Using stable isotope analysis to obtain dietary profiles from old hair: a case study from Plains Indians

Stable isotope composition of human tissue reflects that of foods consumed, and can provide information about diet independent of artifactual remains. Here we refine and test this method by analyzing nitrogen (delta(15)N) and carbon (delta(13)C) isotope ratios in historic North American Plains Indians hair. Gas-source isotope-ratio mass spectrometry provides high-precision data for both delta(15)N and delta(13)C (+/-0.2 per thousand, 1 sigma) in single hair strands as short as 2 cm (100-150 mug). Because hair contains more carbon than nitrogen, if only delta(13)C data are needed, shorter strands (<1 cm) can be analyzed. This reduction in sample size opens new opportunities for analysis of small hair fragments found in archaeological excavations, as well as for analysis of seasonal variations in long hair strands. We find distinct isotope profiles (delta(15)N vs. delta(13)C) for two cultural groups, the Lower Brule reservation Sioux of 1892 and the reservation Blackfoot of 1892 and 1935. The resultant dietary profiles indicate a higher consumption of meat by the Blackfoot and a higher consumption of maize (or of animals that had fed on maize or other C(4) plants) by the Lower Brule. The two groups of Blackfoot yield similar isotopic profiles despite the passage of four decades, suggesting a strong role for cultural preference even as food sources change. Such stable isotope profiles can be used to link samples from the same cultural tradition based on their similar diets.     

Using stable isotope analysis to determine the winter moult extent in migratory birds: the complex moult of Savi's warblers Locustella luscinioides

Patterns of feather wear in birds captured in spring have traditionally been analysed to describe the extent of winter moult in long-distance migrants. However, the interpretation of feather wear may be rendered extremely difficult due to long moult periods, by the progress of the season, and by the existence of complex moult patterns. Here, stable isotope analysis is used to determine the origin of the wing feather generations present in Savi's warblers Locustella luscinioides captured in Portugal. Carbon, nitrogen and hydrogen isotope ratios of feathers of known European origin differed significantly from those known to have grown in Africa. A discriminant analysis, in which 91.1% of the cross validated samples were correctly classified, was used to determine the origin of tail and wing feathers collected from birds caught when they returned to the breeding quarters. The interpretation of feather-wear generally agreed with the stable isotope analysis, but some inconsistencies were identified. The extent of winter moult in Savi's warblers is described and its moult strategy discussed.     

Using stable isotope analysis to determine the winter moult extent in migratory birds: the complex moult of Savi's warblers Locustella luscinioides

Patterns of feather wear in birds captured in spring have traditionally been analysed to describe the extent of winter moult in long‐distance migrants. However, the interpretation of feather wear may be rendered extremely difficult due to long moult periods, by the progress of the season, and by the existence of complex moult patterns. Here, stable isotope analysis is used to determine the origin of the wing feather generations present in Savi's warblers Locustella luscinioides captured in Portugal. Carbon, nitrogen and hydrogen isotope ratios of feathers of known European origin differed significantly from those known to have grown in Africa. A discriminant analysis, in which 91.1% of the cross validated samples were correctly classified, was used to determine the origin of tail and wing feathers collected from birds caught when they returned to the breeding quarters. The interpretation of feather‐wear generally agreed with the stable isotope analysis, but some inconsistencies were identified. The extent of winter moult in Savi's warblers is described and its moult strategy discussed.     

Using three-dimensional kinematics to identify feedback for the Snatch: a case study

This case study evaluated the importance of peak bar velocity and starting posture adopted by a novice weightlifter to the outcome of a Snatch lift. Multiple observations of both successful and unsuccessful attempts were captured using 3D motion analysis (VICON MX: 500 Hz). The following data analysis was then used to derive feedback. In total, 133 attempts of loads ranging from 75 to 100% of 1 repetition maximum (1RM) were performed by the subject (age = 25 years, stature = 171 cm, mass = 74.8 kg, Snatch 1RM = 80 kg). Variables included peak bar velocity, pelvis, hip, knee and ankle joint angles at the starting position for the right side and the difference between (left minus right) sides. No main effects for load, success, or their interactions were found for peak bar velocity. Starting position kinematics were mostly nonsignificant between the outcome of Snatch attempts. Right ankle joint angle was the only exception, where unsuccessful attempts displayed greater (p = 0.0228) dorsiflexion. A more comprehensive finding was achieved through the partition modeling; this analysis provided valuable insight and coaching feedback for the subject in relation to his lower body kinematics at the starting position. Furthermore, the accuracy of this feedback was verified using a holdback data set. Specifically, anterior pelvic tilt (>17.6°) and hip joint (<89.6°) angle were identified as the key features to increasing the likelihood of success. In conclusion, this case study outlines a method of data collection and analysis to assist coaching feedback for an individual.     

Using stable isotope analysis to examine fall armyworm (Lepidoptera: Noctuidae) host strains in a cotton habitat

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), or fall armyworm, is an important agricultural pest of several crops in the Western Hemisphere, including cotton (Gossypium L.). Two morphologically identical host strains of fall armyworm exist that differ in plant host use and habitat distribution. The corn-strain is a primary pest of corn, Zea mays L., whereas the rice-strain is the majority population infesting rice (Oryza spp.) and turfgrass (Cynodon spp.). With the increased use of Bacillus thuringiensis (Bt) toxin-expressing cotton varieties and the necessity of ensuring adequate refuge areas to prevent the spread of Bt toxin resistance, it is crucial to identify the alternative plant hosts available for the fall armyworm population infesting cotton. Stable isotope analysis combined with the molecular analysis of strain-specific markers was used to investigate whether one or both strains routinely develop on cotton grown in the Mississippi delta. We found that the majority of fall armyworm adults present during the early cotton growing season arose from C4 plants (e.g., corn and sorghum, Sorghum vulgare Pers.) and that the only strain likely to be developing on cotton (a C3 plant) in substantial numbers was the corn-strain. The population distribution patterns observed were consistent with corn providing an important refuge for the fall armyworm strain infesting cotton and suggested that late season populations in the Mississippi delta may be migrants from more northern corn areas.     

Using stable isotope analysis to study the diet of Gilchristella aestuaria larvae: preliminary insights into the foodwebs of six South African estuaries

South African estuarine systems are becoming increasingly altered by anthropogenic and environmental factors, but the consequences of such changes for these systems are still not fully understood. The most common approach for evaluating the ecological status of aquatic systems is studying their associated foodwebs. Due to their high abundance and important ecological role, the larvae of estuarine round herring Gilchristella aestuaria (Gilchrist, 1913) are key candidates for examining the foodweb structure and function of southern African estuaries. The foodwebs and trophic interactions of G. aestuaria larvae in six estuaries in South Africa were compared using larvae sampled in November 2013 and analysed using δ¹³C and δ¹⁵N and Bayesian isotopic mixing models. The main prey type for G. aestuaria larvae in all estuaries was zooplankton. We found a high similarity among the Kariega, Gamtoos, Great Fish and Sundays estuaries in terms of consumers and potential sources for both δ¹³C and δ¹⁵N signatures. Significant differences were found in δ¹³C values among marine-dominated estuaries, such as the Kromme Estuary, and the more freshwater-dominated systems. In addition, in the Kromme Estuary particulate organic matter was very important in the diet of G. aestuaria larvae. Our results suggest that both food availability and physical environmental parameters strongly affect the diet and condition of G. aestuaria and, consequently, the entire foodweb in the system.     

Using stable isotope analysis to assess the effects of hypolimnetic oxygenation on diet in a mixed cold- and warmwater fish community

Line-diffuser hypolimnetic oxygenation was initiated in North Twin Lake, Washington, in 2009 to mitigate reductions in Rainbow Trout (Oncorhynchus mykiss) and Brook Trout (Salvelinus fontinalis) habitat due to temperature-dissolved oxygen “habitat squeeze”. Previous studies demonstrated that trout populations rapidly expanded into increased hypolimnetic habitat within the first few years of oxygenation and previous short-term diet analyses indicated an effect on fish diet; however, the long-term effects on fish ecology have yet to be established. In this study, stable isotope analysis of fish liver tissue suggests relatively few differences in feeding ecology of principal coldwater fish species in North Twin Lake compared to unoxygenated South Twin Lake. When compared between lakes, Rainbow Trout and Brook Trout diets contained similar proportions of Daphnia, Chironomidae, and Chaoboridae. Littoral and epilimnetic-focused Golden Shiner (Notemigonus crysoleucas) diets were also similar between lakes. Observed similarities between Golden Shiner and trout diets suggest the effects of interspecific competition between salmonids and non-salmonids may be limiting trout growth and survival. Fisheries managers should therefore consider both habitat limitations and interspecific competition when managing for coldwater fish species in mesotrophic, dimictic lakes.     

Using stable isotopes to test for trophic niche partitioning: a case study with stream salamanders and fish

1. Stream salamanders and fish often co‐occur even though fish prey on and outcompete salamanders. However, the mechanisms that allow palatable salamanders to coexist with fish are unknown. 2. We tested mechanisms in the field that promote coexistence between Idaho giant salamanders (Dicamptodon aterrimus) and stream salmonid fishes in headwater streams. Previous research in this system indicated that salamander dispersal did not promote coexistence with fish. We tested the hypothesis that D. aterrimus shift their diet when they occur with fish, facilitating coexistence through local niche partitioning. 3. We used nitrogen and carbon stable isotopes to describe the trophic niche of D. aterrimus and fish in three co‐occurring populations of salamanders and fish and three populations of salamanders without fish. We used two approaches to quantify trophic niche partitioning with stable isotopes: 95% kernel density estimators and isotopic mixing models. 4. We found that salamanders and fish were generalists that consumed aquatic invertebrates primarily, but both species were also cannibalistic and predatory on one another. We also found no support for trophic niche partitioning as a coexistence mechanism because there were no differences in the trophic niche metrics among salamander populations with and without fish. 5. Although we did not identify mechanisms that facilitate salamander and fish coexistence, our empirical data and use of novel approaches to describe the trophic niche did yield important insights on the role of predator–prey interactions and cannibalism as alternative coexistence mechanisms. In addition, we found that 95% kernel estimators are a simple and robust method to describe population‐level measure of trophic structure.     

Spring arrival response to climate change in birds: a case study from eastern Europe

This paper analyses the dependence of the first spring arrival dates of short/medium- and long-distance migrant bird species on climate warming in eastern Europe. The timing of arrival of the selected species at the observation site correlates with the North Atlantic Oscillation (NAO) index, air temperature, atmospheric pressure, precipitation and wind characteristics. A positive correlation of fluctuations in winter and spring air temperatures with variations in the NAO index has been established in eastern Europe. Positive winter NAO index values are related to earlier spring arrival of birds in the eastern Baltic region and vice versa—arrival is late when the NAO index is negative. The impact of climate warming on the bird’s life cycle depends on local or regional climate characteristics. We tested the hypothesis that differences in climate indices between North Africa and Europe can influence the timing of spring arrival. Our results support the hypothesis that differences in first spring arrival dates between European populations occur after individuals cross the Sahara. We assume that the endogenous programme of migration control in short/medium-distance migrants synchronises with the changing environment on their wintering grounds and along their migration routes, whereas in long-distance migrants it is rather with environmental changes in the second part of their migratory route in Europe. Our results strongly indicate that the mechanism of dynamic balance in the interaction between the endogenous regulatory programme and environmental factors determines the pattern of spring arrival, as well as migration timing.     

Resource allocation to reproduction and soma in Drosophila: a stable isotope analysis of carbon from dietary sugar

Metabolic resources in adults of holometabolous insects may derive either from larval or adult feeding. In Drosophila melanogaster, reproduction and lifespan are differently affected by larval vs. adult resource availability, and it is unknown how larval vs. adult acquired nutrients are differentially allocated to somatic and reproductive function. Here we describe the allocation of carbon derived from dietary sugar in aging female D. melanogaster. Larval and adult flies were fed diets contrasting in sucrose (13)C/(12)C, from which we determined the extent to which carbon acquired at each stage contributed to adult somatic tissue and to egg manufacture. Dietary sugar is very important in egg provisioning; at every age, roughly one half of the carbon in eggs was derived from sugar, which turned over from predominantly larval to entirely adult dietary sources. Sucrose provided approximately 40% of total somatic carbon, of which adult dietary sucrose came to supply approximately 75%. Unlike in eggs, however, adult acquired sucrose did not entirely replace the somatic carbon from larvally acquired sucrose. Because carbon from larval sucrose appears to be fairly "replaceable", larval sucrose cannot be a limiting substrate in resource allocation between reproduction and lifespan.     

The amino acids used in reproduction by butterflies: a comparative study of dietary sources using compound-specific stable isotope analysis

It is a nutritional challenge for nectar-feeding insects to meet the amino acid requirements of oviposition. Here we investigate whether egg amino acids derive from larval diet or are synthesized from nectar sugar in four species of butterfly: Colias eurytheme, Speyeria mormonia, Euphydryas chalcedona, and Heliconius charitonia. These species exhibit a range of life history and differ in degree of shared phylogeny. We use 13C differences among plants to identify dietary sources of amino acid carbon, and we measure amino acid 13C using compound-specific stable isotope analysis. Egg essential amino acids derived solely from the larval diet, with no evidence for metabolic carbon remodeling. Carbon in nonessential amino acids from eggs derived primarily from nectar sugars, with consistent variation in amino acid turnover. There was no relationship between the nonessential amino acids of eggs and host plants, demonstrating extensive metabolic remodeling. Differences between species in carbon turnover were reflected at the molecular level, particularly by glutamate and aspartate. Essential amino acid 13C varied in a highly consistent pattern among larval host plants, reflecting a common isotopic "fingerprint" associated with plant biosynthesis. These data demonstrate conservative patterns of amino acid metabolism among Lepidoptera and the power of molecular stable isotope analyses for evaluating nutrient metabolism in situ.     

Using stable isotope analysis to examine the effect of economic change on breastfeeding practices in Spitalfields, London, UK

Breastfeeding patterns were subject to a number of fads in 18th and 19th century Britain. Feeding infants by hand, rather than maternal breastfeeding or wet-nursing, became more prevalent among both the wealthy and poor. Substitute foods may have been a convenient alternative for mothers employed away from the household. This study used stable isotope ratio analysis to examine the weaning schedule in the 18th and 19th century skeletal assemblage from Spitalfields, London, UK. Analysis of 72 juvenile ribs revealed δ(15) N elevations of 2-3‰ above the adult mean for individuals up to the age of two, while elevations of 1-2‰ were observed in δ(13) C for the first year of life. This suggests that the introduction of solid foods took place before the end of the first year, and that breastfeeding had entirely ceased by 2 years of age. The age at death of many of these infants is known from historical records, and can be used to pinpoint the amount of time required for the breast milk signal to be observed in the stable isotope ratios of rib collagen. Results show that a δ(15) N elevation can be detected in the ribs of individuals who died as young as 5-6 weeks. Not all individuals at Spitalfields were breastfed, and there may not have been a single uniformly practiced weaning scheme. There is, however, more evidence for prolonged breastfeeding during the 19th century than the 18th century.     

Assessing trophic interactions in a guild of primary parasitoids and facultative hyperparasitoids: stable isotope analysis

Facultative hyperparasitism is likely to be the most common form of intraguild predation among parasitoids. However, difficulties associated with studying facultative hyperparasitoids in the field have hampered a thorough understanding of their trophic ecology. In this study, we used a combination of stable isotope analysis and published natural history information to infer trophic interactions in a guild of field-collected primary parasitoids and facultative hyperparasitoids that attack a gall-making midge on Baccharis pilularis. Our three a priori hypotheses were: (1) stable isotope values should increase incrementally from the host plant to higher trophic levels; (2) the two species of ectoparasitoids should exhibit higher stable isotope signatures than the two endoparasitoids, and; (3) the two facultative hyperparasitoids should exhibit stable isotope signatures that fall between zero and one trophic level steps above that observed for the primary parasitoids. Food webs inferred from stable isotope data generally agreed with previously published accounts of community structure. As expected, both δ¹³C and δ¹⁵N were progressively enriched in the heavy isotope from the host plant to the herbivorous midge to the parasitic wasps. Multivariate analysis of stable isotope data revealed that the two primary ectoparasitoids occupied a similar trophic niche, but were significantly different from the primary endoparasitoids. We attribute this result to “coincidental intraguild predation” by ectoparasitoids that develop on already-parasitized midge larvae. One of the facultative hyperparasitoids, Zatropis capitis, exhibited a stable isotope signature approximately one trophic step above the primary parasitoids. Unexpectedly, the second facultative hyperparasitoid, Mesopolobus sp., appeared to be developing as a primary parasitoid at all sites. Coupled with independent assessments of community structure, stable isotope analysis validated trophic links constructed by previous researchers and identified potential taxon-specific differences in trophic interactions for two facultative hyperparasitoids in the B. pilularis gall community.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Using spatial analysis to monitor tree diversity at a large scale: a case study in Northeast China Transect

Aims Monitoring and assessing diversity change at a large scale is important for any meaningful biodiversity conservation and management. Spatial analysis techniques can provide information about different aspects of diversity distribution including change. We applied some common spatial analysis methods and additive partitioning of species diversity in the Northeast China Transect as a case study to show how to characterize the distribution and change of tree diversity in this area from different perspectives.Methods The field data were collected from the permanent plots conducted every 4 km. The additive partitioning of species diversity was used to characterize the diversity of tree species at different scales. Moran's I was used for identifying the spatial scale of autocorrelation, lacunarity was studied for diversity patch contagion and dispersion and spectral entropy was used for assessing the overall spatial distribution.Important findings Data collected from 1986 to 1994 indicate that the change of α diversity was not significant in the study area, but the change of β diversity was significant. The percentage of α diversity in total diversity (γ) increased from 14.2 to 17.2%, and the percentage of β diversity decreased from 85.8 to 82.8%. For both α and β diversities, the scale of spatial autocorrelation decreased at the scale of 25–40 km and increased around 15–20 and 200 km. The lacunarity of α diversity decreased significantly and there was a sudden change at the scale of 56–68 km, but the lacunarity of β diversity increased across scales. The spectral entropy decreased slightly in α diversity and remained similar for β diversity. By using spatial analysis, we can monitor the diversity change over a large area and also assess the effectiveness of the current conservation strategies.     

Possible ideas on carbon and nitrogen trophic fractionation of food chains: a new aspect of food-chain stable isotope analysis in Lake Biwa, Lake Baikal, and the Mongolian grasslands

Trophic fractionation of carbon and nitrogen isotopes (Δδ¹³C, Δδ¹⁵N) was examined using previously complied databases for food chains in Lake Biwa, Lake Baikal, and Mongolian grassland. The following two features were clarified: (1) For each ecosystem, the ratios of trophic fractionation of carbon and nitrogen isotopes (Δδ¹⁵N/Δδ¹³C) throughout food chain could be obtained as the slope of linear regression line on the δ¹⁵N–δ¹³C plot. (2) Further, analysis of covariance (ANCOVA) revealed the slopes on δ¹⁵N–δ¹³C were not significantly different among these various ecosystems and allowed us to have the regression by setting δ¹⁵N as the response variable: δ¹⁵N = 1.61 δ¹³C + [ecosystem specific constant] with standard errors of [±0.41] and [±9.7] for the slope and the intercept, respectively. It was suggested that the slope of the regression (or the ratio Δδ¹⁵N/Δδ¹³C) could be applicable to more complicated food webs in case nitrogen and carbon isotope ratios of primary producers can be assumed constant in space and time within the ecosystems. The results from simple linear regression analyses coincided well with the ANCOVA results for these ecosystems, although there was some discrepancy between the results of the two statistical analyses. Possible factors that govern the linear relationship between δ¹⁵N and δ¹³C along a food chain are discussed together with a new scope for the stable isotope food chain analyses.     

Success of active restoration in grasslands: a case study of birds in southern Brazil

Grasslands in southeastern South America have been extensively converted to various land uses such as agriculture, threatening regional biodiversity. Active restoration has been viewed as a management alternative for recovery of degraded areas worldwide, although most studies are conducted in forests and none has evaluated the effect of active restoration of grasslands in southeastern South America. From 2015 through 2017 we monitored a federally owned tract of grassland from the beginning of the active‐restoration process. We compared the bird community in this active‐restoration area (AR) with a reference area (NG) in Pampa grasslands in southern Brazil. We sampled birds by point counts and surveyed vegetation structure in plots. Over the 3 years of active restoration, bird species richness and abundance were higher in AR (30 species, 171 individuals) than NG (22 species, 154 individuals). The species composition also differed between the two habitats. Grassland bird species were present in both AR and NG. The vegetation structure differed between AR and NG in five attributes: height, short and tall grasses, herbs, and shrubs. Since it has been found that active restoration is useful in promoting species diversity, we encourage studies of the use of long‐term restoration efforts. Our study, even on a local scale, showed a rapid recovery of the bird community in the active‐restoration compared to native grassland, and suggests the potential for recovery of the degraded grasslands of the Brazilian Pampa biome.     

Using motif-based methods in multiple genome analyses: a case study comparing orthologous mesophilic and thermophilic proteins

Protein motifs represent highly conserved regions within protein families and are generally accepted to describe critical regions required for protein stability and/or function. In this comprehensive analysis, we present a robust, unique approach to identify and compare corresponding mesophilic and thermophilic sequence motifs between all orthologous proteins within 44 microbial genomes. Motif similarity is determined through global sequence alignment of mesophilic and thermophilic motif pairs, which are identified by a greedy algorithm. Our results reveal only modest correlation between motif and overall sequence similarity, highlighting the rationale of motif-based approaches in comprehensive multigenome comparisons. Conserved mutations reflect previously suggested physiochemical principles for conferring thermostability. Additionally, comparisons between corresponding mesophilic and thermophilic motif pairs provide key biochemical insights related to thermostability and can be used to test the evolutionary robustness of individual structural comparisons. We demonstrate the ability of our unique approach to provide key insights in two examples: the TATA-box binding protein and glutamate dehydrogenase families. In the latter example, conserved mutations hint at novel origins leading to structural stability differences within the hexamer structures. Additionally, we present amino acid composition data and average protein length comparisons for all 44 microbial genomes.     

Applying DNA barcoding to conservation practice: a case study of endangered birds and large mammals in China

Owning to advantages over traditional species identification methods, DNA barcoding is suggested to be a promising tool in conservation research. However, the use of DNA barcoding to accurately identify unknown samples in conservation practices has not been well documented in the literature. To illustrate this issue, we implemented a survey of endangered birds and mammals in China based on mitochondrial Cytochrome c Oxidase subunit I (COI) gene. We included mostly confiscated specimens and non-invasive samples while concealing species information to simulate real-world scenarios of identification. In total, 47 avian and 39 mammalian specimen were re-identified by sequential analyses of online species assignment, genetic distances, phylogenetic reconstruction, and diagnostic nucleotide method. With this multiple analyses approach, 82 individuals were accurately assigned to the species level and four individuals to the genus level. 78.72% of the avian specimen and 87.18% of mammalian specimen identifications were consistent with morphological classification. Among those inconsistent with morphological classification, we identified several potential errors including misidentification based on morphology and mislabelling that may have occurred while combining results from different analytical methods. Our case study not only enriches the barcode database, but also reports a successful application of DNA barcoding identification to conservation practices, which could effectively facilitate species identification of unknown samples in conservation practices in the future.     

基于近低空遥感技术的国家公园功能分区边界识别: 以钱江源国家公园体制试点区为例

边界划分是国家公园保护与管理的重要手段, 通常以行政区和自然地理边界为参考, 借助人工干预的方法进行划分, 而较少考虑当地生态系统的完整性以及人为干扰因素, 造成边界划分不合理、不清晰。本研究以钱江源国家公园体制试点区中横岭角和古田山访客中心2处干扰较大的典型区为例, 用无人机近低空遥感技术结合实地植被调查, 评估现有功能分区。结果表明, 横岭角和古田山访客中心功能分区修正面积分别为53,550 m ²和19,667 m ², 分别占航拍研究区域面积的29.75%和16.39%。功能分区不合理划分的原因包括: (1)人为干扰较大的区域与自然地物较难分辨; (2)部分边界划分没有考虑生态系统的完整性, 将面积较小或完整性稍差的天然林划分为保护级别较低的区域。本研究采用航拍影像结合地面调查, 从保护当地生态系统完整性和减小人为干扰因素的角度出发, 为国家公园功能分区边界划分与细化提供一种合理可行的方法。