Interaction Strength

FracFeed: Global database of the fraction of feeding predators featured image

FracFeed: Global database of the fraction of feeding predators

The proportion of individuals that are found to have empty stomachs during a survey of a predator population’s diet has been used as an indicator of the average individual’s state …

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Mark Novak
Sea urchin consumption of kelp controlled by the density of drift algae featured image

Sea urchin consumption of kelp controlled by the density of drift algae

Rocky reef kelp forests can exhibit abrupt shifts between forested and barren states where unchecked sea urchin grazing inhibits kelp recovery. Forefront to urchin barren …

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Zachary Randell
In defense of Type I functional responses: The frequency and population-dynamic effects of feeding on multiple prey at a time featured image

In defense of Type I functional responses: The frequency and population-dynamic effects of feeding on multiple prey at a time

Ecologists differ in the degree to which they consider the linear Type I functional response to be an unrealistic versus sufficient representation of predator feeding rates. …

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Mark Novak
Simple, universal rules predict trophic interaction strengths featured image

Simple, universal rules predict trophic interaction strengths

Many critical drivers of ecological systems exhibit regular scaling relationships, yet, often, the underlying mechanisms explaining these relationships are unknown. Trophic …

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Kyle Coblentz
Body mass–biomass scaling modulates species keystone-ness to press perturbations featured image

Body mass–biomass scaling modulates species keystone-ness to press perturbations

Identifying species with disproportionate effects on other species under press perturbations is essential, yet how species traits drive their keystone-ness and how this depends on …

xiaoxiao-li
Age-prevalence curves in a multi-species parasite community featured image

Age-prevalence curves in a multi-species parasite community

The relationship between infection prevalence and host age is informative because it can reveal processes underlying disease dynamics. Most prior work has assumed that …

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Dan Preston
Corrigendum: Geometric complexity and the information-theoretic comparison of functional-response models featured image

Corrigendum: Geometric complexity and the information-theoretic comparison of functional-response models

Due to an error in our formulation of the citardauq solution to quadratic equations, our reformulation of the Steady State Saturation (SSS) model of Jeschke et al. (2002) to a …

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Mark Novak
High variation in handling times confers 35-year stability to predator feeding rates despite community change featured image

High variation in handling times confers 35-year stability to predator feeding rates despite community change

Historical resurveys of ecological communities are important for placing the structure of modern ecosystems in context. Rarely, however, are surveys alone sufficient for providing …

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Mark Novak
Predator feeding rates may often be unsaturated under typical prey densities featured image

Predator feeding rates may often be unsaturated under typical prey densities

Predator feeding rates (described by their functional response) must saturate at high prey densities. Although thousands of manipulative functional response experiments show …

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Kyle Coblentz
Grazer-resource behavior, interactions, and feedbacks control kelp-forest dynamics and stability featured image

Grazer-resource behavior, interactions, and feedbacks control kelp-forest dynamics and stability

How the direct and indirect effects of species interactions cascade to affect community struc- ture, functioning, and stability is a fundamental question in ecology. In temperate …

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Zachary Randell
The effects of formalin fixation and fluid storage on stable isotopes in rodent hair featured image

The effects of formalin fixation and fluid storage on stable isotopes in rodent hair

Stable isotopes are increasingly being used to unlock the wealth of information contained in specimens preserved in museum collections. However, preservation methods that employ …

david-taylor
Geometric complexity and the information-theoretic comparison of functional-response models featured image

Geometric complexity and the information-theoretic comparison of functional-response models

The assessment of relative model performance using information criteria like AIC and BIC has become routine among functional-response studies, reflecting trends in the broader …

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Mark Novak

The predictability of qualitative food web dynamics in response to extinction and invasion

Food webs are extraordinarily complex, containing myriad direct interactions and indirect effects. Determining how this network of interactions and effects influences a food web’s …

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David Rockow
Trematode parasites exceed aquatic insect biomass in Oregon stream food webs featured image

Trematode parasites exceed aquatic insect biomass in Oregon stream food webs

Although parasites are increasingly recognized for their ecosystem roles, it is often assumed that free-living organisms dominate animal biomass in most ecosystems and therefore …

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Dan Preston
Systematic bias in studies of consumer functional responses featured image

Systematic bias in studies of consumer functional responses

Functional responses are a cornerstone to our understanding of consumer-resource interactions, so how to best describe them using models has been actively debated. Here we focus on …

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Mark Novak
Quantifying the effects of intraspecific variation on predator feeding rates through nonlinear averaging featured image

Quantifying the effects of intraspecific variation on predator feeding rates through nonlinear averaging

Theory suggests that intraspecific trait variation will alter species interaction strengths through nonlinear averaging when interaction strengths are nonlinear functions of …

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Kyle Coblentz
Hidden layers of density dependence in consumer feeding rates featured image

Hidden layers of density dependence in consumer feeding rates

Functional responses relate a consumer's feeding rates to variation in its abiotic and biotic environment, providing insight into consumer behaviour and fitness, and underpinning …

daniel-stouffer
Food-web interaction strength distributions are conserved by greater variation between than within predator--prey pairs featured image

Food-web interaction strength distributions are conserved by greater variation between than within predator--prey pairs

Species interactions in food webs are usually recognized as dynamic, varying across species, space, and time because of biotic and abiotic drivers. Yet food webs also show …

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Dan Preston
What drives interaction strengths in complex food webs? A test with feeding rates of a generalist stream predator featured image

What drives interaction strengths in complex food webs? A test with feeding rates of a generalist stream predator

Describing the mechanisms that drive variation in species interaction strengths is central to understanding, predicting, and managing community dynamics. Multiple factors have been …

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Dan Preston
Candidate causes, consequences, and estimation of individual diet specialization featured image

Candidate causes, consequences, and estimation of individual diet specialization

Diet variation among individuals within populations is widespread. Often diet dierences among individuals are attributable to obvious differences among individuals such as age, …

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Kyle Coblentz
Using Survival Models to Estimate Invertebrate Prey Identification Times in a Generalist Stream Fish featured image

Using Survival Models to Estimate Invertebrate Prey Identification Times in a Generalist Stream Fish

Estimates of predator feeding rates are important for understanding trophic dynamics. One common method for quantifying feeding rates in fishes combines mass‐based diet data with …

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Dan Preston
Quantifying predator dependence in the functional response of generalist predators featured image

Quantifying predator dependence in the functional response of generalist predators

A long‐standing debate concerns how functional responses are best described. Theory suggests that ratio dependence is consistent with many food web patterns left unexplained by …

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Mark Novak
Experimental demonstration of a trophic cascade in the Galápagos rocky subtidal:  Effects of consumer identity and behavior featured image

Experimental demonstration of a trophic cascade in the Galápagos rocky subtidal: Effects of consumer identity and behavior

In diverse tropical webs, trophic cascades are presumed to be rare, as species interactions may dampen top-down control and reduce their prevalence. To test this hypothesis, we …

jon-witman

Contributions of parasites to energy flow through a stream food web

Parasites are increasingly recognized for their significant roles in shaping community structure and ecosystem dynamics. Due to their cryptic nature, however, they are often …

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Tamara Layden
Bayesian characterization of uncertainty in species interaction strengths featured image

Bayesian characterization of uncertainty in species interaction strengths

Considerable effort has been devoted to the estimation of species interaction strengths. This effort has focused primarily on statistical significance testing and obtaining point …

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Chris Wolf

Using stable isotopes to quantify species interaction strengths

Understanding ecological interaction strengths is one of the main objectives of ecology. Recently, two methods for estimating interaction strengths of predator- prey interactions …

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Isaac Shepard
Characterizing species interactions to understand press perturbations: What is the community matrix? featured image

Characterizing species interactions to understand press perturbations: What is the community matrix?

The community matrix is among ecology's most important mathematical abstractions, formally encapsulating the interconnected network of effects that species have on one another's …

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Mark Novak
Trophic omnivory across a productivity gradient: intraguild predation theory and the structure and strength of species interactions featured image

Trophic omnivory across a productivity gradient: intraguild predation theory and the structure and strength of species interactions

Intraguild predation theory centres on two predictions: (i) for an omnivore and an intermediate predator (IG-prey) to coexist on shared resources, the IG-prey must be the superior …

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Mark Novak
Using the functional response of a consumer to predict biotic resistance to invasive prey featured image

Using the functional response of a consumer to predict biotic resistance to invasive prey

Predators sometimes provide biotic resistance against invasions by nonnative prey. Understanding and predicting the strength of biotic resistance remains a key challenge in …

laura-twardochleb
Probabilistic patterns of interaction: the effects of link-strength variability on food web structure featured image

Probabilistic patterns of interaction: the effects of link-strength variability on food web structure

Patterns of species interactions affect the dynamics of food webs. An important component of species interactions that is rarely considered with respect to food webs is the …

justin-yeakel
Merging Resource Availability with Isotope Mixing Models: The Role of Neutral Interaction Assumptions featured image

Merging Resource Availability with Isotope Mixing Models: The Role of Neutral Interaction Assumptions

Bayesian mixing models have allowed for the inclusion of uncertainty and prior information in the analysis of trophic interactions using stable isotopes. Formulating prior …

justin-yeakel
Using experimental indices to quantify the strength of species interactions featured image

Using experimental indices to quantify the strength of species interactions

Few methods for demonstrating the effects of species interactions rival that of the manipulative experiment (Kareiva and Levin 2002). The now commonly performed removal or …

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Mark Novak
Estimating interaction strengths in nature: experimental support for an observational approach featured image

Estimating interaction strengths in nature: experimental support for an observational approach

The complexity of food webs poses a significant hurdle for our growing understanding of the structure and dynamics of ecological communities. Empirical methods that measure the …

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Mark Novak

Trophic omnivory and the structure, strength, and nonlinear nature of species interactions across a productivity gradient

Two elements of food webs add significantly to their complexity: The presence of trophic omnivores and the nonlinear nature of predator-prey interactions. I introduce a new …

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Mark Novak
Estimating nonlinear interaction strengths: an observation-based method for species-rich food webs featured image

Estimating nonlinear interaction strengths: an observation-based method for species-rich food webs

Efforts to estimate the strength of species interactions in species‐rich, reticulate food webs have been hampered by the multitude of direct and indirect interactions such systems …

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Mark Novak