Phenotypic flexibility of metabolic rate and evaporative water loss does not vary across a climatic gradient in an Afrotropical passerine bird

dc.contributor.authorNoakes, Matthew J.
dc.contributor.authorMcKechnie, Andrew E.
dc.contributor.emailandrew.mckechnie@up.ac.zaen_ZA
dc.date.accessioned2020-11-09T10:29:19Z
dc.date.issued2020-04
dc.description.abstractSmall birds inhabiting northern temperate and boreal latitudes typically increase metabolic rates during cold winters or acclimation to low air temperatures (Taccl). Recent studies suggest considerable variation in patterns of seasonal metabolic acclimatization in birds from subtropical and tropical regions with milder winters, but there remains a dearth of acclimation studies investigating metabolic flexibility among lower-latitude birds. We used short-term thermal acclimation experiments to investigate phenotypic flexibility in basal metabolic rate (BMR), thermoneutral evaporative water loss (EWL) and summit metabolism (Msum) in three populations of white-browed sparrow-weavers (Plocepasser mahali) along a climatic and aridity gradient. We allocated individuals to one of three Taccl treatments (5, 20 and 35°C; n=11 per population per Taccl) for 28 days, and measured post-acclimation BMR, EWL and Msum using flow-through respirometry. Our data reveal the expected pattern of lower BMR and EWL (∼12% and 25% lower, respectively) in birds at Taccl=35°C compared with cooler Taccl treatments, as observed in previous acclimation studies on subtropical birds. We found no variation in the reaction norms of BMR and EWL among populations in response to acclimation, suggesting previously documented differences in seasonal BMR acclimatization are the result of phenotypic flexibility. In contrast to higher-latitude species,Msum did not significantly vary in response to thermal acclimation. These findings support the idea that factors other than enhancing cold tolerance may be driving patterns of metabolic variation in subtropical birds.en_ZA
dc.description.departmentZoology and Entomologyen_ZA
dc.description.embargo2021-04-09
dc.description.librarianam2020en_ZA
dc.description.sponsorshipThe DST-NRF Centre of Excellence at the FitzPatrick Institute and the National Research Foundation of South Africa.en_ZA
dc.description.urihttp://jeb.biologists.orgen_ZA
dc.identifier.citationNoakes, M.J. & McKechnie, A.E. 2020, 'Phenotypic flexibility of metabolic rate and evaporative water loss does not vary across a climatic gradient in an Afrotropical passerine bird', Journal of Experimental Biology, vol. 223, no. 7, pp. 1-9.en_ZA
dc.identifier.issn0022-0949 (print)
dc.identifier.issn1477-9145 (online)
dc.identifier.other10.1242/jeb.220137
dc.identifier.urihttp://hdl.handle.net/2263/76935
dc.language.isoenen_ZA
dc.publisherCompany of Biologistsen_ZA
dc.rights© 2020. Published by The Company of Biologists Ltd.en_ZA
dc.subjectAdaptive plasticityen_ZA
dc.subjectReaction normen_ZA
dc.subjectAcclimationen_ZA
dc.subjectSubtropical birdsen_ZA
dc.subjectSummit metabolism (Msum)en_ZA
dc.subjectBasal metabolic rate (BMR)en_ZA
dc.subjectEvaporative water loss (EWL)en_ZA
dc.subjectWhite-browed sparrow-weavers (Plocepasser mahali)en_ZA
dc.titlePhenotypic flexibility of metabolic rate and evaporative water loss does not vary across a climatic gradient in an Afrotropical passerine birden_ZA
dc.typeArticleen_ZA

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