Classic Food Web Theory

2011 ◽  
Author(s):  
Kevin S. McCann
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Matrix Theory ◽  
System Matrix ◽  
Modular Theory ◽  
Basic Assumptions ◽  
Community Approach ◽  
The Stability ◽  
Food Web Theory ◽  
Lower Dimensional

This chapter examines the basic assumptions of classic food web theory. It first considers the classic whole-community approach, which assumes that any specific matrix represents a sample from a “statistical universe” of interaction strengths for a given set of n species. It then describes some matrix approaches to see if context-dependent techniques can be applied to matrix theory, along with the simple graphical techniques of Gershgorin discs employed as an intuitive approach to eigenvalues. It argues that there are some rather intriguing “gravitational-like” properties of Gershgorin discs for some important biologically motivated matrices. The chapter proceeds by discussing some classic whole-matrix results that highlight the connections between the stability of lower-dimensional modules and whole food webs. Finally, it shows how the ideas derived from classic whole-system matrix approaches generally agree with the results of modular theory.

scholarly journals Strong nutrient-plant interactions enhance the stability of ecosystems

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Zachariah G. Schonberger ◽  
Kevin McCann ◽  
Gabriel Gellner
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Plant Interactions ◽  
Ecosystem Models ◽  
Resource Interactions ◽  
Ecosystem Theory ◽  
The Stability ◽  
Ecosystem Interactions ◽  
Food Web Theory

AbstractModular food web theory shows how weak energetic fluxes resulting from consumptive interactions plays a major role in stabilizing food webs in space and time. Despite the reliance on energetic fluxes, food web theory surprisingly remains poorly understood within an ecosystem context that naturally focuses on material fluxes. At the same time, while ecosystem theory has employed modular nutrient-limited ecosystem models to understand how limiting nutrients alter the structure and dynamics of food webs, ecosystem theory has overlooked the role of key ecosystem interactions and their strengths (e.g., plant-nutrient; R-N) in mediating the stability of nutrient-limited ecosystems. Here, towards integrating food web theory and ecosystem theory, we first briefly review consumer-resource interactions (C-R) highlighting the relationship between the structure of C-R interactions and the stability of food web modules. We then translate this framework to nutrient-based systems, showing that the nutrient-plant interaction behaves as a coherent extension of current modular food web theory; however, in contrast to the rule that weak C-R interactions tend to be stabilizing we show that strong nutrient-plant interactions are potent stabilizers in nutrient-limited ecosystem models.

scholarly journals The more food webs change, the more they stay the same

2009 ◽  
Vol 364 (1524) ◽  
pp. 1789-1801 ◽  
Author(s):  
Kevin Shear McCann ◽  
Neil Rooney
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Temporal Variability ◽  
Spatial And Temporal Variability ◽  
Scale Invariant ◽  
Food Web Structure ◽  
Behavioural Responses ◽  
Web Structure ◽  
Food Web Ecology ◽  
Food Web Theory

Here, we synthesize a number of recent empirical and theoretical papers to argue that food-web dynamics are characterized by high amounts of spatial and temporal variability and that organisms respond predictably, via behaviour, to these changing conditions. Such behavioural responses on the landscape drive a highly adaptive food-web structure in space and time. Empirical evidence suggests that underlying attributes of food webs are potentially scale-invariant such that food webs are characterized by hump-shaped trophic structures with fast and slow pathways that repeat at different resolutions within the food web. We place these empirical patterns within the context of recent food-web theory to show that adaptable food-web structure confers stability to an assemblage of interacting organisms in a variable world. Finally, we show that recent food-web analyses agree with two of the major predictions of this theory. We argue that the next major frontier in food-web theory and applied food-web ecology must consider the influence of variability on food-web structure.

scholarly journals POPULATION DYNAMICS ON COMPLEX FOOD WEBS

2011 ◽  
Vol 14 (04) ◽  
pp. 635-647 ◽  
Author(s):  
GIAN MARCO PALAMARA ◽  
VINKO ZLATIĆ ◽  
ANTONIO SCALA ◽  
GUIDO CALDARELLI
Keyword(s):  
Population Dynamics ◽  
Simple Model ◽  
Food Web ◽  
Food Webs ◽  
Real Data ◽  
Niche Model ◽  
Ecological Complexity ◽  
Overlap Graphs ◽  
Dynamical Properties ◽  
The Stability

In this work we analyze the topological and dynamical properties of a simple model of complex food webs, namely the niche model. In order to underline competition among species, we introduce "prey" and "predators" weighted overlap graphs derived from the niche model and compare synthetic food webs with real data. Doing so, we find new tests for the goodness of synthetic food web models and indicate a possible direction of improvement for existing ones. We then exploit the weighted overlap graphs to define a competition kernel for Lotka–Volterra population dynamics and find that for such a model the stability of food webs decreases with its ecological complexity.

scholarly journals Anti-predator defence and the complexity–stability relationship of food webs

2007 ◽  
Vol 274 (1618) ◽  
pp. 1617-1624 ◽  
Author(s):  
Michio Kondoh
Keyword(s):  
Species Richness ◽  
Food Web ◽  
Food Webs ◽  
Community Level ◽  
Negative Effects ◽  
Food Web Structure ◽  
Wide Range ◽  
The Stability ◽  
Food Web Complexity ◽  
Predator Defence

The mechanism for maintaining complex food webs has been a central issue in ecology because theory often predicts that complexity (higher the species richness, more the interactions) destabilizes food webs. Although it has been proposed that prey anti-predator defence may affect the stability of prey–predator dynamics, such studies assumed a limited and relatively simpler variation in the food-web structure. Here, using mathematical models, I report that food-web flexibility arising from prey anti-predator defence enhances community-level stability (community persistence and robustness) in more complex systems and even changes the complexity–stability relationship. The model analysis shows that adaptive predator-specific defence enhances community-level stability under a wide range of food-web complexity levels and topologies, while generalized defence does not. Furthermore, while increasing food-web complexity has minor or negative effects on community-level stability in the absence of defence adaptation, or in the presence of generalized defence, in the presence of predator-specific defence, the connectance–stability relationship may become unimodal. Increasing species richness, in contrast, always lowers community-level stability. The emergence of a positive connectance–stability relationship however necessitates food-web compartmentalization, high defence efficiency and low defence cost, suggesting that it only occurs under a restricted condition.

scholarly journals Differential Responses of Food Web Properties to Opposite Assembly Rules and Species Richness

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2828
Author(s):  
Yulun Guo ◽  
Tao Wang ◽  
García Molinos Jorge ◽  
Huan Zhang ◽  
Peiyu Zhang ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
A Priori ◽  
Limiting Similarity ◽  
Assembly Rules ◽  
Scale Invariant ◽  
Ecological Processes ◽  
Energetic Performance ◽  
Food Web Theory ◽  
Specific Food

Trophic niches condition the energetic performance of species within food webs providing a vital link between food web assembly, species diversity, and functioning of ecosystems. Our understanding of this important link is, however, limited by the lack of empirical tools that can be easily applied to compare entire food webs at regional scales. By comparison, with different a priori synthetic models defined according to specific assembly rules (i.e., purely random, limiting similarity, and niche filtering), we demonstrate that a set of food web properties (trophic richness, evenness, and divergence) are controlled by ecological processes. We further demonstrate that although both limiting similarity and niche filtering are statistically significant assembly processes shaping our studied lake food webs, their relative importance is richness-dependent, and contextual to the specific food web property under consideration. Our results have both important theoretical and practical implications. Theoretically, the observed richness-dependent variation on food web properties contradicts the common criticism on food web theory that food web properties are roughly scale-invariant. Practically, these properties can help avoiding spurious conclusions, while providing useful information for multiple food web niche spaces supporting the ecosystem functioning.

scholarly journals The interplay among prey preference, nutrient enrichment and stability in an omnivory system

2009 ◽  
Vol 69 (4) ◽  
pp. 1027-1035 ◽  
Author(s):  
LDB. Faria ◽  
MIS. Costa
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Trophic Interactions ◽  
Nutrient Enrichment ◽  
Strong Influence ◽  
Prey Preference ◽  
Top Predator ◽  
The Subject ◽  
The Stability

Food webs usually display an intricate mix of trophic interactions where multiple prey are common. In this context omnivory has been the subject of intensive analysis regarding food web stability and structure. In a three species omnivory setting it is shown that the modeling of prey preference by the top predator may exert a strong influence on the short as well as on the long term dynamics of the respective food web. Clearly, this has implications concerning the stability and the structure of omnivory systems under disturbances such as nutrient enrichment.

scholarly journals Landscape heterogeneity buffers biodiversity of simulated meta-food-webs under global change through rescue and drainage effects

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Remo Ryser ◽  
Myriam R. Hirt ◽  
Johanna Häussler ◽  
Dominique Gravel ◽  
Ulrich Brose
Keyword(s):  
Habitat Fragmentation ◽  
Food Web ◽  
Food Webs ◽  
Landscape Heterogeneity ◽  
Landscape Connectivity ◽  
Biodiversity Loss ◽  
Mechanistic Explanation ◽  
Population Densities ◽  
Rescue Effect ◽  
Drainage Effect

AbstractHabitat fragmentation and eutrophication have strong impacts on biodiversity. Metacommunity research demonstrated that reduction in landscape connectivity may cause biodiversity loss in fragmented landscapes. Food-web research addressed how eutrophication can cause local biodiversity declines. However, there is very limited understanding of their cumulative impacts as they could amplify or cancel each other. Our simulations of meta-food-webs show that dispersal and trophic processes interact through two complementary mechanisms. First, the ‘rescue effect’ maintains local biodiversity by rapid recolonization after a local crash in population densities. Second, the ‘drainage effect’ stabilizes biodiversity by preventing overshooting of population densities on eutrophic patches. In complex food webs on large spatial networks of habitat patches, these effects yield systematically higher biodiversity in heterogeneous than in homogeneous landscapes. Our meta-food-web approach reveals a strong interaction between habitat fragmentation and eutrophication and provides a mechanistic explanation of how landscape heterogeneity promotes biodiversity.

Long-term vegetation restoration promotes the stability of the soil micro-food web in the Loess Plateau in North-west China

CATENA ◽  
2021 ◽  
Vol 202 ◽  
pp. 105293
Author(s):  
Yang Wu ◽  
WenJing Chen ◽  
Wulan Entemake ◽  
Jie Wang ◽  
HongFei Liu ◽  
...  
Keyword(s):  
Food Web ◽  
Loess Plateau ◽  
Vegetation Restoration ◽  
The Loess Plateau ◽  
West China ◽  
North West ◽  
The Stability

Functional diversity alters the effects of a pulse perturbation on the dynamics of tritrophic food webs

2021 ◽  
Author(s):  
Ruben Ceulemans ◽  
Laurie Anne Myriam Wojcik ◽  
Ursula Gaedke
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Feedback Loop ◽  
Environmental Changes ◽  
Biodiversity Loss ◽  
Trophic Levels ◽  
Nutrient Pulse ◽  
Trade Offs ◽  
Food Web Model

Biodiversity decline causes a loss of functional diversity, which threatens ecosystems through a dangerous feedback loop: this loss may hamper ecosystems' ability to buffer environmental changes, leading to further biodiversity losses. In this context, the increasing frequency of climate and human-induced excessive loading of nutrients causes major problems in aquatic systems. Previous studies investigating how functional diversity influences the response of food webs to disturbances have mainly considered systems with at most two functionally diverse trophic levels. Here, we investigate the effects of a nutrient pulse on the resistance, resilience and elasticity of a tritrophic---and thus more realistic---plankton food web model depending on its functional diversity. We compare a non-adaptive food chain with no diversity to a highly diverse food web with three adaptive trophic levels. The species fitness differences are balanced through trade-offs between defense/growth rate for prey and selectivity/half-saturation constant for predators. We showed that the resistance, resilience and elasticity of tritrophic food webs decreased with larger perturbation sizes and depended on the state of the system when the perturbation occured. Importantly, we found that a more diverse food web was generally more resistant, resilient, and elastic. Particularly, functional diversity dampened the probability of a regime shift towards a non-desirable alternative state. In addition, despite the complex influence of the shape and type of the dynamical attractors, the basal-intermediate interaction determined the robustness against a nutrient pulse. This relationship was strongly influenced by the diversity present and the third trophic level. Overall, using a food web model of realistic complexity, this study confirms the destructive potential of the positive feedback loop between biodiversity loss and robustness, by uncovering mechanisms leading to a decrease in resistance, resilience and elasticity as functional diversity declines.

scholarly journals Asymptotic Stability of Caputo Type Fractional Neutral Dynamical Systems with Multiple Discrete Delays

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Hai Zhang ◽  
Daiyong Wu ◽  
Jinde Cao
Keyword(s):  
Asymptotic Stability ◽  
Matrix Theory ◽  
Sufficient Conditions ◽  
Algebraic Approach ◽  
Stability Criteria ◽  
Differential Systems ◽  
Discrete Delays ◽  
Transcendental Equations ◽  
The Stability ◽  
Theoretical Results

We discuss the delay-independent asymptotic stability of Caputo type fractional-order neutral differential systems with multiple discrete delays. Based on the algebraic approach and matrix theory, the sufficient conditions are derived to ensure the asymptotic stability for all time-delay parameters. By applying the stability criteria, one can avoid solving the roots of transcendental equations. The results obtained are computationally flexible and convenient. Moreover, an example is provided to illustrate the effectiveness and applicability of the proposed theoretical results.

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