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Rogers EJ, Gerson AR. Water restriction increases oxidation of endogenous amino acids in house sparrows (Passer domesticus). J Exp Biol 2024; 227:jeb246483. [PMID: 38380522 PMCID: PMC11093224 DOI: 10.1242/jeb.246483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 02/06/2024] [Indexed: 02/22/2024]
Abstract
Animals can cope with dehydration in a myriad of ways, both behaviorally and physiologically. The oxidation of protein produces more metabolic water per kilojoule than that of fat or carbohydrate, and it is well established that birds increase protein catabolism in response to high rates of water loss. However, the fate of amino acids mobilized in response to water restriction has not been explicitly determined. While protein catabolism releases bound water, we hypothesized that water-restricted birds would also oxidize the resulting amino acids, producing additional water as a product of oxidative phosphorylation. To test this, we fed captive house sparrows (Passer domesticus) 13C-labeled leucine for 9 weeks to label endogenous proteins. We conducted weekly trials during which we measured the physiological response to water restriction as changes in lean mass, fat mass, metabolism and the enrichment of 13C in exhaled CO2 (δ13Cbreath). If water-restricted birds catabolized proteins and oxidized the resulting amino acids, we expected to simultaneously observe greater lean mass loss and elevated δ13Cbreath relative to control birds. We found that water-restricted birds catabolized more lean tissue and also had enriched δ13Cbreath in response to water restriction, supporting our hypothesis. δ13Cbreath, however, varied with metabolic rate and the length of the water restriction period, suggesting that birds may spare protein when water balance can be achieved using other physiological strategies.
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Affiliation(s)
- Elizabeth J. Rogers
- Organismic and Evolutionary Biology Program, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Alexander R. Gerson
- Organismic and Evolutionary Biology Program, University of Massachusetts Amherst, Amherst, MA 01003, USA
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003, USA
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2
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Reid REB, Crowley BE, Haupt RJ. The prospects of poop: a review of past achievements and future possibilities in faecal isotope analysis. Biol Rev Camb Philos Soc 2023; 98:2091-2113. [PMID: 37438959 DOI: 10.1111/brv.12996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 07/14/2023]
Abstract
What can the stable isotope values of human and animal faeces tell us? This often under-appreciated waste product is gaining recognition across a variety of disciplines. Faecal isotopes provide a means of monitoring diet, resource partitioning, landscape use, tracking nutrient inputs and cycling, and reconstructing past climate and environment. Here, we review what faeces are composed of, their temporal resolution, and how these factors may be impacted by digestive physiology and efficiency. As faeces are often used to explore diet, we clarify how isotopic offsets between diet and faeces can be calculated, as well as some differences among commonly used calculations that can lead to confusion. Generally, faecal carbon isotope (δ13 C) values are lower than those of the diet, while faecal nitrogen isotope values (δ15 N) values are higher than in the diet. However, there is considerable variability both within and among species. We explore the role of study design and how limitations stemming from a variety of factors can affect both the reliability and interpretability of faecal isotope data sets. Finally, we summarise the various ways in which faecal isotopes have been applied to date and provide some suggestions for future research. Despite remaining challenges, faecal isotope data are poised to continue to contribute meaningfully to a variety of fields.
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Affiliation(s)
- Rachel E B Reid
- Department of Geosciences, Virginia Tech, 4044 Derring Hall, 926 West Campus Dr, Blacksburg, VA, 24061, USA
| | - Brooke Erin Crowley
- Department of Geosciences, University of Cincinnati, 500 Geology Physics Building, 345 Clifton Court, Cincinnati, OH, 45221-0013, USA
- Department of Anthropology, University of Cincinnati, 481 Braunstein Hall, Cincinnati, OH, 45221-0380, USA
| | - Ryan J Haupt
- National Youth Science Foundation, PO Box 3387, Charleston, WV, 25333-3387, USA
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3
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Hewitt DE, Taylor MD, Raoult V, Smith TM, Gaston TF. Diet-tissue discrimination and turnover of δ 13 C and δ 15 N in muscle tissue of a penaeid prawn. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9167. [PMID: 34494325 DOI: 10.1002/rcm.9167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 07/13/2021] [Accepted: 07/16/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE Stable isotopes are used to study trophic and movement ecology in aquatic systems, as they provide spatially distinct, time-integrated signatures of diet. Stable isotope ecology has been used to quantify species-habitat relationships in many important fisheries species (e.g., penaeid prawns), with approaches that typically assume constant values for diet-tissue discrimination and diet-tissue steady state, but these can be highly variable. Here we provide the first report of these processes in Metapenaeus macleayi (eastern school prawn). METHODS Here we explicitly measure and model carbon (δ13 C) and nitrogen (δ15 N) diet-tissue discrimination and turnover in eastern school prawn muscle tissue as a function of experimental time following a change in diet to an isotopically distinct food source. RESULTS Diet-tissue discrimination factors were 5 and 0.6‰ for δ13 C and δ15 N, respectively. Prawn muscle tissue reached an approximate steady state after approximately 50 and 30 days for δ13 C and δ15 N. Half-lives indicated faster turnover of δ15 N (~8 days) than δ13 C (~14 days). CONCLUSIONS Our diet-tissue discrimination factors deviate from 'typical' values with larger values for carbon than nitrogen isotopes, but are generally similar to those measured in other crustaceans. Similarly, our estimates of isotopic turnover align with those in other penaeid species. These findings confirm muscle tissue as a reliable indicator of long-term diet and movement patterns in eastern school prawn.
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Affiliation(s)
- Daniel E Hewitt
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW, Australia
| | - Matthew D Taylor
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW, Australia
- New South Wales Department of Primary Industries, Port Stephens Fisheries Institute, Nelson Bay, NSW, Australia
| | - Vincent Raoult
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW, Australia
| | - Timothy M Smith
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW, Australia
- Centre for Tropical Water and Aquatic Ecosystems Research (TropWATER), James Cook University, Cairns, QLD, Australia
| | - Troy F Gaston
- School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW, Australia
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4
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Kroska AC, Wolf N, Planas JV, Baker MR, Smeltz TS, Harris BP. Controlled experiments to explore the use of a multi-tissue approach to characterizing stress in wild-caught Pacific halibut ( Hippoglossus stenolepis). CONSERVATION PHYSIOLOGY 2021; 9:coab001. [PMID: 33575032 PMCID: PMC7868037 DOI: 10.1093/conphys/coab001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 09/30/2020] [Accepted: 01/04/2021] [Indexed: 06/12/2023]
Abstract
The integration of multiple tissues in physiological and ecological analyses can enhance methodological approaches, increase applications for data and extend interpretation of results. Previous investigations of the stress response in fish have focused primarily on cortisol levels in a single matrix-blood plasma-which confines interpretations of cortisol levels to a short temporal frame. Epidermal mucus has been proposed as an alternative or complement to plasma that may provide a view to cortisol levels over a different temporal window allowing comparative assessment. Here, we explore the potential for multi-tissue cortisol analysis using both plasma and epidermal mucus in Pacific halibut (Hippoglossus stenolepis). The relative timing at which cortisol increased and decreased in the two matrices as well as cortisol concentrations at estimated peak levels were compared in two trials after (i) inducing cortisol synthesis by adrenocorticotropic hormone (ACTH1-24) administration and (ii) inducing cortisol elimination using cortisol (hydrocortisone, 98%) injection. The ACTH treatment elicited a peak plasma cortisol response approximately 12 hours post-injection, while mucus cortisol concentrations peaked later at approximately 62 hours post-injection. Exogenous cortisol treatments suggested relatively little transfer of cortisol from plasma to mucus, potentially reflecting differential effects of endogenous and exogenous cortisol. Our results suggest the potential utility of mucus as a sampling matrix that provides an extended window for detection of the stress response as compared to plasma. Results also suggest the utility of a multi-tissue approach to cortisol analysis with potential applications to applied fisheries research. Increased understanding of the relative scale of the cortisol response to stress (e.g. capture) will allow researchers and managers to better interpret the physiological condition and survival outcome of fish subjected to regulatory discard.
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Affiliation(s)
- Anita C Kroska
- Fisheries, Aquatic Science, and Technology Laboratory, Alaska Pacific University, 4101 University Dr., Anchorage, AK 99508, USA
| | - Nathan Wolf
- Fisheries, Aquatic Science, and Technology Laboratory, Alaska Pacific University, 4101 University Dr., Anchorage, AK 99508, USA
| | - Josep V Planas
- Fisheries, Aquatic Science, and Technology Laboratory, Alaska Pacific University, 4101 University Dr., Anchorage, AK 99508, USA
- International Pacific Halibut Commission, 2320 W Commodore Way, Seattle, WA 98199, USA
| | - Matthew R Baker
- Fisheries, Aquatic Science, and Technology Laboratory, Alaska Pacific University, 4101 University Dr., Anchorage, AK 99508, USA
- North Pacific Research Board, 1007 W 3rd Ave #100, Anchorage, AK 99501, USA
| | - T Scott Smeltz
- Fisheries, Aquatic Science, and Technology Laboratory, Alaska Pacific University, 4101 University Dr., Anchorage, AK 99508, USA
| | - Bradley P Harris
- Fisheries, Aquatic Science, and Technology Laboratory, Alaska Pacific University, 4101 University Dr., Anchorage, AK 99508, USA
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Exploring source differences on diet-tissue discrimination factors in the analysis of stable isotope mixing models. Sci Rep 2020; 10:15816. [PMID: 32978550 PMCID: PMC7519091 DOI: 10.1038/s41598-020-73019-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 09/10/2020] [Indexed: 11/08/2022] Open
Abstract
Stable isotope mixing models are regularly used to provide probabilistic estimates of source contributions to dietary mixtures. Whilst Bayesian implementations of isotope mixing models have become prominent, the use of appropriate diet-tissue discrimination factors (DTDFs) remains as the least resolved aspect. The DTDFs are critical in providing accurate inferences from these models. Using both simulated and laboratory-based experimental data, this study provides conceptual and practical applications of isotope mixing models by exploring the role of DTDFs. The experimental study used Mozambique Tilapia Oreochromis mossambicus, a freshwater fish, to explore multi-tissue variations in isotopic incorporation patterns, and to evaluate isotope mixing model outputs based on the experiment- and literature-based DTDFs. Isotope incorporation patterns were variable for both muscle and fin tissues among the consumer groups that fed diet sources with different stable isotope values. Application of literature-based DTDFs in isotope mixing models consistently underestimated the dietary proportions of all single-source consumer groups. In contrast, application of diet-specific DTDFs provided better dietary estimates for single-source consumer groups. Variations in the proportional contributions of the individual sources were, nevertheless, observed for the mixed-source consumer group, which suggests that isotope assimilation of the individual food sources may have been influenced by other underlying physiological processes. This study provides evidence that stable isotope values from different diet sources exhibit large variations as they become incorporated into consumer tissues. This suggests that the application of isotope mixing models requires consideration of several aspects such as diet type and the associated biological processes that may influence DTDFs.
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6
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Isotopic and compositional evidence for carbon and nitrogen dynamics during wood decomposition by saprotrophic fungi. FUNGAL ECOL 2020. [DOI: 10.1016/j.funeco.2020.100915] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Boucher NP, Derocher AE, Richardson ES. Spatial and temporal variability in ringed seal ( Pusa hispida) stable isotopes in the Beaufort Sea. Ecol Evol 2020; 10:4178-4192. [PMID: 32489588 PMCID: PMC7246210 DOI: 10.1002/ece3.6186] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 12/02/2022] Open
Abstract
Arctic ecosystem dynamics are shifting in response to warming temperatures and sea ice loss. Such ecosystems may be monitored by examining the diet of upper trophic level species, which varies with prey availability. To assess interannual variation in the Beaufort Sea ecosystem, we examined spatial and temporal trends in ringed seal (Pusa hispida) δ13C and δ15N in claw growth layers grown from 1964 to 2011. Stable isotopes were correlated with climate indices, environmental conditions, seal population productivity, and geographic location. Sex and age did not influence stable isotopes. Enriched 13C was linked to cyclonic circulation regimes, seal productivity, and westward sampling locations. Higher δ15N was linked to lower sea surface temperatures, a higher percentage of pups in the subsistence harvest, and sample locations that were eastward and further from shore. From the 1960s to 2000s, ringed seal niche width expanded, suggesting a diversification of diet due to expansion of prey and/or seal space use. Overall, trends in ringed seal stable isotopes indicate changes within the Beaufort Sea ecosystem affected by water temperatures and circulation regimes. We suggest that continued monitoring of upper trophic level species will yield insights into changing ecosystem structure with climate change.
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Affiliation(s)
- Nicole P. Boucher
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada
| | | | - Evan S. Richardson
- Wildlife Research Division, Science and Technology BranchEnvironment and Climate Change CanadaWinnipegMBCanada
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Eckrich CA, Albeke SE, Flaherty EA, Bowyer RT, Ben‐David M. rKIN: Kernel‐based method for estimating isotopic niche size and overlap. J Anim Ecol 2020; 89:757-771. [DOI: 10.1111/1365-2656.13159] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/11/2019] [Indexed: 11/28/2022]
Affiliation(s)
| | - Shannon E. Albeke
- Wyoming Geographic Information Science Center University of Wyoming Laramie WY USA
- Program in Ecology University of Wyoming Laramie WY USA
| | - Elizabeth A. Flaherty
- Department of Forestry and Natural Resources Purdue University West Lafayette IN USA
| | - R. Terry Bowyer
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks AK USA
| | - Merav Ben‐David
- Program in Ecology University of Wyoming Laramie WY USA
- Department of Zoology and Physiology University of Wyoming Laramie WY USA
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Space use patterns affect stable isotopes of polar bears (Ursus maritimus) in the Beaufort Sea. Polar Biol 2019. [DOI: 10.1007/s00300-019-02546-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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10
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The Importance of Isotopic Turnover for Understanding Key Aspects of Animal Ecology and Nutrition. DIVERSITY-BASEL 2019. [DOI: 10.3390/d11050084] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Stable isotope-based methods have proved to be immensely valuable for ecological studies ranging in focus from animal movements to species interactions and community structure. Nevertheless, the use of these methods is dependent on assumptions about the incorporation and turnover of isotopes within animal tissues, which are oftentimes not explicitly acknowledged and vetted. Thus, the purpose of this review is to provide an overview of the estimation of stable isotope turnover rates in animals, and to highlight the importance of these estimates for ecological studies in terrestrial, freshwater, and marine systems that may use a wide range of stable isotopes. Specifically, we discuss 1) the factors that contribute to variation in turnover among individuals and across species, which influences the use of stable isotopes for diet reconstructions, 2) the differences in turnover among tissues that underlie so-called ‘isotopic clocks’, which are used to estimate the timing of dietary shifts, and 3) the use of turnover rates to estimate nutritional requirements and reconstruct histories of nutritional stress from tissue isotope signatures. As we discuss these topics, we highlight recent works that have effectively used estimates of turnover to design and execute informative ecological studies. Our concluding remarks suggest several steps that will improve our understanding of isotopic turnover and support its integration into a wider range of ecological studies.
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Kambikambi MJ, Chakona A, Kadye WT. The influence of diet composition and tissue type on the stable isotope incorporation patterns of a small-bodied southern African minnow Enteromius anoplus (Cypriniformes, Cyprinidae). RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:613-623. [PMID: 30672616 DOI: 10.1002/rcm.8393] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/17/2019] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
RATIONALE In trophic ecology, the use of stable isotope data relies on the general understanding of isotope turnover rates and diet-to-tissue discrimination factors (DTDFs). Recent studies on the application of stable isotope data have shown that isotope turnover rates and DTDFs can be influenced by many factors, including diet composition and tissue type. This study investigated the influence of diet composition and tissue type on stable isotope incorporation patterns in a small-bodied African minnow, the chubbyhead barb Enteromius anoplus. METHODS The isotopic incorporation patterns of carbon (δ13 C values) and nitrogen (δ15 N values) into white muscle and caudal fin tissues of the chubbyhead barb were examined using two isotopically different diets. Controlled-diet stable isotope feeding trials using a fishmeal-based diet (diet 1) and a soya-based diet (diet 2) were conducted over a 180-day period for the chubbyhead barb. RESULTS The two diets had contrasting isotopic incorporation patterns: diet 1 was associated with progressively high δ13 C and δ15 N values, whereas diet 2 was associated with progressively low δ13 C and δ15 N values over time for both muscle and fin tissues. The δ13 C turnover rates were similar for both tissues (56 and 61 days), whereas the δ15 N turnover rates differed between fin and muscle tissue in both diets (diet 1 = 4 and 130 days, and diet 2 = 72 and 300 days, respectively). The DTDFs were similar for both tissues in diet 1 (Δ13 C: -3.96 to -2.62‰, Δ15 N: 1.98 to 2.61‰) and diet 2 (Δ13 C: 4.05 to 5.24‰, Δ15 N: 8.45 to 9.69‰). CONCLUSIONS These results suggest that fin tissue can potentially be used as an alternative for muscle tissue in food web studies with a reasonable level of error. The isotopic turnover rate and DTDFs estimates for E. anoplus, however, require consideration of diet composition because different diets may differ in their isotopic incorporation patterns.
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Affiliation(s)
- Manda J Kambikambi
- Department of Ichthyology and Fisheries Science, Rhodes University, PO Box 94, Grahamstown, 6140, South Africa
| | - Albert Chakona
- South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140, South Africa
| | - Wilbert T Kadye
- Department of Ichthyology and Fisheries Science, Rhodes University, PO Box 94, Grahamstown, 6140, South Africa
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Carter WA, Whiteman JP, Cooper-Mullin C, Newsome SD, McWilliams SR. Dynamics of Individual Fatty Acids in Muscle Fat Stores and Membranes of a Songbird and Its Functional and Ecological Importance. Physiol Biochem Zool 2019; 92:239-251. [PMID: 30741598 DOI: 10.1086/702667] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Although tissue fatty acid (FA) composition has been linked to whole-animal performance (e.g., aerobic endurance, metabolic rate, postexercise recovery) in a wide range of animal taxa, we do not adequately understand the pace of changes in FA composition and its implications for the ecology of animals. Therefore, we used a C4 to C3 diet shift experiment and compound-specific δ13C analysis to estimate the turnover rates of FAs in the polar and neutral fractions of flight muscle lipids (corresponding to membranes and lipid droplets) of exercised and sedentary zebra finches (Taeniopygia guttata). Turnover was fastest for linoleic acid (LA; 18:2n6) and palmitic acid (PA; 16:0), with 95% replacement times of 10.8-17.7 d in the polar fraction and 17.2-32.8 d in the neutral fraction, but was unexpectedly slow for the long-chain polyunsaturated FAs (LC-PUFAs) arachidonic acid (20:4n6) and docosahexaenoic acid (22:6n3) in the polar fraction, with 95% replacement in 64.9-136.5 d. Polar fraction LA and PA turnover was significantly faster in exercised birds (95% replacement in 8.5-13.3 d). Our results suggest that FA turnover in intramuscular lipid droplets is related to FA tissue concentrations and that turnover does not change in response to exercise. In contrast, we found that muscle membrane FA turnover is likely driven by a combination of selective LC-PUFA retention and consumption of shorter-chain FAs in energy metabolism. The unexpectedly fast turnover of membrane-associated FAs in muscle suggests that songbirds during migration could substantially remodel their membranes within a single migration stopover, and this may have substantial implications for how the FA composition of diet affects energy metabolism of birds during migration.
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Majdi N, Hette-Tronquart N, Auclair E, Bec A, Chouvelon T, Cognie B, Danger M, Decottignies P, Dessier A, Desvilettes C, Dubois S, Dupuy C, Fritsch C, Gaucherel C, Hedde M, Jabot F, Lefebvre S, Marzloff MP, Pey B, Peyrard N, Powolny T, Sabbadin R, Thébault E, Perga ME. There's no harm in having too much: A comprehensive toolbox of methods in trophic ecology. FOOD WEBS 2018. [DOI: 10.1016/j.fooweb.2018.e00100] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Carter WA, Cooper-Mullin C, McWilliams SR. Turnover of muscle lipids and response to exercise differ between neutral and polar fractions in a model songbird, the zebra finch. ACTA ACUST UNITED AC 2018; 221:jeb.168823. [PMID: 29444847 DOI: 10.1242/jeb.168823] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 02/01/2018] [Indexed: 01/12/2023]
Abstract
The turnover rates of tissues and their constituent molecules give us insights into animals' physiological demands and their functional flexibility over time. Thus far, most studies of this kind have focused on protein turnover, and few have considered lipid turnover despite an increasing appreciation of the functional diversity of this class of molecules. We measured the turnover rates of neutral and polar lipids from the pectoralis muscles of a model songbird, the zebra finch (Taeniopygia guttata, N=65), in a 256 day C3/C4 diet shift experiment, with tissue samples taken at 10 time points. We also manipulated the physiological state of a subset of these birds with a 10 week flight training regimen to test the effect of exercise on lipid turnover. We measured lipid δ13C values via isotope ratio mass spectrometry (IRMS) and estimated turnover in different fractions and treatment groups with non-linear mixed-effect regression. We found a significant difference between the mean retention times (τ) of neutral and polar lipids (t119=-2.22, P=0.028), with polar lipids (τ=11.80±1.28 days) having shorter retention times than neutral lipids (τ=19.47±3.22 days). When all birds were considered, we also found a significant decrease in the mean retention time of polar lipids in exercised birds relative to control birds (difference=-2.2±1.83 days, t56=-2.37, P=0.021), but not neutral lipids (difference=4.2± 7.41 days, t56=0.57, P=0.57). A larger, more variable neutral lipid pool and the exposure of polar lipids in mitochondrial membranes to oxidative damage and increased turnover provide mechanisms consistent with our results.
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Affiliation(s)
- Wales A Carter
- Department of Natural Resources Science, University of Rhode Island, Kingston, RI 02881, USA
| | - Clara Cooper-Mullin
- Department of Natural Resources Science, University of Rhode Island, Kingston, RI 02881, USA
| | - Scott R McWilliams
- Department of Natural Resources Science, University of Rhode Island, Kingston, RI 02881, USA
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Boggie MA, Carleton SA, Collins DP, Vradenburg J, Sroka CJ. Using stable isotopes to estimate reliance on agricultural food subsidies and migration timing for a migratory bird. Ecosphere 2018. [DOI: 10.1002/ecs2.2083] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- Matthew A. Boggie
- Department of Biology; New Mexico State University; Las Cruces New Mexico 88003 USA
| | - Scott A. Carleton
- U.S. Fish and Wildlife Service; Migratory Bird Office, Region 2; Albuquerque New Mexico 87103 USA
| | - Daniel P. Collins
- U.S. Fish and Wildlife Service; Migratory Bird Office, Region 2; Albuquerque New Mexico 87103 USA
| | - John Vradenburg
- Kalamath Basin National Wildlife Refuge Complex; Tulelake California 96134 USA
| | - Christopher J. Sroka
- Department of Economics, Applied Statistics, & International Business; College of Business; New Mexico State University; Las Cruces New Mexico 88003 USA
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16
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Colborne SF, Fisk AT, Johnson TB. Tissue-specific turnover and diet-tissue discrimination factors of carbon and nitrogen isotopes of a common forage fish held at two temperatures. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:1405-1414. [PMID: 28590512 DOI: 10.1002/rcm.7922] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 05/26/2017] [Accepted: 06/05/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE The application of stable isotopes to foraging ecology is dependent on understanding life-history and environmental factors unrelated to diet that may influence isotopic composition. Diet-tissue discrimination factors (DTDFs) and turnover rates will increase the accuracy of isotope-based studies. Furthermore, little consideration has been given to the effects of temperature or life-history stage on isotopic ratios despite the prevalence of variation in temperature and growth rates throughout life. METHODS We measured δ13 C and δ15 N values with an elemental analyzer coupled to a continuous flow isotope ratio mass spectrometer. These values were used to estimate turnover and DTDFs for Emerald Shiners (Notropis atherinoides), a common North American freshwater forage fish. Fish were assigned to a temperature treatment, either 10°C (Low) or 20°C (High), and provided one of three diets (commercial pellet, Artemia salina, or Hemimysis anomala). At regular intervals fish were sampled and the isotopic compositions of whole body and liver tissues were determined. RESULTS Tissue turnover rates for fish fed Artemia were faster for liver than for whole body, but were also influenced by temperature. Turnover occurred faster at higher temperatures for body and liver δ15 N values, but not for δ13 C values. The pellet and Hemimysis treatments were in isotopic equilibrium from the start of the experiment and estimated DTDFs based on these treatments were lower than assumed for Δ15 N (+0.6 to 2.7‰) and variable, but within expected ranges for Δ13 C (-1.9 to +1.5‰). CONCLUSIONS The results for Emerald Shiners differed from commonly made assumptions for applying stable isotopes to ecological questions, possibly related to a bias in the use of juveniles in studies of turnover and DTDFs and assumptions regarding thermal-independence of isotopic relationships. The species-specific DTDF and tissue turnover estimates provided here will inform interpretations of stable isotope data for smaller fish species and improve food-web studies.
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Affiliation(s)
- S F Colborne
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada
| | - A T Fisk
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada
| | - T B Johnson
- Ontario Ministry of Natural Resources and Forestry, Glenora Fisheries Station, Picton, ON, Canada
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Lacombe RJS, Giuliano V, Colombo SM, Arts MT, Bazinet RP. Compound-specific isotope analysis resolves the dietary origin of docosahexaenoic acid in the mouse brain. J Lipid Res 2017; 58:2071-2081. [PMID: 28694298 DOI: 10.1194/jlr.d077990] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/05/2017] [Indexed: 12/23/2022] Open
Abstract
DHA (22:6n-3) may be derived from two dietary sources, preformed dietary DHA or through synthesis from α-linolenic acid (ALA; 18:3n-3). However, conventional methods cannot distinguish between DHA derived from either source without the use of costly labeled tracers. In the present study, we demonstrate the proof-of-concept that compound-specific isotope analysis (CSIA) by GC-isotope ratio mass spectrometry (IRMS) can differentiate between sources of brain DHA based on differences in natural 13C enrichment. Mice were fed diets containing either purified ALA or DHA as the sole n-3 PUFA. Extracted lipids were analyzed by CSIA for natural abundance 13C enrichment. Brain DHA from DHA-fed mice was significantly more enriched (-23.32‰ to -21.92‰) compared with mice on the ALA diet (-28.25‰ to -27.49‰). The measured 13C enrichment of brain DHA closely resembled the dietary n-3 PUFA source, -21.86‰ and -28.22‰ for DHA and ALA, respectively. The dietary effect on DHA 13C enrichment was similar in liver and blood fractions. Our results demonstrate the effectiveness of CSIA, at natural 13C enrichment, to differentiate between the incorporation of preformed or synthesized DHA into the brain and other tissues without the need for tracers.
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Affiliation(s)
- R J Scott Lacombe
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 3E2, Canada
| | - Vanessa Giuliano
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 3E2, Canada
| | - Stefanie M Colombo
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada
| | - Michael T Arts
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada
| | - Richard P Bazinet
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 3E2, Canada
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18
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Maldonado K, Bozinovic F, Newsome SD, Sabat P. Testing the niche variation hypothesis in a community of passerine birds. Ecology 2017; 98:903-908. [DOI: 10.1002/ecy.1769] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 01/27/2017] [Accepted: 02/01/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Karin Maldonado
- Departamento de Ciencias Ecológicas; Universidad de Chile; Santiago Chile
| | - Francisco Bozinovic
- Departamento de Ecología and Center of Applied Ecology & Sustainability (CAPES); Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago 6513677 Chile
| | - Seth D. Newsome
- Department of Biology; University of New Mexico; Albuquerque New Mexico 87131 USA
| | - Pablo Sabat
- Departamento de Ciencias Ecológicas; Universidad de Chile; Santiago Chile
- Departamento de Ecología and Center of Applied Ecology & Sustainability (CAPES); Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago 6513677 Chile
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19
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Villegas M, Newsome SD, Blake JG. Seasonal patterns in δ 2 H values of multiple tissues from Andean birds provide insights into elevational migration. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:2381-2387. [PMID: 27907263 DOI: 10.1002/eap.1456] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 09/24/2016] [Accepted: 09/26/2016] [Indexed: 06/06/2023]
Abstract
Elevational migration is a widespread phenomenon in tropical avifauna but it is difficult to identify using traditional approaches. Hydrogen isotope (δ2 H) values of precipitation decrease with elevation so δ2 H analysis of multiple bird tissues with different isotopic incorporation rates may be a reliable method for characterizing seasonal elevational migration. Here we compare δ2 H values in metabolically inert (feathers and claws) and metabolically active (whole blood) tissues to examine whether an upslope migration occurs prior to the breeding season in the Yungas Manakin (Chiroxiphia boliviana). We compare results from C. boliviana with data from a known elevational migrant, the Streak-necked Flycatcher (Mionectes striaticollis). Opposite to our expectations, tissue δ2 H values increased over time, largely reflecting seasonal patterns in precipitation δ2 H rather than elevational effects; linear mixed-effects models with strongest support included ordinal date, tissue type, and elevation. This seasonal increase in precipitation δ2 H is a general phenomenon in both tropical and temperate mountain ranges. We use these data to propose a hypothetical framework that predicts different patterns in tissue δ2 H values collected in different seasons from residents and elevational migrants. This framework can serve as a reference for future studies that assess elevational migration in birds and other animals.
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Affiliation(s)
- Mariana Villegas
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 32611, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - John G Blake
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 32611, USA
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20
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Kreitals NM, Hobson KA, Hoemsen BM, Crane AL, Wishingrad V, Sloychuk J, Pollock MS, Chivers DP, Phillips ID. Turnover of hydrogen isotopes in lake sturgeon blood: implications for tracking movements of wild populations. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2016; 52:592-602. [PMID: 26981716 DOI: 10.1080/10256016.2016.1147440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 11/28/2015] [Indexed: 06/05/2023]
Abstract
Naturally occurring deuterium ((2)H) in biota can be used to trace movement, migration and geographic origin of a range of organisms. However, to evaluate movements of animals using δ(2)H measurements of tissues, it is necessary to establish the turnover time of (2)H in the tissues and the extent of isotopic discrimination from different environmental (2)H sources to those tissues. We investigated the turnover of (2)H in lake sturgeon (Acipenser fulvescens) blood by manipulating both environmental water δ(2)H and diet δ(2)H over a four-month period. The half-life of deuterium in lake sturgeon blood was 37.9 days after an increase in the environmental water δ(2)H of +714 ‰. However, no clear turnover in blood (2)H occurred over the same period in a separate trial following a change of -63.8 ‰ or +94.2 ‰ in diet. These findings suggest that environmental water (2)H exchanges much faster with blood than diets and that blood δ(2)H values can be used to trace movements of sturgeon and other fish moving among isotopically distinct waters.
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Affiliation(s)
- Natasha M Kreitals
- a Department of Biology , University of Saskatchewan , Saskatchewan , Canada
- b TRoutreach Saskatchewan, Saskatchewan Wildlife Federation , Saskatchewan , Canada
| | | | - Brittney M Hoemsen
- a Department of Biology , University of Saskatchewan , Saskatchewan , Canada
- b TRoutreach Saskatchewan, Saskatchewan Wildlife Federation , Saskatchewan , Canada
| | - Adam L Crane
- a Department of Biology , University of Saskatchewan , Saskatchewan , Canada
| | - Van Wishingrad
- a Department of Biology , University of Saskatchewan , Saskatchewan , Canada
| | - Janelle Sloychuk
- a Department of Biology , University of Saskatchewan , Saskatchewan , Canada
| | | | - Douglas P Chivers
- a Department of Biology , University of Saskatchewan , Saskatchewan , Canada
| | - Iain D Phillips
- a Department of Biology , University of Saskatchewan , Saskatchewan , Canada
- b TRoutreach Saskatchewan, Saskatchewan Wildlife Federation , Saskatchewan , Canada
- d Water Security Agency , Saskatchewan , Canada
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21
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Davis M, Pineda Munoz S. The temporal scale of diet and dietary proxies. Ecol Evol 2016; 6:1883-97. [PMID: 27087936 PMCID: PMC4801961 DOI: 10.1002/ece3.2054] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 02/08/2016] [Accepted: 02/12/2016] [Indexed: 11/09/2022] Open
Abstract
Diets estimated from different proxies such as stable isotopes, stomach contents, and dental microwear often disagree, leading to nominally well-supported but greatly differing estimates of diet for both extinct and extant species that complicate our understanding of ecology. We show that these perceived incongruences can be caused by proxies recording diet over vastly different timescales. Field observations reveal a diet averaged over minutes or hours, whereas dental morphology may reflect the diet of a lineage over millions of years of evolution. Failing to explicitly consider the scale of proxies and the potentially large temporal variability in diet can cause erroneous predictions in any downstream analyses such as conservation planning or paleohabitat reconstructions. We propose a cross-scale framework for conceptualizing diet suitable for both modern ecologists and paleontologists and provide recommendations for any studies involving dietary data. Treating diet in this temporally explicit framework and matching the scale of our questions with the scale of our data will lead to a much richer and clearer understanding of ecological and evolutionary processes.
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Affiliation(s)
- Matt Davis
- Department of Geology and Geophysics Yale University New Haven Connecticut 06520; Department of Paleobiology National Museum of Natural History Smithsonian Institution Washington District of Columbia 20004
| | - Silvia Pineda Munoz
- Department of Paleobiology National Museum of Natural History Smithsonian Institution Washington District of Columbia 20004
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22
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McCue MD, Welch KC. (13)C-Breath testing in animals: theory, applications, and future directions. J Comp Physiol B 2015; 186:265-85. [PMID: 26660654 DOI: 10.1007/s00360-015-0950-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 11/11/2015] [Accepted: 11/25/2015] [Indexed: 10/22/2022]
Abstract
The carbon isotope values in the exhaled breath of an animal mirror the carbon isotope values of the metabolic fuels being oxidized. The measurement of stable carbon isotopes in carbon dioxide is called (13)C-breath testing and offers a minimally invasive method to study substrate oxidation in vivo. (13)C-breath testing has been broadly used to study human exercise, nutrition, and pathologies since the 1970s. Owing to reduced use of radioactive isotopes and the increased convenience and affordability of (13)C-analyzers, the past decade has witnessed a sharp increase in the use of breath testing throughout comparative physiology--especially to answer questions about how and when animals oxidize particular nutrients. Here, we review the practical aspects of (13)C-breath testing and identify the strengths and weaknesses of different methodological approaches including the use of natural abundance versus artificially-enriched (13)C tracers. We critically compare the information that can be obtained using different experimental protocols such as diet-switching versus fuel-switching. We also discuss several factors that should be considered when designing breath testing experiments including extrinsic versus intrinsic (13)C-labelling and different approaches to model nutrient oxidation. We use case studies to highlight the myriad applications of (13)C-breath testing in basic and clinical human studies as well as comparative studies of fuel use, energetics, and carbon turnover in multiple vertebrate and invertebrate groups. Lastly, we call for increased and rigorous use of (13)C-breath testing to explore a variety of new research areas and potentially answer long standing questions related to thermobiology, locomotion, and nutrition.
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23
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Cloyed CS, Newsome SD, Eason PK. Trophic Discrimination Factors and Incorporation Rates of Carbon- and Nitrogen-Stable Isotopes in Adult Green Frogs, Lithobates clamitans. Physiol Biochem Zool 2015; 88:576-85. [PMID: 26658253 DOI: 10.1086/682576] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Stable isotope analysis is an increasingly useful ecological tool, but its accuracy depends on quantifying the tissue-specific trophic discrimination factors (TDFs) and isotopic incorporation rates for focal taxa. Despite the technique's ubiquity, most laboratory experiments determining TDFs and incorporation rates have focused on birds, mammals, and fish; we know little about terrestrial ectotherms, and amphibians in particular are understudied. In this study we used two controlled feeding experiments to determine carbon (δ(13)C) and nitrogen (δ(15)N) isotope TDFs for skin, whole blood, and bone collagen and incorporation rates for skin and whole blood in adult green frogs, Lithobates clamitans. The mean (±SD) TDFs for δ(13)C were 0.1‰ (±0.4‰) for skin, 0.5‰ (±0.5‰) for whole blood, and 1.6‰ (0.6‰) for bone collagen. The mean (±SD) TDFs for δ(15)N were 2.3‰ (±0.5‰) for skin, 2.3‰ (±0.4‰) for whole blood, and 3.1‰ (±0.6‰) for bone collagen. A combination of different isotopic incorporation models was best supported by our data. Carbon in skin was the only tissue in which incorporation was best explained by two compartments, which had half-lives of 89 and 8 d. The half-life of carbon in whole blood was 69 d. Half-lives for nitrogen were 75 d for skin and 71 d for whole blood. Our results help fill a taxonomic gap in our knowledge of stable isotope dynamics and provide ecologists with a method to measure anuran diets.
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Affiliation(s)
- Carl S Cloyed
- Department of Biology, University of Louisville, Louisville, Kentucky 40292; 2Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131
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24
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Abstract
Diet is a leading modifiable risk factor for chronic disease, but it remains difficult to measure accurately due to the error and bias inherent in self-reported methods of diet assessment. Consequently, there is a pressing need for more objective biomarkers of diet for use in health research. The stable isotope ratios of light elements are a promising set of candidate biomarkers because they vary naturally and reproducibly among foods, and those variations are captured in molecules and tissues with high fidelity. Recent studies have identified valid isotopic measures of short- and long-term sugar intake, meat intake, and fish intake in specific populations. These studies provide a strong foundation for validating stable isotopic biomarkers in the general US population. Approaches to improve specificity for specific foods are needed; for example, by modeling intake using multiple stable isotope ratios or by isolating and measuring specific molecules linked to foods of interest.
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Affiliation(s)
- Diane M O'Brien
- Center for Alaska Native Health Research, Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska, Fairbanks, Alaska 99775-7000;
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25
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deVries MS, del Rio CM, Tunstall TS, Dawson TE. Isotopic incorporation rates and discrimination factors in mantis shrimp crustaceans. PLoS One 2015; 10:e0122334. [PMID: 25835953 PMCID: PMC4383329 DOI: 10.1371/journal.pone.0122334] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 02/10/2015] [Indexed: 11/19/2022] Open
Abstract
Stable isotope analysis has provided insights into the trophic ecology of a wide diversity of animals. Knowledge about isotopic incorporation rates and isotopic discrimination between the consumer and its diet for different tissue types is essential for interpreting stable isotope data, but these parameters remain understudied in many animal taxa and particularly in aquatic invertebrates. We performed a 292-day diet shift experiment on 92 individuals of the predatory mantis shrimp, Neogonodactylus bredini, to quantify carbon and nitrogen incorporation rates and isotope discrimination factors in muscle and hemolymph tissues. Average isotopic discrimination factors between mantis shrimp muscle and the new diet were 3.0 ± 0.6 ‰ and 0.9 ± 0.3 ‰ for carbon and nitrogen, respectively, which is contrary to what is seen in many other animals (e.g. C and N discrimination is generally 0–1 ‰ and 3–4 ‰, respectively). Surprisingly, the average residence time of nitrogen in hemolymph (28.9 ± 8.3 days) was over 8 times longer than that of carbon (3.4 ± 1.4 days). In muscle, the average residence times of carbon and nitrogen were of the same magnitude (89.3 ± 44.4 and 72.8 ± 18.8 days, respectively). We compared the mantis shrimps’ incorporation rates, along with rates from four other invertebrate taxa from the literature, to those predicted by an allometric equation relating carbon incorporation rate to body mass that was developed for teleost fishes and sharks. The rate of carbon incorporation into muscle was consistent with rates predicted by this equation. Our findings provide new insight into isotopic discrimination factors and incorporation rates in invertebrates with the former showing a different trend than what is commonly observed in other animals.
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Affiliation(s)
- Maya S. deVries
- Department of Integrative Biology, University of California, Berkeley, California, United States of America
- * E-mail:
| | - Carlos Martínez del Rio
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, United States of America
| | - Tate S. Tunstall
- Department of Integrative Biology, University of California, Berkeley, California, United States of America
| | - Todd E. Dawson
- Department of Integrative Biology, University of California, Berkeley, California, United States of America
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26
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Vander Zanden MJ, Clayton MK, Moody EK, Solomon CT, Weidel BC. Stable isotope turnover and half-life in animal tissues: a literature synthesis. PLoS One 2015; 10:e0116182. [PMID: 25635686 PMCID: PMC4321325 DOI: 10.1371/journal.pone.0116182] [Citation(s) in RCA: 208] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 12/04/2014] [Indexed: 11/27/2022] Open
Abstract
Stable isotopes of carbon, nitrogen, and sulfur are used as ecological tracers for a variety of applications, such as studies of animal migrations, energy sources, and food web pathways. Yet uncertainty relating to the time period integrated by isotopic measurement of animal tissues can confound the interpretation of isotopic data. There have been a large number of experimental isotopic diet shift studies aimed at quantifying animal tissue isotopic turnover rate λ (%·day(-1), often expressed as isotopic half-life, ln(2)/λ, days). Yet no studies have evaluated or summarized the many individual half-life estimates in an effort to both seek broad-scale patterns and characterize the degree of variability. Here, we collect previously published half-life estimates, examine how half-life is related to body size, and test for tissue- and taxa-varying allometric relationships. Half-life generally increases with animal body mass, and is longer in muscle and blood compared to plasma and internal organs. Half-life was longest in ecotherms, followed by mammals, and finally birds. For ectotherms, different taxa-tissue combinations had similar allometric slopes that generally matched predictions of metabolic theory. Half-life for ectotherms can be approximated as: ln (half-life) = 0.22*ln (body mass) + group-specific intercept; n = 261, p<0.0001, r2 = 0.63. For endothermic groups, relationships with body mass were weak and model slopes and intercepts were heterogeneous. While isotopic half-life can be approximated using simple allometric relationships for some taxa and tissue types, there is also a high degree of unexplained variation in our models. Our study highlights several strong and general patterns, though accurate prediction of isotopic half-life from readily available variables such as animal body mass remains elusive.
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Affiliation(s)
- M. Jake Vander Zanden
- Center for Limnology, University of Wisconsin—Madison, Madison,
Wisconsin, United States of America
| | - Murray K. Clayton
- Department of Statistics, University of Wisconsin—Madison, Madison,
Wisconsin, United States of America
| | - Eric K. Moody
- Center for Limnology, University of Wisconsin—Madison, Madison,
Wisconsin, United States of America
- School of Life Sciences, Arizona State University, Tempe, Arizona, United
States of America
| | - Christopher T. Solomon
- Department of Natural Resource Sciences, McGill University, Ste. Anne de
Bellevue, Quebec, Canada
| | - Brian C. Weidel
- Lake Ontario Biological Station, USGS, Oswego, New York, United States of
America
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27
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Thomas SM, Crowther TW. Predicting rates of isotopic turnover across the animal kingdom: a synthesis of existing data. J Anim Ecol 2015; 84:861-870. [DOI: 10.1111/1365-2656.12326] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 11/29/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Stephen M. Thomas
- Department of Environmental Sciences; University of Helsinki; P.O. Box 65 Helsinki FI-00014 Finland
| | - Thomas W. Crowther
- Yale School of Forestry and Environmental Studies; Yale University; 370 Prospect St New Haven CT USA
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28
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Yoshida S, Date Y, Akama M, Kikuchi J. Comparative metabolomic and ionomic approach for abundant fishes in estuarine environments of Japan. Sci Rep 2014; 4:7005. [PMID: 25387575 PMCID: PMC4228347 DOI: 10.1038/srep07005] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 09/17/2014] [Indexed: 12/23/2022] Open
Abstract
Environmental metabolomics or ionomics is widely used to characterize the effects of environmental stressors on the health of aquatic organisms. However, most studies have focused on liver and muscle tissues of fish, and little is known about how the other organs are affected by environmental perturbations and effects such as metal pollutants or eutrophication. We examined the metabolic and mineral profiles of three kinds of abundant fishes in estuarine ecosystem, yellowfin goby, urohaze-goby, and juvenile Japanese seabass sampled from Tsurumi River estuary, Japan. Multivariate analyses, including nuclear magnetic resonance-based metabolomics and inductively coupled plasma optical emission spectrometry-based ionomics approaches, revealed that the profiles were clustered according to differences among body tissues rather than differences in body size, sex, and species. The metabolic and mineral profiles of the muscle and fin tissues, respectively, suggest that these tissues are most appropriate for evaluating environmental perturbations. Such analyses will be highly useful in evaluating the environmental variation and diversity in aquatic ecosystems.
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Affiliation(s)
- Seiji Yoshida
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Yasuhiro Date
- 1] Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan [2] RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Makiko Akama
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Jun Kikuchi
- 1] Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan [2] RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan [3] RIKEN Biomass Engineering Program, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan [4] Graduate School of Bioagricultural Sciences, Nagoya University, 1 Furo-cho, Chikusa-ku, Nagoya, Aichi 464-0810, Japan
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29
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Bradley CJ, Madigan DJ, Block BA, Popp BN. Amino acid isotope incorporation and enrichment factors in Pacific bluefin tuna, Thunnus orientalis. PLoS One 2014; 9:e85818. [PMID: 24465724 PMCID: PMC3899081 DOI: 10.1371/journal.pone.0085818] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 12/02/2013] [Indexed: 11/18/2022] Open
Abstract
Compound specific isotopic analysis (CSIA) of amino acids has received increasing attention in ecological studies in recent years due to its ability to evaluate trophic positions and elucidate baseline nutrient sources. However, the incorporation rates of individual amino acids into protein and specific trophic discrimination factors (TDFs) are largely unknown, limiting the application of CSIA to trophic studies. We determined nitrogen turnover rates of individual amino acids from a long-term (up to 1054 days) laboratory experiment using captive Pacific bluefin tuna, Thunnus orientalis (PBFT), a large endothermic pelagic fish fed a controlled diet. Small PBFT (white muscle δ(15)N∼11.5‰) were collected in San Diego, CA and transported to the Tuna Research and Conservation Center (TRCC) where they were fed a controlled diet with high δ(15)N values relative to PBFT white muscle (diet δ(15)N∼13.9‰). Half-lives of trophic and source amino acids ranged from 28.6 to 305.4 days and 67.5 to 136.2 days, respectively. The TDF for the weighted mean values of amino acids was 3.0 ‰, ranging from 2.2 to 15.8 ‰ for individual combinations of 6 trophic and 5 source amino acids. Changes in the δ(15)N values of amino acids across trophic levels are the underlying drivers of the trophic (15)N enrichment. Nearly all amino acid δ(15)N values in this experiment changed exponentially and could be described by a single compartment model. Significant differences in the rate of (15)N incorporation were found for source and trophic amino acids both within and between these groups. Varying half-lives of individual amino acids can be applied to migratory organisms as isotopic clocks, determining the length of time an individual has spent in a new environment. These results greatly enhance the ability to interpret compound specific isotope analyses in trophic studies.
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Affiliation(s)
- Christina J. Bradley
- Department of Oceanography, University of Hawaii, Honolulu, Hawaii, United States of America
| | - Daniel J. Madigan
- Tuna Research and Conservation Center, Pacific Grove, California, United States of America
- Stanford University, Hopkins Marine Station, Pacific Grove, California, United States of America
| | - Barbara A. Block
- Monterey Bay Aquarium, Monterey, California, United States of America
| | - Brian N. Popp
- Department of Geology and Geophysics, University of Hawaii, Honolulu, Hawaii, United States of America
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30
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Dietz MW, Piersma T, Dekinga A, Korthals H, Klaassen M. Unusual patterns in ¹⁵N blood values after a diet switch in red knot shorebirds. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2013; 49:283-292. [PMID: 23656233 DOI: 10.1080/10256016.2013.776045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
When a diet switch results in a change in dietary isotopic values, isotope ratios of the consumer's tissues will change until a new equilibrium is reached. This change is generally best described by an exponential decay curve. Indeed, after a diet switch in captive red knot shorebirds (Calidris canutus islandica), the depletion of (13)C in both blood cells and plasma followed an exponential decay curve. Surprisingly, the diet switch with a dietary (15)N/(14)N ratio (δ(15)N) change from 11.4 to 8.8 ‰ had little effect on δ(15)N in the same tissues. The diet-plasma and diet-cellular discrimination factors of (15)N with the initial diet were very low (0.5 and 0.2 ‰, respectively). δ(15)N in blood cells and plasma decreased linearly with increasing body mass, explaining about 40 % of the variation in δ(15)N. δ(15)N in plasma also decreased with increasing body-mass change (r (2)=.07). This suggests that the unusual variation in δ(15)N with time after the diet switch was due to interferences with simultaneous changes in body-protein turnover.
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Affiliation(s)
- Maurine W Dietz
- Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands.
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31
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Liberoff AL, Riva Rossi CM, Fogel ML, Ciancio JE, Pascual MA. Shifts in δ15 N signature following the onset of exogenous feeding in rainbow trout Oncorhynchus mykiss: importance of combining length and age data. JOURNAL OF FISH BIOLOGY 2013; 82:1423-1432. [PMID: 23557318 DOI: 10.1111/jfb.12063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 01/16/2013] [Indexed: 06/02/2023]
Abstract
The δ(15) N isotopic change of recently emerged rainbow trout Oncorhynchus mykiss due to diet shift from yolk sac to exogenous feeding was evaluated in a field study. The fit of a general model including both fish length and age in days as co-variables indicates that the specific δ(15) N of individual fish at any given time along the ontogeny is determined by its growth trajectory. The results suggest that estimations based on fish size alone could bias data interpretation and maternal origin determinations in partially migratory salmonids.
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Affiliation(s)
- A L Liberoff
- Centro Nacional Patagónico-CONICET, Boulevard Brown 2915, 9120, Puerto Madryn, Chubut, Argentina.
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Codron J, Kirkman K, Duffy KJ, Sponheimer M, Lee-Thorp JA, Ganswindt A, Clauss M, Codron D. Stable isotope turnover and variability in tail hairs of captive and free-ranging African elephants (Loxodonta africana) reveal dietary niche differences within populations. CAN J ZOOL 2013. [DOI: 10.1139/cjz-2012-0155] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Many herbivore species expand their dietary niche breadths by switching from browse-rich diets in dry seasons to grass-rich diets in rainy seasons, in response to phenological changes in plant availability and quality. We analyzed stable isotope series along tail hairs of captive and free-ranging African elephant (Loxodonta africana (Blumenbach, 1797)) to compare patterns of seasonal dietary variability across individuals. Results from elephants translocated from the wild into captivity, where their diets are semicontrolled, revealed tail hair growth rates of ∼0.34 mm/day, on average, and relatively rapid isotope turnover through the transition from wild into captivity. Sampling hairs at 10 mm increments thus archives dietary chronologies at a resolution suitable for tracking diet switches at seasonal, and even subseasonal, scales. Hairs of free-ranging elephants showed extensive carbon isotopic variability within individuals, consistent with seasonal switches between C3-browsing and C4-grazing. Similarly extensive, but asynchronous, shifts in nitrogen isotope ratios were also observed, suggesting an influence of factors other than seasonality. Across individuals, switching patterns differed across habitats, and across age classes, with older, larger animals including increasing amounts of C3 browse into their diets. These results demonstrate how stable isotope approaches characterize complex patterns of resource use in wildlife populations.
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Affiliation(s)
- Jacqueline Codron
- School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, RSA; Institute of Systems Science, Durban University of Technology, Durban, South Africa; Department of Archaeology, University of Cape Town, Private Bag, Rondebosch, 7701, RSA
| | - Kevin Kirkman
- School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, RSA
| | - Kevin J. Duffy
- Institute of Systems Science, Durban University of Technology, Durban, South Africa
| | - Matt Sponheimer
- Department of Anthropology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Julia A. Lee-Thorp
- Research Laboratory for Archaeology, University of Oxford, South Parks Road, Oxford OX1 3QY, UK
| | - Andre Ganswindt
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, 0110, RSA; Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0002, RSA
| | - Marcus Clauss
- Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zürich, Winterthurerstrasse 260, CH-8057 Zürich, Switzerland
| | - Daryl Codron
- School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, RSA; Florisbad Quaternary Research, National Museum, P.O. Box 266, Bloemfontein, 9300, RSA; Department of Anthropology, University of Colorado at Boulder, Boulder, CO 80309, USA; Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zürich, Winterthurerstrasse 260, CH-8057 Zürich, Switzerland
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Authier M, Dragon AC, Cherel Y, Guinet C. How large is large: estimating ecologically meaningful isotopic differences in observational studies of wild animals. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:2657-2664. [PMID: 23124655 DOI: 10.1002/rcm.6389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
RATIONALE In ecological studies of wildlife movements and foraging, bio-logging and isotopic data are routinely collected and increasingly analyzed in tandem. Such analyses have two shortcomings: (1) small sample size linked with the number of telemetric tags that can be deployed, and (2) the observational nature of isotopic gradients. Wildlife ecologists are thus put in a statistical conundrum known as the small n, large p problem. METHODS Using shrinkage regression, which directly addresses the issue of accurately estimating effects from sparse data, we studied what counts as a biologically meaningful isotopic difference (a prerequisite to delineate isoscapes) in the southern elephant seal (Mirounga leonina), a large and elusive marine predator. RESULTS Seals foraging in Antarctic waters had a lower carbon isotopic value (by ≈ 2‰) than seals foraging either in the interfrontal zone or on the Kerguelen Plateau. The latter two foraging strategies were indistinguishable on the sole basis of δ(13) C values with our data. CONCLUSIONS Shrinkage regression is a conservative statistical technique that has wide applicability in isotopic ecology to help separate robust biological signals from noise.
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Affiliation(s)
- Matthieu Authier
- Centre d'Études Biologiques de Chizé, UPR 1934 du CNRS, 79 360, Villiers-en-Bois, France.
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Abstract
Stable isotopes can illuminate resource usage by organisms, but effective interpretation is predicated on laboratory validation. Here we develop stable isotope clocks to track resource shifts in anadromous rainbow trout (Oncorhynchus mykiss). We used a diet-switch experiment and model fitting to quantify N stable isotope (δ(15)N) turnover rates and discrimination factors for seven tissues: plasma, liver, fin, mucus, red blood cells, muscle, and scales. Among tissues, diet-tissue δ(15)N discrimination factors ranged from 1.3 to 3.4 ‰. Model-supported tissue turnover half-lives ranged from 9.0 (fin) to 27.7 (scale) days. We evaluated six tissue turnover models using Akaike's information criterion corrected for small sample sizes. The use of equilibrium tissue values was supported in all tissues and two-compartment models were supported in plasma, liver, and mucus. Using parameter estimates and their uncertainty we developed stable isotope clocks to estimate the time since resource shifts. Longer turnover tissues provided accurate estimates of time since resource switch for durations approximately twice their half-life. Faster turnover tissues provided even higher precision estimates, but only within their half-life post-switch. Averaging estimates of time since resource shift from multiple tissues provided the highest precision estimates of time since resource shift for the longest duration (up to 64 days). This study therefore provides insight into physiological processes that underpin stable isotope patterns, explicitly tests alternative models, and quantifies key parameters that are the foundation of field-based stable isotope analysis.
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The isotopic composition and insect content of diet predict tissue isotopic values in a South American passerine assemblage. J Comp Physiol B 2012; 183:419-30. [PMID: 23014885 DOI: 10.1007/s00360-012-0711-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 08/30/2012] [Accepted: 08/31/2012] [Indexed: 10/27/2022]
Abstract
We analyzed the carbon and nitrogen isotopic values of the muscle, liver, and crop contents ("diet") of 132 individuals of 16 species of Chilean birds. The nitrogen content of diet was tightly correlated with the fraction of gut contents represented by insects relative to plant material. The carbon and nitrogen isotopic values of diet, liver, and muscle were all linearly correlated, implying high temporal consistency in the isotopic value of the diet of these birds. However, δ(15)N was not significantly related with the percentage of insects in diet. These results cast doubt on the applicability of the use of (15)N enrichment to diagnose trophic level in, at least some, terrestrial ecosystems. However, the residuals of the relationship relating the isotopic value of bird tissues with those of their diet were weakly negatively correlated with insect intake. We hypothesize that this negative correlation stems from the higher quality of protein found in insects relative to that of plant materials. Finally, our data corroborated a perplexing and controversial negative relationship between tissue to diet isotopic discrimination and the isotopic value of diet. We suggest that this relationship is an example of the commonly observed regression to the mean effect that plagues many scientific studies.
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Wolf N, Newsome SD, Fogel ML, del Rio CM. An experimental exploration of the incorporation of hydrogen isotopes from dietary sources into avian tissues. J Exp Biol 2012; 215:1915-22. [DOI: 10.1242/jeb.065219] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
The analysis of hydrogen stable isotopes (∂D) is a potentially powerful tool for studying animal ecology. Unlike other stable isotopes used in ecological research, however, we are less familiar with the physiological processes that influence the incorporation of hydrogen isotopes from dietary resources to animal tissues. Here we present the results of a controlled feeding experiment utilizing Japanese quail (Cortunix japonica) that was designed to: (1) estimate the relative contributions of diet to the ∂D signatures of blood plasma, red blood cells, intestine, liver, muscle and feathers; (2) investigate possible differences among these same tissues in diet to tissue discrimination; and (3) explore the differences in incorporation dynamics between deuterium (2H) and a well-studied isotope, 13C, for blood plasma solids and red blood cells. Tissues differed in both the relative contribution of diet to tissue ∂D and diet to tissue discrimination. The average residence time of both hydrogen and carbon was significantly lower in plasma solids than in red blood cells. The average residence time of hydrogen was significantly lower than that of carbon in plasma solids, but not in red blood cells. Although the average residence times of hydrogen and carbon were positively correlated, the correlation was weak. Hence the incorporation of carbon seems to be a poor predictor of that of hydrogen.
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Affiliation(s)
- Nathan Wolf
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA
| | - Seth D. Newsome
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA
| | - Marilyn L. Fogel
- Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA
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Newsome SD, Yeakel JD, Wheatley PV, Tinker MT. Tools for quantifying isotopic niche space and dietary variation at the individual and population level. J Mammal 2012. [DOI: 10.1644/11-mamm-s-187.1] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Martínez del Rio C, Carleton SA. How fast and how faithful: the dynamics of isotopic incorporation into animal tissues: Fig. 1. J Mammal 2012. [DOI: 10.1644/11-mamm-s-165.1] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Ben-David M, Newsome SD, Whiteman JP. Lipid and amino acid composition influence incorporation and discrimination of13C and15N in mink. J Mammal 2012. [DOI: 10.1644/11-mamm-s-168.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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41
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One meadow for two sparrows: resource partitioning in a high elevation habitat. Oecologia 2012; 170:529-40. [DOI: 10.1007/s00442-012-2327-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 03/28/2012] [Indexed: 10/28/2022]
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Hussey NE, MacNeil MA, Olin JA, McMeans BC, Kinney MJ, Chapman DD, Fisk AT. Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions. JOURNAL OF FISH BIOLOGY 2012; 80:1449-84. [PMID: 22497393 DOI: 10.1111/j.1095-8649.2012.03251.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Stable-isotope analysis (SIA) can act as a powerful ecological tracer with which to examine diet, trophic position and movement, as well as more complex questions pertaining to community dynamics and feeding strategies or behaviour among aquatic organisms. With major advances in the understanding of the methodological approaches and assumptions of SIA through dedicated experimental work in the broader literature coupled with the inherent difficulty of studying typically large, highly mobile marine predators, SIA is increasingly being used to investigate the ecology of elasmobranchs (sharks, skates and rays). Here, the current state of SIA in elasmobranchs is reviewed, focusing on available tissues for analysis, methodological issues relating to the effects of lipid extraction and urea, the experimental dynamics of isotopic incorporation, diet-tissue discrimination factors, estimating trophic position, diet and mixing models and individual specialization and niche-width analyses. These areas are discussed in terms of assumptions made when applying SIA to the study of elasmobranch ecology and the requirement that investigators standardize analytical approaches. Recommendations are made for future SIA experimental work that would improve understanding of stable-isotope dynamics and advance their application in the study of sharks, skates and rays.
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Affiliation(s)
- N E Hussey
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, ON N9B 3P4, Canada.
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Boecklen WJ, Yarnes CT, Cook BA, James AC. On the Use of Stable Isotopes in Trophic Ecology. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2011. [DOI: 10.1146/annurev-ecolsys-102209-144726] [Citation(s) in RCA: 623] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- William J. Boecklen
- Laboratory of Ecological Chemistry, Department of Biology, New Mexico State University, Las Cruces, New Mexico 88003; , ,
| | - Christopher T. Yarnes
- Stable Isotope Facility, Department of Plant Sciences, University of California, Davis, Davis, California 95616;
| | - Bethany A. Cook
- Laboratory of Ecological Chemistry, Department of Biology, New Mexico State University, Las Cruces, New Mexico 88003; , ,
| | - Avis C. James
- Laboratory of Ecological Chemistry, Department of Biology, New Mexico State University, Las Cruces, New Mexico 88003; , ,
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Authier M, Martin C, Ponchon A, Steelandt S, Bentaleb I, Guinet C. Breaking the sticks: a hierarchical change-point model for estimating ontogenetic shifts with stable isotope data. Methods Ecol Evol 2011. [DOI: 10.1111/j.2041-210x.2011.00162.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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The influence of microhabitat, moisture and diet on stable-hydrogen isotope variation in a Neotropical avian food web. JOURNAL OF TROPICAL ECOLOGY 2011. [DOI: 10.1017/s0266467411000332] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract:The application of stable-hydrogen isotope (δD) measurements to the study of animal movement, resource use and physiology depends on understanding factors driving variation in δD in animal tissues. The source of micro-scale variation in δD is poorly known, yet understanding micro-scale patterns of δD could shed light on important ecological processes and improve our abilities to track animal movements. Using linear and additive models, we explored the influence of micro-scale habitat use, moisture and diet on tissue δD values of Nicaraguan cloud-forest birds. Using mist nets, we captured 211 individuals of 22 resident Neotropical species at 500–1390 m asl and collected feather and claw samples. Based on three years of data from year-round sampling, our results suggest that microhabitat, seasonal shifts in moisture δD, and diet all influence bird tissue δD values. Our model results reveal a previously undescribed microgeographical effect on δD, where foraging level (understorey versus overstorey) and foraging location (forest interior versus adjacent coffee plantation) were significant predictors of δD values in bird claws and feathers. Mean claw and feather δD values among species varied from −83‰ to −19‰. Top models for claws and feathers explained 57% and 52% of variation in δD respectively. Direct comparisons of understorey (mean ± SD of −30‰ ± 15‰) versus overstorey (−50‰ ± 15‰) claw values suggest that δD may be useful in tracking vertical, micro-scale movement. Higher δD values in forest understorey birds reveal a heavy reliance upon recycled, fog moisture. Fragmentation and climate change may result in increasingly desiccated cloud forest that may exert a more negative influence on the food webs of understorey species that seem to be supported by recycled sources of moisture in the dry season.
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Lecomte N, Ahlstrøm O, Ehrich D, Fuglei E, Ims RA, Yoccoz NG. Intrapopulation variability shaping isotope discrimination and turnover: experimental evidence in arctic foxes. PLoS One 2011; 6:e21357. [PMID: 21731715 PMCID: PMC3121787 DOI: 10.1371/journal.pone.0021357] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 05/31/2011] [Indexed: 11/23/2022] Open
Abstract
Background Tissue-specific stable isotope signatures can provide insights into the trophic ecology of consumers and their roles in food webs. Two parameters are central for making valid inferences based on stable isotopes, isotopic discrimination (difference in isotopic ratio between consumer and its diet) and turnover time (renewal process of molecules in a given tissue usually measured when half of the tissue composition has changed). We investigated simultaneously the effects of age, sex, and diet types on the variation of discrimination and half-life in nitrogen and carbon stable isotopes (δ15N and δ13C, respectively) in five tissues (blood cells, plasma, muscle, liver, nail, and hair) of a top predator, the arctic fox Vulpes lagopus. Methodology/Principal Findings We fed 40 farmed foxes (equal numbers of adults and yearlings of both sexes) with diet capturing the range of resources used by their wild counterparts. We found that, for a single species, six tissues, and three diet types, the range of discrimination values can be almost as large as what is known at the scale of the whole mammalian or avian class. Discrimination varied depending on sex, age, tissue, and diet types, ranging from 0.3‰ to 5.3‰ (mean = 2.6‰) for δ15N and from 0.2‰ to 2.9‰ (mean = 0.9‰) for δ13C. We also found an impact of population structure on δ15N half-life in blood cells. Varying across individuals, δ15N half-life in plasma (6 to 10 days) was also shorter than for δ13C (14 to 22 days), though δ15N and δ13C half-lives are usually considered as equal. Conclusion/Significance Overall, our multi-factorial experiment revealed that at least six levels of isotopic variations could co-occur in the same population. Our experimental analysis provides a framework for quantifying multiple sources of variation in isotopic discrimination and half-life that needs to be taken into account when designing and analysing ecological field studies.
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Affiliation(s)
- Nicolas Lecomte
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway.
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Codron D, Codron J, Sponheimer M, Bernasconi SM, Clauss M. When animals are not quite what they eat: diet digestibility influences 13C-incorporation rates and apparent discrimination in a mixed-feeding herbivore. CAN J ZOOL 2011. [DOI: 10.1139/z11-010] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The stable carbon isotope composition of animal tissues represents the weighted sum of the variety of food sources eaten. If sources differ in digestibility, tissues may overrepresent intake of more digestible items and faeces may overrepresent less digestible items. We tested this idea using whole blood and faeces of goats ( Capra hircus L., 1758) fed different food mixtures of C3 lucerne ( Medicago sativa L.) and C4 grass ( Themeda triandra Forssk.). Although blood and faecal δ13C values were broadly consistent with diet, results indicate mismatch between consumer and diet isotope compositions: both materials overrepresented the C3 (lucerne) component of diets. Lucerne had lower fibre digestibility than T. triandra, which explains the results for faeces, whereas underrepresentation of dietary C4 in blood is consistent with low protein content of the grass hay. A diet switch experiment revealed an important difference in 13C-incorporation rates across diets, which were slower for grass than lucerne diets, and in fact equilibrium states were not reached for all diets. Although more research is needed to link digestive kinetics with isotope incorporation, these results provide evidence for nonlinear relationships between consumers and their diets, invoking concerns about the conceptual value of “discrimination factors” as the prime currency for contemporary isotope ecology.
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Affiliation(s)
- Daryl Codron
- Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057 Zürich, Switzerland
- School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, Republic of South Africa
| | - Jacqui Codron
- School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, Republic of South Africa
| | - Matt Sponheimer
- Department of Anthropology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | | | - Marcus Clauss
- Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057 Zürich, Switzerland
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Wolf N, Bowen GJ, del Rio CM. The influence of drinking water on the δD and δ18O values of house sparrow plasma, blood and feathers. J Exp Biol 2011; 214:98-103. [DOI: 10.1242/jeb.050211] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
We investigated the relationships between the δdeuterium (δD) and the δ18oxygen (δ18O) of drinking water and the δD and δ18O of blood plasma, red blood cells and feathers in house sparrows (Passer domesticus) fed on diets with identical hydrogen and oxygen isotopic compositions and five isotopically distinct drinking water treatments. We expected and, with only one exception (18O in blood plasma), found linear relationships between the δD and δ18O values of drinking water and those of bird tissues. The slopes of these relationships, which estimate the percentage contributions of drinking water to the tissue isotopic signatures, were lower than those of previous studies. We found significant differences in the δD and δ18O values of feathers, red blood cells and plasma solids. In feathers and red blood cells, δD and δ18O values were linearly correlated. Our results have three implications for isotopic field studies: (1) if the isotopic composition of drinking water differs from that of food, its effect on tissue isotope values can confound the assignment of animals to a site of origin; (2) comparisons of the δD and δ18O values of different tissues must account for inter-tissue discrimination factors; and (3) δD/δ18O linear relationships are probably as prevalent in animal systems as they are in geohydrological systems. These relationships may prove to be useful tools in animal isotopic ecology.
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Affiliation(s)
- Nathan Wolf
- Department of Zoology and Physiology, University of Wyoming, 1000 University Ave, Laramie, WY 82071, USA
| | - Gabriel J. Bowen
- Department of Earth and Atmospheric Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, USA
| | - Carlos Martinez del Rio
- Department of Zoology and Physiology, University of Wyoming, 1000 University Ave, Laramie, WY 82071, USA
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Warne RW, Gilman CA, Wolf BO. Tissue-carbon incorporation rates in lizards: implications for ecological studies using stable isotopes in terrestrial ectotherms. Physiol Biochem Zool 2010; 83:608-17. [PMID: 20441446 DOI: 10.1086/651585] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Carbon stable isotope (delta(13)C) analysis can be used to infer the origin and to estimate the flow of nutrient resources through animals and across ecological compartments. These applications require knowledge of the rates at which carbon is incorporated into animal tissues and diet-to-tissue discrimination factors (Delta(13)C). Studies of carbon dynamics in terrestrial vertebrates to date have focused almost solely on endothermic animals; ectotherms such as reptiles have received little attention. Here we determined carbon incorporation rates and Delta(13)C in tissues of prairie lizards (Sceloporus undulatus consobrinus) and collared lizards (Crotaphytus collaris). The smaller lizard, S. undulatus, had carbon retention times of 25 and 61 d in plasma and red blood cells (RBC), respectively, compared with 44 and 311 d for the larger C. collaris. Liver, muscle, and skin carbon retention times for S. undulatus were 21, 81, and 94 d. Growth contributed 9%-19% of the carbon incorporated into these tissues. This contribution is similar to endotherms measured at comparable developmental stages. Mean Delta(13)C for plasma (-0.2 per thousand +/- 0.4 per thousand Vienna Pee Dee Belemnite Standard) and RBCs (-1.3 per thousand +/- 0.8 per thousand) were similar to values reported for other vertebrates. Carbon incorporation rates for these ectotherms, however, are seven times slower than in similarly sized adult endotherms. Although a limited comparison with data for warm-water fishes suggests comparable incorporation rates between aquatic and terrestrial ectotherms, this study highlights the lack of experimental data for isotope dynamics in ectotherms across a range of temperatures, body sizes, and developmental stages.
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Affiliation(s)
- Robin W Warne
- Biology Department, University of New Mexico, Albuquerque, NM 87131-0001, USA.
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Auerswald K, Wittmer MHOM, Zazzo A, Schäufele R, Schnyder H. Biases in the analysis of stable isotope discrimination in food webs. J Appl Ecol 2010. [DOI: 10.1111/j.1365-2664.2009.01764.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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