Many weak interactions and few strong; food-web feasibility depends on the combination of the strength of species’ interactions and their correct arrangement

Wootton, Kate L.; Stouffer, Daniel B.

doi:10.1007/s12080-015-0279-3

Cited by 52 publications

(60 citation statements)

References 75 publications

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“…One consequence may be decreased stability, because trophic niche 'compression' indicates that energy flow paths are more homogenous, potentially leading to less stable food-web structures (Layman, Quattrochi, et al, 2007;Rooney et al, 2006). This may be particularly profound where landscape disturbances alter the stabilizing influence of trophic interactions with differing strengths and distributions (Wootton & Stouffer, 2016). Whilst it seems likely that terrestrial resource subsidies help offset changes for higher trophic levels in our streams, trophic simplification may still render top predators more susceptible to population fluctuations and local extinctions (Layman, Quattrochi, et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

“…Greater horizontal diversity may increase biomass and resource uptake (Duffy et al, 2007), and increased vertical diversity links to theory about food-chain length and omnivory, with implications for trophic cascades (McHugh, McIntosh, & Jellyman, 2010). To investigate trophic interactions in food webs, increasingly sophisticated methods are being used including stable isotopes, molecular tools and network analyses (Raso et al, 2014;Wootton & Stouffer, 2016). However, empirical studies of food webs that use underlying environmental gradients remain rare, despite their potential to help disentangle causal relationships between changing habitat conditions and ecosystem functioning (Thompson et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Mechanisms of trophic niche compression: Evidence from landscape disturbance

Burdon

McIntosh

Harding

2019

Journal of Animal Ecology

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Natural and anthropogenic disturbances commonly alter patterns of biodiversity and ecosystem functioning. However, how networks of interacting species respond to these changes remains poorly understood. We described aquatic food webs using invertebrate and fish community composition, functional traits and stable isotopes from twelve agricultural streams along a landscape disturbance gradient. We predicted that excessive deposition of fine inorganic sediment (sedimentation) associated with agricultural activities would negatively influence aquatic trophic diversity (e.g. reduced vertical and horizontal trophic niche breadths). We hypothesized that multiple mechanisms might cause trophic niche ‘compression’, as indicated by changes in realized trophic roles. Food‐web properties based on consumer stable isotope data (δ13C and δ15N) showed that increasing sediment disturbance was associated with reduced trophic diversity. In particular, the aquatic invertebrate community occupied a smaller area in isotopic niche space along the sedimentation gradient that was best explained by a narrowing of the invertebrate community δ13C range. Decreased niche partitioning, driven by increasing habitat homogeneity, environmental filtering and resource scarcity all seemingly lead to greater trophic equivalency caused by the collapse of the autochthonous food‐web channel. Bayesian mixing‐model analyses supported this contention with invertebrate consumers increasingly reliant on detritus along the sedimentation gradient, and predatory invertebrates relying more on the prey using these basal resources. The narrowing of the fish community δ13C range along the sedimentation gradient contributed to an apparent ‘trophic shift’ towards terrestrial carbon, further indicating the loss of the autochthonous food‐web channel. On the vertical trophic niche axis, fish became increasingly separated from aquatic invertebrates with an increase in their estimated trophic position. In combination, these responses were most likely mediated through reduced fish densities and a diminished reliance on aquatic prey. Although species losses remain a major threat to ecosystem integrity, the functional roles of biota that persist dictate how food webs and ecosystem functioning respond to environmental change. Sedimentation was associated with nonlinear reductions in trophic diversity which could affect the functioning and stability of aquatic ecosystems. Our study helps explain how multiple mechanisms may radically reshape food‐web properties in response to this type of disturbance.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanisms of trophic niche compression: Evidence from landscape disturbance

Burdon

McIntosh

Harding

2019

Journal of Animal Ecology

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“…Knowing how recruitment interactions are structured in the network also allows predicting its stability (Levine et al., ; Wootton & Stouffer, ). The structure of RNs confers plant communities with a high resistance to species loss and allows the long‐term coexistence of many species.…”

Section: Introductionmentioning

confidence: 99%

Unifying facilitation and recruitment networks

Alcántara

Garrido

Montesinos‐Navarro

et al. 2019

J Vegetation Science

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Ecological network studies are providing important advances about the organization, stability and dynamics of ecological systems. However, the ecological networks approach is being integrated very slowly in plant community ecology, even though the first studies on plant facilitation networks (FNs) were published more than a decade ago. The study of interaction networks between established plants and plants recruiting beneath them, which we call Recruitment Networks (RNs), can provide new insights on mechanisms driving plant community structure and dynamics. RNs basically describe which plants recruit under which others, so they can be seen as a generalisation of the classic FNs since they do not imply any particular effect (positive, negative or neutral) of the established plants on recruiting ones. RNs summarise information on the structure of sapling banks. More importantly, the information included in RNs can be incorporated into models of replacement dynamics to evaluate how different aspects of network structure, or different mechanisms of network assembly, may affect plant community stability and species coexistence. To allow an efficient development of the study of FNs and RNs, here we unify concepts, synthesise current knowledge, clarify some conceptual issues, and propose basic methodological guidelines to standardise sampling methods that could make future studies of these networks directly comparable.

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“…Where weak links are paired with strong ones, perturbations to the community tend to dissipate. This reduces the likelihood of a permanent change to the system, stabilizing it (McCann et al 1998, Wootton andStouffer 2016). Due to their complex life cycles and dependence on specific hosts, parasites may be unusually vulnerable to perturbations to their communities (Lafferty and Kuris 2009).…”

Section: Discussionmentioning

confidence: 99%

Host taxonomy constrains the properties of trophic transmission routes for parasites in lake food webs

Cirtwill

Lagrue

Poulin

et al. 2017

Ecology

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Abstract. Some parasites move from one host to another via trophic transmission, the consumption of the parasite (inside its current host) by its future host. Feeding links among free-living species can thus be understood as potential transmission routes for parasites. As these links have different dynamic and structural properties, they may also vary in their effectiveness as trophic transmission routes. That is, some links may be better than others in allowing parasites to complete their complex life cycles. However, not all links are accessible to parasites as most are restricted to a small number of host taxa. This restriction means that differences between links involving host and non-host taxa must be considered when assessing whether transmission routes for parasites have different food web properties than other links. Here we use four New Zealand lake food webs to test whether link properties (contribution of a link to the predator's diet, prey abundance, prey biomass, amount of biomass transferred, centrality, and asymmetry) affect trophic transmission of parasites. Critically, we do this using both models that neglect the taxonomy of free-living species and models that explicitly include information about which free-living species are members of suitable host taxa. Although the best-fit model excluding taxonomic information suggested that transmission routes have different properties than other feeding links, when including taxonomy, the best-fit model included only an intercept. This means that the taxonomy of free-living species is a key determinant of parasite transmission routes and that food-web properties of transmission routes are constrained by the properties of host taxa. In particular, many intermediate hosts (prey) attain high biomasses and are involved in highly central links while links connecting intermediate to definitive (predator) hosts tend to be dynamically weak.

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Many weak interactions and few strong; food-web feasibility depends on the combination of the strength of species’ interactions and their correct arrangement

Cited by 52 publications

References 75 publications

Mechanisms of trophic niche compression: Evidence from landscape disturbance

Mechanisms of trophic niche compression: Evidence from landscape disturbance

Unifying facilitation and recruitment networks

Host taxonomy constrains the properties of trophic transmission routes for parasites in lake food webs

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