Food web functional responses

Frontiers in Ecology and Evolution, Journal Year: 2022, Volume and Issue: 10

Published: Aug. 9, 2022

This article reviews the nature of functional responses that have commonly been used to represent feeding relationships in ecological literature. It compares these with range response forms are likely characterize species natural communities. The latter set involves many more variables. history models, and examines previous work has allowed a predator single type prey depend on additional variables beyond abundance type. While number complex discussed over years, affecting rates still typically omitted from models food webs. influences trophic levels above or below particularly be ignored, although data suggested they can large effects response. adaptive behavior time-scale measurement also too often ignored. Some known unknown consequences omissions discussed.

Language: Английский

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A mechanistic model of functional response provides new insights into indirect interactions among arctic tundra prey

Ecology, Journal Year: 2022, Volume and Issue: 103(8)

Published: April 25, 2022

Prey handling processes are considered a dominant mechanism leading to short-term positive indirect effects between prey that share predator. However, growing body of research indicates predators not necessarily limited by such in the wild. Density-dependent changes predator foraging behavior can also generate but they rarely included as explicit functions densities functional response models. With aim untangling proximate mechanisms species interactions natural communities and improving our ability quantify interaction strength, we extended multi-prey version Holling disk equation including density-dependent behavior. Our model, based on traits behavior, was inspired vertebrate community arctic tundra, where main (the fox) is an active forager feeding primarily cyclic small rodent (lemming) eggs various tundra-nesting bird species. Short-term lemmings birds have been documented over circumpolar Arctic underlying remain poorly understood. We used unique data set, containing high-frequency GPS tracking, accelerometer, behavioral, experimental parameterize 15-year time series nesting success evaluate strength found (1) play minor role system (2) fox daily activity budget distance traveled partly explain predation release observed during lemming peaks. These adjustments with respect density thus appear commonly reported among tundra prey. components little studied deserve more attention improve interactions.

Language: Английский

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Predator feeding rates may often be unsaturated under typical prey densities

Ecology Letters, Journal Year: 2022, Volume and Issue: 26(2), P. 302 - 312

Published: Dec. 5, 2022

Predator feeding rates (described by their functional response) must saturate at high prey densities. Although thousands of manipulative response experiments show rate saturation densities under controlled conditions, it remains unclear how saturated are natural The general degree has important implications for the processes determining and they respond to changes in density. To address this, we linked two databases-one parameters one on mass-abundance scaling-through mass calculate a index. We find that: (1) may commonly be unsaturated (2) varies with predator taxonomic identities body sizes, habitat, interaction dimension temperature. These results reshape our conceptualisation predator-prey interactions nature suggest new research ecological evolutionary rates.

Language: Английский

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Toward a modular theory of trophic interactions

Authorea (Authorea), Journal Year: 2024, Volume and Issue: unknown

Published: Jan. 30, 2024

Species traits and environmental conditions determine the existence strength of trophic interactions, but how they do so is poorly understood. To enable informed inclusion such driving factors in dynamic trophic-interaction models, we revisit expand functional numerical response functions using a modular approach which readily integrated into existing models. We divide interaction between predator prey eight steps: (1) search, (2) detection, (3) attack decision, (4) pursuit, (5) subjugation, (6) ingestion, (7) digestion, (8) nutrient allocation. Formulating this as functional-response function, build general dynamical model where interactions can be explicitly parameterized for multiple factors. then concretize by outlining specific community modeled selecting key modules (steps) parameterizing them relevant This exemplify terrestrial arthropods empirical data on body size temperature responses. With species at core dynamics, our allows quantification comparisons importance different steps, traits, abiotic across ecosystems types, provides powerful tool trait-based prediction food-web structure dynamics.

Language: Английский

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Top-down origins of the predator-prey power law?

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: April 6, 2024

Abstract The ratio of predator-to-prey biomass density is not constant along ecological gradients: denser ecosystems tend to have fewer predators per prey, following a scaling relation known as the “predator-prey power law”. origin this surprisingly general pattern, particularly its connection with environmental factors and predator-prey dynamics, unknown. Here, we explore some ways that sublinear could emerge from density-dependent interactions among between prey (which call top-down origin), rather than (bottom-up origin) proposed in Hatton et al . (2015). We combine two complementary theoretical approaches. First, use phenomenological differential equations role parameters dynamical properties controlling ratio. Second, simulate an agent-based model tunable predator self-regulation investigate emergence plausible microscopic rules. While cannot rule out alternative explanations, our results show mechanisms relative predation intraspecific interactions, including saturation, interference, self-regulation, offer potential explanations for law.

Language: Английский

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Towards understanding interactions in a complex world: Design and analysis of multi‐species functional response experiments

Methods in Ecology and Evolution, Journal Year: 2024, Volume and Issue: 15(9), P. 1704 - 1719

Published: June 23, 2024

Abstract The functional response describes feeding rates of consumers as a function resource density. While models for on single species are well studied and supported by large body empirical research, multiple ubiquitous in nature. However, laboratory experiments designed parameterizing multi‐species responses (MSFR) extremely rare, mainly due to logistical challenges the non‐trivial nature their statistical analysis. Here, we describe how these can be fitted data Bayesian framework. Specifically, address problem prey depletion during experiments, which accounted through dynamical modelling. In comprehensive simulation study, test effects experimental design, sample size noise level identifiability four distinct MSFR models. Additionally, demonstrate method's versatility applying it list datasets. We identify designs trials that produce most accurate parameter estimates two‐ three‐prey scenarios. Although introduces systematic bias estimates, model selection performs surprisingly MSFRs, almost always identifying correct even small This flexible framework allows simultaneous analysis from both single‐ multi‐prey scenarios, either with or without depletion. will help elucidate mechanisms such selectivity, switching implications food web stability biodiversity. Our approach equips researchers appropriate tools improve understanding interactions complex ecosystems.

Language: Английский

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Quantifying predator functional responses under field conditions reveals interactive effects of temperature and interference with sex and stage

Journal of Animal Ecology, Journal Year: 2022, Volume and Issue: 91(7), P. 1431 - 1443

Published: April 15, 2022

Predator functional responses describe predator feeding rates and are central to predator-prey theory. Originally defined as the relationship between prey densities, it is now well known that shaped by a multitude of factors. However, much our knowledge about how these factors influence based on laboratory studies generally logistically constrained examining only few simultaneously have unclear links conditions organisms experience in field. We apply an observational approach for measuring understand sex/stage differences, temperature densities interact response zebra jumping spiders midges under natural conditions. used field surveys infer their examine relationships rates, sex/stage, midge density, density using generalized additive models. then supported models fit parametric data. find follow some expectations from previous such increasing with body size decreasing densities. contrast results, results also show lack spider differential decreases females juveniles different sexes/stages. Our illustrate multidimensional nature settings reveal influencing can one another through behaviour morphology. Further investigating multiple mechanisms will increase understanding drivers interaction strengths consequences communities ecosystems.

Language: Английский

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Ratio-Dependence in Predator-Prey Systems as an Edge and Basic Minimal Model of Predator Interference

Frontiers in Ecology and Evolution, Journal Year: 2021, Volume and Issue: 9

Published: Dec. 7, 2021

The functional response (trophic function or individual ration) quantifies the average amount of prey consumed per unit time by a single predator. Since seminal Lotka-Volterra model, it is key element predation theory. Holling has enhanced theory classifying prey-dependent responses into three types that long remained generally accepted basis modeling predator-prey interactions. However, contradictions between observed dynamics natural ecosystems and properties models with Holling-type trophic functions, such as paradox enrichment, biological control, paradoxical enrichment mediated cascades, required further improvement This led to idea inclusion predator interference function. Various depending on both densities have been suggested compared in their performance fit data. At end 1980s, Arditi Ginzburg stimulated lively debate having strong impact They proposed concept spectrum predator-dependent two opposite edges being ratio-dependent cases, they revising using edge null model interference. Ratio-dependence offers simplest way accounting for mutual models, resolving abovementioned observations. Depending practical needs availability observations, more detailed can be built this theoretical basis.

Language: Английский

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Functional Responses Shape Node and Network Level Properties of a Simplified Boreal Food Web

Frontiers in Ecology and Evolution, Journal Year: 2022, Volume and Issue: 10

Published: May 20, 2022

Ecological communities are fundamentally connected through a network of trophic interactions that often complex and difficult to model. Substantial variation exists in the nature magnitude these across various predators prey time. However, empirical data needed characterize relationships obtain natural systems, even for relatively simple food webs. Consequently, prey-dependent specifically hyperbolic form (Holling’s Type II), which consumption increases with density but ultimately becomes saturated or limited by time spent handling prey, most widely used albeit without knowledge their appropriateness. Here, we investigate sensitivity simplified web model natural, boreal system Kluane region Yukon, Canada type functional response used. Intensive study this community has permitted best-fit be determined, comprise linear (type I), sigmoidal III), prey- ratio-dependent relationships, inverse where kill rates alternate driven densities focal prey. We compare node- network-level properties interaction strengths estimated using responses one exclusively responses. show alone fail capture important ecological such as switching, surplus killing caching, predator interference, turn affect estimates cumulative rates, vulnerability generality predators, connectance. Exclusive use also affected trends observed metrics over underestimated annual several metrics, is given typically short periods. Our findings highlight need more comprehensive research aimed at characterizing when modeling predator-prey structure function, work toward mechanistic understanding linking dynamics systems.

Language: Английский

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Widespread analytical pitfalls in empirical coexistence studies and a checklist for improving their statistical robustness

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2023, Volume and Issue: unknown

Published: July 4, 2023

Abstract Modern Coexistence Theory (MCT) offers a conceptually straightforward approach for connecting empirical observations with an elegant theoretical framework, gaining popularity rapidly over the past decade. However, beneath this surface-level simplicity lie various assumptions and subjective choices made during data analysis. These can lead researchers to draw qualitatively different conclusions from same set of experiments. As predictions MCT studies are often treated as outcomes, many readers reviewers may not be familiar framework’s assumptions, there is particular risk “researcher degrees freedom” inflating confidence in results, thereby affecting reproducibility predictive power. To tackle these concerns, we introduce checklist consisting statistical best-practices promote more robust applications MCT. Our recommendations organised into four categories: presentation sharing raw data, testing model fits, managing uncertainty associated coefficients, incorporating coexistence predictions. We surveyed published 15 years discovered high degree variation level rigour adherence best practices. present case illustrate dependence results on seemingly innocuous among competition structure error distributions, which some cases reversed predicted outcomes. demonstrate how analytical approaches profoundly alter interpretation experimental underscoring importance carefully considering thoroughly justifying each step taken analysis pathway. serves resource authors alike, providing guidance strengthen foundation analyses. field shifts descriptive, trailblazing phase stage consolidation, emphasise need caution when building upon findings earlier studies. ensure that progress ecological based reliable evidence, it crucial subject our predictions, conclusions, generalizability rigorous assessment than currently trend.

Language: Английский

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