title: Similar metabolic rate-temperature relationships after acclimation at constant and fluctuating temperatures in caterpillars of a sub-Antarctic moth.
abstract: Temperature compensation in whole-animal metabolic rate is one of the responses thought, controversially, to characterize insects from low temperature environments. Temperature compensation may either involve a change in absolute values of metabolic rates or a change in the slope of the metabolic rate - temperature relationship. Moreover, assessments of compensation may be complicated by animal responses to fluctuating temperatures. Here we examined whole animal metabolic rates, at 0 °C, 5 °C, 10 °C and 15 °C, in caterpillars of the sub-Antarctic moth, Pringleophaga marioni Viette (Tineidae), following one week acclimations to 5 °C, 10 °C and 15 °C, and fluctuating temperatures of 0-10 °C, 5-15 °C, and 10-20 °C. Over the short term, temperature compensation was found following acclimation to 5 °C, but the effect size was small (3-14%). By comparison with caterpillars of 13 other lepidopteran species, no effect of temperature compensation was present, with the relationship between metabolic rate and temperature having a Q10 of 2 among species, and no effect of latitude on temperature-corrected metabolic rate. Fluctuating temperature acclimations for the most part had little effect compared with constant temperatures of the same mean value. Nonetheless, fluctuating temperatures of 5-15 °C resulted in lower metabolic rates at all test temperatures compared with constant 10 °C acclimation, in keeping with expectations from the literature. Absence of significant responses, or those of large effect, in metabolic rates in response to acclimation, may be a consequence of the unpredictable temperature variation over the short-term on sub-Antarctic Marion Island, to which P. marioni is endemic.
authors.affiliation: School of Biological Sciences, Monash University, Victoria 3800, Australia. Electronic address: steven.chown@monash.edu.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Chown
authors.affiliation: Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
authors.forename: Tanya M
authors.initials: TM
authors.lastname: Haupt
authors.affiliation: Department of Biology, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
authors.forename: Brent J
authors.initials: BJ
authors.lastname: Sinclair
mesh_terms: D000064:Acclimatization; D000818:Animals; D000864:Antarctic Regions; D004777:Environment; D007700:Kinetics; D009036:Moths / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature
keywords: Fluctuating temperatures; Lepidoptera; Metabolic rate; Polar environments; Temperature compensation