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Individual (co)variation in thermal reaction norms of standard and maximal metabolic rates in wild-caught slimy salamanders
journal contribution
posted on 2014-10-01, 00:00 authored by Vincent Careau, M E Gifford, Peter BiroPeter BiroStandard metabolic rate (SMR) and maximal metabolic rate (MMR) are fundamental measures in ecology and evolution because they set the scope within which animals can perform activities that directly affect fitness. In ectotherms, both SMR and MMR are repeatable over time when measured at a single ambient temperature (Ta). Many ectotherms encounter variable Ta from day to day and over their lifetime, yet it is currently unknown whether individual differences hold across an ecologically relevant range of Ta (i.e. thermal repeatability; RT). Moreover, it is possible that thermal sensitivity of SMR and MMR are important individual attributes, and correlated with one another, but virtually nothing is known about this at present. We measured SMR and MMR across an ecologically relevant Ta gradient (i.e. from 10 to 25 °C) in wild-caught salamanders (Plethodon albagula) and found that RT was significant in both traits. SMR and MMR were also positively correlated, resulting in a lower RT in absolute and factorial aerobic scopes (AAS and FAS). We found significant individual differences in thermal sensitivity for both SMR and MMR, but not for AAS and FAS. The intercept (at Ta = 0 °C) and the slope of the thermal reaction norms were negatively correlated; individuals with low MR at low Ta had a higher thermal sensitivity. Finally, individuals with a high thermal sensitivity for SMR also had high thermal sensitivity for MMR. Our results suggest that natural selection occurring over variable Ta may efficiently target the overall level of - and thermal sensitivity in - SMR and MMR. However, this may not be the case for metabolic scopes, as the positive correlation between SMR and MMR, in addition to their combined changes in response to Ta, yielded little individual variation in AAS and FAS. Our results support the idea that organisms with low metabolism at low Ta have a high metabolic thermal sensitivity as a compensatory mechanism to benefit in periods of warmer environmental conditions. Hence, our study reveals the importance of considering within-individual variation in metabolism, as it may represent additional sources of adaptive (co)variation.
History
Journal
Functional ecologyVolume
28Issue
5Pagination
1175 - 1186Publisher
Wiley-Blackwell PublishingLocation
Oxford, EnglandPublisher DOI
ISSN
0269-8463eISSN
1365-2435Language
engPublication classification
C Journal article; C1 Refereed article in a scholarly journalCopyright notice
2014, Wiley-Blackwell PublishingUsage metrics
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No categories selectedKeywords
Activation energyBasal metabolic rateMetabolic cold adaptationPerformancePlasticity integrationQ10VO2-maxQ 10Science & TechnologyLife Sciences & BiomedicineEcologyEnvironmental Sciences & Ecology(10)JUVENILE ATLANTIC SALMONAEROBIC CAPACITY MODELOXYGEN-CONSUMPTIONENERGY-METABOLISMCOLD ADAPTATIONINTERINDIVIDUAL VARIATIONPHENOTYPIC PLASTICITYREPEATABILITYTEMPERATURE
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