Consumer-Resource Dynamics: Building Consumptive Food Webs

2011 ◽  
Author(s):  
Kevin S. McCann
Keyword(s):  
Food Webs ◽  
Empirical Data ◽  
Interaction Strength ◽  
Building Blocks ◽  
Resource Theory ◽  
Focal Species ◽  
Resource Interactions ◽  
Resource Dynamics ◽  
Underlying Mechanisms ◽  
Consumer Resource

This chapter examines the dynamics of consumer–resource interaction, one of the fundamental building blocks of food webs. In particular, it considers how consumer–resource systems that are nonexcitable and excitable respond to changes in interaction strength. The chapter begins with a discussion of two classes of interaction-strength metrics: the first focuses on instantaneous rates of change in one species with respect to another species; the second follows the longer-term influence of the removal of (or change in) one species on the density of another focal species. Continuous consumer–resource models are then described, after which two underlying mechanisms that are behind the stabilization of consumer–resource interactions are analyzed. The chapter concludes with a review of microcosm experiments and empirical data that show consistency with the proposed consumer–resource theory.

Adding the Ecosystem

2011 ◽  
Author(s):  
Kevin S. McCann
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Closed System ◽  
Nutrient Recycling ◽  
Interaction Strength ◽  
Nonequilibrium Dynamics ◽  
Nutrient Pool ◽  
Food Web Dynamics ◽  
Resource Interactions ◽  
Consumer Resource

This chapter examines how nutrient recycling and decomposition affect the dynamics and stability of food webs. It first reviews some of the existing theory on detritus and food web dynamics before discussing the basics of a model that takes into account grazing food webs and whole ecosystems. It then describes the N-R-D (nutrient pool, resource, detritus) submodule as well as the full N-C-R-D (nutrient pool, consumer, resource, detritus) model. It also explores how detritus may act to distribute nutrients by considering a model that begets nonequilibrium dynamics. It shows that detritus tends to stabilize consumer–resource interactions relative to the purely community module (no recycling) because the detritus tends to fall out of phase with the resource–nutrient interaction. The addition of a consumer–resource incteraction to the N-R-D module, even in a closed system, eventually can drive overshoot dynamics and destabilization by increased production, coupling, or interaction strength.

Lagged Consumer-Resource Dynamics

2011 ◽  
Author(s):  
Kevin S. McCann
Keyword(s):  
Food Web ◽  
Alternative Stable States ◽  
Interaction Strength ◽  
Population Level ◽  
Stage Structure ◽  
Stable States ◽  
Food Web Interactions ◽  
Resource Interactions ◽  
Resource Dynamics ◽  
Consumer Resource

This chapter examines the influence of biological lags on consumer–resource dynamics, with particular emphasis on how consumer–resource cycles, or the lack thereof, interact with population level dynamical phenomena. It first considers discrete consumer–resource interactions before discussing the dynamics of stage-structured consumer–resource interactions. It then explains how stage structure promotes the possibility of alternative stable states and changes consumer–resource interaction strength. It also shows how a change in population structure affects food web interactions and/or the strengths of food webs. Finally, it reviews empirical results that show how stage structure and food web interaction influence ecological stability. The chapter argues that weak and inherently stable consumer–resource interactions can mute a potentially unstable population level phenomenon, and that a dynamically decoupled stable stage class can strongly stabilize other stages and the consumer–resource interaction.

Of Modules, Motifs, and Whole Webs

2011 ◽  
Author(s):  
Kevin S. McCann
Keyword(s):  
Food Webs ◽  
Interaction Strength ◽  
Food Chains ◽  
Concerted Effort ◽  
Modular Theory ◽  
Resource Interactions ◽  
Individual Module ◽  
Consumer Resource

This chapter explains the use of modular or motif-based theory to interpret the dynamics of whole food webs. According to Robert Holt, modules are “as motifs with muscles.” Holt's modular theory focuses on the implications of the strength of the interactions on the dynamics and persistence of these units. In this book, the term “module” means all motifs that include interaction strength, whereas the term “motif” represents all possible subsystem connections, including the trivial one-node/species case to the n-node/species cases. Part 2 considers the dynamics of important ecological modules or motifs such as populations, consumer–resource interactions, food chains, and omnivory, while Part 3 uses the logic attained from this modular or motif-based theory in order to elucidate the dynamics of whole food webs. The book argues that ecologists must make a concerted effort to understand how coupling different modules ultimately modifies flux within each individual module.

scholarly journals Viewing communities as coupled oscillators: elementary forms from Lotka and Volterra to Kuramoto

2020 ◽  
Author(s):  
Zachary Hajian-Forooshani ◽  
John Vandermeer
Keyword(s):  
Coupled Oscillators ◽  
Community Organization ◽  
Building Blocks ◽  
Kuramoto Model ◽  
Volterra Equations ◽  
Ecological Communities ◽  
Shared Resources ◽  
Resource Interactions ◽  
The Kuramoto Model ◽  
Consumer Resource

AbstractEcosystems and their embedded ecological communities are almost always by definition collections of oscillating populations. This is apparent given the qualitative reality that oscillations emerge from consumer-resource interactions, which are the simple building blocks for ecological communities. It is also likely always the case that oscillatory consumer-resource pairs will be connected to one another via trophic cross-feeding with shared resources or via competitive interactions among resources. Thus, one approach to understanding the dynamics of communities conceptualizes them as collections of oscillators coupled in various arrangements. Here we look to the pioneering work of Kuramoto on coupled oscillators and ask to what extent can his insights and approaches be translated to ecological systems. We explore all possible coupling arrangements of the simple case of three oscillator systems with both the Kuramoto model and with the classical Lotka-Volterra equations that are foundational to ecology. Our results show that the six-dimensional analogous Lotka-Volterra systems behave strikingly similarly to that of the corresponding Kuramoto systems across all possible coupling combinations. This qualitative similarity in the results between these two approaches suggests that a vast literature on coupled oscillators that has largely been ignored by ecologists may in fact be relevant in furthering our understanding of ecosystem and community organization.

scholarly journals Pollinators in food webs: Mutualistic interactions increase diversity, stability, and function in multiplex networks

2019 ◽  
Author(s):  
Kayla R. S. Hale ◽  
Fernanda S. Valdovinos ◽  
Neo D. Martinez
Keyword(s):  
Food Webs ◽  
Network Theory ◽  
Temporal Stability ◽  
Different Types ◽  
Reproductive Services ◽  
Resource Interactions ◽  
And Function ◽  
Plant Pollinator ◽  
Consumer Resource ◽  
Feeding Interactions

ABSTRACTEcosystems are composed of complex networks of many species interacting in different ways. While ecologists have long studied food webs of feeding interactions, recent studies increasingly focus on mutualistic networks including plants that exchange food for reproductive services provided by animals such as pollinators. Here, we synthesize both types of consumer-resource interactions to better understand the controversial effects of mutualism on ecosystems at the species, guild, and whole-community levels. We find that consumer-resource mechanisms underlying plant-pollinator mutualisms can increase the persistence, productivity, abundance, and temporal stability of both mutualists and non-mutualists in food webs. These effects strongly increase with floral reward productivity and are qualitatively robust to variation in the prevalence of mutualism and pollinators feeding upon resources in addition to rewards. This work advances the ability of mechanistic network theory to synthesize different types of interactions and illustrates how mutualism can enhance the diversity, stability, and function of complex ecosystems.

scholarly journals A framework to improve predictions of warming effects on consumer-resource interactions

2020 ◽  
Author(s):  
Alexis D. Synodinos ◽  
Bart Haegeman ◽  
Arnaud Sentis ◽  
José M. Montoya
Keyword(s):  
Community Dynamics ◽  
Explanatory Power ◽  
Interaction Strength ◽  
Energetic Efficiency ◽  
Biological Parameters ◽  
Thermal Dependence ◽  
Resource Interactions ◽  
Cross System ◽  
Theoretical Analyses ◽  
Consumer Resource

AbstractChanges in temperature affect consumer-resource interactions which underpin the functioning of ecosystems. However, existing studies report contrasting predictions regarding the impacts of warming on biological rates and community dynamics. To improve prediction accuracy and comparability, we develop a framework that combines two approaches: sensitivity analysis and aggregate parameters. The former determines which biological parameters impact the community most strongly. The use of aggregate parameters (i.e., maximal energetic efficiency, ρ, and interaction strength, κ), that combine multiple biological parameters, increases explanatory power and reduces the complexity of theoretical analyses. We illustrate the framework using empirically-derived thermal dependence curves of biological rates and applying it to consumer-resource biomass ratio and community stability. Based on our analyses, we present four predictions: 1) resource growth rate regulates biomass distributions at mild temperatures, 2) interaction strength alone determines the thermal boundaries of the community, 3) warming destabilises dynamics at low and mild temperatures only, 4) interactions strength must decrease faster than maximal energetic efficiency for warming to stabilise dynamics. We argue that directly measuring the aggregate parameters should increase the accuracy of predictions on warming impacts on food webs and promote cross-system comparisons.

scholarly journals Ecological character displacement destabilizes food webs

2019 ◽  
Author(s):  
Matthew A. Barbour
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Phenotypic Diversity ◽  
Interaction Strength ◽  
Character Displacement ◽  
Shared Resources ◽  
Adaptive Process ◽  
Ecological Character ◽  
Ecological Character Displacement ◽  
Resource Interactions

AbstractEcological character displacement is an adaptive process that generally increases phenotypic diversity. Despite the fact that this diversification is due to an eco-evolutionary feedback between consumers competing for shared resources, its consequences for food-web dynamics have received little attention. Here, I study a model of two consumers competing for two shared resources to examine how character displacement in consumer attack rates affects resource abundances and the resilience of food webs to perturbations. I found that character displacement always strengthened consumer-resource interactions whenever consumers competed for resources that occurred in different habitats. This increase in interaction strength resulted in lower resource abundances and less resilient food webs. This occurred under different evolutionary tradeoffs and in both simple and more realistic foraging scenarios. Taken together, my results show that the adaptive process of character displacement may come with the ecological cost of decreasing food-web resilience.

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