scholarly journals Feasibility and coexistence of large ecological communities

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Jacopo Grilli ◽  
Matteo Adorisio ◽  
Samir Suweis ◽  
György Barabás ◽  
Jayanth R. Banavar ◽  
...  
Keyword(s):  
Asymptotic Stability ◽  
Species Interactions ◽  
Ecological Communities ◽  
Ecological Network ◽  
Small Perturbations ◽  
Local Asymptotic Stability ◽  
Species Abundances ◽  
The Stability ◽  
Empirical Networks

Abstract The role of species interactions in controlling the interplay between the stability of ecosystems and their biodiversity is still not well understood. The ability of ecological communities to recover after small perturbations of the species abundances (local asymptotic stability) has been well studied, whereas the likelihood of a community to persist when the conditions change (structural stability) has received much less attention. Our goal is to understand the effects of diversity, interaction strengths and ecological network structure on the volume of parameter space leading to feasible equilibria. We develop a geometrical framework to study the range of conditions necessary for feasible coexistence. We show that feasibility is determined by few quantities describing the interactions, yielding a nontrivial complexity–feasibility relationship. Analysing more than 100 empirical networks, we show that the range of coexistence conditions in mutualistic systems can be analytically predicted. Finally, we characterize the geometric shape of the feasibility domain, thereby identifying the direction of perturbations that are more likely to cause extinctions.

scholarly journals Vulnerable species interactions are important for the stability of mutualistic networks

2019 ◽  
Author(s):  
Benno I. Simmons ◽  
Hannah S. Wauchope ◽  
Tatsuya Amano ◽  
Lynn V. Dicks ◽  
William J. Sutherland ◽  
...  
Keyword(s):  
Species Interactions ◽  
Species Coexistence ◽  
Species Interaction ◽  
Interaction Networks ◽  
Ecological Communities ◽  
Ecological Context ◽  
Intrinsic Properties ◽  
Network Stability ◽  
Starting Point ◽  
The Stability

AbstractSpecies are central to ecology and conservation. However, it is the interactions between species that generate the functions on which ecosystems and humans depend. Despite the importance of interactions, we lack an understanding of the risk that their loss poses to ecological communities. Here, we quantify risk as a function of the vulnerability (likelihood of loss) and importance (contribution to network stability in terms of species coexistence) of 4330 mutualistic interactions from 41 empirical pollination and seed dispersal networks across six continents. Remarkably, we find that more vulnerable interactions are also more important: the interactions that contribute most to network stability are those that are most likely to be lost. Furthermore, most interactions tend to have more similar vulnerability and importance across networks than expected by chance, suggesting that vulnerability and importance may be intrinsic properties of interactions, rather than only a function of ecological context. These results provide a starting point for prioritising interactions for conservation in species interaction networks and, in areas lacking network data, could allow interaction properties to be inferred from taxonomy alone.

Exploring Complex Dynamics of Spatial Predator–Prey System: Role of Predator Interference and Additional Food

2020 ◽  
Vol 30 (07) ◽  
pp. 2050102
Author(s):  
Vandana Tiwari ◽  
Jai Prakash Tripathi ◽  
Debaldev Jana ◽  
Satish Kumar Tiwari ◽  
Ranjit Kumar Upadhyay
Keyword(s):  
Asymptotic Stability ◽  
Equilibrium Solution ◽  
Model System ◽  
Positive Equilibrium ◽  
Additional Food ◽  
Predator Prey ◽  
Local Asymptotic Stability ◽  
Diffusive Model ◽  
Predator Interference

In this paper, an attempt has been made to understand the role of predator’s interference and additional food on the dynamics of a diffusive population model. We have studied a predator–prey interaction system with mutually interfering predator by considering additional food and Crowley–Martin functional response (CMFR) for both the reaction–diffusion model and associated spatially homogeneous system. The local stability analysis ensures that as the quantity of alternative food decreases, predator-free equilibrium stabilizes. Moreover, we have also obtained a condition providing a threshold value of additional food for the global asymptotic stability of coexisting steady state. The nonspatial model system changes stability via transcritical bifurcation and switches its stability through Hopf-bifurcation with respect to certain ranges of parameter determining the quantity of additional food. Conditions obtained for local asymptotic stability of interior equilibrium solution of temporal system determines the local asymptotic stability of associated diffusive model. The global stability of positive equilibrium solution of diffusive model system has been established by constructing a suitable Lyapunov function and using Green’s first identity. Using Harnack inequality and maximum modulus principle, we have established the nonexistence of nonconstant positive equilibrium solution of the diffusive model system. A chain of patterns on increasing the strength of additional food as spots[Formula: see text][Formula: see text][Formula: see text]stripes[Formula: see text][Formula: see text][Formula: see text]spots has been obtained. Various kind of spatial-patterns have also been demonstrated via numerical simulations and the roles of predator interference and additional food are established.

scholarly journals Stability and Bifurcation in a Delayed Holling-Tanner Predator-Prey System with Ratio-Dependent Functional Response

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Juan Liu ◽  
Zizhen Zhang ◽  
Ming Fu
Keyword(s):  
Hopf Bifurcation ◽  
Asymptotic Stability ◽  
Numerical Simulations ◽  
Functional Response ◽  
Center Manifold ◽  
Predator Prey ◽  
Local Asymptotic Stability ◽  
Prey System ◽  
Ratio Dependent ◽  
The Stability

We analyze a delayed Holling-Tanner predator-prey system with ratio-dependent functional response. The local asymptotic stability and the existence of the Hopf bifurcation are investigated. Direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions are studied by deriving the equation describing the flow on the center manifold. Finally, numerical simulations are presented for the support of our analytical findings.

Some concluding remarks and a look ahead

2019 ◽  
pp. 334-340
Author(s):  
Gary G. Mittelbach ◽  
Brian J. McGill
Keyword(s):  
Climate Change ◽  
Community Assembly ◽  
Ecosystem Functioning ◽  
Species Interactions ◽  
Species Distributions ◽  
Ecological Communities ◽  
Look Ahead ◽  
Local And Regional Processes ◽  
Regional Processes

This chapter reflects on the successes achieved and challenges that remain in the study of ecological communities. It concludes with a discussion of research topics expected to occupy the attention of community ecologists for the next decade or so and that may yield big dividends in terms of understanding the processes that structure communities and govern their functioning. These include metacommunities and the integration of local and regional processes; the drivers of regional biodiversity; community assembly and functional traits; pathogens, parasites and natural enemies; biodiversity and ecosystem functioning; changing technology will change how we collect data; eco-evolutionary feedbacks and regional pool processes; climate change, and its effects on species distributions and species interactions; and the role of time.

scholarly journals Interaction strength and extinction risk in a metacommunity

2005 ◽  
Vol 272 (1572) ◽  
pp. 1571-1576 ◽  
Author(s):  
Frédéric Guichard
Keyword(s):  
Species Interactions ◽  
Large Scale ◽  
Extinction Risk ◽  
Interaction Strength ◽  
Community Stability ◽  
Scale Invariant ◽  
Regional Stability ◽  
Regional Community ◽  
The Stability

Species interactions and connectivity are both central to explaining the stability of ecological communities and the problem of species extinction. Yet, the role of species interactions for the stability of spatially subdivided communities still eludes ecologists. Ecological models currently address the problem of stability by exploring the role of interaction strength in well mixed habitats, or of connectivity in subdivided communities. Here I propose a unification of interaction strength and connectivity as mechanisms explaining regional community stability. I introduce a metacommunity model based on succession dynamics in coastal ecosystems, incorporating limited dispersal and facilitative interactions. I report a sharp transition in regional stability and extinction probability at intermediate interaction strength, shown to correspond to a phase transition that generates scale-invariant distribution and high regional stability. In contrast with previous studies, stability results from intermediate interaction strength only in subdivided communities, and is associated with large-scale (scale-invariant) synchrony. These results can be generalized to other systems exhibiting phase transitions to show how local interaction strength can be used to resolve the link between regional community stability and pattern formation.

On the stability of steady convective motion generated by internal heat sources in a magnetic field

1988 ◽  
Vol 66 (11) ◽  
pp. 990-993 ◽  
Author(s):  
A. A. Kolyshkin
Keyword(s):  
Magnetic Field ◽  
Internal Heat ◽  
Convective Motion ◽  
Transverse Magnetic ◽  
Heat Sources ◽  
Small Perturbations ◽  
Internal Heat Sources ◽  
Prandtl Numbers ◽  
The Stability

The stability of steady convective motion of a viscous incompressible fluid in a transverse magnetic field is investigated using the method of small perturbations. The motion is caused by internal heat sources uniformly distributed within the vertical layer of the fluid. The stability analysis shows that the critical Grasshof number increases with the growth of the magnetic field. The role of the Prandtl and Hartmann numbers on the stability characteristics are discussed. For high Prandtl numbers, instability occurs in the form of thermal running waves.

scholarly journals The balance of interaction types determines the assembly and stability of ecological communities

2019 ◽  
Author(s):  
Jimmy J. Qian ◽  
Erol Akçay
Keyword(s):  
Species Interactions ◽  
Community Dynamics ◽  
Theoretical Work ◽  
Species Interaction ◽  
Ecological Communities ◽  
External Stability ◽  
Ecological Selection ◽  
Interaction Types ◽  
The Stability ◽  
Almost All

What determines the assembly and stability of complex communities is a central question in ecology. Past work has suggested that mutualistic interactions are inherently destabilizing. However, this conclusion relies on assuming that benefits from mutualisms never stop increasing. Furthermore, almost all theoretical work focuses on the internal (asymptotic) stability of communities assembled all-at-once. Here, we present a model with saturating benefits from mutualisms and sequentially assembled communities. We show that such communities are internally stable for any level of diversity and any combination of species interaction types. External stability, or resistance to invasion, is thus an important but overlooked measure of stability. We demonstrate that the balance of different interaction types governs community dynamics. Mutualisms may increase external stability and diversity of communities as well as species persistence, depending on how benefits saturate. Ecological selection increases the prevalence of mutualisms, and limits on biodiversity emerge from species interactions. Our results help resolve longstanding debates on the stability, saturation, and diversity of communities.

scholarly journals Temperature variability alters the stability and thresholds for collapse of interacting species

2020 ◽  
Author(s):  
Laura E. Dee ◽  
Daniel Okamtoto ◽  
Anna Gårdmark ◽  
Jose M. Montoya ◽  
Steve J. Miller
Keyword(s):  
Temperature Variation ◽  
Thermal Performance ◽  
Species Interactions ◽  
Temperature Variability ◽  
Ecological Communities ◽  
Temperature Dependent ◽  
Interacting Species ◽  
Stable Coexistence ◽  
The Stability ◽  
Increasing Temperature

AbstractTemperature variability and extremes can have profound impacts on populations and ecological communities. Predicting impacts of thermal variability poses a challenge because it has both direct physiological effects and indirect effects through species interactions. In addition, differences in thermal performance between predators and prey and non-linear averaging of temperature-dependent performance can result in complex and counterintuitive population dynamics in response to climate change. Yet the combined consequences of these effects remain underexplored. Here, modeling temperature-dependent predator-prey dynamics, we study how changes in temperature variability affect population size, collapse, and stable coexistence of both predator and prey, relative to under constant environments or warming alone. We find that the effects of temperature variation on interacting species can lead to a diversity of outcomes, from predator collapse to stable coexistence, depending on interaction strengths and differences in species’ thermal performance. Temperature variability also alters predictions about population collapse – in some cases allowing predators to persist for longer than predicted when considering warming alone, and in others accelerating collapse. To inform management responses that are robust to future climates with increasing temperature variability and extremes, we need to incorporate the consequences of temperature variation in complex ecosystems.

scholarly journals Synchronization Dynamics in Non-Normal Networks: The Trade-Off for Optimality

Entropy ◽  
2020 ◽  
Vol 23 (1) ◽  
pp. 36
Author(s):  
Riccardo Muolo ◽  
Timoteo Carletti ◽  
James P. Gleeson ◽  
Malbor Asllani
Keyword(s):  
Dynamical Behavior ◽  
Power Grids ◽  
Trade Off ◽  
Optimal Network ◽  
Underlying Network ◽  
The Stability ◽  
Normal Networks ◽  
Empirical Networks ◽  
Standard Techniques

Synchronization is an important behavior that characterizes many natural and human made systems that are composed by several interacting units. It can be found in a broad spectrum of applications, ranging from neuroscience to power-grids, to mention a few. Such systems synchronize because of the complex set of coupling they exhibit, with the latter being modeled by complex networks. The dynamical behavior of the system and the topology of the underlying network are strongly intertwined, raising the question of the optimal architecture that makes synchronization robust. The Master Stability Function (MSF) has been proposed and extensively studied as a generic framework for tackling synchronization problems. Using this method, it has been shown that, for a class of models, synchronization in strongly directed networks is robust to external perturbations. Recent findings indicate that many real-world networks are strongly directed, being potential candidates for optimal synchronization. Moreover, many empirical networks are also strongly non-normal. Inspired by this latter fact in this work, we address the role of the non-normality in the synchronization dynamics by pointing out that standard techniques, such as the MSF, may fail to predict the stability of synchronized states. We demonstrate that, due to a transient growth that is induced by the structure’s non-normality, the system might lose synchronization, contrary to the spectral prediction. These results lead to a trade-off between non-normality and directedness that should be properly considered when designing an optimal network, enhancing the robustness of synchronization.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

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