title: Metabolic cold adaptation contributes little to the interspecific variation in metabolic rates of 65 species of Drosophilidae.
abstract: Metabolic cold adaptation (MCA) is a controversial hypothesis suggesting that cold adapted species display an elevated metabolic rate (MR) compared to their warm climate relatives. Here we test for the presence of MCA in 65 species of drosophilid flies reared under common garden conditions. MR was measured at both 10 and 20°C for both sexes and data were analyzed in relation to the natural thermal environment of these species. We found considerable interspecific variation in MR ranging from 1.34 to 8.99µWmg-1at 10°C. As predicted by Bergmann's rule body mass of fly species correlated negatively with annual mean temperature (AMT), such that larger species were found in colder environments. Because larger flies have a higher total MR we found MR to vary with AMT, however, after inclusion of mass as a co-variate we found no significant effect of AMT. Furthermore, we did not find that thermal sensitivity of MR (Q10) varied with AMT. Based on this broad collection of species we therefore conclude that there is no adaptive pattern of metabolic cold adaptation within drosophilid species ranging from sub-arctic to tropical environments.
authors.affiliation: Department of Bioscience, Aarhus University, DK-8000 Aarhus, Denmark; Faculty of Life Sciences, Manchester University, 46 Grafton Street, M13 9NT Manchester, England, United Kingdom.
authors.forename: Branwen
authors.initials: B
authors.lastname: Messamah
authors.affiliation: Department of Biological Sciences, Monash University, Clayton 3800, Australia.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Kellermann
authors.affiliation: Department of Bioscience, Aarhus University, DK-8000 Aarhus, Denmark.
authors.forename: Hans
authors.initials: H
authors.lastname: Malte
authors.affiliation: Department of Bioscience, Aarhus University, DK-8000 Aarhus, Denmark.
authors.forename: Volker
authors.initials: V
authors.lastname: Loeschcke
authors.affiliation: Department of Bioscience, Aarhus University, DK-8000 Aarhus, Denmark. Electronic address: johannes.overgaard@bios.au.dk.
authors.forename: Johannes
authors.initials: J
authors.lastname: Overgaard
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001481:Basal Metabolism; D003080:Cold Temperature; D018428:Drosophilidae / Q000378:metabolism*; D005260:Female; D008297:Male; D013045:Species Specificity
keywords: Bergmann’s rule; Cold tolerance; Fruit fly; Geographic distribution; Metabolism; Respirometry; Standard metabolic rate