an active predator, continue to favor these higher resource patches. These results suggest that the hunting modes of predators impact their spatial distributions and the spatial distributions of their prey, which has potential to have cascading effects on lower trophic levels. 相似文献
10.
Sustained oscillation is frequently observed in population dynamics of biospecies. The oscillation comes not only from deterministic but also from stochastic characteristics. In the present article, we deal with a finite size lattice which contains prey and predator. The interaction between a pair of lattice points is carried out by two different methods; local and global interactions. In the former, interaction occurs between adjacent sites, while in the latter interaction takes place between any pair of lattice sites. It is found that both systems exhibit undamped oscillations. The amplitude of oscillation decreases with the increase of the total lattice sites. In the case of global interaction, we can present a stochastic differential equation which is composed of two factors, i.e., the Lotka–Volterra equation with density dependence and noise term. The quantitative agreement between theory and simulation results of global interaction is almost perfect. The stochastic theory qualitatively expresses characteristics of sustainable oscillation for local interaction. 相似文献
11.
Adam L. Crane Reid Bryshun Megan McCormack Gabrielle H. Achtymichuk Ita A. E. Rivera-Hernández Maud C. O. Ferrari 《Journal of evolutionary biology》2023,36(1):57-66
Many species possess damage-released chemical alarm cues that function in alerting nearby individuals to a predator attack. One hypothesis for the evolution and/or maintenance of such cues is the Predator Attraction Hypothesis, where predators, rather than prey, are the “intended” recipients of these cues. If a predator attack attracts additional predators, these secondary predators might interfere with the predation event, providing the prey with a better chance to escape. In this study, we conducted two experiments to explore this hypothesis in an amphibian predator/prey system. In Experiment 1, we found that tiger salamanders (Ambystoma mavortium) showed a foraging attraction to chemical cues from wood frog (Lithobates sylvaticus) tadpoles. Salamanders that were experienced with tadpole prey, in particular, were strongly attracted to tadpole alarm cues. In Experiment 2, we observed experimental encounters between a tadpole and either one or two salamanders. The presence of the second predator caused salamanders to increase attack speed at the cost of decreased attack accuracy (i.e., increasing the probability that the tadpole would escape attacks). We also found that the mere presence of visual and chemical cues from a second predator did not affect this speed/accuracy trade-off but did cause enough of a distraction to increase tadpole survival. Thus, our findings are consistent with the Predator Attraction Hypothesis for the evolution and/or maintenance of alarm cues. 相似文献
12.
Marconi Campos‐Cerqueira Wayne J. Arendt Joseph M. Wunderle Jr T. Mitchell Aide 《Ecology and evolution》2017,7(23):9914-9924
An upward shift in elevation is one of the most conspicuous species responses to climate change. Nevertheless, downward shifts and, apparently, the absences of response have also been recently reported. Given the growing evidence of multiple responses of species distributions due to climate change and the paucity of studies in the tropics, we evaluated the response of a montane bird community to climate change, without the confounding effects of land‐use change. To test for elevational shifts, we compared the distribution of 21 avian species in 1998 and 2015 using occupancy models. The historical data set was based on point counts, whereas the contemporary data set was based on acoustic monitoring. We detected a similar number of species in historical (36) and contemporary data sets (33). We show an overall pattern of no significant change in range limits for most species, although there was a significant shift in the range limit of eight species (38%). Elevation limits shifted mostly upward, and this pattern was more common for upper than lower limits. Our results highlight the variability of species responses to climate change and illustrate how acoustic monitoring provides an easy and powerful way to monitor animal populations along elevational gradients. 相似文献
13.
Lotka–Volterra equations are considered a dynamical game, where the phenotypes of the predator and of the prey can vary.
This differs from the usual procedure of specifying as a priori laws according to which strategies are supposed to change.
The question at stake is the survival of each of the species, instead of the maximization of a given pay-off by each player,
as it is commonly discussed in games. The predator needs the prey, while the prey can survive without the predator.
These obvious and simplistic constraints are enough to shape the regulation of the system: notably, the largest closed set
of initial conditions can be delineated, from which there exists at least one evolutionary path where the population can avoid
extinction forever. To these so-called viable trajectories, viable strategies are associated, respectively for the prey or for the predator. A coexistence set can then be defined.
Within this set and outside the boundary, strategies can vary arbitrarily within given bounds while remaining viable, whereas
on the boundary, only specific strategies can guarantee the viability of the system. Thus, the largest set can be determined,
outside of which strategies will never be flexible enough to avoid extinction.
Received 2 May 1995; received in revised form 15 August 1995 相似文献
14.
L. M. Caro P. C. Caycedo‐Rosales R. C. K. Bowie H. Slabbekoorn C. D. Cadena 《Journal of evolutionary biology》2013,26(2):357-374
Local adaptation of populations along elevational gradients is well known, but conclusive evidence that such divergence has resulted in the origin of distinct species in parapatry remains lacking. We integrated morphological, vocal, genetic and behavioural data to test predictions pertaining to the hypothesis of parapatric ecological speciation associated with elevation in populations of a tropical montane songbird, the Grey‐breasted Wood‐wren (Henicorhina leucophrys: Troglodytidae), from the Sierra Nevada de Santa Marta, Colombia. We confirmed that two distinct populations exist along the elevational gradient. Phylogenetic analyses tentatively indicate that the two populations are not sister taxa, suggesting they did not differentiate from a single ancestor along the gradient, but rather resulted from separate colonization events. The populations showed marked divergence in morphometrics, vocalizations and genetic variation in mitochondrial and nuclear loci, and little to no evidence of hybridization. Individuals of both populations responded more strongly to their own local songs than to songs from another elevation. Although the two forms do not appear to have differentiated locally in parapatry, morphological and vocal divergence along the elevational gradient is consistent with adaptation, suggesting a possible link between adaptive evolution in morphology and songs and the origin of reproductive isolation via a behavioural barrier to gene flow. The adaptive value of phenotypic differences between populations requires additional study. 相似文献
15.
Moleón M Sánchez-Zapata JA Gil-Sánchez JM Ballesteros-Duperón E Barea-Azcón JM Virgós E 《Oecologia》2012,168(3):679-689
How predators impact on prey population dynamics is still an unsolved issue for most wild predator–prey communities. When
considering vertebrates, important concerns constrain a comprehensive understanding of the functioning of predator–prey relationships
worldwide; e.g. studies simultaneously quantifying ‘functional’ and ‘numerical responses’ (i.e., the ‘total response’) are
rare. The functional, the numerical, and the resulting total response (i.e., how the predator per capita intake, the population
of predators and the total of prey eaten by the total predators vary with prey densities) are fundamental as they reveal the
predator’s ability to regulate prey population dynamics. Here, we used a multi-spatio-temporal scale approach to simultaneously
explore the functional and numerical responses of a territorial predator (Bonelli’s eagle Hieraaetus fasciatus) to its two main prey species (the rabbit Oryctolagus cuniculus and the red-legged partridge Alectoris rufa) during the breeding period in a Mediterranean system of south Spain. Bonelli’s eagle responded functionally, but not numerically,
to rabbit/partridge density changes. Type II, non-regulatory, functional responses (typical of specialist predators) offered
the best fitting models for both prey. In the absence of a numerical response, Bonelli’s eagle role as a regulating factor
of rabbit and partridge populations seems to be weak in our study area. Simple (prey density-dependent) functional response
models may well describe the short-term variation in a territorial predator’s consumption rate in complex ecosystems. 相似文献
16.
δ13C values of C3 plants are indicators of plant carbon–water relations that integrate plant responses to environmental conditions. However,
few studies have quantified spatial variation in plant δ13C at the landscape scale. We determined variation in leaf δ13C, leaf nitrogen per leaf area (Narea), and specific leaf area (SLA) in April and August 2005 for all individuals of three common woody species within a 308 × 12-m
belt transect spanning an upland–lowland topoedaphic gradient in a subtropical savanna in southern Texas. Clay content, available
soil moisture, and soil total N were all negatively correlated with elevation. The δ13C values of Prosopis glandulosa (deciduous N2-fixing tree legume), Condalia hookeri (evergreen shrub), and Zanthoxylum fagara (evergreen shrub) leaves increased 1–4‰ with decreasing elevation, with the δ13C value of P. glandulosa leaves being 1–3‰ higher than those of the two shrub species. Contrary to theory and results from previous studies, δ13C values were highest where soil water was most available, suggesting that some other variable was overriding or interacting
with water availability. Leaf Narea was positively correlated with leaf δ13C of all species (p < 0.01) and appeared to exert the strongest control over δ13C along this topoedaphic gradient. Since leaf Narea is positively related to photosynthetic capacity, plants with high leaf Narea are likely to have low p
I/p
a ratios and therefore higher δ13C values, assuming stomatal conductance is constant. Specific leaf area was not correlated significantly with leaf δ13C. Following a progressive growing season drought in July/August, leaf δ13C decreased. The lower δ13C in August may reflect the accumulation of 13C-depleted epicuticular leaf wax. We suggest control of leaf δ13C along this topoedaphic gradient is mediated by leaf Narea rather than by stomatal conductance limitations associated with water availability. 相似文献
17.
Mohammad S. Farhadinia Ehsan M. Moqanaki Fatemeh Hosseini-Zavarei 《European Journal of Wildlife Research》2014,60(2):341-349
Management controversies arise when both of the prey and predator in an ecosystem are species of conservation concern. We investigated trophic interactions between the endangered Persian leopard (Panthera pardus saxicolor) and a declining mountain ungulate, urial wild sheep (Ovis vignei), on a high-altitude steppe of Iran. During two consecutive photo-trapping seasons of 1,300 nights in total, a minimum population of four adult leopards (one female and three males) was documented. Scat analysis indicated that urial wild sheep was the staple of the leopard diet with 48.44 % of total biomass consumed. Remains of domestic livestock in leopard scats were negligible yet alarming (14.53 % biomass consumed), followed by wild pigs (8.13 %) and wild goat (1.26 %). Financial costs of leopard depredation to livestock breeders during our study period were comparatively lower than livestock–leopard conflict hotspots across Iran. Using distance sampling, urial density was 15.8 individuals km?2 (±SE 6.2), and a total biomass of 47,621.5 kg for wild ungulates in the study area was estimated. We estimated that the annual removal rate of urial by leopards during our study period was 9.4 % of the total urial population. We suggest that continuous monitoring of the leopard and prey populations to assess predation impact should be considered, particularly in areas where a single species comprises a remarkable proportion of the leopard diet. In the meantime, assessing probable conflicts with local communities is recommended as a parallel management action to ensure long-term human–leopard coexistence. Our findings will aid wildlife managers in prey-depleted arid environments of western Asia to identify susceptible wild prey populations to predation by large carnivores; hence, significantly contribute in development and implementation of effective conservation measures to mitigate management conflicts. 相似文献
18.
《Ecological Complexity》2008,5(1):48-58
An individual-based model describing predator–prey interactions within a closed rectangular habitat was developed to study how different assumptions about the individual movements lead to the emergence at the population level of various kinds of prey- and predator-dependence in the spatially aggregated trophic function.In addition to random walk, both species are capable of directional movement, i.e., the model accounts for the predator prey-taxis and evasion of predators by prey individuals. The taxis stimulus of each species is the odour of the other species, which is distributed continuously in space. Spatial behaviour of individuals is determined by the specific response to the odour gradient and the tendency to maintain the taxis velocity.In order to facilitate the assessment of the trophic function, the model allows removing the effect of demographic density variations on the predator ration, keeping population sizes constant.Analyzing the dependence of the trophic function with the average predator density, we found that, depending on the intensity of taxis, the predator population exhibits various degrees of interference, from very low to very high values. In particular, a moderate taxis generates distinct levels of interference including the ratio-dependent case. The letter maximizes the average consumption rate.A new generalized function containing ratio-dependence and prey-dependence as special cases, at high and low population abundances, is suggested. This trophic function fits the simulated data better than the Hassell–Varley–Holling expression does. 相似文献
19.
Environmental perturbations occur in ecosystems as the result of disturbance, which is closely related to ecosystem stability and resilience. To understand how perturbations can affect ecosystems, we constructed a spatially explicit lattice model to simulate the integrative predator–prey–grass relationships. In this model, a predator (or prey) gives birth to offspring, according to a specific birth probability, when it is able to feed on prey (or grass). When a predator or prey animal was initially introduced or newly born, its health state was set at a given high value. This state decreased by 1 with each time step. When the state of an animal decreased to zero, the animal was considered dead and was removed from the system. In this model, the perturbation was defined as the sudden death of some portion of the population. The heterogeneous landscape was characterized by a parameter, H, which controlled the degree of heterogeneity. When H ≥ 0.6, the predator population size was positively influenced by the perturbation. However, the perturbation had little effect upon the population sizes of prey or grass, regardless of the value of H. 相似文献
20.
Invasive species cause enormous problems in ecosystems around the world. Motivated by introduced feral cats that prey on bird populations and threaten to drive them extinct on remote oceanic islands, we formulate and analyze optimal control problems. Their novelty is that they involve both scalar and time-dependent controls. They represent different forms of control, namely the initial release of infected predators on the one hand and culling as well as trapping, infecting, and returning predators on the other hand. Combinations of different control methods have been proposed to complement their respective strengths in reducing predator numbers and thus protecting endangered prey. Here, we formulate and analyze an eco-epidemiological model, provide analytical results on the optimal control problem, and use a forward–backward sweep method for numerical simulations. By taking into account different ecological scenarios, initial conditions, and control durations, our model allows to gain insight how the different methods interact and in which cases they could be effective. 相似文献