1
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Cedden D, Güney G, Toprak U. The integral role of de novo lipogenesis in the preparation for seasonal dormancy. Proc Natl Acad Sci U S A 2024; 121:e2406194121. [PMID: 38990942 PMCID: PMC11260141 DOI: 10.1073/pnas.2406194121] [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: 03/26/2024] [Accepted: 06/11/2024] [Indexed: 07/13/2024] Open
Abstract
Animals can alter their body compositions in anticipation of dormancy to endure seasons with limited food availability. Accumulation of lipid reserves, mostly in the form of triglycerides (TAGs), is observed during the preparation for dormancy in diverse animals, including insects (diapause) and mammals (hibernation). However, the mechanisms involved in the regulation of lipid accumulation and the ecological consequences of failure to accumulate adequate lipid stores in preparation for animal dormancy remain understudied. In the broadest sense, lipid reserves can be accumulated in two ways: the animal either receives lipids directly from the environment or converts the sugars and amino acids present in food to fatty acids through de novo lipogenesis and then to TAGs. Here, we show that preparation for diapause in the Colorado potato beetle (Leptinotarsa decemlineata) involves orchestrated upregulation of genes involved in lipid metabolism with a transcript peak in 8- and 10-d-old diapause-destined insects. Regulation at the transcript abundance level was associated with the accumulation of substantial fat stores. Furthermore, the knockdown of de novo lipogenesis enzymes (ACCase and FAS-1) prolonged the preparatory phase, while the knockdown of fatty acid transportation genes shortened the preparatory phase. Our findings suggest a model in which the insects dynamically decide when to transition from the preparation phase into diapause, depending on the progress in lipid accumulation through de novo lipogenesis.
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Affiliation(s)
- Doga Cedden
- Molecular Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara06110, Türkiye
- Department of Evolutionary Developmental Genetics, Johann-Friedrich-Blumenbach Institute, Göttingen Center for Molecular Biosciences, University of Göttingen, Göttingen37077, Germany
| | - Gözde Güney
- Molecular Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara06110, Türkiye
- Agricultural Entomology, Department of Crop Sciences, University of Göttingen, Göttingen37077, Germany
| | - Umut Toprak
- Molecular Entomology Laboratory, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara06110, Türkiye
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2
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Pagano AM, Rode KD, Lunn NJ, McGeachy D, Atkinson SN, Farley SD, Erlenbach JA, Robbins CT. Polar bear energetic and behavioral strategies on land with implications for surviving the ice-free period. Nat Commun 2024; 15:947. [PMID: 38351211 PMCID: PMC10864307 DOI: 10.1038/s41467-023-44682-1] [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: 08/11/2023] [Accepted: 12/21/2023] [Indexed: 02/16/2024] Open
Abstract
Declining Arctic sea ice is increasing polar bear land use. Polar bears on land are thought to minimize activity to conserve energy. Here, we measure the daily energy expenditure (DEE), diet, behavior, movement, and body composition changes of 20 different polar bears on land over 19-23 days from August to September (2019-2022) in Manitoba, Canada. Polar bears on land exhibited a 5.2-fold range in DEE and 19-fold range in activity, from hibernation-like DEEs to levels approaching active bears on the sea ice, including three individuals that made energetically demanding swims totaling 54-175 km. Bears consumed berries, vegetation, birds, bones, antlers, seal, and beluga. Beyond compensating for elevated DEE, there was little benefit from terrestrial foraging toward prolonging the predicted time to starvation, as 19 of 20 bears lost mass (0.4-1.7 kg•day-1). Although polar bears on land exhibit remarkable behavioral plasticity, our findings reinforce the risk of starvation, particularly in subadults, with forecasted increases in the onshore period.
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Affiliation(s)
- Anthony M Pagano
- U. S. Geological Survey, Alaska Science Center, Anchorage, AK, 99508, USA.
| | - Karyn D Rode
- U. S. Geological Survey, Alaska Science Center, Anchorage, AK, 99508, USA
| | - Nicholas J Lunn
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Edmonton, AB, T6G 2E9, Canada
| | - David McGeachy
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Edmonton, AB, T6G 2E9, Canada
| | | | - Sean D Farley
- Alaska Department of Fish and Game, Anchorage, AK, 99518, USA
| | - Joy A Erlenbach
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
- U.S. Fish and Wildlife Service, Kodiak National Wildlife Refuge, Kodiak, AK, 99615, USA
| | - Charles T Robbins
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
- School of the Environment, Washington State University, Pullman, WA, 99164, USA
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3
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Vincent EP, Perry BW, Kelley JL, Robbins CT, Jansen HT. Circadian gene transcription plays a role in cellular metabolism in hibernating brown bears, Ursus arctos. J Comp Physiol B 2023; 193:699-713. [PMID: 37819371 DOI: 10.1007/s00360-023-01513-5] [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: 06/29/2023] [Revised: 08/28/2023] [Accepted: 09/05/2023] [Indexed: 10/13/2023]
Abstract
Hibernation is a highly seasonal physiological adaptation that allows brown bears (Ursus arctos) to survive extended periods of low food availability. Similarly, daily or circadian rhythms conserve energy by coordinating body processes to optimally match the environmental light/dark cycle. Brown bears express circadian rhythms in vivo and their cells do in vitro throughout the year, suggesting that these rhythms may play important roles during periods of negative energy balance. Here, we use time-series analysis of RNA sequencing data and timed measurements of ATP production in adipose-derived fibroblasts from active and hibernation seasons under two temperature conditions to confirm that rhythmicity was present. Culture temperature matching that of hibernation body temperature (34 °C) resulted in a delay of daily peak ATP production in comparison with active season body temperatures (37 °C). The timing of peaks of mitochondrial gene transcription was altered as were the amplitudes of transcripts coding for enzymes of the electron transport chain. Additionally, we observed changes in mean expression and timing of key metabolic genes such as SIRT1 and AMPK which are linked to the circadian system and energy balance. The amplitudes of several circadian gene transcripts were also reduced. These results reveal a link between energy conservation and a functioning circadian system in hibernation.
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Affiliation(s)
- Ellery P Vincent
- School of Biological Sciences, Washington State University, Pullman, WA, 99163, USA
| | - Blair W Perry
- School of Biological Sciences, Washington State University, Pullman, WA, 99163, USA
| | - Joanna L Kelley
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, 95060, USA
| | - Charles T Robbins
- School of Biological Sciences, Washington State University, Pullman, WA, 99163, USA
- School of the Environment, Washington State University, Pullman, WA, 99163, USA
| | - Heiko T Jansen
- School of Biological Sciences, Washington State University, Pullman, WA, 99163, USA.
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99163, USA.
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4
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Perry BW, McDonald AL, Trojahn S, Saxton MW, Vincent EP, Lowry C, Evans Hutzenbiler BD, Cornejo OE, Robbins CT, Jansen HT, Kelley JL. Feeding during hibernation shifts gene expression toward active season levels in brown bears ( Ursus arctos). Physiol Genomics 2023; 55:368-380. [PMID: 37486084 PMCID: PMC10642923 DOI: 10.1152/physiolgenomics.00030.2023] [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: 04/10/2023] [Revised: 06/28/2023] [Accepted: 07/17/2023] [Indexed: 07/25/2023] Open
Abstract
Hibernation in bears involves a suite of metabolical and physiological changes, including the onset of insulin resistance, that are driven in part by sweeping changes in gene expression in multiple tissues. Feeding bears glucose during hibernation partially restores active season physiological phenotypes, including partial resensitization to insulin, but the molecular mechanisms underlying this transition remain poorly understood. Here, we analyze tissue-level gene expression in adipose, liver, and muscle to identify genes that respond to midhibernation glucose feeding and thus potentially drive postfeeding metabolical and physiological shifts. We show that midhibernation feeding stimulates differential expression in all analyzed tissues of hibernating bears and that a subset of these genes responds specifically by shifting expression toward levels typical of the active season. Inferences of upstream regulatory molecules potentially driving these postfeeding responses implicate peroxisome proliferator-activated receptor gamma (PPARG) and other known regulators of insulin sensitivity, providing new insight into high-level regulatory mechanisms involved in shifting metabolic phenotypes between hibernation and active states.
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Affiliation(s)
- Blair W Perry
- School of Biological Sciences, Washington State University, Pullman, Washington, United States
| | - Anna L McDonald
- School of Biological Sciences, Washington State University, Pullman, Washington, United States
| | - Shawn Trojahn
- School of Biological Sciences, Washington State University, Pullman, Washington, United States
| | - Michael W Saxton
- School of Biological Sciences, Washington State University, Pullman, Washington, United States
| | - Ellery P Vincent
- School of Biological Sciences, Washington State University, Pullman, Washington, United States
| | - Courtney Lowry
- School of Biological Sciences, Washington State University, Pullman, Washington, United States
| | | | - Omar E Cornejo
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, United States
| | - Charles T Robbins
- School of the Environment, Washington State University, Pullman, Washington, United States
| | - Heiko T Jansen
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington, United States
| | - Joanna L Kelley
- Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, United States
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5
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Gao W, Yang Y, Shi L. Seasonal dietary shifts alter the gut microbiota of a frugivorous lizard Teratoscincus roborowskii (Squamata, Sphaerodactylidae). Ecol Evol 2023; 13:e10363. [PMID: 37546566 PMCID: PMC10396791 DOI: 10.1002/ece3.10363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 07/03/2023] [Accepted: 07/14/2023] [Indexed: 08/08/2023] Open
Abstract
Seasonal dietary shifts in animals are important strategies for ecological adaptation. An increasing number of studies have shown that seasonal dietary shifts can influence or even determine the composition of gut microbiota. The Turpan wonder gecko, Teratoscincus roborowskii, lives in extreme desert environments and has a flexible dietary shift to fruit-eating in warm seasons. However, the effect of such shifts on the gut microbiota is poorly understood. In this study, 16S rRNA sequencing and LC-MS metabolomics were used to examine changes in the gut microbiota composition and metabolic patterns of T. roborowskii. The results demonstrated that the gut microbes of T. roborowskii underwent significant seasonal changes, and the abundance of phylum level in autumn was significantly higher than spring, but meanwhile, the diversity was lower. At the family level, the abundance and diversity of the gut microbiota were both higher in autumn. Firmicutes, Bacteroidetes, and Proteobacteria were the dominant gut microbes of T. roborowskii. Verrucomicrobia and Proteobacteria exhibited dynamic ebb and flow patterns between spring and autumn. Metabolomic profiling also revealed differences mainly related to the formation of secondary bile acids. The pantothenate and CoA biosynthesis, and lysine degradation pathways identified by KEGG enrichment symbolize the exuberant metabolic capacity of T. roborowskii. Furthermore, strong correlations were detected between metabolite types and bacteria, and this correlation may be an important adaptation of T. roborowskii to cope with dietary shifts and improve energy acquisition. Our study provides a theoretical basis for exploring the adaptive evolution of the special frugivorous behavior of T. roborowskii, which is an important progress in the study of gut microbes in desert lizards.
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Affiliation(s)
- Wei‐Zhen Gao
- College of Life SciencesXinjiang Agricultural UniversityUrumqiChina
| | - Yi Yang
- College of Life SciencesXinjiang Agricultural UniversityUrumqiChina
| | - Lei Shi
- College of Life SciencesXinjiang Agricultural UniversityUrumqiChina
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6
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Penk SR, Sadana P, Archer LC, Pagano AM, Cattet MRL, Lunn NJ, Thiemann GW, Molnár PK. A body composition model with multiple storage compartments for polar bears ( Ursus maritimus). CONSERVATION PHYSIOLOGY 2023; 11:coad043. [PMID: 37346266 PMCID: PMC10281502 DOI: 10.1093/conphys/coad043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 05/08/2023] [Accepted: 06/15/2023] [Indexed: 06/23/2023]
Abstract
Climate warming is rapidly altering Arctic ecosystems. Polar bears (Ursus maritimus) need sea ice as a platform from which to hunt seals, but increased sea-ice loss is lengthening periods when bears are without access to primary hunting habitat. During periods of food scarcity, survival depends on the energy that a bear has stored in body reserves, termed storage energy, making this a key metric in predictive models assessing climate change impacts on polar bears. Here, we developed a body composition model for polar bears that estimates storage energy while accounting for changes in storage tissue composition. We used data of dissected polar bears (n = 31) to link routinely collected field measures of total body mass and straight-line body length to the body composition of individual bears, described in terms of structural mass and two storage compartments, adipose and muscle. We then estimated the masses of metabolizable proteins and lipids within these storage compartments, giving total storage energy. We tested this multi-storage model by using it to predict changes in the lipid stores from an independent dataset of wild polar bears (n = 36) that were recaptured 8-200 days later. Using length and mass measurements, our model successfully predicted direct measurements of lipid changes via isotopic dilutions (root mean squared error of 14.5 kg). Separating storage into two compartments, and allowing the molecular composition of storage to vary, provides new avenues for quantifying energy stores of individuals across their life cycle. The multi-storage body composition model thus provides a basis for further exploring energetic costs of physiological processes that contribute to individual survival and reproductive success. Given bioenergetic models are increasingly used as a tool to predict individual fitness and population dynamics, our approach for estimating individual energy stores could be applicable to a wide range of species.
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Affiliation(s)
- Stephanie R Penk
- Corresponding author: Laboratory of Quantitative Global Change Ecology, Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada. E-mail:
| | - Pranav Sadana
- Laboratory of Quantitative Global Change Ecology, Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, Manitoba R3B 2E9, Canada
| | - Louise C Archer
- Laboratory of Quantitative Global Change Ecology, Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada
| | - Anthony M Pagano
- U.S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508 USA
| | - Marc R L Cattet
- Fish and Wildlife Branch, Department of Environment, Government of Yukon, 10 Burns Road, Whitehorse, Yukon Y1A 4Y9, Canada
| | - Nicholas J Lunn
- Wildlife Research Division, Science and Technology Branch, Environment Canada and Climate Change Canada, 11455 Saskatchewan Dr., Edmonton, Alberta T6G 2E9, Canada
| | - Gregory W Thiemann
- Faculty of Environmental and Urban Change, York University, 4700 Keele St., Toronto, Ontario M3J 1P3, Canada
| | - Péter K Molnár
- Laboratory of Quantitative Global Change Ecology, Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2 Canada
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7
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Perry BW, Armstrong EE, Robbins CT, Jansen HT, Kelley JL. Temporal Analysis of Gene Expression and Isoform Switching in Brown Bears (Ursus arctos). Integr Comp Biol 2022; 62:1802-1811. [PMID: 35709393 DOI: 10.1093/icb/icac093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/01/2022] [Accepted: 06/09/2022] [Indexed: 01/05/2023] Open
Abstract
Hibernation in brown bears is an annual process involving multiple physiologically distinct seasons-hibernation, active, and hyperphagia. While recent studies have characterized broad patterns of differential gene regulation and isoform usage between hibernation and active seasons, patterns of gene and isoform expression during hyperphagia remain relatively poorly understood. The hyperphagia stage occurs between active and hibernation seasons and involves the accumulation of large fat reserves in preparation for hibernation. Here, we use time-series analyses of gene expression and isoform usage to interrogate transcriptomic regulation associated with all three seasons. We identify a large number of genes with significant differential isoform usage (DIU) across seasons and show that these patterns of isoform usage are largely tissue-specific. We also show that DIU and differential gene-level expression responses are generally non-overlapping, with only a small subset of multi-isoform genes showing evidence of both gene-level expression changes and changes in isoform usage across seasons. Additionally, we investigate nuanced regulation of candidate genes involved in the insulin signaling pathway and find evidence of hyperphagia-specific gene expression and isoform regulation that may enhance fat accumulation during hyperphagia. Our findings highlight the value of using temporal analyses of both gene- and isoform-level gene expression when interrogating complex physiological phenotypes and provide new insight into the mechanisms underlying seasonal changes in bear physiology.
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Affiliation(s)
- Blair W Perry
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Ellie E Armstrong
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Charles T Robbins
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA.,School of the Environment, Washington State University, Pullman, WA 99164, USA
| | | | - Joanna L Kelley
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
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8
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Saxton MW, Perry BW, Evans Hutzenbiler BD, Trojahn S, Gee A, Brown AP, Merrihew GE, Park J, Cornejo OE, MacCoss MJ, Robbins CT, Jansen HT, Kelley JL. Serum plays an important role in reprogramming the seasonal transcriptional profile of brown bear adipocytes. iScience 2022; 25:105084. [PMID: 36317158 PMCID: PMC9617460 DOI: 10.1016/j.isci.2022.105084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 06/30/2022] [Accepted: 09/01/2022] [Indexed: 11/19/2022] Open
Abstract
Understanding how metabolic reprogramming happens in cells will aid the progress in the treatment of a variety of metabolic disorders. Brown bears undergo seasonal shifts in insulin sensitivity, including reversible insulin resistance in hibernation. We performed RNA-sequencing on brown bear adipocytes and proteomics on serum to identify changes possibly responsible for reversible insulin resistance. We observed dramatic transcriptional changes, which depended on both the cell and serum season of origin. Despite large changes in adipocyte gene expression, only changes in eight circulating proteins were identified as related to the seasonal shifts in insulin sensitivity, including some that have not previously been associated with glucose homeostasis. The identified serum proteins may be sufficient for shifting hibernation adipocytes to an active-like state. Hibernation in grizzly bears is marked by insulin resistance Bear adipocytes were stimulated with active and hibernating bear blood serum Serum elicited dramatic gene expression responses related to insulin signaling Eight serum proteins were implicated in driving this transcriptional response
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Affiliation(s)
- Michael W. Saxton
- School of Biological Sciences, Washington State University, Pullman, WA 99163, USA
| | - Blair W. Perry
- School of Biological Sciences, Washington State University, Pullman, WA 99163, USA
| | | | - Shawn Trojahn
- School of Biological Sciences, Washington State University, Pullman, WA 99163, USA
| | - Alexia Gee
- School of Biological Sciences, Washington State University, Pullman, WA 99163, USA
| | - Anthony P. Brown
- School of Biological Sciences, Washington State University, Pullman, WA 99163, USA
| | | | - Jea Park
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Omar E. Cornejo
- School of Biological Sciences, Washington State University, Pullman, WA 99163, USA
| | - Michael J. MacCoss
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Charles T. Robbins
- School of Biological Sciences, Washington State University, Pullman, WA 99163, USA
- School of the Environment, Washington State University, Pullman, WA 99163, USA
| | - Heiko T. Jansen
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99163, USA
| | - Joanna L. Kelley
- School of Biological Sciences, Washington State University, Pullman, WA 99163, USA
- Corresponding author
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9
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Hairong D, Xiaoliang Z, Minghai Z, Xiangdong R, Lee TM. Spatial Distribution and Conservation Strategies of Large Carnivores in Human-Dominated Landscape: A Case Study of Asiatic Black Bear in Jilin, China. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.882282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Large carnivores maintain the balance of ecosystems. Understanding distribution and population changes are necessary prerequisites for scientific conservation strategy. The east of Jilin Province is the habitat of endangered Amur tiger (Panthera tigris altaica). The Chinese government has focused the monitoring on protecting the Amur tiger. However, little is known about Asiatic black bear (ABB, Ursus thibetanus) distribution, population dynamics in the wild, and protection awareness of local residents in Jilin Province, China. We conducted a integrative survey in mountain areas of eastern Jilin to determine ABB distribution. We explored the drivers of the distribution of ABB in Jilin using logstic regression, we further predicted the habitat suitability and potential suitable habitat of the ABB. Totally, we surveyed 112 grids (15 km × 15 km) from November 2015 to January 2019. Logistic regression analysis revealed that the main factors driving ABB distribution in Jilin are forest coverage, distance from protected areas, distance from main roads (railways and highways), and distance from water bodies. The results of questionnaire survey showed that the local residents’ understanding of ABB distribution is congruent with our field research. They believed that the number of ABBs has gradually increased in the past ten years. Nevertheless, the local residents have a negative attitude toward the ABBs, which may adversely affect efforts to protect them, possibly leading to more conflicts between humans and bears. Therefore, there is a need to consider ways to change the attitude of the locals through the strengthening of the protection propaganda and advocating management as being critical for the protection of ABBs. Our research provides a scientific basis for future conservation planning. We recommend taking local people’s attitude into consideration during conservation management strategy making to reduce human-bear conflicts and promote the coexistence of humans and bears.
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10
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Nespolo RF, Mejias C, Bozinovic F. Why bears hibernate? Redefining the scaling energetics of hibernation. Proc Biol Sci 2022; 289:20220456. [PMID: 35473385 PMCID: PMC9043729 DOI: 10.1098/rspb.2022.0456] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Hibernation is a natural state of suspended animation that many mammals experience and has been interpreted as an adaptive strategy for saving energy. However, the actual amount of savings that hibernation represents, and particularly its dependence on body mass (the 'scaling') has not been calculated properly. Here, we estimated the scaling of daily energy expenditure of hibernation (DEEH), covering a range of five orders of magnitude in mass. We found that DEEH scales isometrically with mass, which means that a gram of hibernating bat has a similar metabolism to that of a gram of bear, 20 000 times larger. Given that metabolic rate of active animals scales allometrically, the point where these scaling curves intersect with DEEH represents the mass where energy savings by hibernation are zero. For BMR, these zero savings are attained for a relatively small bear (approx. 75 kg). Calculated on a per cell basis, the cellular metabolic power of hibernation was estimated to be 1.3 × 10-12 ± 2.6 × 10-13 W cell-1, which is lower than the minimum metabolism of isolated mammalian cells. This supports the idea of the existence of a minimum metabolism that permits cells to survive under a combination of cold and hypoxia.
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Affiliation(s)
- Roberto F Nespolo
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile.,Millenium Nucleus of Patagonian Limit of Life (LiLi) and Millennium Institute for Integrative Biology (iBio), Santiago, Chile.,Center for Applied Ecology and Sustainability (CAPES), Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carlos Mejias
- Magister en Ecología Aplicada, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.,Millenium Nucleus of Patagonian Limit of Life (LiLi) and Millennium Institute for Integrative Biology (iBio), Santiago, Chile
| | - Francisco Bozinovic
- Center for Applied Ecology and Sustainability (CAPES), Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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11
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Mejías C, Navedo J, Sabat P, Franco LM, Bozinovic F, Nespolo RF. Body Composition and Energy Savings by Hibernation: Lessons from the South American Marsupial Dromiciops gliroides. Physiol Biochem Zool 2022; 95:239-250. [DOI: 10.1086/719932] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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12
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Regehr EV, Runge MC, Von Duyke A, Wilson RR, Polasek L, Rode KD, Hostetter NJ, Converse SJ. Demographic risk assessment for a harvested species threatened by climate change: polar bears in the Chukchi Sea. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02461. [PMID: 34582601 PMCID: PMC9286533 DOI: 10.1002/eap.2461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 02/09/2021] [Accepted: 04/05/2021] [Indexed: 06/13/2023]
Abstract
Climate change threatens global biodiversity. Many species vulnerable to climate change are important to humans for nutritional, cultural, and economic reasons. Polar bears Ursus maritimus are threatened by sea-ice loss and represent a subsistence resource for Indigenous people. We applied a novel population modeling-management framework that is based on species life history and accounts for habitat loss to evaluate subsistence harvest for the Chukchi Sea (CS) polar bear subpopulation. Harvest strategies followed a state-dependent approach under which new data were used to update the harvest on a predetermined management interval. We found that a harvest strategy with a starting total harvest rate of 2.7% (˜85 bears/yr at current abundance), a 2:1 male-to-female ratio, and a 10-yr management interval would likely maintain subpopulation abundance above maximum net productivity level for the next 35 yr (approximately three polar bear generations), our primary criterion for sustainability. Plausible bounds on starting total harvest rate were 1.7-3.9%, where the range reflects uncertainty due to sampling variation, environmental variation, model selection, and differing levels of risk tolerance. The risk of undesired demographic outcomes (e.g., overharvest) was positively related to harvest rate, management interval, and projected declines in environmental carrying capacity; and negatively related to precision in population data. Results reflect several lines of evidence that the CS subpopulation has been productive in recent years, although it is uncertain how long this will last as sea-ice loss continues. Our methods provide a template for balancing trade-offs among protection, use, research investment, and other factors. Demographic risk assessment and state-dependent management will become increasingly important for harvested species, like polar bears, that exhibit spatiotemporal variation in their response to climate change.
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Affiliation(s)
- Eric V. Regehr
- Polar Science CenterApplied Physics LaboratoryUniversity of WashingtonSeattleWashington98105USA
| | - Michael C. Runge
- Patuxent Wildlife Research CenterU.S. Geological SurveyLaurelMaryland20708USA
| | - Andrew Von Duyke
- Department of Wildlife ManagementNorth Slope BoroughUtqiaġvikAlaska99723USA
| | - Ryan R. Wilson
- Marine Mammals ManagementU.S. Fish and Wildlife ServiceAnchorageAlaska99503USA
| | - Lori Polasek
- Division of Wildlife ConservationAlaska Department of Fish and GameJuneauAlaska99802USA
| | - Karyn D. Rode
- Alaska Science CenterU.S. Geological SurveyAnchorageAlaska99508USA
| | - Nathan J. Hostetter
- Washington Cooperative Fish and Wildlife Research UnitSchool of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashington98105USA
| | - Sarah J. Converse
- Washington Cooperative Fish and Wildlife Research UnitSchool of Environmental and Forest Sciences (SEFS) & School of Aquatic and Fishery Sciences (SAFS)U.S. Geological SurveyUniversity of WashingtonSeattleWashington98105USA
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13
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Maher CJ, Gibson A, Dixon LM, Bacon H. Developing a Reliable Welfare Assessment Tool for Captive Hibernatory Bear Species. Animals (Basel) 2021; 11:3090. [PMID: 34827822 PMCID: PMC8614556 DOI: 10.3390/ani11113090] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/22/2021] [Accepted: 10/27/2021] [Indexed: 11/16/2022] Open
Abstract
Animal welfare assessments are essential for the identification of welfare hazards and benchmarking of welfare improvements, though welfare assessments for zoo species are lacking. Bears are commonly housed in zoos but currently no composite welfare assessment tool exists for captive bears. This study describes the development of such a tool for use across hibernating bear species. A draft tool was developed using indicators derived from the literature and a modified Delphi analysis with an international group of bear keepers. A total of 18 bear keepers from 12 zoos were recruited to trial the tool on 24 brown bears and American black bears. The participating keepers assessed their bears three times across a period of nine days. Intraclass correlation coefficients analysis was used to analyse inter-, intra-rater and item reliability. The inter- and intra-rater reliability showed good to excellent levels of agreement (>0.7, p < 0.05). Item reliability was also assessed and showed good to excellent levels of agreement (>0.75, p < 0.05). The resulting bear welfare assessment is an important step in identifying and understanding challenges to bear welfare in captivity.
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Affiliation(s)
- Chloe J. Maher
- The Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Angela Gibson
- The Oakland Zoo, 9777 Golf Links Rd, Oakland, CA 94605, USA;
- The Bear Care Group, P.O. Box 7174, Alexandria, VA 22307, USA;
| | - Laura M. Dixon
- Animal Behaviour and Welfare Department, SRUC, Roslin Institute Building, Easter Bush, Edinburgh EH25 9RG, UK;
| | - Heather Bacon
- The Bear Care Group, P.O. Box 7174, Alexandria, VA 22307, USA;
- The School of Veterinary Medicine, The University of Central Lancashire, Preston PR1 2HE, UK
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14
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Fatty acid profiles of feeding and fasting bears: estimating calibration coefficients, the timeframe of diet estimates, and selective mobilization during hibernation. J Comp Physiol B 2021; 192:379-395. [PMID: 34687352 DOI: 10.1007/s00360-021-01414-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 09/20/2021] [Accepted: 10/03/2021] [Indexed: 10/20/2022]
Abstract
Accurate information on diet composition is central to understanding and conserving carnivore populations. Quantitative fatty acid signature analysis (QFASA) has emerged as a powerful tool for estimating the diets of predators, but ambiguities remain about the timeframe of QFASA estimates and the need to account for species-specific patterns of metabolism. We conducted a series of feeding experiments with four juvenile male brown bears (Ursus arctos) to (1) track the timing of changes in adipose tissue composition and QFASA diet estimates in response to a change in diet and (2) quantify the relationship between consumer and diet FA composition (i.e., determine "calibration coefficients"). Bears were fed three compositionally distinct diets for 90-120 days each. Two marine-based diets were intended to approximate the lipid content and composition of the wild diet of polar bears (U. maritimus). Bear adipose tissue composition changed quickly in the direction of the diet and showed evidence of stabilization after 60 days. During hibernation, FA profiles were initially stable but diet estimates after 10 weeks were sensitive to calibration coefficients. Calibration coefficients derived from the marine-based diets were broadly similar to each other and to published values from marine-fed mink (Mustela vison), which have been used as a model for free-ranging polar bears. For growing bears on a high-fat diet, the temporal window for QFASA estimates was 30-90 days. Although our results reinforce the importance of accurate calibration, the similarities across taxa and diets suggest it may be feasible to develop a generalized QFASA approach for mammalian carnivores.
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15
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Ma Y, Wang M, Wei F, Nie Y. Geographic distributions shape the functional traits in a large mammalian family. Ecol Evol 2021; 11:13175-13185. [PMID: 34646461 PMCID: PMC8495830 DOI: 10.1002/ece3.8039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 01/27/2023] Open
Abstract
Traits of organisms are shaped by their living environments and also determined in part by their phylogenetic relationships. For example, phylogenetic relationships often affect the geographic distributions of animals and cause variation in their living environments, which usually play key roles in the life history and determine the functional traits of species. As an ancient family of mammals, bears widely distribute and have evolved some specific strategies for survival and reproduction during their long-term evolutionary histories. Many studies on the ecology of bears have been conducted in recent decades, but few have focused on the relationships between their geographic distributions and ecological adaptations. Here, using bears as a model system, we collected and reanalyzed data from the available literatures to explore how geographic distributions and phylogenetic relationships shape the functional traits of animals. We found a positive relationship between phylogenetic relatedness and geographic distributions, with bears distributed in adjacent areas applying more similar strategies to survive and reproduce: (a) Bears living at high latitudes consumed a higher proportion of vertebrates, which may provide more fat for adaptation to low temperatures, and (b) their reproduction rhythms follow fluctuations in seasonal forage availability and quality, in which bears reach mating status from March to May and give birth in approximately November or later.
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Affiliation(s)
- Yingjie Ma
- Key Laboratory of Animal Ecology and Conservation BiologyInstitute of ZoologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Meng Wang
- Key Laboratory of Animal Ecology and Conservation BiologyInstitute of ZoologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Fuwen Wei
- Key Laboratory of Animal Ecology and Conservation BiologyInstitute of ZoologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
- Center for Excellence in Animal Evolution and GeneticsChinese Academy of SciencesKunmingChina
| | - Yonggang Nie
- Key Laboratory of Animal Ecology and Conservation BiologyInstitute of ZoologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
- Center for Excellence in Animal Evolution and GeneticsChinese Academy of SciencesKunmingChina
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16
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Jansen HT, Evans Hutzenbiler B, Hapner HR, McPhee ML, Carnahan AM, Kelley JL, Saxton MW, Robbins CT. Can offsetting the energetic cost of hibernation restore an active season phenotype in grizzly bears (Ursus arctos horribilis)? J Exp Biol 2021; 224:269178. [PMID: 34137891 DOI: 10.1242/jeb.242560] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/12/2021] [Indexed: 01/14/2023]
Abstract
Hibernation is characterized by depression of many physiological processes. To determine if this state is reversible in a non-food caching species, we fed hibernating grizzly bears (Ursus arctos horribilis) dextrose for 10 days to replace 53% or 100% of the estimated minimum daily energetic cost of hibernation. Feeding caused serum concentrations of glycerol and ketones (β-hydroxybutyrate) to return to active season levels irrespective of the amount of glucose fed. By contrast, free fatty acids (FFAs) and indices of metabolic rate, such as general activity, heart rate, strength of heart rate circadian rhythm, and insulin sensitivity were restored to approximately 50% of active season levels. Body temperature was unaffected by feeding. To determine the contribution of adipose to the metabolic effects observed after glucose feeding, we cultured bear adipocytes collected at the beginning and end of the feeding and performed metabolic flux analysis. We found a ∼33% increase in energy metabolism after feeding. Moreover, basal metabolism before feeding was 40% lower in hibernation cells compared with fed cells or active cells cultured at 37°C, thereby confirming the temperature independence of metabolic rate. The partial depression of circulating FFAs with feeding likely explains the incomplete restoration of insulin sensitivity and other metabolic parameters in hibernating bears. Further depression of metabolic function is likely to be an active process. Together, the results provide a highly controlled model to examine the relationship between nutrient availability and metabolism on the hibernation phenotype in bears.
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Affiliation(s)
- Heiko T Jansen
- Dept. Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Brandon Evans Hutzenbiler
- Dept. Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Hannah R Hapner
- School of Biological Sciences, College of Arts and Sciences, Washington State University, Pullman, WA 99164, USA
| | - Madeline L McPhee
- Dept. Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Anthony M Carnahan
- School of Biological Sciences, College of Arts and Sciences, Washington State University, Pullman, WA 99164, USA
| | - Joanna L Kelley
- School of Biological Sciences, College of Arts and Sciences, Washington State University, Pullman, WA 99164, USA
| | - Michael W Saxton
- School of Biological Sciences, College of Arts and Sciences, Washington State University, Pullman, WA 99164, USA
| | - Charles T Robbins
- School of Biological Sciences, College of Arts and Sciences, Washington State University, Pullman, WA 99164, USA.,School of the Environment, College of Agricultural, Human and Natural Resource Sciences, Washington State University, Pullman, WA 99164, USA
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17
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Rode KD, Regehr EV, Bromaghin JF, Wilson RR, St Martin M, Crawford JA, Quakenbush LT. Seal body condition and atmospheric circulation patterns influence polar bear body condition, recruitment, and feeding ecology in the Chukchi Sea. GLOBAL CHANGE BIOLOGY 2021; 27:2684-2701. [PMID: 33644944 DOI: 10.1111/gcb.15572] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/10/2021] [Indexed: 06/12/2023]
Abstract
Polar bears (Ursus maritimus) are experiencing loss of sea ice habitats used to access their marine mammal prey. Simultaneously, ocean warming is changing ecosystems that support marine mammal populations. The interactive effects of sea ice and prey are not well understood yet may explain spatial-temporal variation in the response of polar bears to sea ice loss. Here, we examined the potential combined effects of sea ice, seal body condition, and atmospheric circulation patterns on the body condition, recruitment, diet, and feeding probability of 469 polar bears captured in the Chukchi Sea, 2008-2017. The body condition of ringed seals (Pusa hispida), the primary prey of females and subadults, was related to dietary proportions of ringed seal, feeding probability, and the body condition of females and cubs. In contrast, adult males consumed more bearded seals (Erignathus barbatus) and exhibited better condition when bearded seal body condition was higher. The litter size, number of yearlings per adult female, and the condition of dependent young were higher following winters characterized by low Arctic Oscillation conditions, consistent with a growing number of studies. Body condition, recruitment, and feeding probability were either not associated or negatively associated with sea ice conditions, suggesting that, unlike some subpopulations, Chukchi Sea bears are not currently limited by sea ice availability. However, spring sea ice cover declined 2% per year during our study reaching levels not previously observed in the satellite record and resulting in the loss of polar bear hunting and seal pupping habitat. Our study suggests that the status of ice seal populations is likely an important factor that can either compound or mitigate the response of polar bears to sea ice loss over the short term. In the long term, neither polar bears nor their prey are likely robust to limitless loss of their sea ice habitat.
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Affiliation(s)
- Karyn D Rode
- Alaska Science Center, U.S. Geological Survey, Anchorage, AK, USA
| | - Eric V Regehr
- Polar Science Center, University of Washington, Seattle, WA, USA
| | | | - Ryan R Wilson
- Marine Mammals Management, U.S. Fish and Wildlife Service, Anchorage, AK, USA
| | - Michelle St Martin
- Marine Mammals Management, U.S. Fish and Wildlife Service, Anchorage, AK, USA
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18
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Fowler NL, Spady TJ, Wang G, Leopold BD, Belant JL. Denning, metabolic suppression, and the realisation of ecological opportunities in Ursidae. Mamm Rev 2021. [DOI: 10.1111/mam.12246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Nicholas L. Fowler
- Global Wildlife Conservation Center State University of New York College of Environmental Science and Forestry 1 Forestry Drive Syracuse NY13210USA
| | - Thomas J. Spady
- Department of Biological Sciences California State University San Marcos San Marcos CA92096USA
| | - Guiming Wang
- Department of Wildlife, Fisheries, and Aquaculture Mississippi State UniversityMississippi State Box 9690MS39762USA
| | - Bruce D. Leopold
- Department of Wildlife, Fisheries, and Aquaculture Mississippi State UniversityMississippi State Box 9690MS39762USA
| | - Jerrold L. Belant
- Global Wildlife Conservation Center State University of New York College of Environmental Science and Forestry 1 Forestry Drive Syracuse NY13210USA
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19
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Pagano AM, Williams TM. Physiological consequences of Arctic sea ice loss on large marine carnivores: unique responses by polar bears and narwhals. J Exp Biol 2021; 224:224/Suppl_1/jeb228049. [PMID: 33627459 DOI: 10.1242/jeb.228049] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Rapid environmental changes in the Arctic are threatening the survival of marine species that rely on the predictable presence of the sea ice. Two Arctic marine mammal specialists, the polar bear (Ursus maritimus) and narwhal (Monodon monoceros), appear especially vulnerable to the speed and capriciousness of sea ice deterioration as a consequence of their unique hunting behaviors and diet, as well as their physiological adaptations for slow-aerobic exercise. These intrinsic characteristics limit the ability of these species to respond to extrinsic threats associated with environmental change and increased industrial activity in a warming Arctic. In assessing how sea ice loss may differentially affect polar bears that hunt on the ice surface and narwhals that hunt at extreme depths below, we found that major ice loss translated into elevated locomotor costs that range from 3- to 4-fold greater than expected for both species. For polar bears this instigates an energy imbalance from the combined effects of reduced caloric intake and increased energy expenditure. For narwhals, high locomotor costs during diving increase the risk of ice entrapment due to the unreliability of breathing holes. These species-specific physiological constraints and extreme reliance on the polar sea ice conspire to make these two marine mammal specialists sentinels of climate change within the Arctic marine ecosystem that may foreshadow rapid changes to the marine ecosystem.
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Affiliation(s)
- Anthony M Pagano
- Institute for Conservation Research, San Diego Zoo Global, San Diego, CA 92027, USA
| | - Terrie M Williams
- University of California, Santa Cruz, Department of Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
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20
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Owen MA, Pagano AM, Wisdom SS, Kirschhoffer B, Bowles AE, O'Neill C. Estimating the Audibility of Industrial Noise to Denning Polar Bears. J Wildl Manage 2021. [DOI: 10.1002/jwmg.21977] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Megan A. Owen
- Institute for Conservation Research, San Diego Zoo Global San Diego CA 92027 USA
| | - Anthony M. Pagano
- Institute for Conservation Research, San Diego Zoo Global San Diego CA 92027 USA
| | | | | | - Ann E. Bowles
- Hubbs‐SeaWorld Research Institute San Diego CA 92109 USA
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21
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Jagielski PM, Dey CJ, Gilchrist HG, Richardson ES, Semeniuk CA. Polar bear foraging on common eider eggs: estimating the energetic consequences of a climate-mediated behavioural shift. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2020.11.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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22
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Johnson AC, Reimer JR, Lunn NJ, Stirling I, McGeachy D, Derocher AE. Influence of sea ice dynamics on population energetics of Western Hudson Bay polar bears. CONSERVATION PHYSIOLOGY 2020; 8:coaa132. [PMID: 33408870 PMCID: PMC7772618 DOI: 10.1093/conphys/coaa132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/23/2020] [Accepted: 12/07/2020] [Indexed: 05/27/2023]
Abstract
The Arctic marine ecosystem has experienced extensive changes in sea ice dynamics, with significant effects on ice-dependent species such as polar bears (Ursus maritimus). We used annual estimates of the numbers of bears onshore in the core summering area, age/sex structure and body condition data to estimate population energy density and storage energy in Western Hudson Bay polar bears from 1985 to 2018. We examined intra-population variation in energetic patterns, temporal energetic trends and the relationship between population energetics and sea ice conditions. Energy metrics for most demographic classes declined over time in relation to earlier sea ice breakup, most significantly for solitary adult females and subadult males, suggesting their greater vulnerability to nutritional stress than other age/sex classes. Temporal declines in population energy metrics were related to earlier breakup and longer lagged open-water periods, suggesting multi-year effects of sea ice decline. The length of the open-water period ranged from 102 to 166 days and increased significantly by 9.9 days/decade over the study period. Total population energy density and storage energy were significantly lower when sea ice breakup occurred earlier and the lagged open-water period was longer. At the earliest breakup and a lagged open-water period of 180 days, population energy density was predicted to be 33% lower than our minimum estimated energy density and population storage energy was predicted to be 40% lower than the minimum estimated storage energy. Consequently, over the study, the total population energy density declined by 53% (mean: 3668 ± 386 MJ kg-1/decade) and total population storage energy declined by 56% (mean: 435900 ± 46770 MJ/decade). This study provides insights into ecological mechanisms linking population responses to sea ice decline and highlights the significance of maintaining long-term research programs.
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Affiliation(s)
- Amy C Johnson
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Jody R Reimer
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Mathematics, University of Utah, Salt Lake City, UT 84112, USA
| | - Nicholas J Lunn
- Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Ian Stirling
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - David McGeachy
- Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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23
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Rode KD, Atwood TC, Thiemann GW, St. Martin M, Wilson RR, Durner GM, Regehr EV, Talbot SL, Sage GK, Pagano AM, Simac KS. Identifying reliable indicators of fitness in polar bears. PLoS One 2020; 15:e0237444. [PMID: 32813753 PMCID: PMC7437918 DOI: 10.1371/journal.pone.0237444] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 07/27/2020] [Indexed: 01/08/2023] Open
Abstract
Animal structural body size and condition are often measured to evaluate individual health, identify responses to environmental change and food availability, and relate food availability to effects on reproduction and survival. A variety of condition metrics have been developed but relationships between these metrics and vital rates are rarely validated. Identifying an optimal approach to estimate the body condition of polar bears is needed to improve monitoring of their response to decline in sea ice habitat. Therefore, we examined relationships between several commonly used condition indices (CI), body mass, and size with female reproductive success and cub survival among polar bears (Ursus maritimus) measured in two subpopulations over three decades. To improve measurement and application of morphometrics and CIs, we also examined whether CIs are independent of age and structural size–an important assumption for monitoring temporal trends—and factors affecting measurement precision and accuracy. Maternal CIs and mass measured the fall prior to denning were related to cub production. Similarly, maternal CIs, mass, and length were related to the mass of cubs or yearlings that accompanied her. However, maternal body mass, but not CIs, measured in the spring was related to cub production and only maternal mass and length were related to the probability of cub survival. These results suggest that CIs may not be better indicators of fitness than body mass in part because CIs remove variation associated with body size that is important in affecting fitness. Further, CIs exhibited variable relationships with age for growing bears and were lower for longer bears despite body length being related to cub survival and female reproductive success. These results are consistent with findings from other species indicating that body mass is a useful metric to link environmental conditions and population dynamics.
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Affiliation(s)
- Karyn D. Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, United States of America
- * E-mail:
| | - Todd C. Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, United States of America
| | | | - Michelle St. Martin
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, Alaska, United States of America
| | - Ryan R. Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, Alaska, United States of America
| | - George M. Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, United States of America
| | - Eric V. Regehr
- University of Washington, Polar Science Center, Seattle, Washington, United States of America
| | - Sandra L. Talbot
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, United States of America
| | - George K. Sage
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, United States of America
| | - Anthony M. Pagano
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, United States of America
| | - Kristin S. Simac
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, United States of America
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24
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Boonstra R, Bodner K, Bosson C, Delehanty B, Richardson ES, Lunn NJ, Derocher AE, Molnár PK. The stress of Arctic warming on polar bears. GLOBAL CHANGE BIOLOGY 2020; 26:4197-4214. [PMID: 32364624 DOI: 10.1111/gcb.15142] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 04/15/2020] [Accepted: 04/23/2020] [Indexed: 05/25/2023]
Abstract
Arctic ecosystems are changing rapidly in response to climate warming. While Arctic mammals are highly evolved to these extreme environments, particularly with respect to their stress axis, some species may have limited capacity to adapt to this change. We examined changes in key components of the stress axis (cortisol and its carrier protein-corticosteroid binding globulin [CBG]) in polar bears (Ursus maritimus) from western Hudson Bay (N = 300) over a 33 year period (1983-2015) during which time the ice-free period was increasing. Changing sea ice phenology limits spring hunting opportunities and extends the period of onshore fasting. We assessed the response of polar bears to a standardized stressor (helicopter pursuit, darting, and immobilization) during their onshore fasting period (late summer-autumn) and quantified the serum levels of the maximum corticosteroid binding capacity (MCBC) of CBG, the serum protein that binds cortisol strongly, and free cortisol (FC). We quantified bear condition (age, sex, female with cubs or not, fat condition), sea ice (breakup in spring-summer, 1 year lagged freeze-up in autumn), and duration of fasting until sample collection as well as cumulative impacts of the latter environmental traits from the previous year. Data were separated into "good" years (1983-1990) when conditions were thought to be optimal and "poor" years (1991-2015) when sea ice conditions deteriorated and fasting on land was extended. MCBC explained 39.4% of the variation in the good years, but only 28.1% in the poor ones, using both biological and environmental variables. MCBC levels decreased with age. Changes in FC were complex, but more poorly explained. Counterintuitively, MCBC levels increased with increased time onshore, 1 year lag effects, and in poor ice years. We conclude that MCBC is a biomarker of stress in polar bears and that the changes we document are a consequence of climate warming.
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Affiliation(s)
- Rudy Boonstra
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
| | - Korryn Bodner
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Curtis Bosson
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
| | - Brendan Delehanty
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
| | - Evan S Richardson
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Winnipeg, MB, Canada
| | - Nicholas J Lunn
- Environment and Climate Change Canada, Biological Sciences Building, University of Alberta, Edmonton, AB, Canada
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Péter K Molnár
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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25
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Regulation of metabolism during hibernation in brown bears (Ursus arctos): Involvement of cortisol, PGC-1α and AMPK in adipose tissue and skeletal muscle. Comp Biochem Physiol A Mol Integr Physiol 2019; 240:110591. [PMID: 31669707 DOI: 10.1016/j.cbpa.2019.110591] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 10/15/2019] [Accepted: 10/18/2019] [Indexed: 12/19/2022]
Abstract
The purpose of this study was to investigate changes in expression of known cellular regulators of metabolism during hyperphagia (Sept) and hibernation (Jan) in skeletal muscle and adipose tissue of brown bears and determine whether signaling molecules and transcription factors known to respond to changes in cellular energy state are involved in the regulation of these metabolic adaptations. During hibernation, serum levels of cortisol, glycerol, and triglycerides were elevated, and protein expression and activation of AMPK in skeletal muscle and adipose tissue were reduced. mRNA expression of the co-activator PGC-1α was reduced in all tissues in hibernation whereas mRNA expression of the transcription factor PPAR-α was reduced in the vastus lateralis muscle and adipose tissue only. During hibernation, gene expression of ATGL and CD36 was not altered; however, HSL gene expression was reduced in adipose tissue. During hibernation gene expression of the lipogenic enzyme DGAT in all tissues and the expression of the FA oxidative enzyme LCAD in the vastus lateralis muscle were reduced. Gene and protein expression of the glucose transporter GLUT4 was decreased in adipose tissue in hibernation. Our data suggest that high cortisol levels are a key adaptation during hibernation and link cortisol to a reduced activation of the AMPK/PGC-1α/PPAR-α axis in the regulation of metabolism in skeletal muscle and adipose tissue. Moreover, our results indicate that during this phase of hibernation at a time when metabolic rate is significantly reduced metabolic adaptations in peripheral tissues seek to limit the detrimental effects of unduly large energy dissipation.
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26
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Furusaka S, Tochigi K, Yamazaki K, Naganuma T, Inagaki A, Koike S. Estimating the seasonal energy balance in Asian black bears and associated factors. Ecosphere 2019. [DOI: 10.1002/ecs2.2891] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Shino Furusaka
- Tokyo University of Agriculture and Technology 3‐5‐8 Saiwai‐Cho Fuchu Tokyo 183‐8509 Japan
| | - Kahoko Tochigi
- Tokyo University of Agriculture and Technology 3‐5‐8 Saiwai‐Cho Fuchu Tokyo 183‐8509 Japan
| | - Koji Yamazaki
- Tokyo University of Agriculture 1‐1‐1 Sakuragaoka Setagaya Tokyo 156‐8502 Japan
| | - Tomoko Naganuma
- Tokyo University of Agriculture and Technology 3‐5‐8 Saiwai‐Cho Fuchu Tokyo 183‐8509 Japan
| | - Akino Inagaki
- Tokyo University of Agriculture and Technology 3‐5‐8 Saiwai‐Cho Fuchu Tokyo 183‐8509 Japan
| | - Shinsuke Koike
- Tokyo University of Agriculture and Technology 3‐5‐8 Saiwai‐Cho Fuchu Tokyo 183‐8509 Japan
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Reimer JR, Mangel M, Derocher AE, Lewis MA. Modeling optimal responses and fitness consequences in a changing Arctic. GLOBAL CHANGE BIOLOGY 2019; 25:3450-3461. [PMID: 31077520 DOI: 10.1111/gcb.14681] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 04/29/2019] [Indexed: 06/09/2023]
Abstract
Animals must balance a series of costs and benefits while trying to maximize their fitness. For example, an individual may need to choose how much energy to allocate to reproduction versus growth, or how much time to spend on vigilance versus foraging. Their decisions depend on complex interactions between environmental conditions, behavioral plasticity, reproductive biology, and energetic demands. As animals respond to novel environmental conditions caused by climate change, the optimal decisions may shift. Stochastic dynamic programming provides a flexible modeling framework with which to explore these trade-offs, but this method has not yet been used to study possible changes in optimal trade-offs caused by climate change. We created a stochastic dynamic programming model capturing trade-off decisions required by an individual adult female polar bear (Ursus maritimus) as well as the fitness consequences of her decisions. We predicted optimal foraging decisions throughout her lifetime as well as the energetic thresholds below which it is optimal for her to abandon a reproductive attempt. To explore the effects of climate change, we shortened the spring feeding period by up to 3 weeks, which led to predictions of riskier foraging behavior and higher reproductive thresholds. The resulting changes in fitness may be interpreted as a best-case scenario, where bears adapt instantaneously and optimally to new environmental conditions. If the spring feeding period was reduced by 1 week, her expected fitness declined by 15%, and if reduced by 3 weeks, expected fitness declined by 68%. This demonstrates an effective way to explore a species' optimal response to a changing landscape of costs and benefits and highlights the fact that small annual effects can result in large cumulative changes in expected lifetime fitness.
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Affiliation(s)
- Jody R Reimer
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, Canada
| | - Marc Mangel
- Institute of Marine Sciences and Department of Applied Mathematics and Statistics, University of California, Santa Cruz, Santa Cruz, California
- Department of Biology, University of Bergen, Bergen, Norway
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Mark A Lewis
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, Canada
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Jansen HT, Trojahn S, Saxton MW, Quackenbush CR, Evans Hutzenbiler BD, Nelson OL, Cornejo OE, Robbins CT, Kelley JL. Hibernation induces widespread transcriptional remodeling in metabolic tissues of the grizzly bear. Commun Biol 2019; 2:336. [PMID: 31531397 PMCID: PMC6744400 DOI: 10.1038/s42003-019-0574-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 08/12/2019] [Indexed: 12/20/2022] Open
Abstract
Revealing the mechanisms underlying the reversible physiology of hibernation could have applications to both human and animal health as hibernation is often associated with disease-like states. The present study uses RNA-sequencing to reveal the tissue and seasonal transcriptional changes occurring in grizzly bears (Ursus arctos horribilis). Comparing hibernation to other seasons, bear adipose has a greater number of differentially expressed genes than liver and skeletal muscle. During hyperphagia, adipose has more than 900 differentially expressed genes compared to active season. Hibernation is characterized by reduced expression of genes associated with insulin signaling, muscle protein degradation, and urea production, and increased expression within muscle protein anabolic pathways. Across all three tissues we find a subset of shared differentially expressed genes, some of which are uncharacterized, that together may reflect a common regulatory mechanism. The identified gene families could be useful for developing novel therapeutics to treat human and animal diseases.
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Affiliation(s)
- Heiko T. Jansen
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164 USA
| | - Shawn Trojahn
- School of Biological Sciences, Washington State University, Pullman, WA 99164 USA
| | - Michael W. Saxton
- School of Biological Sciences, Washington State University, Pullman, WA 99164 USA
| | - Corey R. Quackenbush
- School of Biological Sciences, Washington State University, Pullman, WA 99164 USA
| | - Brandon D. Evans Hutzenbiler
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164 USA
- School of the Environment, Washington State University, Pullman, WA 99164 USA
| | - O. Lynne Nelson
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164 USA
| | - Omar E. Cornejo
- School of Biological Sciences, Washington State University, Pullman, WA 99164 USA
| | - Charles T. Robbins
- School of Biological Sciences, Washington State University, Pullman, WA 99164 USA
- School of the Environment, Washington State University, Pullman, WA 99164 USA
| | - Joanna L. Kelley
- School of Biological Sciences, Washington State University, Pullman, WA 99164 USA
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29
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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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Pagano AM, Durner GM, Rode KD, Atwood TC, Atkinson SN, Peacock E, Costa DP, Owen MA, Williams TM. High-energy, high-fat lifestyle challenges an Arctic apex predator, the polar bear. Science 2018; 359:568-572. [DOI: 10.1126/science.aan8677] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 12/19/2017] [Indexed: 11/02/2022]
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31
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Ecological significance of mitochondrial toxicants. Toxicology 2017; 391:64-74. [DOI: 10.1016/j.tox.2017.07.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/19/2017] [Accepted: 07/24/2017] [Indexed: 12/15/2022]
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Blix AS. Adaptations to polar life in mammals and birds. ACTA ACUST UNITED AC 2017; 219:1093-105. [PMID: 27103673 DOI: 10.1242/jeb.120477] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 01/25/2016] [Indexed: 12/22/2022]
Abstract
This Review presents a broad overview of adaptations of truly Arctic and Antarctic mammals and birds to the challenges of polar life. The polar environment may be characterized by grisly cold, scarcity of food and darkness in winter, and lush conditions and continuous light in summer. Resident animals cope with these changes by behavioural, physical and physiological means. These include responses aimed at reducing exposure, such as 'balling up', huddling and shelter building; seasonal changes in insulation by fur, plumage and blubber; and circulatory adjustments aimed at preservation of core temperature, to which end the periphery and extremities are cooled to increase insulation. Newborn altricial animals have profound tolerance to hypothermia, but depend on parental care for warmth, whereas precocial mammals are well insulated and respond to cold with non-shivering thermogenesis in brown adipose tissue, and precocial birds shiver to produce heat. Most polar animals prepare themselves for shortness of food during winter by the deposition of large amounts of fat in times of plenty during autumn. These deposits are governed by a sliding set-point for body fatness throughout winter so that they last until the sun reappears in spring. Polar animals are, like most others, primarily active during the light part of the day, but when the sun never sets in summer and darkness prevails during winter, high-latitude animals become intermittently active around the clock, allowing opportunistic feeding at all times. The importance of understanding the needs of the individuals of a species to understand the responses of populations in times of climate change is emphasized.
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Affiliation(s)
- Arnoldus Schytte Blix
- Department of Arctic Biology, University of Tromsø, Tromsø 9037, Norway St Catharine's College, Cambridge CB2 1RL, UK
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Wilder JM, Vongraven D, Atwood T, Hansen B, Jessen A, Kochnev A, York G, Vallender R, Hedman D, Gibbons M. Polar bear attacks on humans: Implications of a changing climate. WILDLIFE SOC B 2017. [DOI: 10.1002/wsb.783] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- James M. Wilder
- U.S. Fish and Wildlife Service, Marine Mammals Management; 1011 E. Tudor Road Anchorage AK 99503 USA
| | - Dag Vongraven
- Norwegian Polar Institute, Fram Center; N-9296 Tromsø Norway
| | - Todd Atwood
- U.S. Geological Survey, Alaska Science Center; 4210 University Road Anchorage AK 99508 USA
| | - Bob Hansen
- Government of Nunavut; Igloolik NU X0A 0L0 Canada
| | - Amalie Jessen
- Government of Greenland, Department of Wildlife and Agriculture; P.O. Box 269 3900 Nuuk Greenland
| | - Anatoly Kochnev
- Russian Academy of Sciences, Far East Branch, Institute of Biological Problems of the North, Mammals Ecology Lab; 18 Portovaya Street 685000 Magadan Russia
| | - Geoff York
- Polar Bears International; PO Box 3008 Bozeman MT 59772 USA
| | - Rachel Vallender
- Canadian Wildlife Service, Environment Canada; 351 St. Joseph Boulevard Gatineau QC K1A 0H3 Canada
| | - Daryll Hedman
- Manitoba Conservation and Water Stewardship; Northeast Region, Box 28 Thompson MB R8N 1N2 Canada
| | - Melissa Gibbons
- Wapusk National Park and Manitoba North National Historic Sites, Parks Canada; Box 127 Churchill MB R0B 0E0 Canada
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Implications of Rapid Environmental Change for Polar Bear Behavior and Sociality. MARINE MAMMAL WELFARE 2017. [DOI: 10.1007/978-3-319-46994-2_24] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Gehring JL, Rigano KS, Evans Hutzenbiler BD, Nelson OL, Robbins CT, Jansen HT. A protocol for the isolation and cultivation of brown bear (Ursus arctos) adipocytes. Cytotechnology 2016; 68:2177-91. [PMID: 26856588 PMCID: PMC5023558 DOI: 10.1007/s10616-015-9937-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 12/09/2015] [Indexed: 12/18/2022] Open
Abstract
Brown bears (Ursus arctos) exhibit hyperphagia each fall and can become obese in preparation for hibernation. They do this without displaying the physiological problems typically seen in obese humans, such as Type 2 diabetes and heart disease. The study of brown bear hibernation biology could therefore aid in the development of novel methods for combating metabolic diseases. To this end, we isolated mesenchymal stem cells from subcutaneous fat biopsies, and culture methods were developed to differentiate these into the adipogenic lineage. Biopsies were taken from 8 captive male (N = 6) and female (N = 2) brown bears, ages 2-12 years. Plastic adherent, fibroblast-like cells were proliferated and subsequently cryopreserved or differentiated. Differentiation conditions were optimized with respect to fetal bovine serum content and time spent in differentiation medium. Cultures were characterized through immunostaining, RT-qPCR, and Oil red O staining to quantify lipid accumulation. Adiponectin, leptin, and glycerol medium concentrations were also determined over the course of differentiation. The culturing protocol succeeded in generating hormone-sensitive lipase-expressing, lipid-producing white-type adipocytes (UCP1 negative). Serum concentration and time of exposure to differentiation medium were both positively related to lipid production. Cells cultured to low passage numbers retained similar lipid production and expression of lipid markers PLIN2 and FABP4. Ultimately, the protocols described here may be useful to biologists in the field investigating the health of wild bear populations and could potentially increase our understanding of metabolic disorders in humans.
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Affiliation(s)
- J L Gehring
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA.
| | - K S Rigano
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - B D Evans Hutzenbiler
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164, USA
| | - O L Nelson
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164, USA
| | - C T Robbins
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - H T Jansen
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164, USA
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Jansen HT, Leise T, Stenhouse G, Pigeon K, Kasworm W, Teisberg J, Radandt T, Dallmann R, Brown S, Robbins CT. The bear circadian clock doesn't 'sleep' during winter dormancy. Front Zool 2016; 13:42. [PMID: 27660641 PMCID: PMC5026772 DOI: 10.1186/s12983-016-0173-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 08/22/2016] [Indexed: 01/25/2023] Open
Abstract
Background Most biological functions are synchronized to the environmental light:dark cycle via a circadian timekeeping system. Bears exhibit shallow torpor combined with metabolic suppression during winter dormancy. We sought to confirm that free-running circadian rhythms of body temperature (Tb) and activity were expressed in torpid grizzly (brown) bears and that they were functionally responsive to environmental light. We also measured activity and ambient light exposures in denning wild bears to determine if rhythms were evident and what the photic conditions of their natural dens were. Lastly, we used cultured skin fibroblasts obtained from captive torpid bears to assess molecular clock operation in peripheral tissues. Circadian parameters were estimated using robust wavelet transforms and maximum entropy spectral analyses. Results Captive grizzly bears housed in constant darkness during winter dormancy expressed circadian rhythms of activity and Tb. The rhythm period of juvenile bears was significantly shorter than that of adult bears. However, the period of activity rhythms in adult captive bears was virtually identical to that of adult wild denning bears as was the strength of the activity rhythms. Similar to what has been found in other mammals, a single light exposure during the bear’s active period delayed subsequent activity onsets whereas these were advanced when light was applied during the bear’s inactive period. Lastly, in vitro studies confirmed the expression of molecular circadian rhythms with a period comparable to the bear’s own behavioral rhythms. Conclusions Based on these findings we conclude that the circadian system is functional in torpid bears and their peripheral tissues even when housed in constant darkness, is responsive to phase-shifting effects of light, and therefore, is a normal facet of torpid bear physiology. Electronic supplementary material The online version of this article (doi:10.1186/s12983-016-0173-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Heiko T Jansen
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Mailstop 7620, Veterinary and Biomedical Research Bldg., Room 205, Pullman, WA 99164-7620 USA
| | - Tanya Leise
- Department of Mathematics and Statistics, Amherst College, Amherst, MA 01002 USA
| | | | - Karine Pigeon
- Foothills Research Institute, Hinton, AB T7V 1X6 Canada
| | | | | | | | - Robert Dallmann
- Institute for Pharmacology and Toxicology, University of Zürich, Zürich, 8057 Switzerland ; Present address: Warwick Medical School and Warwick Systems Biology Centre, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
| | - Steven Brown
- Institute for Pharmacology and Toxicology, University of Zürich, Zürich, 8057 Switzerland
| | - Charles T Robbins
- School of the Environment, Washington State University, Pullman, WA 99164 USA
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Pilfold NW, Hedman D, Stirling I, Derocher AE, Lunn NJ, Richardson E. Mass Loss Rates of Fasting Polar Bears. Physiol Biochem Zool 2016; 89:377-88. [DOI: 10.1086/687988] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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38
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Pigeon KE, Stenhouse G, Côté SD. Drivers of hibernation: linking food and weather to denning behaviour of grizzly bears. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2180-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2023]
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39
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Lunn NJ, Servanty S, Regehr EV, Converse SJ, Richardson E, Stirling I. Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:1302-1320. [PMID: 27755745 DOI: 10.1890/15-1256] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 11/30/2015] [Accepted: 12/01/2015] [Indexed: 05/25/2023]
Abstract
Changes in the abundance and distribution of wildlife populations are common consequences of historic and contemporary climate change. Some Arctic marine mammals, such as the polar bear (Ursus maritimus), may be particularly vulnerable to such changes due to the loss of Arctic sea ice. We evaluated the impacts of environmental variation on demographic rates for the Western Hudson Bay (WH), polar bear subpopulation from 1984 to 2011 using live-recapture and dead-recovery data in a Bayesian implementation of multistate capture-recapture models. We found that survival of female polar bears was related to the annual timing of sea ice break-up and formation. Using estimated vital rates (e.g., survival and reproduction) in matrix projection models, we calculated the growth rate of the WH subpopulation and projected population responses under different environmental scenarios while accounting for parametric uncertainty, temporal variation, and demographic stochasticity. Our analysis suggested a long-term decline in the number of bears from 1185 (95% Bayesian credible interval [BCI] = 993-1411) in 1987 to 806 (95% BCI = 653-984) in 2011. In the last 10 yr of the study, the number of bears appeared stable due to temporary stability in sea ice conditions (mean population growth rate for the period 2001-2010 = 1.02, 95% BCI = 0.98-1.06). Looking forward, we estimated long-term growth rates for the WH subpopulation of ~1.02 (95% BCI = 1.00-1.05) and 0.97 (95% BCI = 0.92-1.01) under hypothetical high and low sea ice conditions, respectively. Our findings support previous evidence for a demographic linkage between sea ice conditions and polar bear population dynamics. Furthermore, we present a robust framework for sensitivity analysis with respect to continued climate change (e.g., to inform scenario planning) and for evaluating the combined effects of climate change and management actions on the status of wildlife populations.
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Affiliation(s)
- Nicholas J Lunn
- Wildlife Research Division, Science & Technology Branch, Environment and Climate Change Canada, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
| | - Sabrina Servanty
- Colorado Cooperative Fish and Wildlife Research Unit, Colorado State University, Fort Collins, Colorado, 80523, USA
- Patuxent Wildlife Research Center, US Geological Survey, 12100 Beech Forest Road, Laurel, Maryland, 20708, USA
| | - Eric V Regehr
- Marine Mammals Management, US Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, Alaska, 99503, USA
| | - Sarah J Converse
- Patuxent Wildlife Research Center, US Geological Survey, 12100 Beech Forest Road, Laurel, Maryland, 20708, USA
| | - Evan Richardson
- Wildlife Research Division, Science & Technology Branch, Environment and Climate Change Canada, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
| | - Ian Stirling
- Wildlife Research Division, Science & Technology Branch, Environment and Climate Change Canada, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
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40
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Atwood TC, Marcot BG, Douglas DC, Amstrup SC, Rode KD, Durner GM, Bromaghin JF. Forecasting the relative influence of environmental and anthropogenic stressors on polar bears. Ecosphere 2016. [DOI: 10.1002/ecs2.1370] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- Todd C. Atwood
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
| | - Bruce G. Marcot
- Pacific Northwest Research StationU.S.D.A. Forest Service Portland Oregon 97208 USA
| | - David C. Douglas
- Alaska Science CenterU.S. Geological Survey Juneau Alaska 99801 USA
| | | | - Karyn D. Rode
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
| | - George M. Durner
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
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41
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Atwood TC, Peacock E, McKinney MA, Lillie K, Wilson R, Douglas DC, Miller S, Terletzky P. Rapid Environmental Change Drives Increased Land Use by an Arctic Marine Predator. PLoS One 2016; 11:e0155932. [PMID: 27249673 PMCID: PMC4889047 DOI: 10.1371/journal.pone.0155932] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 05/06/2016] [Indexed: 11/18/2022] Open
Abstract
In the Arctic Ocean’s southern Beaufort Sea (SB), the length of the sea ice melt season (i.e., period between the onset of sea ice break-up in summer and freeze-up in fall) has increased substantially since the late 1990s. Historically, polar bears (Ursus maritimus) of the SB have mostly remained on the sea ice year-round (except for those that came ashore to den), but recent changes in the extent and phenology of sea ice habitat have coincided with evidence that use of terrestrial habitat is increasing. We characterized the spatial behavior of polar bears spending summer and fall on land along Alaska’s north coast to better understand the nexus between rapid environmental change and increased use of terrestrial habitat. We found that the percentage of radiocollared adult females from the SB subpopulation coming ashore has tripled over 15 years. Moreover, we detected trends of earlier arrival on shore, increased length of stay, and later departure back to sea ice, all of which were related to declines in the availability of sea ice habitat over the continental shelf and changes to sea ice phenology. Since the late 1990s, the mean duration of the open-water season in the SB increased by 36 days, and the mean length of stay on shore increased by 31 days. While on shore, the distribution of polar bears was influenced by the availability of scavenge subsidies in the form of subsistence-harvested bowhead whale (Balaena mysticetus) remains aggregated at sites along the coast. The declining spatio-temporal availability of sea ice habitat and increased availability of human-provisioned resources are likely to result in increased use of land. Increased residency on land is cause for concern given that, while there, bears may be exposed to a greater array of risk factors including those associated with increased human activities.
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Affiliation(s)
- Todd C. Atwood
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK, 99508, United States of America
- * E-mail:
| | - Elizabeth Peacock
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK, 99508, United States of America
| | - Melissa A. McKinney
- University of Connecticut, Center for Environmental Sciences and Engineering and Department of Natural Resources and the Environment, 1376 Storrs Road, Storrs, CT, 06269, United States of America
| | - Kate Lillie
- Utah State University, Department of Wildland Resources, Logan, UT, 84322–5230, United States of America
| | - Ryan Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, AK, 99503, United States of America
| | - David C. Douglas
- U.S. Geological Survey, Alaska Science Center, 250 Egan Drive, Juneau, AK, 99801, United States of America
| | - Susanne Miller
- U.S. Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, AK, 99503, United States of America
| | - Pat Terletzky
- Utah State University, Department of Wildland Resources, Logan, UT, 84322–5230, United States of America
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Rode KD, Stricker CA, Erlenbach J, Robbins CT, Cherry SG, Newsome SD, Cutting A, Jensen S, Stenhouse G, Brooks M, Hash A, Nicassio N. Isotopic Incorporation and the Effects of Fasting and Dietary Lipid Content on Isotopic Discrimination in Large Carnivorous Mammals. Physiol Biochem Zool 2016; 89:182-97. [DOI: 10.1086/686490] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Pigeon KE, Côté SD, Stenhouse GB. Assessing den selection and den characteristics of grizzly bears. J Wildl Manage 2016. [DOI: 10.1002/jwmg.1069] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Karine E. Pigeon
- Département de biologie and Centre d'études nordiques; Université Laval; 1045 Av. de la Médecine Québec QC G1V 0A6 Canada
| | - Steeve D. Côté
- Département de biologie and Centre d'études nordiques; Université Laval; 1045 Av. de la Médecine Québec QC G1V 0A6 Canada
| | - Gordon B. Stenhouse
- fRI Research Grizzly Bear Program (FRIGBP); 1176 Switzer Drive Hinton AB T7V 1V3 Canada
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Hertel AG, Steyaert SMJG, Zedrosser A, Mysterud A, Lodberg-Holm HK, Gelink HW, Kindberg J, Swenson JE. Bears and berries: species-specific selective foraging on a patchily distributed food resource in a human-altered landscape. Behav Ecol Sociobiol 2016; 70:831-842. [PMID: 27217612 PMCID: PMC4859851 DOI: 10.1007/s00265-016-2106-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/14/2016] [Accepted: 03/17/2016] [Indexed: 11/26/2022]
Abstract
Abstract When animals are faced with extraordinary energy-consuming events, like hibernation, finding abundant, energy-rich food resources becomes particularly important. The profitability of food resources can vary spatially, depending on occurrence, quality, and local abundance. Here, we used the brown bear (Ursus arctos) as a model species to quantify selective foraging on berries in different habitats during hyperphagia in autumn prior to hibernation. During the peak berry season in August and September, we sampled berry occurrence, abundance, and sugar content, a proxy for quality, at locations selected by bears for foraging and at random locations in the landscape. The factors determining selection of berries were species specific across the different habitats. Compared to random locations, bears selected locations with a higher probability of occurrence and higher abundance of bilberries (Vaccinium myrtillus) and a higher probability of occurrence, but not abundance, of lingonberries (Vaccinium vitis-idaea). Crowberries (Empetrum hermaphroditum) were least available and least used. Sugar content affected the selection of lingonberries, but not of bilberries. Abundance of bilberries at random locations decreased and abundance of lingonberries increased during fall, but bears did not adjust their foraging strategy by increasing selection for lingonberries. Forestry practices had a large effect on berry occurrence and abundance, and brown bears responded by foraging most selectively in mature forests and on clearcuts. This study shows that bears are successful in navigating human-shaped forest landscapes by using areas of higher than average berry abundance in a period when abundant food intake is particularly important to increase body mass prior to hibernation. Significance statement Food resources heterogeneity, caused by spatial and temporal variation of specific foods, poses a challenge to foragers, particularly when faced with extraordinary energy-demanding events, like hibernation. Brown bears in Sweden inhabit a landscape shaped by forestry practices. Bilberries and lingonberries, the bears’ main food resources in autumn prior to hibernation, show different temporal and habitat-specific ripening patterns. We quantified the bears’ selective foraging on these berry species on clearcuts, bogs, young, and mature forests compared to random locations. Despite a temporal decline of ripe bilberries, bears used locations with a greater occurrence and abundance of bilberries, but not lingonberries. We conclude that bears successfully navigated in this heavily human-shaped landscape by selectively foraging in high-return habitats for bilberries, but did not compensate for the decline in bilberries by eating more lingonberries. Electronic supplementary material The online version of this article (doi:10.1007/s00265-016-2106-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anne G. Hertel
- />Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, 1430 Ås, Norway
| | - Sam M. J. G. Steyaert
- />Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, 1430 Ås, Norway
| | - Andreas Zedrosser
- />Department of Environmental and Health Sciences, Telemark University College, 3901 Porsgrunn, Norway
- />Institute for Wildlife Biology and Game Management, University for Natural Resources and Life Sciences, 1180 Vienna, Austria
| | - Atle Mysterud
- />Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, 0316 Oslo, Norway
| | - Hanna K. Lodberg-Holm
- />Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, 1430 Ås, Norway
| | - Henriette Wathne Gelink
- />Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, 1430 Ås, Norway
| | - Jonas Kindberg
- />Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | - Jon E. Swenson
- />Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, 1430 Ås, Norway
- />Norwegian Institute for Nature Research, 7485 Trondheim, Norway
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Rode KD, Wilson RR, Regehr EV, St. Martin M, Douglas DC, Olson J. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions. PLoS One 2015; 10:e0142213. [PMID: 26580809 PMCID: PMC4651550 DOI: 10.1371/journal.pone.0142213] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/19/2015] [Indexed: 11/21/2022] Open
Abstract
Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986–1995 and 2008–2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.
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Affiliation(s)
- Karyn D. Rode
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, Alaska, 99508, United States of America
- * E-mail:
| | - Ryan R. Wilson
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, Alaska, 99503, United States of America
| | - Eric V. Regehr
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, Alaska, 99503, United States of America
| | - Michelle St. Martin
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, Alaska, 99503, United States of America
| | - David C. Douglas
- U.S. Geological Survey, Alaska Science Center, 250 Egan Drive, Juneau, Alaska, 99801, United States of America
| | - Jay Olson
- Brigham Young University, Plant and Wildlife Sciences, 5049 LSB, Provo, Utah, 84602, United States of America
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46
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Miller S, Wilder J, Wilson RR. Polar bear–grizzly bear interactions during the autumn open-water period in Alaska. J Mammal 2015. [DOI: 10.1093/jmammal/gyv140] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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47
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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: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [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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Gabrielsen KM, Krokstad JS, Obregon MJ, Villanger GD, Sonne C, Dietz R, Jenssen BM. Thyroid hormones and deiodinase activities in plasma and tissues from East Greenland polar bears (Ursus maritimus) during winter season. Polar Biol 2015. [DOI: 10.1007/s00300-015-1694-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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49
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Thermoregulation and energetics in hibernating black bears: metabolic rate and the mystery of multi-day body temperature cycles. J Comp Physiol B 2015; 185:447-61. [DOI: 10.1007/s00360-015-0891-y] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 01/12/2015] [Accepted: 01/17/2015] [Indexed: 11/30/2022]
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50
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Welch AJ, Bedoya-Reina OC, Carretero-Paulet L, Miller W, Rode KD, Lindqvist C. Polar bears exhibit genome-wide signatures of bioenergetic adaptation to life in the arctic environment. Genome Biol Evol 2015; 6:433-50. [PMID: 24504087 PMCID: PMC3942037 DOI: 10.1093/gbe/evu025] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Polar bears (Ursus maritimus) face extremely cold temperatures and periods of fasting, which might result in more severe energetic challenges than those experienced by their sister species, the brown bear (U. arctos). We have examined the mitochondrial and nuclear genomes of polar and brown bears to investigate whether polar bears demonstrate lineage-specific signals of molecular adaptation in genes associated with cellular respiration/energy production. We observed increased evolutionary rates in the mitochondrial cytochrome c oxidase I gene in polar but not brown bears. An amino acid substitution occurred near the interaction site with a nuclear-encoded subunit of the cytochrome c oxidase complex and was predicted to lead to a functional change, although the significance of this remains unclear. The nuclear genomes of brown and polar bears demonstrate different adaptations related to cellular respiration. Analyses of the genomes of brown bears exhibited substitutions that may alter the function of proteins that regulate glucose uptake, which could be beneficial when feeding on carbohydrate-dominated diets during hyperphagia, followed by fasting during hibernation. In polar bears, genes demonstrating signatures of functional divergence and those potentially under positive selection were enriched in functions related to production of nitric oxide (NO), which can regulate energy production in several different ways. This suggests that polar bears may be able to fine-tune intracellular levels of NO as an adaptive response to control trade-offs between energy production in the form of adenosine triphosphate versus generation of heat (thermogenesis).
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Affiliation(s)
- Andreanna J Welch
- Department of Biological Sciences, University at Buffalo (SUNY), Buffalo
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