scholarly journals Metabolic adjustment enhances food web stability

2018 ◽  
Author(s):  
Pierre Quévreux ◽  
Ulrich Brose
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Nutrient Enrichment ◽  
Environmental Changes ◽  
Metabolic Rates ◽  
Adaptive Responses ◽  
Species Survival ◽  
Average Biomass ◽  
Adaptive Foraging ◽  
Metabolic Adjustment

AbstractUnderstanding ecosystem stability is one of the greatest challenges of ecology. Over several decades, it has been shown that allometric scaling of biological rates and feeding interactions provide stability to complex food web models. Moreover, introducing adaptive responses of organisms to environmental changes (e.g. like adaptive foraging that enables organisms to adapt their diets depending on resources abundance) improved species per-sistence in food webs. Here, we introduce the concept of metabolic adjustment, i.e. the ability of species to slow down their metabolic rates when facing starvation and to increase it in time of plenty. We study the reactions of such a model to nutrient enrichment and the adjustment speed of metabolic rates. We found that increasing nutrient enrichment leads to a paradox of enrichment (increase in biomasses and oscillation amplitudes and ultimately extinction of species) but metabolic adjustment stabilises the system by dampening the oscillations. Metabolic adjustment also increases the average biomass of the top predator in a tri-trophic food chain. In complex food webs, metabolic adjustment has a stabilising effect as it promotes species survival by creating a large diversity of metabolic rates. However, this stabilising effect is mitigated in enriched ecosystems. Phenotypic plasticity of organisms must be considered in food web models to better understand the response of organisms to their environment. As metabolic rate is central in describing biological rates, we must pay attention to its variations to fully understand the population dynamics of natural communities.

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 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 Less is worse than none: ineffective adaptive foraging can destabilise food webs

2021 ◽  
Author(s):  
Hsi-Cheng Ho ◽  
Samraat Pawar ◽  
Jason M. Tylianakis
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Optimal Foraging ◽  
Individual Species ◽  
Food Web Structure ◽  
Species Persistence ◽  
Cognitive Limitations ◽  
Web Structure ◽  
Adaptive Foraging ◽  
Adaptive Diet

Consumers can potentially adjust their diet in response to changing resource abundances, thereby achieving better foraging payoffs. Although previous work has explored how such adaptive foraging scales up to determine the structure and dynamics of food webs, consumers may not be able to perform perfect diet adjustment due to sensory or cognitive limitations. Whether the effectiveness of consumers' diet adjustment alters food-web consequences remains unclear. Here, we study how adaptive foraging, specifically the effectiveness (i.e. rate) with which consumers adjust their diet, influences the structure, dynamics, and overall species persistence in synthetic food webs. We model metabolically-constrained optimal foraging as the mechanistic basis of adaptive diet adjustment and ensuing population dynamics within food webs. We compare food-web dynamical outcomes among simulations sharing initial states but differing in the effectiveness of diet adjustment. We show that adaptive diet adjustment generally makes food-web structure resilient to species loss. Effective diet adjustment that maintains optimal foraging in the face of changing resource abundances facilitates species persistence in the community, particularly reducing the extinction of top consumers. However, a greater proportion of intermediate consumers goes extinct as optimal foraging becomes less-effective and, unexpectedly, slow diet adjustment leads to higher extinction rates than no diet adjustment at all. Therefore, food-web responses cannot be predicted from species' responses in isolation, as even less-effective adaptive foraging benefits individual species (better than non-adaptive) but can harm species' persistence in the food web as a whole (worse than non-adaptive). Whether adaptive foraging helps or harms species coexistence has been contradictory in literature. Our finding that it can stabilise or destabilise the food web depending on how effectively it is performed help reconcile this conflict. Inspired by our simulations, we deduce that there may exist a positive association between consumers' body size and adaptive-foraging effectiveness in the real world. We also infer that such effectiveness may be higher when consumers cognise complete information about their resources, or when trophic interactions are driven more by general traits than by specific trait-matching. We thereby suggest testable hypotheses on species persistence and food-web structure for future research, in both theoretical and empirical systems.

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.

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 Link flexibility: evidence for environment-dependent adaptive foraging in a food web time-series

Ecology ◽  
2016 ◽  
Vol 97 (6) ◽  
pp. 1381-1387 ◽  
Author(s):  
D. C. Henri ◽  
F. J. F. van Veen
Keyword(s):  
Time Series ◽  
Food Web ◽  
Link Flexibility ◽  
Adaptive Foraging

scholarly journals The use of DNA barcodes in food web construction—terrestrial and aquatic ecologists unite!

Genome ◽  
2016 ◽  
Vol 59 (9) ◽  
pp. 603-628 ◽  
Author(s):  
Tomas Roslin ◽  
Sanna Majaneva
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Taxonomic Resolution ◽  
Dna Barcodes ◽  
Food Web Structure ◽  
Web Studies ◽  
Web Structure ◽  
Asking Questions ◽  
Web Construction ◽  
Interaction Webs

By depicting who eats whom, food webs offer descriptions of how groupings in nature (typically species or populations) are linked to each other. For asking questions on how food webs are built and work, we need descriptions of food webs at different levels of resolution. DNA techniques provide opportunities for highly resolved webs. In this paper, we offer an exposé of how DNA-based techniques, and DNA barcodes in particular, have recently been used to construct food web structure in both terrestrial and aquatic systems. We highlight how such techniques can be applied to simultaneously improve the taxonomic resolution of the nodes of the web (i.e., the species), and the links between them (i.e., who eats whom). We end by proposing how DNA barcodes and DNA information may allow new approaches to the construction of larger interaction webs, and overcome some hurdles to achieving adequate sample size. Most importantly, we propose that the joint adoption and development of these techniques may serve to unite approaches to food web studies in aquatic and terrestrial systems—revealing the extent to which food webs in these environments are structured similarly to or differently from each other, and how they are linked by dispersal.

scholarly journals Nutrient Enrichment and Food Web Composition Affect Ecosystem Metabolism in an Experimental Seagrass Habitat

PLoS ONE ◽  
2009 ◽  
Vol 4 (10) ◽  
pp. e7473 ◽  
Author(s):  
Amanda C. Spivak ◽  
Elizabeth A. Canuel ◽  
J. Emmett Duffy ◽  
J. Paul Richardson
Keyword(s):  
Food Web ◽  
Nutrient Enrichment ◽  
Ecosystem Metabolism ◽  
Seagrass Habitat

scholarly journals Microbial food web dynamics along a soil chronosequence of a glacier forefield

2011 ◽  
Vol 8 (11) ◽  
pp. 3283-3294 ◽  
Author(s):  
J. Esperschütz ◽  
A. Pérez-de-Mora ◽  
K. Schreiner ◽  
G. Welzl ◽  
F. Buegger ◽  
...  
Keyword(s):  
Food Web ◽  
Microbial Communities ◽  
Food Webs ◽  
Litter Decomposition ◽  
Developmental Stages ◽  
Food Web Dynamics ◽  
Glacier Forefield ◽  
Microbial Food Webs ◽  
And Function ◽  
The 19Th Century

Abstract. Microbial food webs are critical for efficient nutrient turnover providing the basis for functional and stable ecosystems. However, the successional development of such microbial food webs and their role in "young" ecosystems is unclear. Due to a continuous glacier retreat since the middle of the 19th century, glacier forefields have expanded offering an excellent opportunity to study food web dynamics in soils at different developmental stages. In the present study, litter degradation and the corresponding C fluxes into microbial communities were investigated along the forefield of the Damma glacier (Switzerland). 13C-enriched litter of the pioneering plant Leucanthemopsis alpina (L.) Heywood was incorporated into the soil at sites that have been free from ice for approximately 10, 60, 100 and more than 700 years. The structure and function of microbial communities were identified by 13C analysis of phospholipid fatty acids (PLFA) and phospholipid ether lipids (PLEL). Results showed increasing microbial diversity and biomass, and enhanced proliferation of bacterial groups as ecosystem development progressed. Initially, litter decomposition proceeded faster at the more developed sites, but at the end of the experiment loss of litter mass was similar at all sites, once the more easily-degradable litter fraction was processed. As a result incorporation of 13C into microbial biomass was more evident during the first weeks of litter decomposition. 13C enrichments of both PLEL and PLFA biomarkers following litter incorporation were observed at all sites, suggesting similar microbial foodwebs at all stages of soil development. Nonetheless, the contribution of bacteria, especially actinomycetes to litter turnover became more pronounced as soil age increased in detriment of archaea, fungi and protozoa, more prominent in recently deglaciated terrain.

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