Stable carbon and nitrogen isotope ratios of collagen from bone and dentin have frequently been used for dietary reconstruction, but this method is limited by protein preservation. Isotopes of the ...trace element zinc (Zn) in bioapatite constitute a promising proxy to infer dietary information from extant and extinct vertebrates. The 66Zn/64Zn ratio (expressed as δ66Zn value) shows an enrichment of the heavy isotope in mammals along each trophic step. However, preservation of diet-related δ66Zn values in fossil teeth has not been assessed yet. Here, we analyzed enamel of fossil teeth from the Late Pleistocene (38.4–13.5 ka) mammalian assemblage of the Tam Hay Marklot (THM) cave in northeastern Laos, to reconstruct the food web and assess the preservation of original δ66Zn values. Distinct enamel δ66Zn values of the fossil taxa (δ66Zncarnivore < δ66Znomnivore < δ66Znherbivore) according to their expected feeding habits were observed, with a trophic carnivore-herbivore spacing of +0.60‰ and omnivores having intermediate values. Zn and trace element concentration profiles similar to those of modern teeth also indicate minimal impact of diagenesis on the enamel. While further work is needed to explore preservation for settings with different taphonomic conditions, the diet-related δ66Zn values in fossil enamel from THM cave suggest an excellent long-term preservation potential, even under tropical conditions that are well known to be adverse for collagen preservation. Zinc isotopes could thus provide a new tool to assess the diet of fossil hominins and associated fauna, as well as trophic relationships in past food webs.
The spatial structure of communities has recently gained much attention in ecology. Spatial structure comprises an important element in communities, but the literature lacks a thorough investigation ...about possible among‐organism or among‐ecosystem differences in the degree of spatial structure. Here, I conducted a quantitative review to determine if the degree of spatial structure varied predictably between the major organism types and ecosystems. Spatial structure was quantified as the relative fraction of community variation explained purely by spatial variables (fraction S/E). I integrated data from 322 variation partition analyses both in a generalized linear model (GLM) and using a boosted regression tree method, and showed that a mean of 11.0% of the variation in community composition was explained purely by spatial variables. Across all taxa, a body size–S/E relationship was positive. In GLM, fraction S/E increased highly significantly with study extent, it was highest among terrestrial taxa and higher in ectotherms than in homoiotherms. Spatial structure was also higher in omnivores than in autotrophs. These results suggest that the degree of spatial structure is jointly driven by extrinsic factors such as study extent and ecosystem type, and intrinsic factors such as body size, thermoregulation and interactions between body size and dispersal mode. These results should be important not only for basic research, but also conservation and bioassessment programs would benefit from the information about the magnitude of spatial variation in nature. Synthesis Spatial processes comprise an important element in most ecological communities, but the degree to which spatial structure varies across organisms or ecosystems is poorly known. Here, a quantitative review of 322 variation partition analyses indicated that spatial component varied predictably across ecological communities – it was driven by study extent and ecosystem type as well as by species traits such as body size and thermoregulation. These results give deep insights into the magnitude of spatial variation in nature and should be highly beneficial for conservation and bioassessment programs that are built on the information about how communities vary in space.
Machine learning ecological networks O’Gorman, Eoin J.
Science (American Association for the Advancement of Science),
08/2022, Letnik:
377, Številka:
6609
Journal Article
Recenzirano
Deep-learning tools can help to construct historical, modern-day, and future food webs
It is perhaps unsurprising that apex predators, such as whales, sharks, leopards, and tigers, also tend to be ...the rarest species (
1
). This is largely because of the imperfect transfer of energy through each level in a food chain (
2
), which makes these carnivores more susceptible to starvation than herbivores, detritivores, or omnivores. Their survival also depends on having a large home range for them to roam far and wide to find the mates and resources needed to sustain their populations (
3
). These vulnerabilities make them particularly susceptible to human activities, such as habitat loss or being targeted by hunters for their trophy status. On page 1008 of this issue, Fricke
et al.
(
4
) adopt a network-based approach to establish how humans have disrupted apex predators and other mammalian fauna over the past 130,000 years.
The intestine is a site of direct encounter with the external environment and must consequently balance barrier defense with nutrient uptake. To investigate how nutrient uptake is regulated in the ...small intestine, we tested the effect of diets with different macronutrient compositions on epithelial gene expression. We found that enzymes and transporters required for carbohydrate digestion and absorption were regulated by carbohydrate availability. The "on-demand" induction of this machinery required γδ T cells, which regulated this program through the suppression of interleukin-22 production by type 3 innate lymphoid cells. Nutrient availability altered the tissue localization and transcriptome of γδ T cells. Additionally, transcriptional responses to diet involved cellular remodeling of the epithelial compartment. Thus, this work identifies a role for γδ T cells in nutrient sensing.
The digestive tract microbiota (DTM) plays a plethora of functions that enable hosts to exploit novel niches. However, our understanding of the DTM of birds, particularly passerines, and the turnover ...of microbial communities along the digestive tract are limited. To better understand how passerine DTMs are assembled, and how the composition changes along the digestive tract, we investigated the DTM of seven different compartments along the digestive tract of nine New Guinean passerine bird species using Illumina MiSeq sequencing of the V4 region of the 16S rRNA. Overall, passerine DTMs were dominated by the phyla Firmicutes and Proteobacteria. We found bird species-specific DTM assemblages and the DTM of different compartments from the same species tended to cluster together. We also found a notable relationship between gut community similarity and feeding guilds (insectivores vs. omnivores). The dominant bacterial genera tended to differ between insectivores and omnivores, with insectivores mainly having lactic acid bacteria that may contribute to the breakdown of carbohydrates. Omnivorous DTMs were more diverse than insectivores and dominated by the bacterial phyla Proteobacteria and Tenericutes. These bacteria may contribute to nitrogen metabolism, and the diverse omnivorous DTMs may allow for more flexibility with varying food availability as these species have wider feeding niches. In well-sampled omnivorous species, the dominant bacterial genera changed along the digestive tracts, which was less prominent for insectivores. In conclusion, the DTMs of New Guinean passerines seem to be species specific and, at least in part, be shaped by bird diet. The sampling of DTM along the digestive tract improved capturing of a more complete set of members, with implications for our understanding of the interactions between symbiont and gut compartment functions.
The Psychology of Eating Animals Loughnan, Steve; Bastian, Brock; Haslam, Nick
Current directions in psychological science : a journal of the American Psychological Society,
04/2014, Letnik:
23, Številka:
2
Journal Article
Recenzirano
Most people both eat animals and care about animals. Research has begun to examine the psychological processes that allow people to negotiate this "meat paradox." To understand the psychology of ...eating animals, we examine characteristics of the eaters (people), the eaten (animals), and the eating (the behavior). People who value masculinity, enjoy meat and do not see it as a moral issue, and find dominance and inequality acceptable are most likely to consume animals. Perceiving animals as highly dissimilar to humans and as lacking mental attributes, such as the capacity for pain, also supports meat-eating. In addition to these beliefs, values, and perceptions, the act of eating meat triggers psychological processes that regulate negative emotions associated with eating animals. We conclude by discussing the implications of this research for understanding the psychology of morality.
As opportunistic omnivores, humans are evolutionarily adapted to obtain calories and nutrients from both plant and animal food sources. Today, many people overconsume animal products, often-processed ...meats high in saturated fats and chemical additives. Alternatively, strict veganism can cause nutritional deficiencies and predispose to osteopenia, sarcopenia, and anemia. A logical compromise is a plant-rich diet with fish/seafood as principal sources of animal food. This paper reviews cumulative evidence regarding diet and health, incorporating data from landmark clinical trials of the Mediterranean diet and recommendations from recent authoritative guidelines, to support the hypothesis that a Pesco-Mediterranean diet is ideal for optimizing cardiovascular health. The foundation of this diet is vegetables, fruits, nuts, seeds, legumes, whole grains, and extra-virgin olive oil with fish/seafood and fermented dairy products. Beverages of choice are water, coffee, and tea. Time-restricted eating is recommended, whereby intermittent fasting is done for 12 to 16 h each day.
Changes in the ecological stoichiometry of primary producers may have considerable implications for energy and matter transfer in food webs. We hypothesized that nutrient enrichment shifts the ...trophic position of omnivores towards herbivory, as the nutritional quality of primary producers increases. This hypothesis was tested by analyzing the ecological stoichiometry and stable isotope signature of primary producers and a wide range of aquatic macroinvertebrates, including primary consumers (herbivores) and secondary consumers (both potential omnivores and strict carnivores), along a eutrophication gradient in an agricultural landscape. Our results showed (1) that carbon :nutrient ratios of primary producers decreased along the eutrophication gradient, while the elemental composition of consumers remained homeostatic, and (2) that the trophic position of several omnivores and the generalist predator Notonecta decreased, while the trophic position of most other consumers remained constant. These findings suggest that shifts in the diets of aquatic invertebrates induced by increasing eutrophication may affect species interactions and food web structure in aquatic ecosystems.
To better understand dietary requirements, trophic shifts, and trophic interactions of the threatened green turtle (
Chelonia mydas
), we conducted a comprehensive global review and literature ...tabulation (177 studies) reporting diets of individuals > 25 cm carapace length. We analysed those studies involving natural sites and healthy animals that reported relative proportions of all diet components (67 studies, 89 datasets at 75 sites, 13 geographic sub-regions, 3 oceans). We compared diets by sub-region and foraging site relative to four diet components, i.e., seagrass, macroalgae, terrestrial plants (including mangroves) and animal matter. To assess sea surface temperature (SST) as an environmental driver, values were extracted from satellite data (single year) and site-specific observations (study durations) and examined relative to diet composition. Satellite data indicated that at warmer sites with temperatures > 25 °C (≥ 6 months annually), diet was predominantly herbivorous (mean = 92.97%; SE = 9.85;
n
= 69 datasets). At higher latitude sites and in cold-water currents with SST < 20 °C (≥ 6 months annually), dietary animal matter featured prominently (mean = 51.47%; SE = 4.84;
n
= 20 datasets). Site-specific observations indicated that SST had a small but significant effect on contributions of animal matter (
r
2
= 0.17,
P
= < 0.001) and seagrass (
r
2
= 0.24,
P
= < 0.001) but not macroalgae and terrestrial plants. Our study presents the first quantitative evidence at a global scale that temperature may be an important driver of omnivory, providing a new perspective on variations in green turtle diet, especially in light of global warming and climate change.
The giant panda feeds almost exclusively on bamboo, a diet highly enriched in lignin and cellulose, but is characterized by a digestive tract similar to carnivores. It is still large unknown if and ...how the giant panda gut microbiota contributes to lignin and cellulose degradation. Here we show the giant pandas' gut microbiota does not significantly contribute to cellulose and lignin degradation. We found that no operational taxonomic unit had a nearest neighbor identified as a cellulolytic species or strain with a significant higher abundance in juvenile than cubs, a very low abundance of putative lignin and cellulose genes existed in part of analyzing samples but a significant higher abundance of genes involved in starch and hemicellulose degradation in juveniles than cubs. Moreover, a significant lower abundance of putative cellulolytic genes and a significant higher abundance of putative α-amylase and hemicellulase gene families were present in giant pandas than in omnivores or herbivores.
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