151
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Bioenergetics of torpor in the microbiotherid marsupial, monito del monte (Dromiciops gliroides): the role of temperature and food availability. J Comp Physiol B 2010; 180:767-73. [PMID: 20165853 DOI: 10.1007/s00360-010-0449-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 01/21/2010] [Accepted: 01/23/2010] [Indexed: 10/19/2022]
Abstract
Torpor is the physiologically controlled reduction of metabolic rate and body temperature experienced by small birds and mammals when facing periods of low temperature and/or food shortage. In this study, we provide a first quantitative description of torpor in the relict marsupial Dromiciops gliroides by: (1) characterizing body temperature (T (B)) and torpor patterns, (2) evaluating the combined effects of ambient temperature and different levels of food restriction on torpor incidence and (3) exploring the metabolic depression during torpor. D. gliroides exhibited short bouts of torpor on a daily basis, during which T (B) decreased close to ambient temperature. During the active phase, T (B) also exhibited pronounced variation (range 34-38 degrees C). In order to evaluate the consistency of torpor, we computed the repeatability of T (B). Using the whole dataset, repeatability was significant (tau = 0.28). However, when torpid individuals were excluded from the analysis, repeatability was non-significant: some individuals were more prone to experience torpor than others. Our results indicate that this species also exhibits short bouts of daily torpor, whose depth and duration depends on the joint effects of T (A) and food availability. At T (A) = 20 degrees C, the maximum torpor incidence was found at 70-80% food reduction, while at both extremes of the food continuum (100 and 0-10% food reduction) individuals were completely active, although considerable variation in T (B) was recorded. At T (A) = 10 degrees C, individuals developed a deep form of torpor that was independent of the amount of food provided. On average, torpid D. gliroides reduced their metabolic rate up to 92% of their active values. In general, our results suggest that T (A) was the most immediate determinant of torpor, followed by energy availability.
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152
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Larivée ML, Boutin S, Speakman JR, McAdam AG, Humphries MM. Associations between over-winter survival and resting metabolic rate in juvenile North American red squirrels. Funct Ecol 2010. [DOI: 10.1111/j.1365-2435.2009.01680.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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153
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Biro PA, Beckmann C, Stamps JA. Small within-day increases in temperature affects boldness and alters personality in coral reef fish. Proc Biol Sci 2010; 277:71-7. [PMID: 19793748 PMCID: PMC2842624 DOI: 10.1098/rspb.2009.1346] [Citation(s) in RCA: 204] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Accepted: 09/08/2009] [Indexed: 11/12/2022] Open
Abstract
Consistent individual differences in behaviour, termed personality, are common in animal populations and can constrain their responses to ecological and environmental variation, such as temperature. Here, we show for the first time that normal within-daytime fluctuations in temperature of less than 3 degrees C have large effects on personality for two species of juvenile coral reef fish in both observational and manipulative experiments. On average, individual scores on three personality traits (PTs), activity, boldness and aggressiveness, increased from 2.5- to sixfold as a function of temperature. However, whereas most individuals became more active, aggressive and bold across temperature contexts (were plastic), others did not; this changed the individual rank order across temperatures and thus altered personality. In addition, correlations between PTs were consistent across temperature contexts, e.g. fish that were active at a given temperature also tended to be both bold and aggressive. These results (i) highlight the importance of very carefully controlling for temperature when studying behavioural variation among and within individuals and (ii) suggest that individual differences in energy metabolism may contribute to animal personality, given that temperature has large direct effects on metabolic rates in ectotherms.
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Affiliation(s)
- Peter A Biro
- Department of Environmental Science, and Institute for Water and Environmental Resource Management, University of Technology Sydney, Box 123, Broadway, NSW 2007, Australia.
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154
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Broggi J, Hohtola E, Koivula K, Orell M, Nilsson J�. Long-term repeatability of winter basal metabolic rate and mass in a wild passerine. Funct Ecol 2009. [DOI: 10.1111/j.1365-2435.2009.01561.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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155
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Williams TD, Vézina F, Speakman JR. Individually variable energy management during egg production is repeatable across breeding attempts. ACTA ACUST UNITED AC 2009; 212:1101-5. [PMID: 19329743 DOI: 10.1242/jeb.026815] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
It is axiomatic that whole-animal metabolism, measured for example as daily energy expenditure (DEE), plays a central role in determining reproductive success and survival (fitness) in all organisms. Nevertheless, strong evidence for consistent systematic relationships between DEE and either individual traits (age, sex, body size), environmental factors (e.g. food availability, temperature) or 'fitness' traits (e.g. number of offspring, survival) remains far from compelling in birds and mammals. Recently, we suggested that female birds might utilise complex, individually variable energy management strategies to meet the metabolic demands of reproduction, generating a wide spectrum of effects on reproductive DEE, from overcompensation (net decrease in DEE) to additive effects (net increase in DEE). Here we show that this individually variable adjustment or 'plasticity' in energy expenditure associated with egg production is repeatable among individuals between successive breeding attempts in female zebra finches (Taeniopygia guttata). Our study highlights the importance (a) of measuring 'plasticity' or change associated with transitions of physiological state (e.g. non-breeding to breeding) based on multiple measurements of the same individual, and (b) of extending consideration of how selection might drive the evolution of phenotypic plasticity per se to include physiological and metabolic traits.
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Affiliation(s)
- Tony D Williams
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, Canada, V5A 1S6.
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156
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157
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Boratyński Z, Koteja P. The association between body mass, metabolic rates and survival of bank voles. Funct Ecol 2009. [DOI: 10.1111/j.1365-2435.2008.01505.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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158
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Cortés P, Quijano SA, Nespolo RF. Bioenergetics and inter-individual variation in physiological capacities in a relict mammal - the Monito del Monte (Dromiciops gliroides). ACTA ACUST UNITED AC 2009; 212:297-304. [PMID: 19112149 DOI: 10.1242/jeb.021212] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In evolutionary physiology, studies of inter-individual variation (i.e. repeatability) in functional capacities are valuable as they indicate - within populations - what attributes could respond to natural selection. Although repeatability and quantitative genetics of physiological traits in energy metabolism of eutherian mammals have been well characterized, few or no studies have been performed on marsupials. We studied the repeatability (i.e. intraclass correlation coefficient, tau) of bioenergetics for Monito del Monte (Dromiciops gliroides), the sole living representative of an otherwise extinct marsupial order (Microbiotheria). We measured resting metabolic rate as CO(2) production (V(CO(2))) and O(2) consumption (V(O(2))) simultaneously, together with minimum thermal conductance (C), evaporative water loss (EWL) and respiratory quotient (RQ), in a sample of ca. 20 individuals. Our results suggest that D. gliroides exhibits poor control of body temperature (T(b)), with a thermal amplitude of ca. 10 degrees C in normothermia. As a consequence, repeatability of T(b) and metabolic rate (either as V(CO(2)) or V(O(2))) were relatively low (tau(T)(b)=0.25+/-0.04, tau(VCO2)=0.14+/-0.03, tau(V)(O2)=0.24+/-0.02, jackknife estimations of standard errors). Thermal conductance exhibited near-zero or negative repeatability and was lower than expected for marsupials. However, we found significant repeatability for RQ and EWL (tau=0.32+/-0.03 and 0.49+/-0.09, respectively). In general, these results suggest that Monito del Monte exhibits some ;reptilian' physiological characteristics. The relatively low repeatability of physiological variables, which otherwise exhibit large inter-individual and genetic variance in eutherian mammals, suggests that these capacities do not exhibit evolutionary potential in the ancient order Microbiotheria.
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Affiliation(s)
- Pablo Cortés
- Instituto de Ecología y Evolución, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
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159
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Artacho P, Nespolo R. Intrapopulation Variation in the Standard Metabolism of a Terrestrial Mollusc: Repeatability of the CO2Production in the Land SnailHelix aspersa. Physiol Biochem Zool 2009; 82:181-9. [DOI: 10.1086/590222] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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160
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Versteegh MA, Helm B, Dingemanse NJ, Tieleman BI. Repeatability and individual correlates of basal metabolic rate and total evaporative water loss in birds: A case study in European stonechats. Comp Biochem Physiol A Mol Integr Physiol 2008; 150:452-7. [DOI: 10.1016/j.cbpa.2008.05.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 05/12/2008] [Accepted: 05/12/2008] [Indexed: 10/22/2022]
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161
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Adolph SC, Pickering T. Estimating maximum performance: effects of intraindividual variation. J Exp Biol 2008; 211:1336-43. [DOI: 10.1242/jeb.011296] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYResearchers often estimate the performance capabilities of animals using a small number of trials per individual. This procedure inevitably underestimates maximum performance, but few studies have examined the magnitude of this effect. In this study we explored the effects of intraindividual variation and individual sample size on the estimation of locomotor performance parameters. We measured sprint speed of the lizard Sceloporus occidentalis at two temperatures (20°C and 35°C),obtaining 20 measurements per individual. Speed did not vary temporally,indicating no training or fatigue effects. About 50% of the overall variation in speed at each temperature was due to intraindividual variation. While speed was repeatable, repeatability decreased slightly with increasing separation between trials. Speeds at 20°C and 35°C were positively correlated,indicating repeatability across temperatures as well. We performed statistical sampling experiments in which we randomly drew a subset of each individual's full set of 20 trials. As expected, the sample's maximum speed increased with the number of trials per individual; for example, five trials yielded an estimate averaging 89% of the true maximum. The number of trials also influenced the sample correlation between mean speeds at 20°C and 35°C; for example, five trials yielded a correlation coefficient averaging 90% of the true correlation. Therefore, intraindividual variation caused underestimation of maximal speed and the correlation between speeds across temperatures. These biases declined as the number of trials per individual increased, and depended on the magnitude of intraindividual variation, as illustrated by running sampling experiments that used modified data sets.
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Affiliation(s)
- Stephen C. Adolph
- Department of Biology, Harvey Mudd College, 301 Platt Boulevard,Claremont, CA 91711, USA
| | - Trevor Pickering
- Department of Biology, Harvey Mudd College, 301 Platt Boulevard,Claremont, CA 91711, USA
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162
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163
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Gray EM, Chown SL. Bias, precision and accuracy in the estimation of cuticular and respiratory water loss: a case study from a highly variable cockroach, Perisphaeria sp. JOURNAL OF INSECT PHYSIOLOGY 2008; 54:169-179. [PMID: 17949739 DOI: 10.1016/j.jinsphys.2007.08.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 08/27/2007] [Accepted: 08/28/2007] [Indexed: 05/25/2023]
Abstract
We compared the precision, bias and accuracy of two techniques that were recently proposed to estimate the contributions of cuticular and respiratory water loss to total water loss in insects. We performed measurements of VCO2 and VH2O in normoxia, hyperoxia and anoxia using flow through respirometry on single individuals of the highly variable cockroach Perisphaeria sp. to compare estimates of cuticular and respiratory water loss (CWL and RWL) obtained by the VH2O-VCO2 y-intercept method with those obtained by the hyperoxic switch method. Precision was determined by assessing the repeatability of values obtained whereas bias was assessed by comparing the methods' results to each other and to values for other species found in the literature. We found that CWL was highly repeatable by both methods (R0.88) and resulted in similar values to measures of CWL determined during the closed-phase of discontinuous gas exchange (DGE). Repeatability of RWL was much lower (R=0.40) and significant only in the case of the hyperoxic method. RWL derived from the hyperoxic method is higher (by 0.044 micromol min(-1)) than that obtained from the method traditionally used for measuring water loss during the closed-phase of DGE, suggesting that in the past RWL may have been underestimated. The very low cuticular permeability of this species (3.88 microg cm(-2) h(-1) Torr(-1)) is reasonable given the seasonally hot and dry habitat where it lives. We also tested the hygric hypothesis proposed to account for the evolution of discontinuous gas exchange cycles and found no effect of respiratory pattern on RWL, although the ratio of mean VH2O to VCO2 was higher for continuous patterns compared with discontinuous ones.
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Affiliation(s)
- Emilie M Gray
- Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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164
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Russell GA, Rezende EL, Hammond KA. Development partly determines the aerobic performance of adult deer mice,Peromyscus maniculatus. J Exp Biol 2008; 211:35-41. [DOI: 10.1242/jeb.012658] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYPrevious studies suggest that genetic factors and acclimation can account for differences in aerobic performance(V̇O2max) between high and low altitude populations of small mammals. However, it remains unclear to what extent development at different oxygen partial pressures(PO2) can affect aerobic performance during adulthood. Here we compared the effects of development at contrasting altitudes versus effects of acclimation during adulthood on V̇O2max. Two groups of deer mice were born and raised for 5 weeks at one of two altitudes(340 and 3800 m above sea level). Then, a subset of each group was acclimated to the opposite altitude for 8 weeks. We measured V̇O2max for each individual in hypoxia (PO2=13.5 kPa, 14%O2 at 3800 m) and normoxia (PO2=20.4 kPa, 21% O2 at 340 m) to control for PO2 effects. At 5 weeks of age, high altitude born mice attained significantly higher V̇O2max than low altitude born mice (37.1% higher in hypoxia and 72.1% higher in normoxia). Subsequently, deer mice acclimated for 8 weeks to high altitude had significantly higher V̇O2max regardless of their birth site (21.0% and 72.9% difference in hypoxia and normoxia,respectively). A significant development × acclimation site interaction comparing V̇O2maxin hypoxia and normoxia at 13 weeks of age suggests that acclimation effects depend on development altitude. Thus, reversible plasticity during adulthood cannot fully compensate for developmental effects on aerobic performance. We also found that differences in aerobic performance in previous studies may have been underestimated if animals from contrasting altitudes were measured at different PO2.
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Affiliation(s)
- Gregory A. Russell
- Department of Biology, University of California at Riverside, Riverside, CA 92521, USA
| | - Enrico L. Rezende
- Integrative Ecology Group, Estación Biológica de Doñana,CSIC, Apdo. 1056, E-41080 Sevilla, Spain
| | - Kimberly A. Hammond
- Department of Biology, University of California at Riverside, Riverside, CA 92521, USA
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