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Przybylska-Piech AS, Jefimow M. Siberian hamsters nonresponding to short photoperiod use fasting-induced torpor. J Exp Biol 2022; 225:275527. [PMID: 35615921 DOI: 10.1242/jeb.244222] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/17/2022] [Indexed: 11/20/2022]
Abstract
Nonresponding Siberian hamsters Phodopus sungorus do not develop the winter phenotype with white fur, low body mass (mb) and spontaneous torpor use in response to short photoperiod. However, their thermoregulatory response to fasting remains unknown. We measured body temperature and mb of 12 nonresponders acclimated to short photoperiod and then to cold, and fasted four times for 24h. Four individuals used torpor and in total we recorded 19 torpor bouts, which were shallow, short, and occurred at night. Moreover fasting increased the heterothermy index in all hamsters. Low mb was not a prerequisite for torpor use and mb loss correlated with neither heterothermy index nor torpor use. This is the first evidence that individuals which do not develop the winter phenotype, can use torpor or increase body temperature variability to face unpredictable, adverse environmental conditions. Despite the lack of seasonal changes, thermoregulatory adjustments may increase winter survival probability of nonresponders.
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Affiliation(s)
- Anna S Przybylska-Piech
- Department of Vertebrate Zoology and Ecology; Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, ul. Lwowska 1, 87-100 Toruń, Poland
| | - Małgorzata Jefimow
- Department of Animal Physiology and Neurobiology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, ul. Lwowska 1, 87-100 Toruń, Poland
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2
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Nespolo RF, Mejías C, Espinoza A, Quintero-Galvis J, Rezende EL, Fontúrbel FE, Bozinovic F. Heterothermy as the Norm, Homeothermy as the Exception: Variable Torpor Patterns in the South American Marsupial Monito del Monte ( Dromiciops gliroides). Front Physiol 2021; 12:682394. [PMID: 34322034 PMCID: PMC8311349 DOI: 10.3389/fphys.2021.682394] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/11/2021] [Indexed: 12/30/2022] Open
Abstract
Hibernation (i.e., multiday torpor) is considered an adaptive strategy of mammals to face seasonal environmental challenges such as food, cold, and/or water shortage. It has been considered functionally different from daily torpor, a physiological strategy to cope with unpredictable environments. However, recent studies have shown large variability in patterns of hibernation and daily torpor ("heterothermic responses"), especially in species from tropical and subtropical regions. The arboreal marsupial "monito del monte" (Dromiciops gliroides) is the last living representative of the order Microbiotheria and is known to express both short torpor episodes and also multiday torpor depending on environmental conditions. However, only limited laboratory experiments have documented these patterns in D. gliroides. Here, we combined laboratory and field experiments to characterize the heterothermic responses in this marsupial at extreme temperatures. We used intraperitoneal data loggers and simultaneous measurement of ambient and body temperatures (T A and T B, respectively) for analyzing variations in the thermal differential, in active and torpid animals. We also explored how this differential was affected by environmental variables (T A, natural photoperiod changes, food availability, and body mass changes), using mixed-effects generalized linear models. Our results suggest that: (1) individuals express short bouts of torpor, independently of T A and even during the reproductive period; (2) seasonal torpor also occurs in D. gliroides, with a maximum bout duration of 5 days and a mean defended T B of 3.6 ± 0.9°C (one individual controlled T B at 0.09°C, at sub-freezing T A); (3) the best model explaining torpor occurrence (Akaike information criteria weight = 0.59) discarded all predictor variables except for photoperiod and a photoperiod by food interaction. Altogether, these results confirm that this marsupial expresses a dynamic form of torpor that progresses from short torpor to hibernation as daylength shortens. These data add to a growing body of evidence characterizing tropical and sub-tropical heterothermy as a form of opportunistic torpor, expressed as daily or seasonal torpor depending on environmental conditions.
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Affiliation(s)
- Roberto F. Nespolo
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile
- Center of Applied Ecology and Sustainability (CAPES), Departamento de Ecología Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile
| | - Carlos Mejías
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile
| | - Angelo Espinoza
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile
| | - Julián Quintero-Galvis
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile
| | - Enrico L. Rezende
- Center of Applied Ecology and Sustainability (CAPES), Departamento de Ecología Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Francisco Bozinovic
- Center of Applied Ecology and Sustainability (CAPES), Departamento de Ecología Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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3
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Wu CW, Storey KB. mTOR Signaling in Metabolic Stress Adaptation. Biomolecules 2021; 11:biom11050681. [PMID: 34062764 PMCID: PMC8147357 DOI: 10.3390/biom11050681] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/28/2021] [Accepted: 04/30/2021] [Indexed: 12/30/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) is a central regulator of cellular homeostasis that integrates environmental and nutrient signals to control cell growth and survival. Over the past two decades, extensive studies of mTOR have implicated the importance of this protein complex in regulating a broad range of metabolic functions, as well as its role in the progression of various human diseases. Recently, mTOR has emerged as a key signaling molecule in regulating animal entry into a hypometabolic state as a survival strategy in response to environmental stress. Here, we review current knowledge of the role that mTOR plays in contributing to natural hypometabolic states such as hibernation, estivation, hypoxia/anoxia tolerance, and dauer diapause. Studies across a diverse range of animal species reveal that mTOR exhibits unique regulatory patterns in an environmental stressor-dependent manner. We discuss how key signaling proteins within the mTOR signaling pathways are regulated in different animal models of stress, and describe how each of these regulations uniquely contribute to promoting animal survival in a hypometabolic state.
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Affiliation(s)
- Cheng-Wei Wu
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada
- Correspondence:
| | - Kenneth B. Storey
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada;
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4
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Blanco MB, Greene LK, Schopler R, Williams CV, Lynch D, Browning J, Welser K, Simmons M, Klopfer PH, Ehmke EE. On the modulation and maintenance of hibernation in captive dwarf lemurs. Sci Rep 2021; 11:5740. [PMID: 33707506 PMCID: PMC7952597 DOI: 10.1038/s41598-021-84727-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 02/18/2021] [Indexed: 11/09/2022] Open
Abstract
In nature, photoperiod signals environmental seasonality and is a strong selective "zeitgeber" that synchronizes biological rhythms. For animals facing seasonal environmental challenges and energetic bottlenecks, daily torpor and hibernation are two metabolic strategies that can save energy. In the wild, the dwarf lemurs of Madagascar are obligate hibernators, hibernating between 3 and 7 months a year. In captivity, however, dwarf lemurs generally express torpor for periods far shorter than the hibernation season in Madagascar. We investigated whether fat-tailed dwarf lemurs (Cheirogaleus medius) housed at the Duke Lemur Center (DLC) could hibernate, by subjecting 8 individuals to husbandry conditions more in accord with those in Madagascar, including alternating photoperiods, low ambient temperatures, and food restriction. All dwarf lemurs displayed daily and multiday torpor bouts, including bouts lasting ~ 11 days. Ambient temperature was the greatest predictor of torpor bout duration, and food ingestion and night length also played a role. Unlike their wild counterparts, who rarely leave their hibernacula and do not feed during hibernation, DLC dwarf lemurs sporadically moved and ate. While demonstrating that captive dwarf lemurs are physiologically capable of hibernation, we argue that facilitating their hibernation serves both husbandry and research goals: first, it enables lemurs to express the biphasic phenotypes (fattening and fat depletion) that are characteristic of their wild conspecifics; second, by "renaturalizing" dwarf lemurs in captivity, they will emerge a better model for understanding both metabolic extremes in primates generally and metabolic disorders in humans specifically.
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Affiliation(s)
- Marina B Blanco
- Duke Lemur Center, Durham, NC, 27705, USA. .,Department of Biology, Duke University, Durham, NC, 27708, USA.
| | - Lydia K Greene
- Duke Lemur Center, Durham, NC, 27705, USA.,Department of Biology, Duke University, Durham, NC, 27708, USA
| | | | | | | | | | - Kay Welser
- Duke Lemur Center, Durham, NC, 27705, USA
| | | | - Peter H Klopfer
- Department of Biology, Duke University, Durham, NC, 27708, USA
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5
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Giroud S, Habold C, Nespolo RF, Mejías C, Terrien J, Logan SM, Henning RH, Storey KB. The Torpid State: Recent Advances in Metabolic Adaptations and Protective Mechanisms †. Front Physiol 2021; 11:623665. [PMID: 33551846 PMCID: PMC7854925 DOI: 10.3389/fphys.2020.623665] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/21/2020] [Indexed: 12/18/2022] Open
Abstract
Torpor and hibernation are powerful strategies enabling animals to survive periods of low resource availability. The state of torpor results from an active and drastic reduction of an individual's metabolic rate (MR) associated with a relatively pronounced decrease in body temperature. To date, several forms of torpor have been described in all three mammalian subclasses, i.e., monotremes, marsupials, and placentals, as well as in a few avian orders. This review highlights some of the characteristics, from the whole organism down to cellular and molecular aspects, associated with the torpor phenotype. The first part of this review focuses on the specific metabolic adaptations of torpor, as it is used by many species from temperate zones. This notably includes the endocrine changes involved in fat- and food-storing hibernating species, explaining biomedical implications of MR depression. We further compare adaptive mechanisms occurring in opportunistic vs. seasonal heterotherms, such as tropical and sub-tropical species. Such comparisons bring new insights into the metabolic origins of hibernation among tropical species, including resistance mechanisms to oxidative stress. The second section of this review emphasizes the mechanisms enabling heterotherms to protect their key organs against potential threats, such as reactive oxygen species, associated with the torpid state. We notably address the mechanisms of cellular rehabilitation and protection during torpor and hibernation, with an emphasis on the brain, a central organ requiring protection during torpor and recovery. Also, a special focus is given to the role of an ubiquitous and readily-diffusing molecule, hydrogen sulfide (H2S), in protecting against ischemia-reperfusion damage in various organs over the torpor-arousal cycle and during the torpid state. We conclude that (i) the flexibility of torpor use as an adaptive strategy enables different heterothermic species to substantially suppress their energy needs during periods of severely reduced food availability, (ii) the torpor phenotype implies marked metabolic adaptations from the whole organism down to cellular and molecular levels, and (iii) the torpid state is associated with highly efficient rehabilitation and protective mechanisms ensuring the continuity of proper bodily functions. Comparison of mechanisms in monotremes and marsupials is warranted for understanding the origin and evolution of mammalian torpor.
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Affiliation(s)
- Sylvain Giroud
- Research Institute of Wildlife Ecology, Department of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Caroline Habold
- University of Strasbourg, CNRS, IPHC, UMR 7178, Strasbourg, France
| | - Roberto F. Nespolo
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, ANID – Millennium Science Initiative Program-iBio, Valdivia, Chile
- Center of Applied Ecology and Sustainability, Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carlos Mejías
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, ANID – Millennium Science Initiative Program-iBio, Valdivia, Chile
- Center of Applied Ecology and Sustainability, Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jérémy Terrien
- Unité Mécanismes Adaptatifs et Evolution (MECADEV), UMR 7179, CNRS, Muséum National d’Histoire Naturelle, Brunoy, France
| | | | - Robert H. Henning
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, Groningen, Netherlands
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6
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Parallel Accelerated Evolution in Distant Hibernators Reveals Candidate Cis Elements and Genetic Circuits Regulating Mammalian Obesity. Cell Rep 2020; 29:2608-2620.e4. [PMID: 31775032 PMCID: PMC6910134 DOI: 10.1016/j.celrep.2019.10.102] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/21/2019] [Accepted: 10/24/2019] [Indexed: 12/15/2022] Open
Abstract
Obesity is a clinical problem and an important adaptation in many species. Hibernating mammals, for example, become obese, insulin resistant, and hyperinsulinemic to store fat. Here, we combine comparative phylogenomics with large-scale human genome data to uncover candidate cis elements and genetic circuits in different cell types. The Fat Mass and Obesity (FTO) locus, the strongest genetic risk factor for human obesity, is an enriched site for hibernator pARs. Our results uncover noncoding cis elements with putative roles in obesity and hibernation. Obesity is a clinical problem but also an important adaptation in hibernators. By using comparative genomics approaches to analyze the genomes of hibernators from different clades and contrasting the results with human obesity risk loci, Ferris and Gregg found 364 conserved cis elements with putative roles in regulating obesity and hibernation.
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7
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Contrasting effects of climate change on seasonal survival of a hibernating mammal. Proc Natl Acad Sci U S A 2020; 117:18119-18126. [PMID: 32631981 DOI: 10.1073/pnas.1918584117] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Seasonal environmental conditions shape the behavior and life history of virtually all organisms. Climate change is modifying these seasonal environmental conditions, which threatens to disrupt population dynamics. It is conceivable that climatic changes may be beneficial in one season but result in detrimental conditions in another because life-history strategies vary between these time periods. We analyzed the temporal trends in seasonal survival of yellow-bellied marmots (Marmota flaviventer) and explored the environmental drivers using a 40-y dataset from the Colorado Rocky Mountains (USA). Trends in survival revealed divergent seasonal patterns, which were similar across age-classes. Marmot survival declined during winter but generally increased during summer. Interestingly, different environmental factors appeared to drive survival trends across age-classes. Winter survival was largely driven by conditions during the preceding summer and the effect of continued climate change was likely to be mainly negative, whereas the likely outcome of continued climate change on summer survival was generally positive. This study illustrates that seasonal demographic responses need disentangling to accurately forecast the impacts of climate change on animal population dynamics.
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8
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Nowack J, Levesque DL, Reher S, Dausmann KH. Variable Climates Lead to Varying Phenotypes: “Weird” Mammalian Torpor and Lessons From Non-Holarctic Species. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00060] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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9
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Klein A, Strube C, Radespiel U, Springer A, Zimmermann E. Differences in infection patterns of vector-borne blood-stage parasites of sympatric Malagasy primate species ( Microcebus murinus, M. ravelobensis). INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE 2019; 10:59-70. [PMID: 31372336 PMCID: PMC6657000 DOI: 10.1016/j.ijppaw.2019.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/05/2019] [Accepted: 07/06/2019] [Indexed: 01/08/2023]
Abstract
The dynamic relationship of vector-borne parasites, arthropod vectors and their hosts is prone to change under the influence of climate change, global integration, shifting demographics and deforestation. It is therefore essential to better understand parasitism in wildlife populations, including parasites transmitted by blood-feeding vectors, and explore host range and heterogeneity of parasitic infections. We investigated Giemsa stained blood smears of two sympatric Malagasy primate species (Microcebus murinus: 184 samples from 69 individuals and M. ravelobensis: 264 samples from 91 individuals) for blood-stage parasites and tested for a potential influence of host species, sex, body mass and sampling month on blood-stage parasite prevalence and infection intensity. No protozoan parasites were detected in either host species. A host-specific difference was observed in filarial nematode infections, with higher risk of infection in M. murinus (prevalence 30.43%), than in M. ravelobensis (prevalence 6.59%), which may be explained by differences in host behavior and/or immune competence, linked to the period of host-parasite coevolution. Neither sex nor sampling month influenced infection prevalence or intensity significantly. We did not observe a negative effect of microfilarial infections on host fitness when taking body mass as a proxy. Our results support the hypothesis of a long-term evolutionary adaptation of hosts and parasites, leading to persistent infection with low morbidity. Morphological and molecular analyses indicate the finding of a new species, “Lemurfilaria lemuris”. Genetic analysis furthermore showed >99% sequence identity with microfilariae described from a sympatric, larger-bodied lemur species of a different genus, suggesting low host-specificity of the detected filariae and pathogen transmission across genus boundaries. Findings contribute to a more comprehensive picture of vector-borne diseases of Malagasy lemurs. Small Malagasy primate species are hosts of the newly described Lemurfilaria lemuris. Risk of microfilarial infection and infection intensity differed between host species. This could be linked to differences in host socioecology and/or phylogeography. No influence of microfilarial infection on host body mass was observed. >99% sequence identity of filariae from lemur hosts of different genera.
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Affiliation(s)
- Annette Klein
- Institute of Zoology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hanover, Germany.,Institute for Parasitology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hanover, Germany
| | - Christina Strube
- Institute for Parasitology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hanover, Germany
| | - Ute Radespiel
- Institute of Zoology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hanover, Germany
| | - Andrea Springer
- Institute for Parasitology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hanover, Germany
| | - Elke Zimmermann
- Institute of Zoology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hanover, Germany
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10
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Biggar K, Luu B, Wu C, Pifferi F, Perret M, Storey K. Identification of novel and conserved microRNA and their expression in the gray mouse lemur, Microcebus murinus, a primate capable of daily torpor. Gene 2018; 677:332-339. [DOI: 10.1016/j.gene.2018.08.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 07/10/2018] [Accepted: 08/04/2018] [Indexed: 12/13/2022]
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11
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Blanco MB, Dausmann KH, Faherty SL, Yoder AD. Tropical heterothermy is “cool”: The expression of daily torpor and hibernation in primates. Evol Anthropol 2018; 27:147-161. [DOI: 10.1002/evan.21588] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 03/15/2018] [Indexed: 12/19/2022]
Affiliation(s)
| | | | | | - Anne D. Yoder
- Duke Lemur Center; Durham North Carolina
- Department of Biology; Duke University; Durham North Carolina
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12
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Welman S, Tuen AA, Lovegrove BG. Searching for the Haplorrhine Heterotherm: Field and Laboratory Data of Free-Ranging Tarsiers. Front Physiol 2017; 8:745. [PMID: 29018365 PMCID: PMC5623056 DOI: 10.3389/fphys.2017.00745] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Accepted: 09/12/2017] [Indexed: 01/26/2023] Open
Abstract
The observation of heterothermy in a single suborder (Strepsirrhini) only within the primates is puzzling. Given that the placental-mammal ancestor was likely a heterotherm, we explored the potential for heterothermy in a primate closely related to the Strepsirrhini. Based upon phylogeny, body size and habitat stability since the Late Eocene, we selected western tarsiers (Cephalopachus bancanus) from the island of Borneo. Being the sister clade to Strepsirrhini and basal in Haplorrhini (monkeys and apes), we hypothesized that C. bancanus might have retained the heterothermic capacity observed in several small strepsirrhines. We measured resting metabolic rate, subcutaneous temperature, evaporative water loss and the percentage of heat dissipated through evaporation, at ambient temperatures between 22 and 35°C in fresh-caught wild animals (126.1 ± 2.4 g). We also measured core body temperatures in free-ranging animals. The thermoneutral zone was 25-30°C and the basal metabolic rate was 3.52 ± 0.06 W.kg-1 (0.65 ± 0.01 ml O2.g-1.h-1). There was no evidence of adaptive heterothermy in either the laboratory data or the free-ranging data. Instead, animals appeared to be cold sensitive (Tb ~ 31°C) at the lowest temperatures. We discuss possible reasons for the apparent lack of heterothermy in tarsiers, and identify putative heterotherms within Platyrrhini. We also document our concern for the vulnerability of C. bancanus to future temperature increases associated with global warming.
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Affiliation(s)
- Shaun Welman
- School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
| | - Andrew A. Tuen
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan, Malaysia
| | - Barry G. Lovegrove
- School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
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13
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Female dominance in two basal primates, Microcebus murinus and Microcebus lehilahytsara: variation and determinants. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2016.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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14
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Blanco MB, Andriantsalohimisantatra AA, Rivoharison TV, Andriambeloson JB. Evidence of prolonged torpor in Goodman’s mouse lemurs at Ankafobe forest, central Madagascar. Primates 2016; 58:31-37. [DOI: 10.1007/s10329-016-0586-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/01/2016] [Indexed: 11/25/2022]
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15
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The effect of body mass and diet composition on torpor patterns in a Malagasy primate (Microcebus murinus). J Comp Physiol B 2016; 187:677-688. [DOI: 10.1007/s00360-016-1045-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Revised: 10/19/2016] [Accepted: 10/20/2016] [Indexed: 10/20/2022]
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16
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Rakotoniaina JH, Kappeler PM, Ravoniarimbinina P, Pechouskova E, Hämäläinen AM, Grass J, Kirschbaum C, Kraus C. Does habitat disturbance affect stress, body condition and parasitism in two sympatric lemurs? CONSERVATION PHYSIOLOGY 2016; 4:cow034. [PMID: 27656285 PMCID: PMC5020880 DOI: 10.1093/conphys/cow034] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Revised: 07/20/2016] [Accepted: 07/23/2016] [Indexed: 05/25/2023]
Abstract
Understanding how animals react to human-induced changes in their environment is a key question in conservation biology. Owing to their potential correlation with fitness, several physiological parameters are commonly used to assess the effect of habitat disturbance on animals' general health status. Here, we studied how two lemur species, the fat-tailed dwarf lemur (Cheirogaleus medius) and the grey mouse lemur (Microcebus murinus), respond to changing environmental conditions by comparing their stress levels (measured as hair cortisol concentration), parasitism and general body condition across four habitats ordered along a gradient of human disturbance at Kirindy Forest, Western Madagascar. These two species previously revealed contrasting responses to human disturbance; whereas M. murinus is known as a resilient species, C. medius is rarely encountered in highly disturbed habitats. However, neither hair cortisol concentrations nor parasitism patterns (prevalence, parasite species richness and rate of multiple infections) and body condition varied across the gradient of anthropogenic disturbance. Our results indicate that the effect of anthropogenic activities at Kirindy Forest is not reflected in the general health status of both species, which may have developed a range of behavioural adaptations to deal with suboptimal conditions. Nonetheless, a difference in relative density among sites suggests that the carrying capacity of disturbed habitat is lower, and both species respond differently to environmental changes, with C. medius being more negatively affected. Thus, even for behaviourally flexible species, extended habitat deterioration could hamper long-term viability of populations.
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Affiliation(s)
- Josué H Rakotoniaina
- Department of Sociobiology/Anthropology, Georg-August University of Göttingen, Kellnerweg 6, 37077 Göttingen, Germany
- Behavioral Ecology and Sociobiology Unit, Deutsches Primatenzentrum, Kellnerweg 4, 37077 Göttingen, Germany
| | - Peter M Kappeler
- Department of Sociobiology/Anthropology, Georg-August University of Göttingen, Kellnerweg 6, 37077 Göttingen, Germany
- Behavioral Ecology and Sociobiology Unit, Deutsches Primatenzentrum, Kellnerweg 4, 37077 Göttingen, Germany
| | | | - Eva Pechouskova
- Behavioral Ecology and Sociobiology Unit, Deutsches Primatenzentrum, Kellnerweg 4, 37077 Göttingen, Germany
| | - Anni M Hämäläinen
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
T6G 2E9
| | - Juliane Grass
- Department of Psychology, TU Dresden, Andreas-Schubert-Bau, Zellescher Weg 19, 01069 Dresden, Germany
| | - Clemens Kirschbaum
- Department of Psychology, TU Dresden, Andreas-Schubert-Bau, Zellescher Weg 19, 01069 Dresden, Germany
| | - Cornelia Kraus
- Department of Sociobiology/Anthropology, Georg-August University of Göttingen, Kellnerweg 6, 37077 Göttingen, Germany
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Karanewsky CJ, Bauert MR, Wright PC. Effects of Sex and Age on Heterothermy in Goodman’s Mouse Lemur (Microcebus lehilahytsara). INT J PRIMATOL 2015. [DOI: 10.1007/s10764-015-9867-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Biggar KK, Wu CW, Tessier SN, Zhang J, Pifferi F, Perret M, Storey KB. Primate Torpor: Regulation of Stress-activated Protein Kinases During Daily Torpor in the Gray Mouse Lemur, Microcebus murinus. GENOMICS PROTEOMICS & BIOINFORMATICS 2015; 13:81-90. [PMID: 26093282 PMCID: PMC4511785 DOI: 10.1016/j.gpb.2015.03.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/21/2015] [Indexed: 01/19/2023]
Abstract
Very few selected species of primates are known to be capable of entering torpor. This exciting discovery means that the ability to enter a natural state of dormancy is an ancestral trait among primates and, in phylogenetic terms, is very close to the human lineage. To explore the regulatory mechanisms that underlie primate torpor, we analyzed signal transduction cascades to discover those involved in coordinating tissue responses during torpor. The responses of mitogen-activated protein kinase (MAPK) family members to primate torpor were compared in six organs of control (aroused) versus torpid gray mouse lemurs, Microcebus murinus. The proteins examined include extracellular signal-regulated kinases (ERKs), c-jun NH2-terminal kinases (JNKs), MAPK kinase (MEK), and p38, in addition to stress-related proteins p53 and heat shock protein 27 (HSP27). The activation of specific MAPK signal transduction pathways may provide a mechanism to regulate the expression of torpor-responsive genes or the regulation of selected downstream cellular processes. In response to torpor, each MAPK subfamily responded differently during torpor and each showed organ-specific patterns of response. For example, skeletal muscle displayed elevated relative phosphorylation of ERK1/2 during torpor. Interestingly, adipose tissues showed the highest degree of MAPK activation. Brown adipose tissue displayed an activation of ERK1/2 and p38, whereas white adipose tissue showed activation of ERK1/2, p38, MEK, and JNK during torpor. Importantly, both adipose tissues possess specialized functions that are critical for torpor, with brown adipose required for non-shivering thermogenesis and white adipose utilized as the primary source of lipid fuel for torpor. Overall, these data indicate crucial roles of MAPKs in the regulation of primate organs during torpor.
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Affiliation(s)
- Kyle K Biggar
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Biochemistry Department, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Cheng-Wei Wu
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Department of Biology, Genetics Institute, University of Florida, Gainesville, FL 32611, USA
| | - Shannon N Tessier
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Department of Surgery & Center for Engineering in Medicine, Massachusetts General Hospital & Harvard Medical School, Charlestown, MA 02129, USA
| | - Jing Zhang
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Chemistry and Chemical Engineering Department, Royal Military College of Canada, Kingston, ON K7K 7B4, Canada
| | - Fabien Pifferi
- UMR 7179 Centre National de la Recherche Scientifique, Muséum National d'Histoire Naturelle, 91800 Brunoy, France
| | - Martine Perret
- UMR 7179 Centre National de la Recherche Scientifique, Muséum National d'Histoire Naturelle, 91800 Brunoy, France
| | - Kenneth B Storey
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada.
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Tessier SN, Katzenback BA, Pifferi F, Perret M, Storey KB. Cytokine and Antioxidant Regulation in the Intestine of the Gray Mouse Lemur (Microcebus murinus) During Torpor. GENOMICS PROTEOMICS & BIOINFORMATICS 2015; 13:127-35. [PMID: 26092185 PMCID: PMC4511783 DOI: 10.1016/j.gpb.2015.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/24/2015] [Indexed: 11/17/2022]
Abstract
During food shortages, the gray mouse lemur (Microcebus murinus) of Madagascar experiences daily torpor thereby reducing energy expenditures. The present study aimed to understand the impacts of torpor on the immune system and antioxidant response in the gut of these animals. This interaction may be of critical importance given the trade-off between the energetically costly immune response and the need to defend against pathogen entry during hypometabolism. The protein levels of cytokines and antioxidants were measured in the small intestine (duodenum, jejunum, and ileum) and large intestine of aroused and torpid lemurs. While there was a significant decrease of some pro-inflammatory cytokines (IL-6 and TNF-α) in the duodenum and jejunum during torpor as compared to aroused animals, there was no change in anti-inflammatory cytokines. We observed decreased levels of cytokines (IL-12p70 and M-CSF), and several chemokines (MCP-1 and MIP-2) but an increase in MIP-1α in the jejunum of the torpid animals. In addition, we evaluated antioxidant response by examining the protein levels of antioxidant enzymes and total antioxidant capacity provided by metabolites such as glutathione (and others). Our results indicated that levels of antioxidant enzymes did not change between torpor and aroused states, although antioxidant capacity was significantly higher in the ileum during torpor. These data suggest a suppression of the immune response, likely as an energy conservation measure, and a limited role of antioxidant defenses in supporting torpor in lemur intestine.
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Affiliation(s)
- Shannon N Tessier
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Department of Surgery & Center for Engineering in Medicine, Massachusetts General Hospital & Harvard Medical School, Charlestown, MA 02129, USA
| | - Barbara A Katzenback
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Fabien Pifferi
- UMR 7179 Centre National de la Recherche Scientifique, Muséum National d'Histoire Naturelle, Brunoy 91800, France
| | - Martine Perret
- UMR 7179 Centre National de la Recherche Scientifique, Muséum National d'Histoire Naturelle, Brunoy 91800, France
| | - Kenneth B Storey
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada.
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Regulation of Torpor in the Gray Mouse Lemur: Transcriptional and Translational Controls and Role of AMPK Signaling. GENOMICS PROTEOMICS & BIOINFORMATICS 2015; 13:103-10. [PMID: 26092186 PMCID: PMC4511784 DOI: 10.1016/j.gpb.2015.03.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/21/2015] [Indexed: 12/02/2022]
Abstract
The gray mouse lemur (Microcebus murinus) is one of few primate species that is able to enter daily torpor or prolonged hibernation in response to environmental stresses. With an emerging significance to human health research, lemurs present an optimal model for exploring molecular adaptations that regulate primate hypometabolism. A fundamental challenge is how to effectively regulate energy expensive cellular processes (e.g., transcription and translation) during transitions to/from torpor without disrupting cellular homeostasis. One such regulatory mechanism is reversible posttranslational modification of selected protein targets that offers fine cellular control without the energetic burden. This study investigates the role of phosphorylation and/or acetylation in regulating key factors involved in energy homeostasis (AMP-activated protein kinase, or AMPK, signaling pathway), mRNA translation (eukaryotic initiation factor 2α or eIF2α, eukaryotic initiation factor 4E or eIF4E, and initiation factor 4E binding protein or 4EBP), and gene transcription (histone H3) in six tissues of torpid and aroused gray mouse lemurs. Our results indicated selective tissue-specific changes of these regulatory proteins. The relative level of Thr172-phosphorylated AMPKα was significantly elevated in the heart but reduced in brown adipose tissue during daily torpor, as compared to the aroused lemurs, implicating the regulation of AMPK activity during daily torpor in these tissues. Interestingly, the levels of the phosphorylated eIFs were largely unaltered between aroused and torpid animals. Phosphorylation and acetylation of histone H3 were examined as a marker for transcriptional regulation. Compared to the aroused lemurs, level of Ser10-phosphorylated histone H3 decreased significantly in white adipose tissue during torpor, suggesting global suppression of gene transcription. However, a significant increase in acetyl-histone H3 in the heart of torpid lemurs indicated a possible stimulation of transcriptional activity of this tissue. Overall, our study demonstrates that AMPK signaling and posttranslational regulation of selected proteins may play crucial roles in the control of transcription/translation during daily torpor in mouse lemurs.
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Tessier SN, Zhang J, Biggar KK, Wu CW, Pifferi F, Perret M, Storey KB. Regulation of the PI3K/AKT Pathway and Fuel Utilization During Primate Torpor in the Gray Mouse Lemur, Microcebus murinus. GENOMICS PROTEOMICS & BIOINFORMATICS 2015; 13:91-102. [PMID: 26092184 PMCID: PMC4511781 DOI: 10.1016/j.gpb.2015.03.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/23/2015] [Indexed: 12/19/2022]
Abstract
Gray mouse lemurs (Microcebus murinus) from Madagascar present an excellent model for studies of torpor regulation in a primate species. In the present study, we analyzed the response of the insulin signaling pathway as well as controls on carbohydrate sparing in six different tissues of torpid versus aroused gray mouse lemurs. We found that the relative level of phospho-insulin receptor substrate (IRS-1) was significantly increased in muscle, whereas the level of phospho-insulin receptor (IR) was decreased in white adipose tissue (WAT) of torpid animals, both suggesting an inhibition of insulin/insulin-like growth factor-1 (IGF-1) signaling during torpor in these tissues. By contrast, the level of phospho-IR was increased in the liver. Interestingly, muscle, WAT, and liver occupy central roles in whole body homeostasis and each displays regulatory controls operating at the plasma membrane. Changes in other tissues included an increase in phospho-glycogen synthase kinase 3α (GSK3α) and decrease in phospho-ribosomal protein S6 (RPS6) in the heart, and a decrease in phospho-mammalian target of rapamycin (mTOR) in the kidney. Pyruvate dehydrogenase (PDH) that gates carbohydrate entry into mitochondria is inhibited via phosphorylation by pyruvate dehydrogenase kinase (e.g., PDK4). In the skeletal muscle, the protein expression of PDK4 and phosphorylated PDH at Ser 300 was increased, suggesting inhibition during torpor. In contrast, there were no changes in levels of PDH expression and phosphorylation in other tissues comparing torpid and aroused animals. Information gained from these studies highlight the molecular controls that help to regulate metabolic rate depression and balance energetics during primate torpor.
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Affiliation(s)
- Shannon N Tessier
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Department of Surgery & Center for Engineering in Medicine, Massachusetts General Hospital & Harvard Medical School, Charlestown, MA 02129, USA
| | - Jing Zhang
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Chemistry and Chemical Engineering Department, Royal Military College of Canada, Kingston, ON K7K 7B4, Canada
| | - Kyle K Biggar
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Biochemistry Department, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Cheng-Wei Wu
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada; Department of Biology, Genetics Institute, University of Florida, Gainesville, FL 32611, USA
| | - Fabien Pifferi
- UMR 7179 Centre National de la Recherche Scientifique, Muséum National d'Histoire Naturelle, Brunoy 91800, France
| | - Martine Perret
- UMR 7179 Centre National de la Recherche Scientifique, Muséum National d'Histoire Naturelle, Brunoy 91800, France
| | - Kenneth B Storey
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada.
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Blanco MB, Rasoazanabary E, Godfrey LR. Unpredictable environments, opportunistic responses: Reproduction and population turnover in two wild mouse lemur species (Microcebus rufus and M. griseorufus) from eastern and western Madagascar. Am J Primatol 2015; 77:936-947. [PMID: 26031477 DOI: 10.1002/ajp.22423] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Revised: 04/14/2015] [Accepted: 04/19/2015] [Indexed: 11/12/2022]
Abstract
Small-bodied, nocturnal mouse lemurs (Microcebus) are widespread across diverse forest habitats in Madagascar. They are strict seasonal breeders and can, depending on the habitat and species, undergo daily or prolonged torpor to minimize energy expenditure during periods of food and water scarcity. Duration of reproduction, number of litters per season and timing of births vary across individuals and species. The "polyestry-seasonality" hypothesis proposes that the duration of reproduction and number of litters per year are positively correlated with rainfall but negatively correlated with longevity, whereas the "hypervariability" hypothesis suggests that the duration of reproduction is negatively correlated with the degree of predictability of food resources. We test these hypotheses in two mouse lemur species inhabiting contrasting habitats, the brown mouse lemurs, Microcebus rufus, from Ranomafana (a less seasonal and more climatically predictable habitat) and the gray-brown mouse lemurs, M. griseorufus, from Beza Mahafaly (a more seasonal and less climatically predictable environment). We use capture/mark/recapture techniques and records of female reproductive status. We found evidence of polyestry at both study sites but faster population turnover and longer duration of the reproductive season at Beza Mahafaly. The "polyestry-seasonality" hypothesis is not supported but the "hypervariability" hypothesis could not be rejected. We conclude that reproductive output cannot be tied to climatic factors in a simple manner. Paradoxically, polyestry can be expressed in contrasting habitats: less seasonal forests where females can sustain multiple reproductive events, but also highly seasonal environments where females may not fatten sufficiently to sustain prolonged torpor but instead remain active throughout the year by relying on fallback resources. Am. J. Primatol. 77:936-947, 2015. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
| | | | - Laurie R Godfrey
- Department of Anthropology, University of Massachusetts, Amherst, Massachusetts
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Vuarin P, Dammhahn M, Kappeler PM, Henry PY. When to initiate torpor use? Food availability times the transition to winter phenotype in a tropical heterotherm. Oecologia 2015; 179:43-53. [PMID: 25953115 DOI: 10.1007/s00442-015-3328-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 04/18/2015] [Indexed: 11/24/2022]
Abstract
Timing of winter phenotype expression determines individual chances of survival until the next reproductive season. Environmental cues triggering this seasonal phenotypic transition have rarely been investigated, although they play a central role in the compensation of climatic fluctuations via plastic phenotypic adjustments. Initiation of winter daily torpor use-a widespread energy-saving phenotype-could be primarily timed according to anticipatory seasonal cues (anticipatory cues hypothesis), or flexibly fine-tuned according to actual energy availability (food shortage hypothesis). We conducted a food supplementation experiment on wild heterothermic primates (grey mouse lemurs, Microcebus murinus) at the transition to the food-limited dry season, i.e. the austral winter. As expected under the food shortage hypothesis, food-supplemented individuals postponed the seasonal transition to normal torpor use by 1-2 month(s), spent four times less torpid, and exhibited minimal skin temperature 6 °C higher than control animals. This study provides the first in situ experimental evidence that food availability, rather than abiotic cues, times the launching of torpor use. Fine-tuning of the timing of seasonal phenotypic transitions according to actual food shortage should provide heterotherms with a flexible adaptive mechanism to survive unexpected environmental fluctuations.
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Affiliation(s)
- Pauline Vuarin
- Mécanismes adaptatifs et Evolution (MECADEV UMR 7179), Sorbonne Universités, Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, 1 avenue du Petit Château, 91800, Brunoy, France,
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24
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Affiliation(s)
- M. B. Blanco
- Duke Lemur Center; Durham NC USA
- Department of Animal Ecology and Conservation; University of Hamburg; Hamburg Germany
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25
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Sommer S, Rakotondranary SJ, Ganzhorn JU. Maintaining microendemic primate species along an environmental gradient - parasites as drivers for species differentiation. Ecol Evol 2014; 4:4751-65. [PMID: 25558366 PMCID: PMC4278824 DOI: 10.1002/ece3.1311] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/10/2014] [Accepted: 10/10/2014] [Indexed: 11/07/2022] Open
Abstract
Understanding the drivers of species adaptations to changing environments on the one hand and the limits for hybridization on the other hand is among the hottest questions in evolutionary biology. Parasites represent one of the major selective forces driving host evolution and at least those with free-living stages are at the same time dependent on the ecological conditions of their host's habitat. Local immunological adaptations of host species to varying parasite pressure are therefore expected and might represent the genetic basis for ecological speciation and the maintenance of recently diverged species. Madagascar provides one of the rare examples where two partially sympatric primate species (Microcebus griseorufus, M. murinus) and their hybrids, as well as an allopatric species (M. cf rufus) live in close proximity along a very steep environmental gradient ranging from southern dry spiny bush to gallery forest to evergreen eastern humid rain forest, thus mimicking the situation encountered during extensions and retreats of vegetation formations under changing climatic conditions. This system was used to study parasite infection and immune gene (MHC) adaptations to varying parasite pressure that might provide selective advantages to pure species over hybrids. Parasite burdens increased with increasing humidity. M. griseorufus, M. murinus, and their hybrids but not M. rufus shared the same MHC alleles, indicating either retention of ancestral polymorphism or recent gene flow. The hybrids had much higher prevalence of intestinal parasites than either of the parent species living under identical environmental conditions. The different representation of parasites can indicate a handicap for hybrids that maintains species identities.
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Affiliation(s)
- Simone Sommer
- Evolutionary Genetics, Leibniz-Institute for Zoo- and Wildlife ResearchAlfred-Kowalke-Strasse 10, Berlin, 10315, Germany
- Institute for Experimental Ecology, University of UlmAlbert-Einstein Allee 11, Ulm, 89069, Germany
| | - Solofomalla Jacques Rakotondranary
- Department of Animal Ecology and Conservation, University of Hamburg, Biozentrum GrindelMartin-Luther-King Platz 3, Hamburg, 20146, Germany
| | - Jörg U Ganzhorn
- Department of Animal Ecology and Conservation, University of Hamburg, Biozentrum GrindelMartin-Luther-King Platz 3, Hamburg, 20146, Germany
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26
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Affiliation(s)
- Kathrin H. Dausmann
- Animal Ecology & Conservation Biocenter Grindel University Hamburg Hamburg Germany
| | - Julian Glos
- Animal Ecology & Conservation Biocenter Grindel University Hamburg Hamburg Germany
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27
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Affiliation(s)
- K. H. Dausmann
- Department of Animal Ecology and Conservation, Biocentre Grindel; University of Hamburg; Hamburg Germany
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Dausmann KH, Wein J, Turner JM, Glos J. Absence of heterothermy in the European red squirrel (Sciurus vulgaris). Mamm Biol 2013. [DOI: 10.1016/j.mambio.2013.01.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kamilar JM, Muldoon KM, Lehman SM, Herrera JP. Testing Bergmann's rule and the resource seasonality hypothesis in Malagasy primates using GIS-based climate data. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2012; 147:401-8. [PMID: 22271559 DOI: 10.1002/ajpa.22002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 11/22/2011] [Indexed: 11/06/2022]
Abstract
We tested four major hypotheses on the ecological aspects of body mass variation in extant Malagasy strepsirrhines: thermoregulation, resource seasonality/scarcity, resource quality, and primary productivity. These biogeographic hypotheses focus on the ecological aspects of body mass variation, largely ignoring the role of phylogeny for explaining body mass variation within lineages. We tested the independent effects of climate and resource-related variables on variation in body mass among Malagasy primates using recently developed comparative methods that account for phylogenetic history and spatial autocorrelation. We extracted data on lemur body mass and climate variables for a total of 43 species from 39 sites. Climatic data were obtained from the WorldClim database, which is based on climate data from weather stations compiled around the world. Using generalized linear models that incorporate parameters to account for phylogenetic and spatial autocorrelation, we found that diet and climate variables were weak predictors of lemur body mass. Moreover, there was a strong phylogenetic effect relative to the effects of space on lemur body mass in all models. Thus, we failed to find support for any of the four hypotheses on patterns of geography and body mass in extant strepsirrhines. Our results indicate that body mass has been conserved since early in the evolutionary history of each genus, while species diversified into different environmental niches. Our findings are in contrast to some previous studies that have suggested resource and climate related effects on body mass, though these studies have examined this question at different taxonomic and/or geographic scales.
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Affiliation(s)
- Jason M Kamilar
- Department of Anthropology, Yale University, New Haven, CT; Department of Anatomy, Midwestern University, Glendale, AZ, USA.
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Rakotondranary SJ, Ganzhorn JU. Habitat separation of sympatric Microcebus spp. in the dry spiny forest of south-eastern Madagascar. ACTA ACUST UNITED AC 2012; 82:212-23. [PMID: 22236872 DOI: 10.1159/000334816] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 10/26/2011] [Indexed: 01/16/2023]
Abstract
We investigated whether or not habitat structure contributes to the separation of two sister species of lemurs and their hybrids. For this, we studied Microcebus murinus and M. griseorufus along a continuous vegetation gradient where populations of the two species occur in sympatry or in allopatry. In allopatry, the two species are generalists without any sign of microhabitat selectivity. In sympatry, both species differed significantly and discriminated against certain habitat structures: M. murinus was found in microhabitats with larger trees than average while M. griseorufus utilized microhabitats with smaller trees. Hybrids between the two species did not show any significant discrimination for or against microhabitat structure and did not differ in their habitat utilization from either parent species. Both species can go into torpor and hibernation. M. griseorufus is seen more frequently during the cool dry season than M. murinus. We assume that M. murinus goes into extended torpor or hibernation more frequently than M. griseorufus. We interpret the different occurrence of large-sized trees in microhabitats of M. murinus as a prerequisite for M. murinus to be able to spend extended periods of time in tree holes that are isolated and allow hibernation at reduced temperature levels.
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Affiliation(s)
- S Jacques Rakotondranary
- Department of Animal Ecology and Conservation, University of Hamburg, Biozentrum Grindel, Hamburg, Germany.
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32
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Turner JM, Warnecke L, Körtner G, Geiser F. Opportunistic hibernation by a free-ranging marsupial. J Zool (1987) 2011. [DOI: 10.1111/j.1469-7998.2011.00877.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. M. Turner
- Department of Zoology; Centre for Behavioural and Physiological Ecology; University of New England; Armidale; NSW; Australia
| | - L. Warnecke
- Department of Zoology; Centre for Behavioural and Physiological Ecology; University of New England; Armidale; NSW; Australia
| | - G. Körtner
- Department of Zoology; Centre for Behavioural and Physiological Ecology; University of New England; Armidale; NSW; Australia
| | - F. Geiser
- Department of Zoology; Centre for Behavioural and Physiological Ecology; University of New England; Armidale; NSW; Australia
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Rakotondranary SJ, Struck U, Knoblauch C, Ganzhorn JU. Regional, seasonal and interspecific variation in 15N and 13C in sympatric mouse lemurs. Naturwissenschaften 2011; 98:909-17. [PMID: 21881908 DOI: 10.1007/s00114-011-0840-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 08/17/2011] [Accepted: 08/19/2011] [Indexed: 11/30/2022]
Abstract
Madagascar provides some of the rare examples where two or more primate species of the same genus and with seemingly identical niche requirements occur in sympatry. If congeneric primate species co-occur in other parts of the world, they differ in size in a way that is consistent with Hutchinson's rule for coexisting species, or they occupy different ecological niches. In some areas of Madagascar, mouse lemurs do not follow these "rules" and thus seem to violate one of the principles of community ecology. In order to understand the mechanisms that allow coexistence of sympatric congeneric species without obvious niche differentiation, we studied food composition of two identical sized omnivorous mouse lemur species, Microcebus griseorufus and M. murinus with the help of stable isotope analyses (δ(15)N and δ(13)C). The two species are closely related sister species. During the rich season, when food seems abundant, the two species do not differ in their nitrogen isotope composition, indicating that the two species occupy the same trophic level. But they differ in their δ(13)C values, indicating that M. griseorufus feeds more on C(4) and CAM (Crassulacean-acid-metabolism) plants than M. murinus. During the lean season, M. murinus has lower δ(15)N values, indicating that the two species feed at different trophic levels during times of food shortage. Hybrids between the two species showed intermediate food composition. The results reflect subtle differences in foraging or metabolic adaptations that are difficult to quantify by traditional observations but that represent possibilities to allow coexistence of species.
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Affiliation(s)
- S Jacques Rakotondranary
- Department of Animal Ecology and Conservation, University of Hamburg, Biozentrum Grindel, Martin-Luther-King Platz 3, 20146, Hamburg, Germany.
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McKechnie AE, Mzilikazi N. Heterothermy in Afrotropical mammals and birds: a review. Integr Comp Biol 2011; 51:349-63. [PMID: 21705792 DOI: 10.1093/icb/icr035] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Recent years have seen a rapid increase in the number of Afrotropical endotherms known to avoid mismatches between energy supply and demand by using daily torpor and/or hibernation. Among mammals, heterothermy has been reported in 40 species in six orders, namely Macroscelidea, Afrosoricida, Rodentia, Eulipotyphla, Primates and Chiroptera. These species span a range in body mass of 7-770 g, with minimum heterothermic body temperatures ranging from 1-27°C and bout length varying from 1 h to 70 days. Daily torpor is the most common form of heterothermy, with true hibernation being observed in only seven species, Graphiurus murinus, Graphiurus ocularis, Atelerix frontalis, Cheirogaleus medius, Cheirogaleus major, Microcebus murinus and Microcebus griseorufus. The traditional distinction between daily torpor and hibernation is blurred in some species, with free-ranging individuals exhibiting bouts of > 24 h and body temperatures < 16 °C, but none of the classical behaviours associated with hibernation. Several species bask in the sun during rewarming. Among birds, heterothermy has been reported in 16 species in seven orders, and is more pronounced in phylogenetically older taxa. Both in mammals and birds, patterns of heterothermy can vary dramatically among species occurring at a particular site, and even among individuals of a single species. For instance, patterns of heterothermy among cheirogalid primates in western Madagascar vary from daily torpor to uninterrupted hibernation for up to seven months. Other examples of variation among closely-related species involve small owls, elephant shrews and vespertilionid bats. There may also be variation in terms of the ecological correlates of torpor within a species, as is the case in the Freckled Nightjar Caprimulgus tristigma.
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Affiliation(s)
- Andrew E McKechnie
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa.
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Seasonal Changes in Feeding Ecology and Activity Patterns of Two Sympatric Mouse Lemur Species, the Gray Mouse Lemur (Microcebus murinus) and the Golden-brown Mouse Lemur (M. ravelobensis), in Northwestern Madagascar. INT J PRIMATOL 2011. [DOI: 10.1007/s10764-010-9488-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Terrien J, Perret M, Aujard F. Gender markedly modulates behavioral thermoregulation in a non-human primate species, the mouse lemur (Microcebus murinus). Physiol Behav 2010; 101:469-73. [DOI: 10.1016/j.physbeh.2010.07.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 05/28/2010] [Accepted: 07/26/2010] [Indexed: 10/19/2022]
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Blanco MB, Rahalinarivo V. First direct evidence of hibernation in an eastern dwarf lemur species (Cheirogaleus crossleyi) from the high-altitude forest of Tsinjoarivo, central-eastern Madagascar. Naturwissenschaften 2010; 97:945-50. [PMID: 20835697 DOI: 10.1007/s00114-010-0707-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 08/02/2010] [Accepted: 08/04/2010] [Indexed: 12/26/2022]
Abstract
The nocturnal dwarf lemurs of Madagascar (genus Cheirogaleus) are the only primates known to be obligate hibernators. Although the physiology of hibernation has been studied widely in the western, small-bodied species, Cheirogaleus medius, no direct evidence of hibernation, i.e., body temperature recordings, has been reported for any of the three recognized eastern dwarf lemur species. We present skin temperature data collected by external collar transmitters from two eastern dwarf lemur individuals (Cheirogaleus crossleyi) captured in the high-altitude forest of Tsinjoarivo, central-eastern Madagascar. Our study species is larger in body size than western dwarf lemurs and inhabits much colder environments. We present the first evidence of hibernation in an eastern dwarf lemur species, and we compare the results with data available for the western species. Although the hibernation period is shorter in dwarf lemurs from Tsinjoarivo, minimum body temperatures are lower than those reported for C. medius. Both individuals at Tsinjoarivo showed limited passive and extended deep hibernation during which they did not track ambient temperature as observed in most western dwarf lemurs. Because ambient temperatures at Tsinjoarivo never exceed 30°C, dwarf lemurs have to experience arousals to maintain homeostasis during periods of hibernation. We show that large dwarf lemurs (>400 g) are capable of undergoing deep hibernation and suggest that cold, high-altitude forests may render hibernation highly advantageous during periods of food scarcity. This study has implications for understanding the physiology of hibernation in small-bodied lemurs.
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Affiliation(s)
- Marina B Blanco
- Department of Anthropology, University of Massachusetts, 240 Hicks Way, Amherst, MA 01003, USA.
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Lahann P, Dausmann KH. Live fast, die young: flexibility of life history traits in the fat-tailed dwarf lemur (Cheirogaleus medius). Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1055-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Kobbe S, Ganzhorn JU, Dausmann KH. Extreme individual flexibility of heterothermy in free-ranging Malagasy mouse lemurs (Microcebus griseorufus). J Comp Physiol B 2010; 181:165-73. [PMID: 20717683 DOI: 10.1007/s00360-010-0507-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 06/23/2010] [Accepted: 07/29/2010] [Indexed: 11/30/2022]
Abstract
Flexibility in physiological processes is essential to adequately respond to changes in environmental conditions. Madagascar is a particularly challenging environment because climatic conditions seem less predictable than in comparative ecosystems in other parts of the world. We used the reddish-gray mouse lemur (Microcebus griseorufus) from the most unpredictable environment in Madagascar as a model to investigate the flexibility of energy saving strategies to cope with the unpredictability of their habitat. For this we measured T (sk) of free-ranging mouse lemurs throughout the year using temperature data loggers. M. griseorufus showed a very strong seasonal as well as an individual flexibility in thermoregulation. During the rainy season all M. griseorufus remained normothermic. At the beginning of the dry season individuals started to exhibit different energy saving strategies: irregular short torpor bouts, regular daily torpor, prolonged torpor of a few days, and hibernation over several weeks. The accumulation of sufficient seasonal body fat was the crucial factor determining the thermal behavior of individuals. The observed intraspecific and sex independent variation in thermoregulatory patterns within one population inhabiting the same small geographical area is exceptional and gives M. griseorufus the ability to respond to current environmental as well as individual conditions. This thermal plasticity might be seen as a key to success and survival for M. griseorufus in an extremely unpredictable environment.
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Affiliation(s)
- Susanne Kobbe
- Department of Animal Ecology and Conservation, Hamburg University, Biozentrum Grindel, Martin-Luther-King Platz 3, 20146 Hamburg, Germany.
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Stawski C, Geiser F. Seasonality of torpor patterns and physiological variables of a free-ranging subtropical bat. ACTA ACUST UNITED AC 2010; 213:393-9. [PMID: 20086123 DOI: 10.1242/jeb.038224] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Seasonal changes in weather and food availability differ vastly between temperate and subtropical climates, yet knowledge on how free-ranging subtropical insectivorous bats cope with such changes is limited. We quantified ambient temperatures, torpor patterns and thermal physiology of subtropical insectivorous northern long-eared bats, Nyctophilus bifax, during summer (n=13) and winter (n=8) by temperature telemetry. As predicted, ambient conditions varied significantly between seasons, with warmer weather during summer. All bats used torpor on 85% of observation days during summer in comparison to 100% during winter. During summer, patterns of torpor varied and the duration of torpor bouts was not significantly affected by ambient temperature, whereas during winter torpor bout duration was negatively correlated with mean ambient temperature. Mean torpor bout duration in summer was 3.2+/-1.3 h and in winter was 26.8+/-11.3 h. Mean arousal time during summer was in the early afternoon and during winter in the late afternoon, and throughout both seasons arousals for possible foraging periods occurred near sunset. Skin temperature was positively correlated with ambient temperatures in both seasons, but the relationship differed between seasons. We show that torpor is used regularly throughout the year in a free-ranging subtropical bat and provide the first evidence demonstrating that torpor patterns and thermal physiology change with season.
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Affiliation(s)
- C Stawski
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia.
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Terrien J, Zahariev A, Blanc S, Aujard F. Impaired control of body cooling during heterothermia represents the major energetic constraint in an aging non-human primate exposed to cold. PLoS One 2009; 4:e7587. [PMID: 19851464 PMCID: PMC2761491 DOI: 10.1371/journal.pone.0007587] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Accepted: 09/08/2009] [Indexed: 11/18/2022] Open
Abstract
Daily heterothermia is used by small mammals for energy and water savings, and seems to be preferentially exhibited during winter rather than during summer. This feature induces a trade-off between the energy saved during daily heterothermia and the energy cost of arousal, which can impact energy balance and survival under harsh environmental conditions. Especially, aging may significantly affect such trade off during cold-induced energy stress, but direct evidences are still lacking. We hypothesized that aging could alter the energetics of daily heterothermia, and that the effects could differ according to season. In the gray mouse lemur (Microcebus murinus), a non-human primate species which exhibits daily heterothermia, we investigated the effects of exposures to 25 and 12 degrees C on body composition, energy balance, patterns of heterothermia and water turnover in adult (N = 8) and aged animals (N = 7) acclimated to winter-like or summer-like photoperiods. Acclimation to summer prevented animals from deep heterothermia, even during aging. During winter, adult animals at 12 degrees C and aged animals at 25 degrees C exhibited low levels of energy expenditure with minor modulations of heterothermia. The major effects of cold were observed during winter, and were particularly pronounced in aged mouse lemurs which exhibited deep heterothermia phases. Body composition was not significantly affected by age and could not explain the age-related differences in heterothermia patterns. However, aging was associated with increased levels of energy expenditure during cold exposure, in concomitance with impaired energy balance. Interestingly, increased energy expenditure and depth of heterothermia phases were strongly correlated. In conclusion, it appeared that the exhibition of shallow heterothermia allowed energy savings during winter in adult animals only. Aged animals exhibited deep heterothermia and increased levels of energy expenditure, impairing energy balance. Thus, an impaired control of the heterothermic process induced high energy costs in the aging mouse lemur exposed to cold.
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Affiliation(s)
- Jeremy Terrien
- Mécanismes Adaptatifs et Evolution, UMR CNRS/MNHN 7179, Brunoy, France.
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Stawski C, Geiser F. Fat and fed: frequent use of summer torpor in a subtropical bat. Naturwissenschaften 2009; 97:29-35. [DOI: 10.1007/s00114-009-0606-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/20/2009] [Accepted: 08/23/2009] [Indexed: 10/20/2022]
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Kobbe S, Dausmann KH. Hibernation in Malagasy mouse lemurs as a strategy to counter environmental challenge. Naturwissenschaften 2009; 96:1221-7. [PMID: 19618156 DOI: 10.1007/s00114-009-0580-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 06/15/2009] [Accepted: 06/15/2009] [Indexed: 11/26/2022]
Abstract
The spiny forest of southwestern Madagascar is the driest and most unpredictable region of the island. It is characterized by a pronounced seasonality with high fluctuations in ambient temperature, low availability of food, and a lack of water during the cool dry season and, additionally, by changes in environmental conditions between years. One of the few mammalian species that manages to inhabit this challenging habitat is the reddish-gray mouse lemur (Microcebus griseorufus). The aim of our study was to determine whether this small primate uses continuous hibernation as an energy saving strategy, and if so, to characterize its physiological properties. We measured skin temperature of 16 free-ranging individuals continuously over 3 months during the cool dry season using collar temperature data loggers. Prolonged hibernation was found in three mouse lemurs and was not sex dependent (one male, two females). Skin temperature of hibernating individuals tracked ambient temperature passively with a minimum skin temperature of 6.5 degrees C and fluctuated strongly each day (up to 20 degrees C), depending on the insulation capacity of the hibernacula. Individuals remained in continuous hibernation even at an ambient temperature of 37 degrees C. The animals hibernated continuously during the dry season, and hibernation bouts were only interrupted by short spontaneous arousals. The study emphasizes that hibernation is an important measure to counter environmental challenge for more tropical species than previously thought, including primates. It furthermore provides evidence that tropical hibernation is functionally similar among tropical species.
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Affiliation(s)
- Susanne Kobbe
- Department of Animal Ecology and Conservation, Hamburg University, Biozentrum Grindel, Martin-Luther-King Platz 3, Hamburg, Germany.
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Hibernation and daily torpor minimize mammalian extinctions. Naturwissenschaften 2009; 96:1235-40. [DOI: 10.1007/s00114-009-0583-0] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 06/15/2009] [Accepted: 06/19/2009] [Indexed: 11/27/2022]
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Torpor and energetic consequences in free-ranging grey mouse lemurs (Microcebus murinus): a comparison of dry and wet forests. Naturwissenschaften 2009; 96:609-20. [PMID: 19229507 DOI: 10.1007/s00114-009-0515-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 02/03/2009] [Accepted: 02/03/2009] [Indexed: 10/21/2022]
Abstract
Many endotherms save energy during food and water shortage or unpredictable environment using controlled reductions in body temperature and metabolism called torpor. In this study, we measured energy metabolism and water turnover in free-ranging grey mouse lemurs Microcebus murinus (approximately 60 g) using doubly labelled water during the austral winter in the rain forest of southeastern Madagascar. We then compared patterns of thermal biology between grey mouse lemurs from the rain forest and a population from the dry forest. M. murinus from the rain forest, without a distinct dry season, entered daily torpor independent of ambient temperature (T (a)). There were no differences in torpor occurrence, duration and depth between M. murinus from the rain and dry forest. Mouse lemurs using daily torpor reduced their energy expenditure by 11% in the rain forest and by 10.5% in the dry forest, respectively. There was no significant difference in the mean water flux rates of mouse lemurs remaining normothermic between populations of both sites. In contrast, mean water flux rate of individuals from the dry forest that used torpor was significantly lower than those from the rain forest. This study represents the first account of energy expenditure, water flux and skin temperature (T (sk)) in free-ranging M. murinus from the rain forest. Our comparative findings suggest that water turnover and therefore water requirement during the austral winter months plays a more restricting role on grey mouse lemurs from the dry forest than on those from the rain forest.
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