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opencc-zeroJul 2020View details →

Data from: How geographic productivity patterns affect food-web evolution

This dataset contains the generated data analyzed in the manuscript, as well as the code for analyzing the generated data. It also contains the code used to generate the data.

Priority determines tribolium competitive outcome in a food-limited environment

Flour beetles are a classic model system for studying competitive dynamics between species occupying the same ecological niche. Competitive performance is often interpreted in terms of biological species traits such as fecundity, resource use, and predation. However, many studies only measure competitive ability when species enter an environment simultaneously, and thus do not consider how the relative timing of species' arrival may determine competitive outcome (i.e., priority effects). Whether priority effects may influence competition in Tribolium remains to be tested. The present study examined the importance of priority effects in competitions between two common species of flour beetle (Coleoptera: Tenebrionidae): Tribolium castaneum and T. confusum. To investigate whether priority effects confer competitive advantages to Tribolium beetles, relative introduction times of T. castaneum and T. confusum to competitive arenas were manipulated, and adult populations were measured for seven months. Four important patterns were noted: (1) Tribolium species given two-weeks priority access to experimental arenas attained larger populations than their late-arriving competitor, (2) when founding adults were introduced simultaneously, T. castaneum was competitively dominant, (3) T. castaneum benefited more from priority arrival than T. confusum, and (4) available bran resources largely predicted population decline in adult beetles toward the end of the experiment. These results suggest competitive outcome in Tribolium is not always predicted by species' identity, and that performance could instead be determined by the timing of species' arrivals and available resources.

Reproduction affects immune defenses in the guinea pig even under ad libitum food

Reproduction is one of the most costly processes in the life of an animal. Life history theory assumes that when resources are limiting allocation to reproduction will reduce allocation to other essential processes thereby inducing costs of reproduction. The immune system is vital for survival. If reproduction reduces investment in immune function, this could increase the risk of disease, morbidity and mortality. We here test in the guinea pig, if even under ad libitum food conditions, pregnancy and lactation reduce the activity of the adaptive and innate immune system compared to the reaction of non-reproducing animals. In response to a challenge with keyhole limpet haemocyanin the antibody-mediated adaptive immunity during pregnancy and lactation was reduced. Pregnant and lactating females showed higher levels of bacterial killing activity, an integrated measure of innate immunity, than non-reproducing females. However, two major effectors of the innate immunity, the natural antibody and the complement of pregnant and lactating females showed lower levels than in non-reproducing females. Pregnant and lactating females did not differ significantly in the expressed levels of innate immunity. Our results indicate that changes in the immune response during reproduction are physiological adjustments to predictable allocation problems, because they happen even under ad libitum food availability.

Contribution submitted by Antonella Garzelli for the Public consultation on the draft risk assessment of glycoalkaloids in feed and food, in particular in potatoes and potato-derived products

The European Food Safety Authority (EFSA) carried out a public consultation, from 27 February 2020 until 15 April 2020, to receive input from interested parties – organizations or private citizens - on a draft scientific opinion on the risks for animal and human health related to the presence of glycoalkaloids in feed and food, in particular in potatoes and potato-derived products. The draft scientific opinion was prepared by the EFSA Panel on Contaminants in the Food Chain (CONTAM Panel), supported by the Working Group on Glycoalkaloids in feed and food. EFSA used the EU survey tool to receive comments on the draft scientific opinion, and the way these comments were considered for the finalisation of the opinion is described in the Technical Report available at: <a href="https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fefsa.onlinelibrary.wiley.com%2Fdoi%2F10.2903%2Fsp.efsa.2020.EN-1905&data=02%7C01%7C%7C242adcee21744b01890408d82cba24b4%7C406a174be31548bdaa0acdaddc44250b%7C1%7C0%7C637308525272584775&sdata=97Tc3%2FrT1SXtzIN14PCCvUv0OYyaiSO1H76iezwqvnQ%3D&reserved=0">https://efsa.onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2020.EN-1905</a>. Some contributors also attached files to the comments submitted via the EU survey tool. For transparency reasons these files are made available in the public domain as Zenodo uploads.

Contribution submitted by STARCH EU for the Public consultation on the draft risk assessment of glycoalkaloids in feed and food, in particular in potatoes and potato-derived products

Contribution submitted by Matthew Walker for the Public consultation on the draft risk assessment of glycoalkaloids in feed and food, in particular in potatoes and potato-derived products

Data from: Experimental reduction of plant abundance changes interaction frequency of a tri-trophic micro-food web: contrasting responses of generalists and specialists

1. Species abundance is vulnerable to climate change and anthropogenic impact. Although numerous studies have examined the food web response to species loss, their response (e.g. in network topology and interaction frequency) to changes in species abundance has received little attention. 2. We experimentally reduced the abundance (by ca. 60%) of one host plant species (Saussurea nigrescens) in a tri-trophic micro-food web consisting of two common Asteraceae species (S. nigrescens and Anaphalis flavescens), their pre-dispersal seed predators (tephritid flies), and the parasitoid wasps that feed on these seed predators. 3. The neutral process hypothesis posits that network topology and interaction frequency are determined by the relative abundances of the participating species. Accordingly, we hypothesized that interaction frequency (indicated by the rate of flies infesting plants and of parasitoid wasps parasitizing flies) would decrease with decreasing abundance of host plant abundance. 4. Consistent with the neutral process hypothesis, abundance reduction significantly decreased the rate of generalist flies infesting the manipulated plant host species, but increased the rate on unmanipulated plant species. In contrast, abundance reduction significantly increased the rate of specialist flies infesting the manipulated species, but it had no demonstrable effect on the specialists on the unmanipulated plant host. 5. Moreover, abundance reduction significantly increased the rate of parasitoid wasps (as a species group) parasitizing flies in the manipulated species but decreased the rate of the unmanipulated species. These results were not attributable to neutral processes, but can be explained only by adaptive foraging theory. In addition, experimental manipulation did not shift the qualitative presence/absence of the linkages in the micro-food web, and the change in the abundance of both fly and wasp species was smaller than the abundance changes of the manipulated plant species. 6. These observations are interpreted to indicate that both neutral process and/or adaptive foraging likely contributed to food web stability in responses to changes in species abundance. Because species abundance is vulnerable to abiotic and biotic environmental changes, we suggest more research should be conducted to understand how food webs respond to climate change and anthropogenic disturbance.

Data for: Risk in the circular food economy: Glyphosate-based herbicide residues in manure fertilizers decrease crop yield

Glyphosate-based herbicides (GBHs) are the most frequently used herbicides globally. They were launched as a safe solution for weed control, but recently, an increasing number of studies have shown the existence of GBH residues and highlighted the associated risks they pose throughout ecosystems. Conventional agricultural practices often include the use of GBHs, and the use of glyphosate-resistant genetically modified crops is largely based on the application of glyphosate, which increases the likelihood of its residues ending up in animal feed. These residues persist throughout the digestive process of production animals and accumulate in their excretion products. The poultry industry, in particular, is rapidly growing, and excreted products are used as plant fertilizers in line with circular food economy practices. We studied the potential effects of unintentional glyphosate contamination on an agronomically important forage grass, meadow fescue (Festuca pratensis) and a horticulturally important strawberry (Fragaria x vescana) using glyphosate residues containing poultry manure as a plant fertilizer in a common garden experiment. Glyphosate in the manure decreased plant growth in both species and vegetative reproduction in F. x vescana. Furthermore, our results indicate that glyphosate residues in organic fertilizers might have indirect effects on sexual reproduction in F. pratensis and herbivory in F. x vescana because they positively correlate with plant size. Our results highlight that glyphosate can be unintentionally spread via organic fertilizer, counteracting its ability to promote plant growth.

Data from: Communities at the extreme: aquatic food webs in desert landscapes

Studying food webs across contrasting abiotic conditions is an important tool in understanding how environmental variability impacts community structure and ecosystem dynamics. The study of extreme environments provides insight into community-wide level responses to environmental pressures with relevance to the future management of aquatic ecosystems. In the western Lake Eyre Basin of arid Australia, there are two characteristic and contrasting aquatic habitats: springs and rivers. Permanent isolated Great Artesian Basin springs represent hydrologically persistent environments in an arid desert landscape. In contrast, hydrologically variable river waterholes are ephemeral in space and time. We comprehensively sampled aquatic assemblages in contrasting ecosystem types to assess patterns in community composition and to quantify food web attributes with stable isotopes. Springs and rivers were found to have markedly different invertebrate communities, with rivers dominated by more dispersive species and springs associated with species that show high local endemism. Qualitative assessment of basal resources shows autochthonous carbon appears be a key basal resource in both types of habitat, although the particular sources differed between habitats. Food-web variables such as trophic length, trophic breadth and community isotopic niche size were relatively similar in the two habitat types. The basis for the similarity in food-web structure despite differences in community composition appears to be broader isotopic niches for predatory invertebrates and fish in springs as compared with rivers. In contrast to published theory, our findings suggest that the food webs of the hydrologically variable river sites may show less dietary generalisation and more compact food-web modules than in springs.

Data from: Extra food provisioning reduces extra-pair paternity in the lesser kestrel (Falco naumanni)

Female promiscuity can function to acquire both direct and indirect benefits from their social mate and extra-pair males. In many raptor species, intense mate-feeding significantly contributes to female energy requirements before and during egg laying. Moreover, females may use mate-feeding effort to assess male quality. In this study of the lesser kestrel (Falco naumanni), we aimed at experimentally manipulating the female's perception of mate quality by providing females with extra food during egg laying, and evaluated the occurrence of extra-pair paternity in food-supplemented and control broods by parentage analyses. No extra-pair offspring (EPO) was found among 19 food-supplemented broods, whereas EPO occurred in five out of 17 control broods. No significant differences in morphological traits, body condition and reproductive success were found between faithful and unfaithful females. However, clutches containing EPO were laid later in the breeding season. Moreover, un-cuckolded males had longer tarsi than cuckolded ones, indicating larger body size. Hence, extra food provisioning and early breeding reduced the occurrence of EPO in lesser kestrels. In addition, we confirmed the occurrence of intraspecific brood parasitism, as five nestlings were not the offspring of the brooding female. The results of our food-provisioning experiment support the idea that mate-feeding ability is a reliable indicator of male quality, and are in accordance with the hypothesis that male mate-feeding behaviour is a sexually selected trait.

opencc-zeroDec 2019View details →

Prey-switching does not protect a generalist turtle from bioenergetic consequences when its preferred food is scarce

Background: Optimal foraging theory explains how animals make foraging decisions based on the availability, nutritional content, and handling times of different food types. Generalists solve this problem by consuming a variety of food types, and switch between them with relative ease. Specialists eat few food types, and may starve if those food types are not available. We integrated stable isotope analyses with previously-published stomach contents and environmental data to investigate how the foraging ecologies of three sympatric freshwater turtle species vary across four wetlands that differ in turbidity and primary producer abundance. Results: We found that the generalist Emydura macquarii consumes a varied diet (but mostly filamentous green algae) when primary producers are available and water is clear, but switches to a more carnivorous diet when primary producers are scarce, following the predictions of optimal foraging theory. In contrast, two more-specialized carnivorous species, Chelodina expansa and Chelodina longicollis, do not differ in diet across wetlands, and interspecific competition may increase where E. macquarii is carnivorous. When forced to be more carnivorous, E. macquarii exhibits higher rates of empty stomachs, and female turtles have reduced body condition, but neither Chelodina species are affected. Conclusions: Our results provide support for optimal foraging theory, but also show that the ability to change diet does not protect the generalist from experiencing lower foraging success when its preferred food is rare, with direct consequences for their energy budgets. Our results have conservation implications because wetlands in the Murray-Darling river system are increasingly turbid and have low macrophyte abundance, and all three species are declining.

Predator population size structure alters consumption of prey from epigeic and grazing food webs

Numerous studies have found that predators can suppress prey densities and thereby impact important ecosystem processes such as plant productivity and decomposition. However, prey suppression by spiders can be highly variable. Unlike predators that feed on prey within a single energy channel, spiders often consume prey from asynchronous energy channels, such as grazing (live plant) and epigeic (soil surface) channels. Spiders undergo few life cycle changes and thus appear to be ideally suited to link energy channels, but ontogenetic diet shifts in spiders have received little attention. For example, spider use of different food channels may be highly specialized in different life stages and thus a species may be a multichannel omnivore only when we consider all life stages. Using stable isotopes, we investigated whether wolf spider (Pardosa littoralis, henceforth Pardosa) prey consumption is driven by changes in spider size. Small spiders obtained > 80% of their prey from the epigeic channel, whereas larger spiders used grazing and epigeic prey almost equally. Changes in prey consumption were not driven by changes in prey density, but by changes in prey use by different spider size classes. Thus, because the population size structure of Pardosa changes dramatically over the growing season, changes in spider size may have important implications for the strength of trophic cascades. Our research demonstrates that life history can be an important component of predator diet, which may in turn affect community- and ecosystem-level processes.

The invasive pathogenic fungus of ash trees alters arthropod predator – prey food webs in forest plantations

The data set contains data on: 1] Prey type and size (sheet1: prey type and size). In the cells, prey length in mm is provided for each prey item. NA is stated for a prey item that could not be measured. In this sheet, the plot ids and the spider ids are also stated, which enables connection with other sheets. Note: more prey items caught by an individual are stated in one row if they are of different type. Prey items of a same type caught by an individual are itemized in more rows. 2] Information about spider individuals (sheet2: spiders). For each spider individual, it is provided its id, so it can be connected with sheet 1, plot id where it was collected, when it was collected (month), web type, and prosoma length (mm).  3] Characteristics of sampling plots (sheet3: environmental data). It is provided plot id, age, infestation degree by Hymenoscyphus fraxineus, canopy openness, shrub coverage, and herb coverage. 4] Potential prey of spiders (sheet 4: potential prey). Standardized no. of prey per trap (20 x 15 cm, both sides were sticky) in each plot.

opencc-zeroSep 2020View details →

Data from: Seabirds vary responses to supplemental food under dynamic natural prey availability and feeding aggregation composition

While foraging, a predator can feed solitarily or in a group. The net energy gain of joining a group is predicted to vary with prey patch quality, species-specific prey capture behavior and the size and species composition of the predator group. In coastal Newfoundland, Canada, capelin (Mallotus villosus), a key forage fish, migrates inshore to spawn during the summer, resulting in a dramatic shift in prey availability. During July-August, 2015-2017, we examined the numerical and behavioral responses of procellarid (Great Shearwater Ardenna gravis, Sooty Shearwater A. grisea, Northern Fulmar Fulmarus glacialis) and gull species (Herring Gull Larus argentatus, Great Black-backed Gull L. marinus) to fish offal under varying capelin availability as well as flock size and composition using an at-sea experiment on the northeast Newfoundland coast. The experiment consisted of providing a offal every 30 s (10-min experimental period), along with 10-min control periods before and after. We recorded the species-specific number of birds on the water, the number of birds simultaneously attempting to capture offal, and the number of successful attempts ('foraging success'). The number of birds on the water was lower during high capelin availability for all species, except for Northern Fulmar. The number of conspecifics simultaneously attempting increased with the number of conspecifics on the water, but plateaued at different numbers (4-17) for each species. The species-specific proportion of successful attempts (i.e. 'foraging success') varied with flock size and composition (i.e. number of conspecifics, heterospecifics, species). Foraging success of Herring Gulls and fulmars were moderately affected by flock size and composition, suggesting that they may be dominant competitors. Findings suggest that seabirds rely more heavily on supplemental food sources, such as fisheries discards and offal, when natural prey availability declines, potentially resulting in a higher risk of by-catch during fisheries activities as forage fish stocks decline.

opencc-zeroSep 2020View details →

Data from: Food and habitat provisions jointly determine competitive and facilitative interactions among distantly related herbivores

1. Interactions between distantly related herbivores exert powerful influences on ecosystems, but most studies to date have only considered unidirectional effects. Few have simultaneously examined the mutual effects that vertebrate herbivores and insect herbivores have on one another. 2. We conducted a set of manipulative experiments to evaluate the potential competition and facilitation between two pairs of distantly related herbivore taxa: an insect caterpillar (Gynaephora alpherakii) and two large vertebrate herbivores, yak (Bos grunniens) and Tibetan sheep (Ovis aries tibetica). 3. We found that these large herbivores consistently increased the density of caterpillars likely by improving the habitat for caterpillars. The caterpillars, in turn, decreased yak but increased Tibetan sheep foraging time and intake bites by differently changing available food resources of the two large herbivores. Diet preferences of herbivores modified the habitat and food resources, thereby causing a diet-mediated competition between yak and caterpillars, and facilitation between sheep and caterpillars. The vertebrate herbivores non-feeding upon Lamiophlomis rotata and Gentiana straminea, the caterpillars preferred habitat, increased densities of the two plant species, thus favoring the caterpillars. In turn, the caterpillar preference for Kobresia pygmaea, significantly reduced food resources for yak, while promoted food resources (multiple forbs) for sheep. 4. Synthesis. Our study indicates that two different mechanisms (the changes in habitat and food availability) induced by herbivore foraging jointly determine competitive and facilitative interactions between distantly related herbivore species. We also suggest that examining the bidirectional effects between herbivores offers a better understanding of competition and facilitation in terrestrial animal communities.

opencc-by-4.0Mar 2018View details →

Model-based analysis of postprandial glycemic response dynamics for different types of food

Background & aims Knowledge of postprandial glycemic response (PPGR) dynamics is important in nutrition management and diabetes research, care and (self)management. In daily life, food intake is the most important factor influencing the occurrence of hyperglycemia. However, the large variability in PPGR dynamics to different types of food is inadequately predicted by existing glycemic measures. The objective of this study was therefore to quantitatively describe PPGR dynamics using a systems approach. Methods Postprandial glucose and insulin data were collected from literature for many different food products and mixed meals. The predictive value of existing measures, such as the Glycemic Index, was evaluated. A physiology-based dynamic model was used to reconstruct the full postprandial response profiles of both glucose and insulin simultaneously. Results We collected a large range of postprandial glucose and insulin dynamics for 53 common food products and mixed meals. Currently available glycemic measures were found to be inadequate to describe the heterogeneity in postprandial dynamics. By estimating model parameters from glucose and insulin data, the physiology-based dynamic model accurately describes the measured data whilst adhering to physiological constraints. Conclusions The physiology-based dynamic model provides a systematic framework to analyze postprandial glucose and insulin profiles. By changing parameter values the model can be adjusted to simulate impaired glucose tolerance and insulin resistance.

opencc-by-4.0Sep 2020View details →

Dataset of chemical concentration levels in food from the second French total diet study

Information about the TDS2 data set 1. Description of the study The TDSs are based on a standardized method and have been recommended by the World Health Organization (WHO) and the European Food Safety Authority (EFSA) for many years. They consist in collecting food products representative of the population's consumption, preparing these foods "as consumed" taking into account population’s common practices, combining them as composite/pooled samples, analyzing these samples, assessing the population's exposure to the targeted substances and finally assessing the risk for substances for which reference values exist. Within the framework of the 2nd French TDS (TDS2), nearly 20,000 food products were collected in about 30 cities throughout the French metropolitan territory and prepared to form 1,319 samples. These products corresponded to 212 types of food representing nearly 90% of the diet of adults and children in France. Each sample was composed of 15 sub-samples of the same food (same label) and mass, allowing for the representation of different brands and taking into account consumer food preferences (product origin, varieties, brands, preparation methods, places of purchase, etc.). The sub-samples prepared "as consumed" were thus representative of the consumption of the food. With a few exceptions, all samples were replicated twice during the study to cover potential seasonal variability in composition or contamination. Different foods were also collected in different regions of France, to take account of potential regional differences in contamination. The More details about the study methodology are provided in the TDS2 reports: <ul> <li>https://www.anses.fr/en/system/files/PASER2006sa0361Ra1EN.pdf</li> <li>https://www.anses.fr/en/system/files/PASER2006sa0361Ra2EN.pdf</li> </ul>   2. Description of the data set The dataset presents data at the food item level, i.e. seasonal sample values were averaged at the regional level, then regional sample values were averaged to represent the national level. The original regional dataset is available in French at the following URL https://www.data.gouv.fr/fr/datasets/r/06797551-c1ad-40c5-8527-b3515d28fecd. The TDS2 data set includes 173 substances: trace elements, minerals, environmental pollutants, mycotoxins, neoformed compounds, additives and phytoestrogens. The analytical methods used for each family of substances and the analytical limits (LOD and LOQ ) are described in the study reports. 2.1. Pre-processing of concentration data Three hypotheses for the management of left censored data (concentration value below the analytical limits) were applied for all substances: <ul> <li>The lowerbound (LB) hypothesis: Concentrations below the LOD (undetected substances) were replaced by 0, and concentrations below the LOQ but above the LOD (known as "traces") were replaced by the LOD value;</li> <li>The middlebound (MB) hypothesis: Concentrations below the LOD were replaced by ½ LOD, and concentrations below the LOQ but above the LOD were replaced by ½ (LOD+LOQ) ;</li> <li>Upperbound (UB) hypothesis: Concentrations below the LOD have been replaced by the LOD value, and concentrations below the LOQ but above the LOD have been replaced by the LOQ.</li> </ul> In order to use the concentration value to assess exposures in relation to the available toxicological reference values, some data were processed. Thus, for mercury and arsenic, substances analysed in their total form, speciation assumptions were applied to the concentrations in order to estimate the organic and inorganic part in each sample (cf. study report, volume 1, p35). Similarly, for some compounds, sums were calculated. These are for example the sums of dioxins and furans, weighted by the toxic equivalency factors of 2005, or the sums of the 3 congeners of polybrominated biphenyls (PBBs). For these groups, data are available both for the substance details and for the sums of the three PBB congeners. 2.2. Thesaurus he list below presents the variables in the data set and their definitions: <ul> <li>family: name of the chemical group of the substance;</li> <li>subst: abbreviated name of the substance;</li> <li>subst_sn: short name of the substance;</li> <li>subst_cn: complete name of the substance;</li> <li>unit: unit of the mean concentration value of the substance;</li> <li>mean_CONTA_LB: mean of the concentration values of sub-samples of the analyzed food calculated under the lower bound hypothesis;</li> <li>mean_CONTA_MB: mean of the concentration values of sub-samples of the analyzed food calculated under the middle bound hypothesis;</li> <li>mean_CONTA_UB: mean of the concentration values of sub-samples of the analyzed food calculated under the upper bound hypothesis;</li> <li>Food_code: identification number of the analyzed food;</li> <li>Food_group: food category of the analyzed food;</li> <li>Type_foods: analyzed food.</li> </ul> <ul> </ul>

opencc-by-4.0Sep 2020View details →

FOP nutrient labels in Argentina: purchase intent, perception of healthiness and understanding in three processed food categories.

Data analysis (non-statistically significant results) and raw survey response data.

opencc-zeroSep 2020View details →

Data from: Terrestrial contributions to Afrotropical aquatic food webs: the Congo River case

1. Understanding the degree to which aquatic and terrestrial primary production fuel tropical aquatic food webs remains poorly understood, and quantifying the relative contributions of autochthonous and allochthonous inputs is methodologically challenging. Carbon and nitrogen stable isotope ratios (δ13C, δ15N) can provide valuable insights about contributions of terrestrial resources and trophic position respectively, but this approach has caveats when applied in typical complex natural food webs. 2. Here, we used a combination of C, N, and H (δ2H) stable isotope measurements and Bayesian mixing models to estimate the contribution of terrestrial (allochthonous) and aquatic (autochthonous) inputs to fish and invertebrate communities in the Congo River (and some tributaries). 3. Overall, our results show that we gained power to distinguish sources by using a multiple tracer approach and we were able to discriminate aquatic vs. terrestrial sources (esp. including hydrogen isotopes). Fish δ2H values were clearly correlated with their food preferences and revealed a high level of variation in the degree of allochthony in these tropical aquatic communities. 4. At the community level, it is clear that terrestrial C3 plants are an important source fueling the Congo River food web. However, in order to better constrain source contribution in these complex environments will require more robust constraints on stable isotope values of algal and methane-derived C sources.