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133 results for “Isotope analysis”
Data for: Two is better than one: Coupling DNA metabarcoding and stable isotope analysis improves dietary characterizations for a riparian-obligate, migratory songbird
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Supporting isotopic data for: Amino acid isotope analysis reveals variation in gut microbial contribution to host protein metabolism in a wild small mammal community
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Tracking long-distance migration of marine fishes using compound-specific stable isotope analysis of amino acids
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Data from: Toward a standardised protocol for the stable isotope analysis of scleractinian corals
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Multi-year impact of maternal provisioning on a juvenile elasmobranch: pitfalls of tissue type and tracer number for stable isotope analysis
<p>Stable isotope data and R script for all the analysis referred to in the manuscript.</p>
Data from: Multidimensional stable isotope analysis illuminates resource partitioning in a sub-Antarctic island bird community
1. A central theme in community ecology is understanding how similar species co-exist and how their interactions may evolve in the context of climate change. Most studies of resource partitioning among central place foragers, particularly birds, focus on the offspring-rearing period, when they are accessible, but breeding success may be determined earlier and little is known about how such species partition resources at the onset of breeding. 2. We used a non-invasive approach to evaluate resource partitioning in co-existing females at a sub-Antarctic island during their pre-laying periods. 3. Three hypotheses were tested using carbon, nitrogen and oxygen stable isotope ratios measured in shells and membranes of hatched eggs as ecological tracers: 1) resource partitioning by geographic location and trophic level will exist among the 12 bird species and will be enhanced within taxonomic groups; 2) given the absence of strong oxygen gradients in the Southern Ocean we will not detect spatial structuring based on oxygen isotopes, but differences will exist between resident and oceanic species as the former may use meteoric water; 3) capital and income breeder strategies can be differentiated using stable isotopes of egg remains. 4. Two and three dimensional isotopic data showed resource partitioning among species. As predicted, segregation was evident within the four main taxonomic groups: penguins, albatrosses, burrowing petrels and giant petrels. Unexpectedly, oxygen isotopes revealed widespread use of meteoric water among a suite of sub-Antarctic birds. Stable isotopes allowed us to identify females of most species as income breeders at the onset of breeding, with the exception of the two crested penguin females exhibiting a mix of income and capital resources use. 5. Multidimensional isotopic analyses revealed that resource partitioning exists at multiple stages of the annual cycle in ways likely to be important under global change, exhibiting wide potential for ecosystem analysis.
Data from: Retrospective stable isotope analysis reveals ecosystem responses to river regulation over the last century
Disruption of natural flow regimes, nutrient pollution, and other consequences of human population growth and development have impacted most major rivers of the world. Alarming losses of aquatic biodiversity and biotic homogenization coincide with human-caused river alteration, but effects on aquatic ecosystem processes are not as well documented. This is because unaltered systems for comparison are scarce, and some ecosystem-wide effects may take decades to manifest. We evaluated aquatic ecosystem responses to extensive river-floodplain engineering and nutrient addition in the Rio Grande of southwestern North America as revealed by changes in trophic structure of, and resource availability to, the fish community. Stable Isotope Analysis (SIA) was conducted on museum-preserved fishes collected over a 70-year period of intensive river management and exponential human population growth. Trophic complexity and resource heterogeneity for fish consumers (measured as 'isotopic niche breadth') decreased following sediment deprivation and channelization, and these effects persist into the present. Increased nutrient inputs led to δ15N enrichment in the entire fish community at all affected sites, and a shift to autochthonous sources of carbon at the most proximal site downstream of wastewater release probably via 'bottom-up' transfer. Overall, retrospective SIA of apex consumers suggests radical change and functional impairment of a floodplain river ecosystem already marked by significant biodiversity loss.
Data from: Community structure of a Neotropical bat fauna as revealed by stable isotope analysis: Not all species fit neatly into predicted guilds
Neotropical bat communities are among the most diverse mammal communities in the world, and a better understanding of these assemblages may permit inferences about how so many species coexist. While broad trophic guilds (e.g., frugivore, insectivore) of bats are recognized, details of diet and similarities among species remain largely unknown. We used stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) to characterize the community structure of a diverse Neotropical bat fauna from Belize to test predictions of niche theory and the competitive exclusion principle. We predicted that (1) interspecific variation in isotopic overlap would be greater within guilds than between guilds, and (2) no two sympatric populations would have isotopic niches that overlap completely, unless there is variation along some other axis (e.g., temporal, spatial). We additionally tested body size as an explanatory metric of potential overlap, and predicted that larger-bodied animals would have greater niche breadths. Results suggest that while guild-level characterizations of communities is at least somewhat informative, there are multiple examples of intra- and inter-guild species pairs with significantly overlapping isotopic niches, suggesting that, counter to predictions, they may compete for resources. Understanding the trophic structure of animal communities is fundamental to conservation and management of endangered species and ecosystems and important for evolutionary studies, and stable isotope analyses can provide key insights as well as informing hypotheses of the diet of species that are not well known.
Data from: Comparison of diets for largemouth and smallmouth bass in Eastern Lake Ontario using DNA barcoding and stable isotope analysis
Largemouth (LMB: Micropterus salmoides) and Smallmouth Bass (SMB: Micropterus dolomieu) are important species in the recreational fisheries of the Laurentian Great Lakes. The invasion of the Round Goby (Neogobius melanostomus) into these lakes has changed several facets of black bass biology, but there is still much to learn about the relationship between these species. Previous dietary analyses have shown Round Goby to be important prey for bass, but have been limited by low visual identification rates of dissected stomach items. Within the present study, DNA barcoding and stable isotope analysis improve prey identification and provide a more quantitative dietary analysis of adult black bass in Lake Ontario, comparing the importance of Round Goby as prey between these two species. Eighty-four LMB (406mm fork length ±4mm SEM) and two hundred sixty-four SMB (422mm ±2mm) obtained as tournament mortalities had prey identified using DNA-based methods. Round Goby was the most prevalent prey species for both predators. The diet of LMB was three times more diverse than that of SMB, which almost entirely consists of Round Goby. Our results provide further support that recent increases in the size of Lake Ontario bass are a result of Round Goby consumption, and that the effects of this dietary shift on body condition are greater for SMB. Techniques developed in this study include: reverse-oriented dual priming oligonucleotides used as blocking primers for predator DNA, and an automated design approach of restriction fragment length polymorphism tests for identifying prey DNA barcodes.
Data from: Do deposit-feeders compete? Isotopic niche analysis of an invasion in a species-poor system
Successful establishment of invasive species is often related to the existence of vacant niches. Competition occurs when invaders use the same limiting resources as members of the recipient community, which will be reflected in some overlap of their trophic niches. The concept of isotopic niche has been used to study trophic niche partitioning among species. Here, we present a two-year field study comparing isotopic niches of the deposit-feeding community in a naturally species-poor system. The isotopic niche analyses showed no overlap between a recent polychaete invader and any of the native species suggesting that it has occupied a vacant niche. Its narrow isotopic niche suggests specialized feeding, however, the high d15N values compared to natives are most likely due to isotope fractionation effects related to nitrogen recycling and a mismatch between biological stoichiometry of the polychaete and the sediment nitrogen content. Notably, highly overlapping isotopic niches were inferred for the native species, which is surprising in a food-limited system. Therefore, our results demonstrate that invaders may broaden the community trophic diversity and enhance resource utilization, but also raise questions about the congruence between trophic and isotopic niche concepts and call for careful examination of assumptions underlying isotopic niche interpretation.
Data from: The diverse dietary profiles of MIS 3 cave bears from the Romanian Carpathians: insights from stable isotope (δ13C and δ15N) analysis
Late Pleistocene European cave bears (Ursus spelaeus) have been considered to be largely vegetarian, although stable isotope data (δ13C and δ15N values) from the Romanian Carpathians has suggested considerable dietary variation. Here we evaluate previous and additional adult cave bear isotopic data from four Marine Isotope Stage 3 (MIS 3) sites in the Carpathians. Peştera Urşilor (N = 35), Peştera Cioclovina (N = 32), Peştera Muierilor (N = 8), and Peştera cu Oase (N = 72) provide both a dichotomy between samples suggesting vegetarian diets (from Cioclovina and Muierilor) and more omnivorous diets (from Urşilor and Oase), and considerable isotopic variation within samples from each site. While an inference of a strictly vegetarian diet may apply to groups that lived in ecosystems which restricted the available animal protein for these large ursids, the within and between sample isotopic variation among the Carpathian cave bears indicates considerable flexibility in their sources of protein and hence in their dietary regimes. In addition, developmental assessment of Cioclovina isotopic profiles (neonates, juveniles, sub-adults and adults) provides patterns of transfer of stable isotope signatures throughout immature life for both δ13C and δ15N (increase and decrease, respectively), whereas those from Urşilor show little developmental shift.
Data from: Combining micro-volume isotope analysis and numerical simulation to reproduce fish migration history
1. Tracking the movement of migratory fish is of great importance for efficient conservation, although this has been technically difficult to achieve in small fish to which artificial tags cannot be attached. 2. We show that migration history can be reproduced by combining high-resolution otolith stable oxygen isotope ratio (δ18O) analysis and numerical simulation. 3. High-precision micro-milling and micro-volume carbonate analysing systems had the remarkable capability of extracting the otolith δ18O profiles with 10–30 days resolution. Furthermore, reasonable movements were reproduced by searching the routes consistent with the otolith δ18O profile, using an individual-based model with random swimming behaviour. 4. This method will be a valuable alternative to tagging and electronic loggers for revealing migration routes in early life stages, thereby providing crucial information to understand population structures and the environmental cause of recruitment variabilities, and to validate and improve fish movement models.
Isotopic analysis: How our community analyzes soil and plant water samples for their isotopic composition
<p>As part of a project to develop a common methodological framework for water sampling, extraction, and isotopic analysis to study vegetation water use, we conducted an informal survey of current practices. A simple questionnaire via Google form was sent out to all members of the WATer isotopeS in the critical zONE (WATSON) European Cooperation in Science and Technology (COST) Action (#19120, 2020-2024) between July and September 2021. In this repository, we've included a brief write-up of this survey and the survey data. </p>
Individual dietary specialization in a generalist predator: A stable isotope analysis of urban and rural red foxes
<p>Some carnivores are known to survive well in urban habitats, yet the underlying behavioural tactics are poorly understood. One likely explanation for the success in urban habitats might be that carnivores are generalist consumers. However, urban populations of carnivores could as well consist of specialist feeders. Here, we compared the isotopic specialization of red foxes in urban and rural environments, using both a population and an individual level perspective. We measured stable isotope ratios in increments of red fox whiskers and potential food sources. Our results reveal that red foxes have a broad isotopic dietary niche and a large variation in resource use. Despite this large variation, we found significant differences between the variance of the urban and rural population for δ<sup>13</sup>C as well as δ<sup>15</sup>N values, suggesting a habitat-specific foraging behaviour. Although urban regions are more heterogeneous regarding land cover (based on the Shannon index) than rural regions, the dietary range of urban foxes was smaller compared to that of rural conspecifics. Moreover, the higher δ<sup>13</sup>C values and lower δ<sup>15</sup>N values of urban foxes suggest a relatively high input of anthropogenic food sources. The diet of most individuals remained largely constant over a longer period. The low intra-individual variability of urban and rural red foxes suggests a relatively constant proportion of food items consumed by individuals. Urban and rural foxes utilized a small proportion of the potentially available isotopic dietary niche as indicated by the low within-individual variation compared to the between-individual variation. We conclude that generalist fox populations consist of individual food specialists in urban and rural populations<b> </b>at least over those periods covered by our study.</p>
Data and code for "Large volume injection and assessment of reference standards for n-alkane δD and δ13C analysis via gas chromatography isotope ratio mass spectrometry"
<p>This file includes data and code related ot the publication, "<span>Large volume injection and assessment of reference standards for <em>n</em>-alkane δD and δ<sup>13</sup>C analysis via gas chromatography isotope ratio mass spectrometry" in Rapid Communications in Mass Spectrometry (in review). Included are datasets of <em>n</em>-alkane δD and δ<sup>13</sup>C measurements with a recently developed large-volume injeciton method. Measuremtns of reference standards and lake sediment samples from Eifel maar lakes of Germany are included. Additionally, code to implement the correction schemes and reporduce the figures and analysis described in the paper are included. </span></p>
Paired X-ray Micro CT Scanning and individual foraminifera isotopic analysis reveal (de)coupled changes in carbonate preservation and temperature
<p>To assess the coupling between drivers of isotopic variability and carbonate dissolution in foraminifera, we combine individual foraminiferal carbon and oxygen isotopic analyses (IFA) and X-ray MicroCT Scanning (XMCT)-based measurements of test densities (a proxy for the extent of post-depositional dissolution). As a proof-of-concept application of this approach, we analyze Globigerina bulloides tests from both coretop and downcore (latest Miocene/earliest Pliocene-aged) sediment from Ocean Drilling Project (ODP) Site 1088 (Agulhas Ridge).<br>Sediments from both the core intervals were wet-sieved over a 150 μm sieve and oven-dried at 55°C overnight. Individual tests of G. bulloides were picked from the >150 μm size fraction and gently brushed with the wet tip of a paintbrush to remove any adhering clay. Broken or partially fragmented tests were avoided. 25-50 individuals were mounted on a 1.2cm x 1 cm cardboard sample holder using double-sided carbon and imaged at a time on a Bruker Skyscan 1272 Micro-CT Scanner. In total, 123 individuals from the coretop sample and 88 individuals from the downcore sample were scanned.<br>Stable carbon (δ¹³C) and oxygen (δ¹⁸O) isotopic compositions of individual foraminifera were measured using a Kiel Carbonate Device IV coupled to a Thermo Fisher MAT 253 Plus Isotope Ratio Mass Spectrometer (IRMS). All individuals were weighed on a Sartorius ultramicrobalance before analysis, and only samples with mass >10 µg were analyzed as per the long-term precision setup of analyzing small quantities of carbonates on this machine. The XMCT-IFA dataset in this study consists of δ¹³C and δ¹⁸O values of 90 foraminifera (67 coretop and 23 downcore individuals). We compare population averages of XMCT parameters and isotopic compositions from both the coretop and downcore sediments.</p>
Isotope analysis combined with DNA barcoding provide new insights into the dietary niche of khulan in the Mongolian Gobi
<p><span>With increasing livestock numbers, competition and avoidance are increasingly shaping resource availability for wild ungulates. Shifts in the dietary niche of wild ungulates are likely and can be expected to negatively affect their fitness. The Mongolian Gobi constitutes the largest remaining refuge for several threatened ungulates, but unprecedentedly high livestock numbers are sparking growing concerns over rangeland health and impacts on threatened ungulates like the Asiatic wild ass (khulan).</span></p> <p><span>Previous stable isotope analysis of khulan tail hair from the Dzungarian Gobi suggested that they graze in summer but switch to a poorer mixed C3 grass / C4 shrub diet in winter, most likely in reaction to local herders and their livestock. Here we attempt to validate these findings with a different methodology, DNA metabarcoding. Further, we extend the scope of the original study to the South Gobi Region, where we expect higher proportions of low-quality browse in the khulan winter diet due to a higher human and livestock presence.</span></p> <p><span>Barcoding confirmed the assumptions behind the seasonal diet change observed in the Dzungarian Gobi isotope data, and new isotope analysis revealed a strong seasonal pattern and higher C4 plant intake in the South Gobi Region, in line with our expectations. However, DNA barcoding revealed C4 domination of winter diet was due to C4 grasses (rather than shrubs) for the South Gobi Region. Slight climatic differences result in regional shifts in the occurrence of C3 and C4 grasses and shrubs, which do not allow for an isotopic separation along the grazer-browser continuum over the entire Gobi. </span></p> <p><span>Our findings do not allow us to confirm human impacts upon dietary preferences in khulan as we lack seasonal samples from the South Gobi Region. However, these data provide novel insight into khulan diet, raise new questions about plant availability versus preference, and provide a cautionary tale about indirect analysis methods if used in isolation or extrapolated to the landscape level. Good concordance between relative read abundance of C4 genera from barcoding and proportion of C4 plants from isotope analysis adds to a growing body of evidence that barcoding is a promising quantitative tool to understand resource partitioning in ungulates.</span></p>
Isotopic analysis reveals landscape patterns in the diet of a subsidized predator, the common raven
<p>1. Anthropogenic subsidies to native predators can have cascading effects on sensitive prey populations, but the spatial mechanisms behind these effects are often unknown.</p> <p>2. We used a stable isotope mixing model to reconstruct spatially naïve assimilated diets of common raven (Corvus corax) chicks and then used regression analysis to investigate landscape patterns in assimilated chick diet, with particular respect to the eggs and chicks of greater sage-grouse (Centrocercus urophasianus).</p> <p>3. Assimilated raven diets were primarily composed of mammal carrion, followed by anthropogenic food and sage-grouse eggs and chicks.</p> <p>4. Raven diets showed landscape gradients, whereby raven chicks in nests near active greater sage-grouse breeding leks consumed a higher proportion of sage-grouse eggs, sage-grouse chicks, and insects in their diet and less mammal carrion. A majority of raven nests on anthropogenic nesting structures (78.7%) were within 5 km of the nearest sage-grouse lek. Ravens nesting in high-probability greater sage-grouse nesting habitat consumed more insects and plants and less mammal carrion.</p> <p>5. In landscapes devoid of natural raven nesting substrates, such as our study area, anthropogenic nesting substrates can 'anchor' breeding ravens nearer to greater sage-grouse leks, with concomitant increases in raven predation on greater sage-grouse nests. Curtailment of anthropogenic nesting substrates within 5 km of a sage-grouse lek may have a disproportionately positive impact on sage-grouse populations. More generally, these findings highlight that the spatial arrangement of anthropogenic subsidies can result in indirect interactions between humans and predators with direct implications for predators and prey.</p>
Laser Ablation Inductively Coupled Plasma Mass Spectrometric Quantification of Isotope Trace Elements in Human Carcinoma Tissue - Stochastic Dynamics and Theoretical Analysis (SUPPORTING INFORMATION)
<p>Supporting information file of publication [https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4334866]. </p>
Use of amino acid isotope analysis to investigate capital versus income breeding strategies in migratory avian species
<p>Income and capital breeding represent opposing ends of a continuum of reproductive strategies. Quantifying nutrient allocation to reproduction is challenging, but recent advances in compound-specific stable isotope analysis hold promise for tracing the source of individual compounds allocated to reproduction. </p> <p>Here, we describe a novel approach of using measured carbon (δ<sup>13</sup>C) and nitrogen (δ<sup>15</sup>N) isotope values of individual amino acids (AAs) in pectoral muscle of egg-laying females and egg yolk as a useful tool to quantify the reliance on income versus capital breeding in migrating species. We used white-fronted (<em>Anser albifrons frontalis</em>), lesser snow (<em>A. caerulescens caerulescens</em>), and black brant (<em>Branta bernicla nigricans</em>) geese breeding in tundra ecosystems of northern Alaska as model organisms.</p> <p>All three species relied on mixed capital-income breeding strategies, but models based on AA isotope data estimated higher proportional contributions of endogenous resources to yolk synthesis compared to results based on bulk tissue isotope analyses. </p> <p>Tracing income versus capital nutrient allocation in migratory species at the compound level is a major advance from the current 'elemental' perspective obtained from bulk tissue stable isotope analyses. Our framework is applicable to all taxonomic groups, as long as there is a sufficient spatial or temporal isotopic gradient between resources obtained during the breeding and non-breeding periods.</p>
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