Single-species models for many-species food webs

Nature ◽  
2002 ◽  
Vol 417 (6887) ◽  
pp. 541-543 ◽  
Author(s):  
W. W. Murdoch ◽  
B. E. Kendall ◽  
R. M. Nisbet ◽  
C. J. Briggs ◽  
E. McCauley ◽  
...  
Keyword(s):  
Food Webs ◽  
Single Species

scholarly journals Limited evidence for sardine and anchovy asynchrony: re-examining an old story

2020 ◽  
Vol 287 (1922) ◽  
pp. 20192781
Author(s):  
Margaret C. Siple ◽  
Timothy E. Essington ◽  
Lewis A. K. Barnett ◽  
Mark D. Scheuerell
Keyword(s):  
Time Series ◽  
Food Webs ◽  
Low Frequency ◽  
Single Species ◽  
The Other ◽  
Generalist Predators ◽  
Frequency Variation ◽  
Limited Evidence ◽  
Short Time Series ◽  
Short Time

Asynchronous fluctuations in abundance between species with similar ecological roles can stabilize food webs and support coexistence. Sardine ( Sardinops spp.) and anchovy ( Engraulis spp.) have long been used as an example of this pattern because low-frequency variation in catches of these species appears to occur out of phase, suggesting that fisheries and generalist predators could be buffered against shifts in productivity of a single species. Using landings data and biomass and recruitment estimates from five regions, we find that species do not have equivalent peak abundances, suggesting that high abundance in one species does not compensate for low abundance in the other. We find that globally there is a stronger pattern of asynchrony in landings compared to biomass, such that landings data have exaggerated the patterns of asynchrony. Finally, we show that power to detect decadal asynchrony is poor, requiring a time series more than twice the length of the period of fluctuation. These results indicate that it is unlikely that the dynamics of these two species are compensatory enough to buffer fisheries and predators from changes in abundance, and that the measurements of asynchrony have largely been a statistical artefact of using short time series and landings data to infer ecology.

scholarly journals Comparing community response indices in aquatic food web models

2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Ágnes Móréh ◽  
Ferenc Jordán
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Aquatic Ecosystems ◽  
Single Species ◽  
Community Response ◽  
Individual Species ◽  
Relative Importance ◽  
Response Functions ◽  
Local Perturbations ◽  
Aquatic Food

Aquatic ecosystems face several major challenges from the introduction and invasion of species, to overfishing. In order to better manage these situations, we need predictive models, where diverse scenarios can be simulated and tested. One key challenge to address is how to quantify the relationships between single-species disturbances and their multispecies effects. Mapping the spread of direct and indirect effects in food webs helps to link species to communities. Since food webs are complex networks of interactions, it is typically not easy to make predictions, so modelling and simulation may help to reveal general patterns. In food web simulations, one can quantify the effects of local perturbations on other species, i.e., community response. This may provide information about the relative importance of individual species and it is also useful to assess the vulnerability of the whole community to local changes. However, community response can be measured in several ways and various response functions give different results. In order to better understand their similarities and differences, we present a comparative study on a reasonable set of community response functions in food web simulations. These results contribute to build more predictive, multi-species models for systems-based conservation and management.

scholarly journals Environmental variability uncovers disruptive effects of species' interactions on population dynamics

2015 ◽  
Vol 282 (1812) ◽  
pp. 20151126 ◽  
Author(s):  
Sara Gudmundson ◽  
Anna Eklöf ◽  
Uno Wennergren
Keyword(s):  
Population Dynamics ◽  
White Noise ◽  
Food Webs ◽  
Species Interactions ◽  
Environmental Variability ◽  
Single Species ◽  
Ecological Communities ◽  
Species Response ◽  
To Come ◽  
Isolated Species

How species respond to changes in environmental variability has been shown for single species, but the question remains whether these results are transferable to species when incorporated in ecological communities. Here, we address this issue by analysing the same species exposed to a range of environmental variabilities when (i) isolated or (ii) embedded in a food web. We find that all species in food webs exposed to temporally uncorrelated environments (white noise) show the same type of dynamics as isolated species, whereas species in food webs exposed to positively autocorrelated environments (red noise) can respond completely differently compared with isolated species. This is owing to species following their equilibrium densities in a positively autocorrelated environment that in turn enables species–species interactions to come into play. Our results give new insights into species' response to environmental variation. They especially highlight the importance of considering both species' interactions and environmental autocorrelation when studying population dynamics in a fluctuating environment.

In vitro assembly of 2-D crystals from partially purified EA1 protein secreted by Bacillus anthracis strain Delta Sterne-1

1994 ◽  
Vol 52 ◽  
pp. 276-277
Author(s):  
Mary Beth Downs ◽  
Wilson Ribot ◽  
Joseph W. Farchaus
Keyword(s):  
Cell Wall ◽  
Molecular Sieves ◽  
Cell Envelope ◽  
Single Species ◽  
Supporting Cell ◽  
Surface Layers ◽  
Rabbit Igg ◽  
In Vitro Assembly ◽  
Covalently Linked

Many bacteria possess surface layers (S-layers) that consist of a two-dimensional protein lattice external to the cell envelope. These S-layer arrays are usually composed of a single species of protein or glycoprotein and are not covalently linked to the underlying cell wall. When removed from the cell, S-layer proteins often reassemble into a lattice identical to that found on the cell, even without supporting cell wall fragments. S-layers exist at the interface between the cell and its environment and probably serve as molecular sieves that exclude destructive macromolecules while allowing passage of small nutrients and secreted proteins. Some S-layers are refractory to ingestion by macrophages and, generally, bacteria are more virulent when S-layers are present.When grown in rich medium under aerobic conditions, B. anthracis strain Delta Sterne-1 secretes large amounts of a proteinaceous extractable antigen 1 (EA1) into the growth medium. Immunocytochemistry with rabbit polyclonal anti-EAl antibody made against the secreted protein and gold-conjugated goat anti-rabbit IgG showed that EAI was localized at the cell surface (fig 1), which suggests its role as an S-layer protein.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

A STUDY ON ICHTHYO-DIVERSITY OF MUNTJIBPUR POND OF ALLAHABAD (U.P.) INDIA

2017 ◽  
Vol 23 (1) ◽  
Author(s):  
ASHOK KUMAR VERMA
Keyword(s):  
Single Species ◽  
Single Genus ◽  
One Year

An attempt was made to find the ichthyo-diversity of Muntjibpur pond of Allahabad. Systematic surveys were conducted during a period of one year. A total of 13 species of fishes belonging to 12 genera, 8 families and 5 orders were identified. Siluriformes order is represented by 5 genera and 5 species while Cypriniformes order by 4 genera and 5 species. Each of the orders Clupeiformes, Osteoglossiformes and Ophiocephaliformes is represented by single genus and single species.

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