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The Argentine hake (Merluccius hubbsi) is a vital fishery species in the Southwest Atlantic, recognized for its substantial economic importance. Previous studies have identified Anisakidae larvae as common parasites of M. hubbsi. However, the nutritional relationships between these parasites and their host remain poorly understood. This study employs stable isotope techniques to investigate the specific nutritional relationships between Anisakidae larvae and different tissues of M. hubbsi. The findings reveal notable differences in δ13C and δ15N compositions between the parasites and their host. The lower δ13C values in parasites compared to host tissues indicate the utilization of different carbon sources. The δ15N values of the parasites partially overlap with those of the host's stomach, indicating that the parasites primarily derive nutrients from the host's stomach. Nutritional niche indicators show that parasites have a broad carbon range (CR) and nitrogen range (NR), suggesting a high diversity in nutritional sources. The trophic discrimination factor (ΔTDF), which represents the difference in stable isotope values between host tissues and parasites, was analyzed for both δ13C and δ15N. The ΔTDFδ13C between the host liver and the parasites showed the greatest variation, indicating a strong dependence of the parasites on the liver's carbon sources. In contrast, variations in ΔTDFδ15N between host tissues and parasites were minimal. Analyzing ΔTDF across different stages of gonadal maturity in the host fish indicates that, as the gonads of the host fish mature, ΔTDFδ13C between host tissues and parasites significantly decreases (p < 0.01). The Kruskal-Wallis test showed significant differences in ΔTDFδ13C values among different parasite infection levels in muscle, liver, and stomach tissues, while no significant differences were found for ΔTDFδ15N values. These findings offer valuable insights into the nutritional relationships between parasites and hosts, aiding in a better understanding of the growth conditions and habitats of M. hubbsi.

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The concept of uncertainty in an isotopic analysis is not uniform in the scientific community worldwide and can compromise the risk of false compliance assessment applied to carbon isotopic analyses in natural gas exploratory evaluation. In this work, we demonstrated a way to calculate one of the main sources of this uncertainty, which is underestimated in most studies focusing on gas analysis: the δ13C calculation itself is primarily based on the raw analytical data. The carbon isotopic composition of methane, ethane, propane, and CO2 was measured. After a detailed mathematical treatment, the corresponding expanded uncertainties for each analyte were calculated. Next, for the systematic isotopic characterization of the two gas standards, we calculated the standard uncertainty, intermediary precision, combined standard uncertainty, and finally, the expanded uncertainty for methane, ethane, propane, and CO2. We have found an expanded uncertainty value of 1.8‰ for all compounds, except for propane, where a value of 1.6‰ was obtained. The expanded uncertainty values calculated with the approach shown in this study reveal that the error arising from the application of delta calculation algorithms cannot be neglected, and the obtained values are higher than 0.5‰, usually considered as the accepted uncertainty associated with the GC-IRMS analyses. Finally, based on the use of uncertainty information to evaluate the risk of false compliance, the lower and upper acceptance limits for the carbon isotopic analysis of methane in natural gas are calculated, considering the exploratory limits between -55‰ and -50‰: (i) for the underestimated current uncertainty of 0.5‰, the lower and upper acceptance limits, respectively, are -54.6‰ and -50.4‰; and (ii) for the proposed realistic uncertainty of 1.8‰, the lower and upper acceptance limits would be more restrictive; i.e., -53.5‰ and -51.5‰, respectively.

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The southern Mendoza province, located in the northern region of Patagonia, was inhabited by hunter-gatherer groups until historic times. Previous archaeological studies have reported canid remains among faunal assemblages, which were assumed to be part of the human diet. However, the taxonomic identification and significance of these canids within human groups have raised questions. In this study, we used ancient DNA analysis, morphological examination and stable isotope analysis (δ13Ccol and δ15N) to re-evaluate the taxonomic assignment of a canid discovered at the Late Holocene burial site of Cañada Seca. Previous morphological identifications suggested that it belonged to the genus Lycalopex, but our results conclusively demonstrate that the individual belongs to the extinct fox species Dusicyon avus. This finding expands Dusicyon avus' known geographical distribution to Patagonia's northern extremity. Furthermore, statistical predictions based on genetic divergence undermine the hypothesis that hybridization between Canis and Dusicyon, facilitated by the introduction of domestic dogs, played a role in the extinction of Dusicyon species. On the other hand, our findings indicate that a Dusicyon avus individual shared a similar diet and was probably buried alongside humans, suggesting a close relationship between the two species during their lives and deaths.

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OBJECTIVES: Early colonial documents from central Mesoamerica detail raising and planting of European livestock and crops alongside native ones. The extent to which Indigenous people, especially of the rural commoner class, consumed newly introduced foods is less known. This gap in knowledge is addressed through stable isotope analysis and comparison to published archaeological botanical, human, and faunal data. MATERIALS AND METHODS: Stable isotope analysis of bone collagen and bioapatite is applied to 74 skeletal samples of Indigenous human remains representing Colonial period individuals from El Japón-a farming hamlet in the Xochimilco area-to provide insight into long-term individual dietary practices in the context of a rapidly transforming Mesoamerican world. RESULTS: Carbon isotope ratios in collagen (δ13Ccollagen) average -8.10/00 VPDB (SD 0.55), while δ15N averages 8.90/00 AIR (SD 0.50). δ13Cbioapatite averages -2.90/00 VPDB (SD 0.60). Modest increase in carbon isotopic diversity is observed among more recent males from El Japón when compared to earlier males and females. DISCUSSION: Based on the isotopic results, it is estimated that the individuals of El Japón consumed maize or other C4 plants as a central source of carbohydrates. Dietary protein was largely supplied through domestic maize-fed fauna but potentially supplemented by wild terrestrial and aquatic fauna and fowl. Similarity in skeletal isotopic composition between precontact Mesoamericans from other sites and El Japón individuals of both earlier and later stratigraphy is interpreted as continuity in local diets and foodways despite potentially available European alternatives. Colonial taxation demands on preexisting agricultural regimes may have incentivized maize production, thus indirectly contributing to the maize-centered aspect of local foodways.

OBJETIVOS: Los textos de la época colonial temprana del centro de México documentan la producción de cultivos y ganado europeo a la par de los productos agropecuarios nativos. La magnitud a la cuál las comunidades indígenas consumieron estos productos se conoce con menos certeza en especial dentro de los asentamientos rurales. En este trabajo, se analiza la variabilidad de datos de isótopos estables en el sitio El Japón, Xochimilco y los resultados se comparan con respecto al sexo biológico y la cronología; así como también con datos publicados de muestras humanas y faunísticas. MATERIALES Y MÉTODOS: Se aplican los estudios de isotopos estables en colágeno y bioapatita a 74 muestras esqueléticas de El Japón de la época colonial temprana, una aldea agrícola del área de Xochimilco, con tal de abordar las practicas dietéticas en el contexto de un mundo Mesoamericano en transformación tras el contacto europeo. RESULTADOS: Los isótopos estables de carbono en colágeno (δ13Ccollagen) producen un promedio de −8.10/00 VPDB (DE 0.55), mientras tanto los isótopos estables de nitrógeno en el mismo tejido producen un promedio de 8.90/00 AIR (DE 0.50). Los isótopos estables de carbono en la bioapatita (δ13Cbioapatite) producen un promedio de −2.90/00 VPDB (DE 0.60). Se observa un incremento mínimo en la diversidad isotópica entre los individuos de sexo masculino en comparación a los individuos de sexo femenino de la etapa temprana y tardía del sitio. DISCUSIÓN: Con base en los resultados isotópicos, y con base en comparación a muestras humanas de contextos arqueológicos europeos y norteamericanos se estima que los individuos de El Japón consumieron maíz u otros cultivos tipo C4 como fuentes principales de carbohidratos. Las fuentes de proteína dietética posiblemente fueron fauna alimentada con maíz, pero también se pudieron haber suplementado con alimentos silvestres incluyendo aves silvestres, y fauna terrestre o acuática. La similitud en variación isotópica entre sitios mesoamericanos que preceden el contacto europeo y El Japón de ambas etapas (temprana y tardía) se interpretan como persistencia en fuentes de alimentación y tradiciones culinarias a pesar de las posibles alternativas europeas. Las demandas tributarias coloniales sobre la producción agrícola chinampera pudiesen haber contribuido indirectamente a la continuidad del maíz como fuente alimenticia principal.

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The yellowfin tuna is a very abundant tropical tuna species in the western equatorial Atlantic Ocean and an important fishery resource for the Brazilian tuna fleet. In this study we performed stable isotope analysis to better understand the spatial trophodynamics and dietary changes in yellowfin tuna around two insular marine protected areas in Brazil. A total of 65 yellowfin tuna specimens measuring between 47 and 138 cm LT (total length) were sampled around the archipelagos of Fernando de Noronha (FNA; n = 34) and Saint Peter and Saint Paul (SPSPA; n = 31) between July 2018 and September 2019. Bayesian mixing models and generalized additive models were used to investigate the contributions of four different prey items (zooplankton, cephalopods, fish larvae, and flying fish) to yellowfin tuna diet in each area and their potential changes in relation to predator growth. The four prey items were found to have different overall contributions between the two studied areas, with zooplankton being the most important prey in FNA, whereas flying fish was the most relevant prey to the species' diet in SPSPA. Significant changes in the species diet by size were also found, with fish smaller than 90 cm (TL) having a more generalist diet and larger animals relying more on consuming larger and more nutritious prey (i.e., flying fish). Our results suggest that these two marine protected areas play an important role in ocean dynamics, providing important and different foraging grounds for the development of this predator species.

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Forensic anthropologists have used oxygen isotopic analyses (δ18O) in recent decades because of its ability to help estimate probable regions of origin of unidentified individuals based on isotopic composition of bodily tissues. Prior research has found that drinking water is geographically patterned and that tap water is often representative of drinking water in assessing these links between human tissues and geography. Researchers have begun applying the method in a variety of global contexts. This research critically assesses the assumption that tap water is isotopically representative of drinking water in Oaxaca, Mexico. Drinking water samples from Oaxaca were analyzed and compared with predicted δ18O values from a previously constructed tap water isoscape of Mexico. Hair samples from Oaxaca were also analyzed to compare against various water sources. Tap water δ18O values do not reliably reflect drinking water δ18O in sampled regions of Oaxaca, Mexico. Further, the models relating hair keratin to drinking water, built on this assumption, fail to hold predictive power. With an incomplete understanding of tap water's ability to represent drinking water isotopically, researchers need to study the role of other key factors in δ18O values. If the individual's being identified with δ18O are from non-Western communities, forensic practitioners run the risk of incorrectly predicting region of origin because of the method's assumptions. Recognizing the varying sociocultural realities of the communities forensic practitioners seek to aid is paramount as we grow and develop our methods moving forward.

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Biological invasions are expected to alter food web structure, but there are limited empirical data directly comparing invaded versus uninvaded food webs, particularly in species-rich, tropical systems. We characterize for the first time the food web of Lake Gatun-a diverse and highly invaded tropical freshwater lake within the Panama Canal. We used stable isotope analysis to reconstruct the trophic structure of the fish community of Lake Gatun and to compare it to that of a minimally invaded reference lake, Lake Bayano. We found significant differences between the trophic structures of these two Neotropical lakes, notably that Lake Gatun's fish community was characterized by a longer food chain, greater isotopic diversity, a broader range of trophic positions and body sizes, and shifts in the isotopic positions of several native taxa relative to Lake Bayano. The degree of isotopic overlap between native and non-native trophic guilds in Lake Gatun was variable, with herbivores exhibiting the lowest (20%-29%) overlap and carnivores the greatest (81%-100%). Overall, our results provide some of the first empirical evidence for the ways in which multiple introduced and native species may partition isotopic space in a species-rich tropical freshwater food web.

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Invasive species pose a major threat to forest biodiversity, particularly on islands such as the Galapágos. Here, invasive plants are threatening the remnants of the unique cloud forest and its iconic Darwin's finches. We posit that food web disturbances caused by invasive Rubus niveus (blackberry), have contributed to the rapid decline of the insectivourous green warbler finch (Certhidae olivacea). We compared the birds' dietary changes in long-term management, short-term management and unmanaged areas. We measured C:N ratios, and δ15N­nitrogen and δ13C­carbon values in both consumer tissues (bird-blood) and food sources (arthropods), as indicators of resource use change, and collected mass abundance, and arthropod diversity data. We characterised the birds' diets using isotope mixing models. The results revealed that finches in (blackberry-invaded) unmanaged areas foraged more on abundant, yet lower quality, arthropods present in the invaded understory. This suggests that blackberry encroachment leads to a decrease in food source quality with physiological consequences for green warbler finch chicks. Results also implied that blackberry control has a short-term impact on food source quantity, which led to a decrease in chick recruitment that we observed in our previous studies; despite this, in the long-term, these managed systems show signs of recovery within three years of restoration.

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To study how Odontaster validus can influence the spatial structure of Antarctic benthic communities and how they respond to disturbance, it is necessary to assess potential dietary shifts in different habitats. We investigated the diets of O. validus from Maxwell Bay and South Bay in the West Antarctic Peninsula. A multifaceted approach was applied including in situ observations of cardiac stomach everted contents, isotopic niche, and trophic diversity metrics. Results confirm the flexible foraging strategy of this species under markedly different environmental conditions, suggesting plasticity in resource use. The data also showed evidence of isotopic niche expansion, high δ15N values, and Nacella concinna as a common food item for individuals inhabiting a site with low seasonal sea ice (Ardley Cove), which could have significant ecological implications such as new trophic linkages within the Antarctic benthic community. These results highlight the importance of considering trophic changes of key species to their environment as multiple ecological factors can vary as a function of climatic conditions.

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Three decades have passed since the publication in 1991 of the first use of stable isotope analysis applied to a Brazilian archaeological context. Despite being still mainly applied to palaeodietary research, stable isotope analysis in archaeology has been diversified in Brazil. In the last five years, an increasing number of studies has addressed various issues. Such issues are related to population mobility, social differentiation, health and children care, changes and resilience of cultural practices, and identification of the origin of enslaved populations brought by force from the African continent, among others. However, research in this area is still incipient when compared to the large territory of Brazil (WGS 84: -33˚ to 5°N, -73˚ to -34˚E), the diversity of socio-cultural contexts of pre-colonial and indigenous societies, and the country's historical formation process. In terms of radiocarbon dates, data are also sparse and lack essential information as the material used for dating, as this information could be related to necessary corrections, e.g., the marine reservoir effect. The first radiocarbon dates of Brazilian archaeological material are reported, however, since the 1950s and have been more frequently reported in publications across Brazil since the installation of the first Brazilian radiocarbon laboratory (CENA/USP) in 1990 and the first Latin American 14C-AMS facility (LAC-UFF) in 2012. Thus, the purpose of this compilation was to gather all dispersed, and often fragmented, data from analyses of stable and radioactive (focusing on radiocarbon) isotopes carried out in Brazilian archaeological contexts. We compiled data from 1991 until the end of November 2021. The data included here contain information from 71 archaeological sites, 556 humans, 219 animals and 2 plants. Isotopic analyses were performed on 832 organic samples, mainly paired δ13C and δ15N plus δ34S measurements, and on 265 mineral samples, mainly δ13C, δ18O and 86Sr/87Sr measurements. Sr concentrations for 49 mineral samples were also compiled. Radiocarbon or relative dates span from 18 kyr BP to the present. All data from this compilation are deposited in open access on the IsoArcH platform (https://doi.isoarch.eu/doi/2021.005). This extensive work aims to point out the gaps in stable isotopes and radiocarbon dates provided for Brazilian archaeological contexts that could be further explored. Besides, it aims to promote easy access to numerous analyses that, otherwise, would be hard to obtain. Lastly, it seeks to broaden the interdisciplinary collaboration in Brazil and strengthen the international collaboration among peers.

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Oxygen and hydrogen isotope data of meteoric water samples are compiled from several States across Mexico. This dataset includes 287 oxygen and hydrogen (and deuterium excess) isotope data corresponding to meteoric water collected from the surface, groundwater wells, irrigation and observation wells, and water supply boreholes. These data facilitate the development of maps to determine the spatial distribution of water stable isotopes, also known as "isoscapes", of the Mexican territory. As such, this dataset (and the isoscapes built from it) is useful in geographic mobility studies that aim to evaluate geographic origins and residency of particular human and/or non-human individuals in antiquity and in contemporary times. Further discussion about the data and an example of an isoscape of Mexico using the meteoric water oxygen isotope data are provided in "Residential Patterns of Mexica Human Sacrifices at Mexico-Tenochtitlan and Mexico-Tlatelolco: Evidence from Phosphate Oxygen Isotopes" (Moreiras Reynaga et al., 2021). Overall, the dataset is useful in developing interpolated maps of water stable isotopes for relevant archeological, bioarchaeological, forensic, hydrogeological, and ecological research.

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OBJECTIVES: Stable isotope analysis can provide crucial insight into the function and development of early state-level societies on the north coast of Peru. MATERIALS AND METHODS: Multi-tissue (bone collagen, tooth enamel, hair, nail, skin, and tendon) stable isotope analyses (carbon, nitrogen, sulfur, and strontium) were conducted for 13 individuals from the lower Virú Valley. RESULTS: Non-seasonal changes in a predominantly C4 -based terrestrial diet, with minimal inputs of marine foods were identified. One individual (Burial 5), however, had a stable isotope signature unlike any previously found on the north coast of Peru, indicating both a large contribution of C3 -terrestrial resources to their diet and an 87 Sr/86 Sr value suggestive of highland residence during childhood. DISCUSSION: This research provides the first strong stable isotope evidence of a highland individual within a coastal burial in northern Peru, new insight into the ritual killing event at Huaca Santa Clara during the late middle horizon and supporting evidence of the importance of C4 terrestrial resources to the developing Virú polity during the early intermediate period.

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Natural chlorate (ClO3-) is widely distributed in terrestrial and extraterrestrial environments. To improve understanding of the origins and distribution of ClO3-, we developed and tested methods to determine the multi-dimensional isotopic compositions (δ18O, Δ17O, δ37Cl, 36Cl/Cl) of ClO3- and then applied the methods to samples of natural nitrate-rich caliche-type salt deposits in the Atacama Desert, Chile, and Death Valley, USA. Tests with reagents and artificial mixed samples indicate stable-isotope ratios were minimally affected by the purification processes. Chlorate extracted from Atacama samples had δ18O = +7.0 to +11.1‰, Δ17O = +5.7 to +6.4‰, δ37Cl = -1.4 to +1.3‰, and 36Cl/Cl = 48 × 10-15 to 104 × 10-15. Chlorate from Death Valley samples had δ18O = -6.9 to +1.6‰, Δ17O = +0.4 to +2.6‰, δ37Cl = +0.8 to +1.0‰, and 36Cl/Cl = 14 × 10-15 to 44 × 10-15. Positive Δ17O values of natural ClO3- indicate that its production involved reaction with O3, while its Cl isotopic composition is consistent with a tropospheric or near-surface source of Cl. The Δ17O and δ18O values of natural ClO3- are positively correlated, as are those of ClO4- and NO3- from the same localities, possibly indicating variation in the relative contributions of O3 as a source of O in the formation of the oxyanions. Additional isotopic analyses of ClO3- could provide stronger constraints on its production mechanisms and/or post-formational alterations, with applications for environmental forensics, global biogeochemical cycling of Cl, and the origins of oxyanions detected on Mars.

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Isotopic values of two Caribbean sharpnose shark Rhizoprionodon porosus litters (Poey, 1861) with two and three embryos and one litter of 11 smalltail shark Carcharhinus porosus embryos showed enriched 15 N and 13 C compared to their mothers. In R. porosus, embryonic isotope values were 3.06 ± 0.07‰ and 0.69 ± 0.15‰ greater than their mothers' for δ15 N and δ13 C, respectively, whereas in C. porosus, δ15 N and δ13 C were 1.79 ± 0.09‰ and 1.31 ± 0.17‰ greater in embryos than their mothers.

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The widespread importance of variable types of primary production, or energy channels, to consumer communities has become increasingly apparent. However, the mechanisms underlying this "multichannel" feeding remain poorly understood, especially for aquatic ecosystems that pose unique logistical constraints given the diversity of potential energy channels. Here, we use bulk tissue isotopic analysis along with carbon isotope (δ13 C) analysis of individual amino acids to characterize the relative contribution of pelagic and benthic energy sources to a kelp forest consumer community in northern Chile. We measured bulk tissue δ13 C and δ15 N for >120 samples; of these we analyzed δ13 C values of six essential amino acids (EAA) from nine primary producer groups (n = 41) and 11 representative nearshore consumer taxa (n = 56). Using EAA δ13 C data, we employed linear discriminant analysis (LDA) to assess how distinct EAA δ13 C values were between local pelagic (phytoplankton/particulate organic matter), and benthic (kelps, red algae, and green algae) endmembers. With this model, we were able to correctly classify nearly 90% of producer samples to their original groupings, a significant improvement on traditional bulk isotopic analysis. With this EAA isotopic library, we then generated probability distributions for the most important sources of production for each individual consumer and species using a bootstrap-resampling LDA approach. We found evidence for multichannel feeding within the community at the species level. Invertebrates tended to focus on either pelagic or benthic energy, deriving 13-67% of their EAA from pelagic sources. In contrast, mobile (fish) taxa at higher trophic levels used more equal proportions of each channel, ranging from 19% to 47% pelagically derived energy. Within a taxon, multichannel feeding was a result of specialization among individuals in energy channel usage, with 37 of 56 individual consumers estimated to derive >80% of their EAA from a single channel. Our study reveals how a cutting-edge isotopic technique can characterize the dynamics of energy flow in coastal food webs, a topic that has historically been difficult to address. More broadly, our work provides a mechanism as to how multichannel feeding may occur in nearshore communities, and we suggest this pattern be investigated in additional ecosystems.

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As environmental change persists, understanding resource use patterns is of value to predict the consequences of shifting trophic structures. While many sharks are opportunistic predators, some exhibit prey selectivity, putting them at higher risk compared to species with greater trophic plasticity. In the Gulf of Mexico (GOM), Clupeids and Sciaenids comprise 69% of blacktip shark (Carcharhinus limbatus) diets, which is consequential considering potential responses of these prey groups to disturbance and over harvesting. We assessed if blacktips exhibit selectivity for Clupeids and Sciaenids in the western GOM based on stomach contents from sharks in coastal Texas. Clupeids comprised <2% of diets, while striped mullet (Mugil cephalus) and red drum (Sciaenops ocellatus) comprised >70% of identifiable prey. Ontogenetic shifts from smaller (Clupeids, small Sciaenids) to larger, higher trophic level (Ariidae, Elasmobranchii) prey fits our understanding of foraging among coastal sharks, and suggests our regional understanding of blacktip trophic ecology may be limited by the sizes of sampled sharks. Observed increases in blacktip densities coupled with declines in prey (Mugilids, Sciaenids) is concerning if blacktips have limited diet plasticity. Yet GOM blacktips may be more generalized than previously thought, which is promising for conservation and management.

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OBJECTIVES: Ecological similarity between species can lead to interspecific trophic competition. However, when ecologically similar species coexist, they may differ in foraging strategies and habitat use, which can lead to niche partitioning. As the body tissues of consumers contain a stable isotope signature that reflects the isotopic composition of their diet, stable isotope analysis is a useful tool to study feeding behavior. We measured the isotopic niche width, which is a proxy for trophic niche width, of mantled (Alouatta palliata) and black (A. pigra) howler monkeys. Specifically, studied populations in allopatry and sympatry to assess whether these species showed niche partitioning. MATERIALS AND METHODS: Between 2008 and 2012, we collected hair samples from 200 subjects (113 black and 87 mantled howler monkeys) and used continuous flow isotope ratio mass spectrometry to estimate δ13 C and δ15 N. We described the isotopic niche width of each species in allopatry and sympatry with the Bayesian estimation of the standard ellipse areas. RESULTS: In allopatry, isotopic niche width and isotopic variation were similar in both species. In sympatry, black howler monkeys had a significantly broader isotopic niche, which was mainly determined by high δ15 N values, and included the majority of mantled howler monkeys' isotopic niche. The isotopic niche of mantled howler monkeys did not differ between sympatry and allopatry. CONCLUSIONS: The coexistence of these ecologically similar species may be linked to trophic niche adjustments by one species, although the particular features of such adjustments (e.g., dietary, spatial, or sensory partitioning) remain to be addressed.

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We report cadmium (Cd) concentrations in muscle, liver, and blood of striped marlin (Kajikia audax) and blue marlin (Makaira nigricans), caught in the southwest of the Gulf of California. The average Cd concentration was higher in the liver followed by blood and muscle in descending order. This pattern of Cd concentration may be related to the differences in the physiological function of these tissues. In K. audax, the Cd concentration in muscle and liver increased proportionally with body size, but only in animals that have reached the body size corresponding to first sexual maturity (animals exceeding 155 cm of postorbital length). Interspecific differences in dietary composition and Cd content evidenced that food preferences have a significant effect on the bioaccumulation of Cd. No evidence of Cd biomagnification (progressive bioaccumulation of an element along the food web) was found, as the correlation between logarithmic Cd concentrations and δ15N values was not significant when both billfish and their prey items were included in the calculations. Furthermore, the calculated biotransference factor (transfer of an element from food to consumer) suggested that Cd transference is interrupted from prey to marlins.

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The broad negative consequences of habitat degradation on biodiversity have been studied, but the complex effects of natural-agricultural landscape matrices remain poorly understood. Here we used stable carbon and nitrogen isotopes to detect changes in mammal resource and habitat use and trophic structure between preserved areas and human-modified landscapes (HMLs) in a biodiversity hot spot in South America. We classified mammals into trophic guilds and compared resource use (in terms of C3- and C4-derived carbon), isotopic niches, and trophic structure across the 2 systems. In HMLs, approximately one-third of individuals fed exclusively on items from the agricultural matrix (C4), while in preserved areas, ∼68% depended on forest remnant resources (C3). Herbivores, omnivores, and carnivores were the guilds that most incorporated C4 carbon in HMLs. Frugivores maintained the same resource use between systems (C3 resources), while insectivores showed no significant difference. All guilds in HMLs except insectivores presented larger isotopic niches than those in preserved areas. We observed a complex trophic structure in preserved areas, with increasing δ15N values from herbivores to insectivores and carnivores, differing from that in HMLs. This difference is partially explained by species loss and turnover and mainly by the behavioral plasticity of resilient species that use nitrogen-enriched food items. We concluded that the landscape cannot be seen as a habitat/nonhabitat dichotomy because the agricultural landscape matrix in HMLs provides mammal habitat and opportunities for food acquisition. Thus, favorable management of the agricultural matrix and slowing the conversion of forests to agriculture are important for conservation in this region.

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OBJECTIVES: To characterize the paleodiet of individuals from Formative Period (1500 B.C.-A.D. 400) Atacama Desert sites of Ancachi and Quillagua as a means of understanding the dietary and cultural impacts of regional systems of exchange. MATERIALS AND METHODS: Thirty-one bone samples recovered from the cemetery of Ancachi (02QU175) and in/around the nearby town of Quillagua were the subject of carbon and nitrogen stable isotope analysis of bone collagen and hydroxyapatite and multisource mixture modeling (FRUITS, food reconstruction using isotopic transferred signals) of paleodiet. These individuals were compared with nearly 200 other Formative Period individuals from throughout the region to identify differences in dietary behaviors. RESULTS: 80.6% (25/31) of the samples yielded sufficient well-preserved collagen and were included in the multisource mixture model. The FRUITS model, which compared individuals with a robust database of available foods from the region, identified a wide diversity of diets in the Ancachi/Quillagua area (including both coastal and interior individuals), and, most notably, thirteen individuals who consumed an average of 11.2 ± 1.9% terrestrial animals, 19.8 ± 1.9% legumes, and 22.5 ± 3.1% marine fauna, a balanced pattern of protein consumption distinct from both the coastal and inland individuals in our larger regional sample. CONCLUSIONS: The combination of stable isotope analysis and multisource mixture modeling permitted the characterization of dietary behavior of 25 individuals from nodal sites in the Atacama Desert, thus enhancing our understanding of the economic and social relationships that bound together Formative Period sites, populations, and individuals in this hyperarid region.

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