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Steele ZT, Caceres K, Jameson AD, Griego M, Rogers EJ, Whiteman JP. A protocol for distilling animal body water from biological samples and measuring oxygen and hydrogen stable isotopes via cavity ring-down spectroscopy. Isotopes Environ Health Stud 2024:1-22. [PMID: 38472130 DOI: 10.1080/10256016.2024.2323201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 02/01/2024] [Indexed: 03/14/2024]
Abstract
The application of stable isotope analysis (SIA) to the fields of ecology and animal biology has rapidly expanded over the past three decades, particularly with regards to water analysis. SIA now provides the opportunity to monitor migration patterns, examine food webs, and assess habitat changes in current and past study systems. While carbon and nitrogen SIA of biological samples have become common, analyses of oxygen or hydrogen are used more sparingly despite their promising utility for tracing water sources and animal metabolism. Common ecological applications of oxygen or hydrogen SIA require injecting enriched isotope tracers. As such, methods for processing and analyzing biological samples are tailored for enriched tracer techniques, which require lower precision than other techniques given the large signal-to-noise ratio of the data. However, instrumentation advancements are creating new opportunities to expand the applications of high-throughput oxygen and hydrogen SIA. To support these applications, we update methods to distill and measure water derived from biological samples with consistent precision equal to, or better than, ± 0.1 ‰ for δ17O, ± 0.3 ‰ for δ18O, ± 1 ‰ for δ2H, ± 2 ‰ for d-excess, and ± 15 per meg for Δ17O.
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Affiliation(s)
- Zachary T Steele
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
| | - Karen Caceres
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
| | - Austin D Jameson
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
| | - Michael Griego
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
| | - Elizabeth J Rogers
- Organismic & Evolutionary Biology Program, University of Massachusetts, Amherst, MA, USA
| | - John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
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Navarrete L, Lübcker N, Alvarez F, Nespolo R, Sanchez-Hernandez JC, Maldonado K, Sharp ZD, Whiteman JP, Newsome SD, Sabat P. A multi-isotope approach reveals seasonal variation in the reliance on marine resources, production of metabolic water, and ingestion of seawater by two species of coastal passerine to maintain water balance. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1120271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
Tracing how free-ranging organisms interact with their environment to maintain water balance is a difficult topic to study for logistical and methodological reasons. We use a novel combination of triple-oxygen stable isotope analyses of water extracted from plasma (δ16O, δ17O, δ18O) and bulk tissue carbon (δ13C) and nitrogen (δ15N) isotopes of feathers and blood to estimate the proportional contribution of marine resources, seawater, and metabolic water used by two species of unique songbirds (genus Cinclodes) to maintain their water balance in a seasonal coastal environment. We also assessed the physiological adjustments that these birds use to maintain their water balance. In agreement with previous work on these species, δ13C and δ15N data show that the coastal resident and invertivore C. nigrofumosus consumes a diet rich in marine resources, while the diet of migratory C. oustaleti shifts seasonally between marine (winter) to freshwater aquatic resources (summer). Triple-oxygen isotope analysis (Δ17O) of blood plasma, basal metabolic rate (BMR), and total evaporative water loss (TEWL) revealed that ~25% of the body water pool of both species originated from metabolic water, while the rest originated from a mix of seawater and fresh water. Δ17O measurements suggest that the contribution of metabolic water tends to increase in summer in C. nigrofumosus, which is coupled with a significant increase in BMR and TEWL. The two species had similar BMR and TEWL during the austral winter when they occur sympatrically in coastal environments. We also found a positive and significant association between the use of marine resources as measured by δ13C and δ15N values and the estimated δ18O values of ingested (pre-formed) water in both species, which indicates that Cinclodes do not directly drink seawater but rather passively ingest when consuming marine invertebrates. Finally, results obtained from physiological parameters and the isotope-based estimates of marine (food and water) resource use are consistent, supporting the use of the triple-oxygen isotopes to quantify the contribution of water sources to the total water balance of free-ranging birds.
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Griffen BD, Whiteman JP, Pullan S. Significance of autumn and winter food consumption for reproduction by Southern Beaufort Sea polar bears, Ursus maritimus. Polar Biol 2022. [DOI: 10.1007/s00300-022-03066-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractPolar bears (Ursus maritimus) in the southern Beaufort Sea experience long annual periods when preferred seal prey are scarce or are unavailable. Consumption of bowhead whale (Balaena mysticetus) carcasses from native Alaskan subsistence hunting is increasingly common for onshore polar bears, yet the energetic consequences of this consumption remain unclear. We use data on bears captured repeatedly over periods that encompassed autumn and winter, combined with calculations, to show that adult female bears likely consume an average of at least 4 seal equivalents during both autumn and winter periods and that considerable variation in energy intake exists across individual bears. We further show that subsistence-caught whale carcasses provide an upper threshold of > 4000 seal equivalents, which could potentially meet mean consumption needs of ~ 80% of the southern Beaufort Sea bear subpopulation during autumn and winter periods. Finally, we modify an existing model to show that observed mass changes over autumn and winter could substantially alter spring foraging habitat choice by females with cubs and the chance that a female with reduced energy reserves would abort a pregnancy or abandon cubs in favor of increasing her own survival; these behaviors could potentially influence population vital rates. Our study highlights the importance of mass dynamics over the autumn and winter months, points to the need for additional data on foraging and energetics over this period, and indicates that the recent declines in polar bear body condition in some subpopulations could have complex effects on reproduction.
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Whiteman JP, Harlow HJ, Durner GM, Regehr EV, Amstrup SC, Pagano AM, Ben‐David M. The acute physiological response of polar bears to helicopter capture. J Wildl Manage 2022; 86:e22238. [PMID: 35915725 PMCID: PMC9324155 DOI: 10.1002/jwmg.22238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 02/25/2022] [Accepted: 03/29/2022] [Indexed: 11/28/2022]
Abstract
Many wildlife species are live captured, sampled, and released; for polar bears (Ursus maritimus) capture often requires chemical immobilization via helicopter darting. Polar bears reduce their activity for approximately 4 days after capture, likely reflecting stress recovery. To better understand this stress, we quantified polar bear activity (via collar‐mounted accelerometers) and body temperature (via loggers in the body core [Tabd] and periphery [Tper]) during 2–6 months of natural behavior, and during helicopter recapture and immobilization. Recapture induced bouts of peak activity higher than those that occurred during natural behavior for 2 of 5 bears, greater peak Tper for 3 of 6 bears, and greater peak Tabd for 1 of 6 bears. High body temperature (>39.0°C) occurred in Tper for 3 of 6 individuals during recapture and 6 of 6 individuals during natural behavior, and in Tabd for 2 of 6 individuals during recapture and 3 of 6 individuals during natural behavior. Measurements of Tabd and Tper correlated with rectal temperatures measured after immobilization, supporting the use of rectal temperatures for monitoring bear response to capture. Using a larger dataset (n = 66 captures), modeling of blood biochemistry revealed that maximum ambient temperature during recapture was associated with a stress leukogram (7–26% decline in percent lymphocytes, 12–21% increase in percent neutrophils) and maximum duration of helicopter operations had a similar but smaller effect. We conclude that polar bear activity and body temperature during helicopter capture are similar to that which occurs during the most intense events of natural behavior; high body temperature, especially in warm capture conditions, is a key concern; additional study of stress leukograms in polar bears is needed; and additional data collection regarding capture operations would be useful.
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Affiliation(s)
- John P. Whiteman
- Department of Biological Sciences, Old Dominion University Hampton Boulevard Norfolk VA 23529 USA
| | - Henry J. Harlow
- Department of Zoology and Physiology, University of Wyoming University Avenue Laramie WY 82071 USA
| | - George M. Durner
- Alaska Science Center, US Geological Survey University Drive Anchorage AK 99508 USA
| | - Eric V. Regehr
- Polar Science Center University of Washington NE 40th Street Seattle WA 98105 USA
| | | | - Anthony M. Pagano
- Alaska Science Center, US Geological Survey University Drive Anchorage AK 99508 USA
| | - Merav Ben‐David
- Department of Zoology and Physiology, University of Wyoming University Avenue Laramie WY 82071 USA
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Shipley ON, Olin JA, Whiteman JP, Bethea DM, Newsome SD. Bulk and amino acid nitrogen isotopes suggest shifting nitrogen balance of pregnant sharks across gestation. Oecologia 2022; 199:313-328. [PMID: 35718810 DOI: 10.1007/s00442-022-05197-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 05/21/2022] [Indexed: 10/18/2022]
Abstract
Nitrogen isotope (δ15N) analysis of bulk tissues and individual amino acids (AA) can be used to assess how consumers maintain nitrogen balance with broad implications for predicting individual fitness. For elasmobranchs, a ureotelic taxa thought to be constantly nitrogen limited, the isotopic effects associated with nitrogen-demanding events such as prolonged gestation remain unknown. Given the linkages between nitrogen isotope variation and consumer nitrogen balance, we used AA δ15N analysis of muscle and liver tissue collected from female bonnethead sharks (Sphyrna tiburo, n = 16) and their embryos (n = 14) to explore how nitrogen balance may vary across gestation. Gestational stage was a strong predictor of bulk tissue and AA δ15N values in pregnant shark tissues, decreasing as individuals neared parturition. This trend was observed in trophic (e.g., Glx, Ala, Val), source (e.g., Lys), and physiological (e.g., Gly) AAs. Several potential mechanisms may explain these results including nitrogen conservation, scavenging, and bacterially mediated breakdown of urea to free ammonia that is used to synthesize AAs. We observed contrasting patterns of isotopic discrimination in embryo tissues, which generally became enriched in 15N throughout development. This was attributed to greater excretion of nitrogenous waste in more developed embryos, and the role of physiologically sensitive AAs (i.e., Gly and Ser) to molecular processes such as nucleotide synthesis. These findings underscore how AA isotopes can quantify shifts in nitrogen balance, providing unequivocal evidence for the role of physiological condition in driving δ15N variation in both bulk tissues and individual AAs.
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Affiliation(s)
- Oliver N Shipley
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA. .,Beneath the Waves, PO Box 126, Herndon, VA, 20172, USA.
| | - Jill A Olin
- Biological Sciences, Great Lakes Research Center, Michigan Technological University, Houghton, MI, 49931, USA
| | - John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, 23529, USA
| | - Dana M Bethea
- NOAA Fisheries Southeast Regional Office, Saint Petersburg, FL, 33701, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
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Sabat P, Newsome SD, Pinochet S, Nespolo R, Sanchez-Hernandez JC, Maldonado K, Gerson AR, Sharp ZD, Whiteman JP. Triple Oxygen Isotope Measurements (Δ' 17O) of Body Water Reflect Water Intake, Metabolism, and δ 18O of Ingested Water in Passerines. Front Physiol 2021; 12:710026. [PMID: 34552501 PMCID: PMC8450417 DOI: 10.3389/fphys.2021.710026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 08/09/2021] [Indexed: 12/02/2022] Open
Abstract
Understanding physiological traits and ecological conditions that influence a species reliance on metabolic water is critical to creating accurate physiological models that can assess their ability to adapt to environmental perturbations (e.g., drought) that impact water availability. However, relatively few studies have examined variation in the sources of water animals use to maintain water balance, and even fewer have focused on the role of metabolic water. A key reason is methodological limitations. Here, we applied a new method that measures the triple oxygen isotopic composition of a single blood sample to estimate the contribution of metabolic water to the body water pool of three passerine species. This approach relies on Δ'17O, defined as the residual from the tight linear correlation that naturally exists between δ17O and δ18O values. Importantly, Δ'17O is relatively insensitive to key fractionation processes, such as Rayleigh distillation in the water cycle that have hindered previous isotope-based assessments of animal water balance. We evaluated the effects of changes in metabolic rate and water intake on Δ'17O values of captive rufous-collared sparrows (Zonotrichia capensis) and two invertivorous passerine species in the genus Cinclodes from the field. As predicted, colder acclimation temperatures induced increases in metabolic rate, decreases in water intake, and increases in the contribution of metabolic water to the body water pool of Z. capensis, causing a consistent change in Δ'17O. Measurement of Δ'17O also provides an estimate of the δ18O composition of ingested pre-formed (drinking/food) water. Estimated δ18O values of drinking/food water for captive Z. capensis were ~ −11‰, which is consistent with that of tap water in Santiago, Chile. In contrast, δ18O values of drinking/food water ingested by wild-caught Cinclodes were similar to that of seawater, which is consistent with their reliance on marine resources. Our results confirm the utility of this method for quantifying the relative contribution of metabolic versus pre-formed drinking/food water to the body water pool in birds.
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Affiliation(s)
- Pablo Sabat
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.,Center of Applied Ecology and Sustainability (CAPES), Santiago, Chile
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, United States
| | - Stephanie Pinochet
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Roberto Nespolo
- Center of Applied Ecology and Sustainability (CAPES), Santiago, Chile.,Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile.,Millennium Institute for Integrative Biology (iBio), Santiago, Chile
| | | | - Karin Maldonado
- Departamento de Ciencias, Facultad de Artes Liberales, Universidad Adolfo Ibáñez, Santiago, Chile
| | - Alexander R Gerson
- Biology Department, University of Massachusetts, Amherst, MA, United States
| | - Zachary D Sharp
- Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM, United States
| | - John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, United States
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Whiteman JP, Rodriguez Curras M, Feeser KL, Newsome SD. Dietary protein content and digestibility influences discrimination of amino acid nitrogen isotope values in a terrestrial omnivorous mammal. Rapid Commun Mass Spectrom 2021; 35:e9073. [PMID: 33634533 DOI: 10.1002/rcm.9073] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 02/02/2021] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
RATIONALE Ecologists increasingly determine the δ15 N values of amino acids (AA) in animal tissue; "source" AA typically exhibit minor variation between diet and consumer, while "trophic" AA have increased δ15 N values in consumers. Thus, trophic-source δ15 N offsets (i.e., Δ15 NT-S ) reflect trophic position in a food web. However, even minor variations in δ15 Nsource AA values may influence the magnitude of offset that represents a trophic step, known as the trophic discrimination factor (i.e., TDFT-S ). Diet digestibility and protein content can influence the δ15 N values of bulk animal tissue, but the effects of these factors on AA Δ15 NT-S and TDFT-S in mammals are unknown. METHODS We fed captive mice (Mus musculus) either (A) a low-fat, high-fiber diet with low, intermediate, or high protein; or (B) a high-fat, low-fiber diet with low or intermediate protein. Mouse muscle and dietary protein were analyzed for bulk tissue δ15 N using elemental analyzer-isotope ratio mass spectrometry (EA-IRMS), and were also hydrolyzed into free AA that were analyzed for δ15 N using gas chromatography-combustion-IRMS. RESULTS As dietary protein increased, Δ15 NConsumer-Diet slightly declined for bulk muscle tissue in both experiments; increased for AA in the low-fat, high-fiber diet (A); and remained the same or decreased for AA in the high-fat, low-fiber diet (B). The effects of dietary protein on Δ15 NT-S and on TDFT-S varied by AA but were consistent between variables. CONCLUSIONS Diets were less digestible and included more protein in Experiment A than in Experiment B. As a result, the mice in Experiment A probably oxidized more AA, resulting in greater Δ15 NConsumer-Diet values. However, the similar responses of Δ15 NT-S and of TDFT-S to diet variation suggest that if diet samples are available, Δ15 NT-S accurately tracks trophic position. If diet samples are not available, the patterns presented here provide a basis to interpret Δ15 NT-S values. The trophic-source offset of Pro-Lys did not vary across diets, and therefore may be more reliable for omnivores than other offsets (e.g., Glu-Phe).
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Affiliation(s)
- John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, 23529, USA
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Mauriel Rodriguez Curras
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, WI, 53706, USA
| | - Kelli L Feeser
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
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Khadpekar Y, Whiteman JP, Durrant BS, Owen MA, Prakash S. Scent-marking behavior by female sloth bears during estrus. URSUS 2021. [DOI: 10.2192/ursus-d-19-00011.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yaduraj Khadpekar
- Department of Zoology, Dayalbagh Educational Institute, Dayalbagh, Agra, Uttar Pradesh, 282005, India
| | - John P. Whiteman
- Institute for Conservation Research, San Diego Zoo Global, 15600 San Pasqual Valley Road, Escondido, CA 92027, USA
| | - Barbara S. Durrant
- Institute for Conservation Research, San Diego Zoo Global, 15600 San Pasqual Valley Road, Escondido, CA 92027, USA
| | - Megan A. Owen
- Institute for Conservation Research, San Diego Zoo Global, 15600 San Pasqual Valley Road, Escondido, CA 92027, USA
| | - Sant Prakash
- Department of Zoology, Dayalbagh Educational Institute, Dayalbagh, Agra, Uttar Pradesh, 282005, India
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Whiteman JP, Newsome SD, Bustamante P, Cherel Y, Hobson KA. Quantifying capital versus income breeding: New promise with stable isotope measurements of individual amino acids. J Anim Ecol 2020; 90:1408-1418. [PMID: 33300602 DOI: 10.1111/1365-2656.13402] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 11/09/2020] [Indexed: 11/29/2022]
Abstract
Capital breeders accumulate nutrients prior to egg development, then use these stores to support offspring development. In contrast, income breeders rely on local nutrients consumed contemporaneously with offspring development. Understanding such nutrient allocations is critical to assessing life-history strategies and habitat use. Despite the contrast between these strategies, it remains challenging to trace nutrients from endogenous stores or exogenous food intake into offspring. Here, we tested a new solution to this problem. Using tissue samples collected opportunistically from wild emperor penguins Aptenodytes forsteri, which exemplify capital breeding, we hypothesized that the stable carbon (δ13 C) and nitrogen (δ15 N) isotope values of individual amino acids (AAs) in endogenous stores (e.g. muscle) and in egg yolk and albumen reflect the nutrient sourcing that distinguishes capital versus income breeding. Unlike other methods, this approach does not require untested assumptions or diet sampling. We found that over half of essential AAs had δ13 C values that did not differ between muscle and yolk or albumen, suggesting that most of these AAs were directly routed from muscle into eggs. In contrast, almost all non-essential AAs differed in δ13 C values between muscle and yolk or between muscle and albumen, suggesting de novo synthesis. Over half of AAs that have labile nitrogen atoms (i.e. 'trophic' AA) had higher δ15 N values in yolk and albumen than in muscle, suggesting that they were transaminated during their routing into egg tissue. This effect was smaller for AAs with less labile nitrogen atoms (i.e. 'source' AA). Our results indicate that the δ15 N offset between trophic-source AAs (Δ15 Ntrophic-source ) may provide an index of the extent of capital breeding. The value of emperor penguin Δ15 NPro-Phe was higher in yolk and albumen than in muscle, reflecting the mobilization of endogenous stores; in comparison, the value of Δ15 NPro-Phe was similar across muscle and egg tissue in previously published data for income-breeding herring gulls Larus argentatus smithsonianus. Our results provide a quantitative basis for using AA δ13 C and δ15 N, and isotopic offsets among AAs (e.g. Δ15 NPro-Phe ), to explore the allocation of endogenous versus exogenous nutrients across the capital versus income spectrum of avian reproduction.
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Affiliation(s)
- John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA.,Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Paco Bustamante
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 du CNRS-La Rochelle Université, La Rochelle, France
| | - Yves Cherel
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 du CNRS-La Rochelle Université, Villiers-en-Bois, France
| | - Keith A Hobson
- Department of Biology, University of Western Ontario, London, Ontario, Canada.,Environment and Climate Change Canada, Saskatoon, SK, Canada
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Lübcker N, Whiteman JP, Newsome SD, Millar RP, de Bruyn PJN. Can the carbon and nitrogen isotope values of offspring be used as a proxy for their mother's diet? Using foetal physiology to interpret bulk tissue and amino acid δ 15N values. Conserv Physiol 2020; 8:coaa060. [PMID: 32765882 PMCID: PMC7397484 DOI: 10.1093/conphys/coaa060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 04/14/2020] [Accepted: 06/14/2020] [Indexed: 06/11/2023]
Abstract
The measurement of bulk tissue nitrogen (δ15N) and carbon isotope values (δ13C) chronologically along biologically inert tissues sampled from offspring can provide a longitudinal record of their mothers' foraging habits. This study tested the important assumption that mother-offspring stable isotope values are positively and linearly correlated. In addition, any change in the mother-offspring bulk tissues and individual amino acids that occurred during gestation was investigated. Whiskers sampled from southern elephant seal pups (Mirounga leonina) and temporally overlapping whiskers from their mothers were analyzed. This included n = 1895 chronologically subsampled whisker segments for bulk tissue δ15N and δ13C in total and n = 20 whisker segments for amino acid δ15N values, sampled from recently weaned pups (n = 17), juvenile southern elephant seals (SES) < 2 years old (n = 23) and adult female SES (n = 17), which included nine mother-offspring pairs. In contrast to previous studies, the mother-offspring pairs were not in isotopic equilibrium or linearly correlated during gestation: the Δ15N and Δ13C mother-offspring offsets increased by 0.8 and 1.2‰, respectively, during gestation. The foetal bulk δ15N values were 1.7 ± 0.5‰ (0.9-2.7‰) higher than mothers' δ15N values before birth, while the foetal δ13C increased by ~1.7‰ during gestation and were 1.0 ± 0.5‰ (0.0-1.9‰) higher than their mothers' δ13C at the end of pregnancy. The mother-offspring serine and glycine Δ15N differed by ~4.3‰, while the foetal alanine δ15N values were 1.4‰ lower than that of their mothers during the third trimester of pregnancy. The observed mother-offspring δ15N differences are likely explained by shuttling of glutamate-glutamine and glycine-serine amongst skeletal muscle, liver, placenta and foetal tissue. Foetal development relies primarily on remobilized endogenous maternal proteinaceous sources. Researchers should consider foetal physiology when using offspring bulk tissue isotope values as biomarkers for the mother's isotopic composition as part of monitoring programmes.
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Affiliation(s)
- Nico Lübcker
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria, 0028, South Africa
| | - John P Whiteman
- Department of Biological Sciences, Old Dominion University, 5115 Hampton Boulevard, Norfolk, VA, 23529, USA
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Robert P Millar
- Centre for Neuroendocrinology and Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, 0001, South Africa
- Department of Integrative Biomedical Sciences, Neurosciences Institute and Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Anzio Road, Observatory 7925, South Africa
| | - P J Nico de Bruyn
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria, 0028, South Africa
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11
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Lübcker N, Whiteman JP, Millar RP, de Bruyn PJN, Newsome SD. Fasting affects amino acid nitrogen isotope values: a new tool for identifying nitrogen balance of free-ranging mammals. Oecologia 2020; 193:53-65. [PMID: 32300864 DOI: 10.1007/s00442-020-04645-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 04/07/2020] [Indexed: 11/25/2022]
Abstract
Changes in the nutritional status of free-ranging animals have a strong influence on individual fitness, yet it remains challenging to monitor longitudinally. Nitrogen (δ15N) and carbon (δ13C) isotope values measured chronologically along the length of metabolically inert keratinous tissues can be used as a nutritional biomarker to retrospectively reconstruct the foraging ecology and eco-physiology of consumers. We quantitatively describe the physiological effects of fasting on amino acid metabolism using sequentially measured bulk tissue and amino acid δ15N values along the length of whiskers sampled from free-ranging juvenile, subadults, adult female, and male southern elephant seals (SES; Mirounga leonina) on Marion Island in the Southern Ocean. For both juveniles and adult females, whisker segments representing fasting had significantly higher bulk tissue δ15N values of 0.6 ± 0.5‰ and 1.3-1.8‰, respectively, in comparison to segments unaffected by fasting. We also found a large increase (2-6‰) in δ15N values for most glucogenic amino acids and a simultaneous depletion (2-3‰) of alanine in segments reflecting fasting, which enabled us to accurately predict (74%) the nutritional status of our model species. We hypothesize that the glucose-alanine cycle is the mechanism driving the observed depletion of alanine δ15N values during fasting. We demonstrated that keratinaceous tissues can be used as a longitudinal nutritional biomarker to detect changes in the nitrogen balance of an individual. Moreover, it is evident that physiological factors have an important influence on tissue δ15N values and can lead to erroneous bulk tissue or amino acid isotope-based reconstructions of foraging habits.
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Affiliation(s)
- Nico Lübcker
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
| | - John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, 23529, USA.,Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Robert P Millar
- Centre for Neuroendocrinology and Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, 0001, South Africa
| | - P J Nico de Bruyn
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
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Abstract
Abstract
The dynamics of animal body water and metabolism are integral aspects of biological function but are difficult to measure, particularly in free-ranging individuals. We demonstrate a new method to estimate inputs to body water via analysis of Δ17O, a measure of 17O/16O relative to 18O/16O. Animal body water is primarily a mixture of drinking or food water (meteoric water; Δ17O ≈ 0.030 per mille [‰]) and metabolic water synthesized from atmospheric oxygen (Δ17O ≈ –0.450‰). Greater drinking or food water intake should increase Δ17O toward 0.030‰, whereas greater metabolic rate should decrease Δ17O toward –0.450‰. We found that wild mammal Δ17O values generally increased with body mass, consistent with both a decline in mass-specific metabolic rate and an increase in water intake. Captive mouse (Peromyscus maniculatus) Δ17O values were higher than predicted but exhibited the expected relative change based on metabolic rate and water intake. Measurements of Δ17O may enable novel ecophysiological studies.
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Affiliation(s)
- John P Whiteman
- Department of Biological Sciences at Old Dominion University, in Norfolk, Virginia
| | | | | | - Seth D Newsome
- Department of Biology, at the University of New Mexico, in Albuquerque
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13
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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] [What about the content of this article? (0)] [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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14
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Whiteman JP, Harlow HJ, Durner GM, Regehr EV, Amstrup SC, Ben-David M. Heightened Immune System Function in Polar Bears Using Terrestrial Habitats. Physiol Biochem Zool 2019; 92:1-11. [DOI: 10.1086/698996] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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15
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Khadpekar Y, Whiteman JP, Durrant BS, Owen MA, Prakash S. Approaches to studying behavior in captive sloth bears through animal keeper feedback. Zoo Biol 2018; 37:408-415. [PMID: 30465725 DOI: 10.1002/zoo.21455] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 08/16/2018] [Accepted: 10/22/2018] [Indexed: 02/06/2023]
Abstract
Animal keepers at zoos and wildlife rescue centers often possess in-depth knowledge of the health and behavior of the individuals under their care. While it is often not feasible for keepers to regularly collect behavior data through formal scientific methods, efforts should be made to find alternative means to capture this knowledge. We investigated the use of keeper feedback to study the behavior of sloth bears at the Agra Bear Rescue Facility (ABRF; Agra, India). We prepared a survey with 5 questions focused on behaviors indicative of playfulness, boldness, aggressiveness, and the tendency to express self-directed behaviors (SDB). We asked keepers to rate bears on a Likert scale from 1 (least likely to exhibit a behavior) to 5 (most likely) for 44 adult female bears (5-21 years of age). We validated this method by comparing keeper ratings of SDB with formal behavior observations, finding that time of day had an influence on the accuracy of keeper assessments. We found a significant negative correlation between housing bears in larger groups (>15) and SDB. In addition, we correlated ratings given by keepers for all study behaviors. Social play had significant negative correlation with aggression toward people. There was no correlation between social play and aggression toward other bears, possibly due to the existence of cohesive social groups in group housing or high dimensionality of the data. We found that keeper feedback is an efficient tool to gather behavior data on captive sloth bears and recommend its use in future studies.
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Affiliation(s)
- Yaduraj Khadpekar
- Department of Zoology, Dayalbagh Educational Institute, Agra, Uttar Pradesh, India.,Wildlife SOS, New Delhi, India
| | - John P Whiteman
- Institute for Conservation Research, San Diego Zoo Global, Escondido, California
| | - Barbara S Durrant
- Institute for Conservation Research, San Diego Zoo Global, Escondido, California
| | - Megan A Owen
- Institute for Conservation Research, San Diego Zoo Global, Escondido, California
| | - Sant Prakash
- Department of Zoology, Dayalbagh Educational Institute, Agra, Uttar Pradesh, India
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16
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Affiliation(s)
- John P Whiteman
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
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Whiteman JP, Harlow HJ, Durner GM, Regehr EV, Amstrup SC, Ben-David M. Phenotypic plasticity and climate change: can polar bears respond to longer Arctic summers with an adaptive fast? Oecologia 2017; 186:369-381. [DOI: 10.1007/s00442-017-4023-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 11/22/2017] [Indexed: 02/02/2023]
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18
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Hughes KL, Whiteman JP, Newsome SD. The relationship between dietary protein content, body condition, and Δ15N in a mammalian omnivore. Oecologia 2017; 186:357-367. [DOI: 10.1007/s00442-017-4010-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 11/09/2017] [Indexed: 11/29/2022]
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19
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Durner GM, Douglas DC, Albeke SE, Whiteman JP, Amstrup SC, Richardson E, Wilson RR, Ben-David M. Increased Arctic sea ice drift alters adult female polar bear movements and energetics. Glob Chang Biol 2017; 23:3460-3473. [PMID: 28586523 DOI: 10.1111/gcb.13746] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 03/17/2017] [Accepted: 04/13/2017] [Indexed: 06/07/2023]
Abstract
Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio-tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences for energy demands of adult females in the Beaufort and Chukchi seas during two periods with different sea ice characteristics. Westward and northward drift of the sea ice used by polar bears in both regions increased between 1987-1998 and 1999-2013. To remain within their home ranges, polar bears responded to the higher westward ice drift with greater eastward movements, while their movements north in the spring and south in fall were frequently aided by ice motion. To compensate for more rapid westward ice drift in recent years, polar bears covered greater daily distances either by increasing their time spent active (7.6%-9.6%) or by increasing their travel speed (8.5%-8.9%). This increased their calculated annual energy expenditure by 1.8%-3.6% (depending on region and reproductive status), a cost that could be met by capturing an additional 1-3 seals/year. Polar bears selected similar habitats in both periods, indicating that faster drift did not alter habitat preferences. Compounding reduced foraging opportunities that result from habitat loss; changes in ice drift, and associated activity increases, likely exacerbate the physiological stress experienced by polar bears in a warming Arctic.
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Affiliation(s)
- George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - David C Douglas
- U.S. Geological Survey, Alaska Science Center, Juneau, AK, USA
| | - Shannon E Albeke
- Wyoming Geographic Information Science Center, University of Wyoming, Laramie, WY, USA
| | - John P Whiteman
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | | | - Evan Richardson
- Environment and Climate Change Canada, University of Alberta, Edmonton, AB, Canada
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Merav Ben-David
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
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20
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Whiteman JP, Harlow HJ, Durner GM, Regehr EV, Rourke BC, Robles M, Amstrup SC, Ben-David M. Polar bears experience skeletal muscle atrophy in response to food deprivation and reduced activity in winter and summer. Conserv Physiol 2017; 5:cox049. [PMID: 28835844 PMCID: PMC5550809 DOI: 10.1093/conphys/cox049] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 07/05/2017] [Accepted: 07/26/2017] [Indexed: 05/31/2023]
Abstract
When reducing activity and using stored energy during seasonal food shortages, animals risk degradation of skeletal muscles, although some species avoid or minimize the resulting atrophy while experiencing these conditions during hibernation. Polar bears may be food deprived and relatively inactive during winter (when pregnant females hibernate and hunting success declines for other demographic groups) as well as summer (when sea ice retreats from key foraging habitats). We investigated muscle atrophy in samples of biceps femoris collected from free-ranging polar bears in the Southern Beaufort Sea (SBS) throughout their annual cycle. Atrophy was most pronounced in April-May as a result of food deprivation during the previous winter, with muscles exhibiting reduced protein concentration, increased water content, and lower creatine kinase mRNA. These animals increased feeding and activity in spring (when seal prey becomes more available), initiating a period of muscle recovery. During the following ice melt of late summer, ~30% of SBS bears abandon retreating sea ice for land; in August, these 'shore' bears exhibited no muscle atrophy, indicating that they had fully recovered from winter food deprivation. These individuals subsequently scavenged whale carcasses deposited by humans and by October, had retained good muscle condition. In contrast, ~70% of SBS bears follow the ice north in late summer, into deep water with less prey. These 'ice' bears fast; by October, they exhibited muscle protein loss and rapid changes in myosin heavy-chain isoforms in response to reduced activity. These findings indicate that, unlike other bears during winter hibernation, polar bears without food in summer cannot mitigate atrophy. Consequently, prolonged summer fasting resulting from climate change-induced ice loss creates a risk of greater muscle atrophy and reduced abilities to travel and hunt.
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Affiliation(s)
- John P. Whiteman
- Program in Ecology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
- Department of Zoology and Physiology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
| | - Henry J. Harlow
- Department of Zoology and Physiology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
| | - George M. Durner
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
| | - Eric V. Regehr
- Marine Mammals Management, U.S. Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503, USA
- Current: Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105, USA
| | - Bryan C. Rourke
- Department of Biological Sciences, California State University, 1250 Bellflower Blvd, Long Beach, CA 90840, USA
| | - Manuel Robles
- Department of Biological Sciences, California State University, 1250 Bellflower Blvd, Long Beach, CA 90840, USA
| | | | - Merav Ben-David
- Program in Ecology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
- Department of Zoology and Physiology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
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Whiteman JP, Harlow HJ, Durner GM, Anderson-Sprecher R, Albeke SE, Regehr EV, Amstrup SC, Ben-David M. Animal physiology. Summer declines in activity and body temperature offer polar bears limited energy savings. Science 2015; 349:295-8. [PMID: 26185248 DOI: 10.1126/science.aaa8623] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 06/11/2015] [Indexed: 11/02/2022]
Abstract
Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, on shore. Although the physiology of "ice" bears in summer is unknown, "shore" bears purportedly minimize energy losses by entering a hibernation-like state when deprived of food. Such a strategy could partially compensate for the loss of on-ice foraging opportunities caused by climate change. However, here we report gradual, moderate declines in activity and body temperature of both shore and ice bears in summer, resembling energy expenditures typical of fasting, nonhibernating mammals. Also, we found that to avoid unsustainable heat loss while swimming, bears employed unusual heterothermy of the body core. Thus, although well adapted to seasonal ice melt, polar bears appear susceptible to deleterious declines in body condition during the lengthening period of summer food deprivation.
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Affiliation(s)
- J P Whiteman
- Program in Ecology, University of Wyoming, Laramie, WY 82071, USA. Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA
| | - H J Harlow
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA
| | - G M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK 99508, USA
| | | | - S E Albeke
- Wyoming Geographic Information Science Center, University of Wyoming, Laramie, WY 82071, USA
| | - E V Regehr
- Marine Mammals Management, U.S. Fish and Wildlife Service, Anchorage, AK 99503, USA
| | - S C Amstrup
- Polar Bears International, Bozeman, MT 59772, USA
| | - M Ben-David
- Program in Ecology, University of Wyoming, Laramie, WY 82071, USA. Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA
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23
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Whiteman JP, Frank N, Greller KA, Harlow HJ, Ben-David M. Characterization of blood lipoproteins and validation of cholesterol and triacylglycerol assays for free-ranging polar bears (Ursus maritimus). J Vet Diagn Invest 2013; 25:423-7. [DOI: 10.1177/1040638713486114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Blood triacylglycerol (TG) and lipoproteins are important variables for evaluating nutritional status of wildlife, but measurements are often expensive and difficult. Performance of a small, portable blood analyzer intended for human medical diagnostics was evaluated in measuring these variables in plasma and serum from free-ranging polar bears ( Ursus maritimus), which are experiencing nutritional stress related to sea ice loss. The analyzer accurately tracked changes in concentration of total cholesterol (Ctotal), cholesterol associated with high-density lipoprotein (CHDL), and TG during a validation protocol of diluting samples and spiking them with exogenous cholesterol and glycerol. Values of Ctotal and TG agreed well with values obtained by other methods (ultracentrifugation followed by colorimetric assays); agreement was variable for values of cholesterol associated with specific lipoproteins. Similar to a study of captive polar bears, ultracentrifugation methods revealed greater TG in very low-density lipoproteins than in low-density lipoprotein, which is unusual and merits additional study.
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Affiliation(s)
- John P. Whiteman
- Department of Zoology and Physiology (Whiteman, Greller, Harlow, Ben-David), University of Wyoming, Laramie, WY
- Program in Ecology (Whiteman, Ben-David), University of Wyoming, Laramie, WY
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN (Frank)
- Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, MA (Frank)
| | - Nicholas Frank
- Department of Zoology and Physiology (Whiteman, Greller, Harlow, Ben-David), University of Wyoming, Laramie, WY
- Program in Ecology (Whiteman, Ben-David), University of Wyoming, Laramie, WY
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN (Frank)
- Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, MA (Frank)
| | - Katie A. Greller
- Department of Zoology and Physiology (Whiteman, Greller, Harlow, Ben-David), University of Wyoming, Laramie, WY
- Program in Ecology (Whiteman, Ben-David), University of Wyoming, Laramie, WY
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN (Frank)
- Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, MA (Frank)
| | - Henry J. Harlow
- Department of Zoology and Physiology (Whiteman, Greller, Harlow, Ben-David), University of Wyoming, Laramie, WY
- Program in Ecology (Whiteman, Ben-David), University of Wyoming, Laramie, WY
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN (Frank)
- Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, MA (Frank)
| | - Merav Ben-David
- Department of Zoology and Physiology (Whiteman, Greller, Harlow, Ben-David), University of Wyoming, Laramie, WY
- Program in Ecology (Whiteman, Ben-David), University of Wyoming, Laramie, WY
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN (Frank)
- Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, MA (Frank)
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Whiteman JP, Greller KA, Harlow HJ, Felicetti LA, Rode KD, Ben-David M. Carbon isotopes in exhaled breath track metabolic substrates in brown bears (Ursus arctos). J Mammal 2012. [DOI: 10.1644/11-mamm-s-178.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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25
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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] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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27
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Affiliation(s)
- Jonathan N Pauli
- Program in Ecology, University of Wyoming, Laramie, WY 82071, USA.
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