title: Novel approaches to the calculation and comparison of thermoregulatory parameters: Non-linear regression of metabolic rate and evaporative water loss in Australian rodents.
abstract: The calculation and comparison of physiological characteristics of thermoregulation has provided insight into patterns of ecology and evolution for over half a century. Thermoregulation has typically been explored using linear techniques; I explore the application of non-linear scaling to more accurately calculate and compare characteristics and thresholds of thermoregulation, including the basal metabolic rate (BMR), peak metabolic rate (PMR) and the lower (Tlc) and upper (Tuc) critical limits to the thermo-neutral zone (TNZ) for Australian rodents. An exponentially-modified logistic function accurately characterised the response of metabolic rate to ambient temperature, while evaporative water loss was accurately characterised by a Michaelis-Menten function. When these functions were used to resolve unique parameters for the nine species studied here, the estimates of BMR and TNZ were consistent with the previously published estimates. The approach resolved differences in rates of metabolism and water loss between subfamilies of Australian rodents that haven't been quantified before. I suggest that non-linear scaling is not only more effective than the established segmented linear techniques, but also is more objective. This approach may allow broader and more flexible comparison of characteristics of thermoregulation, but it needs testing with a broader array of taxa than those used here.
authors.affiliation: Kings Park and Botanic Gardens, The Botanic Gardens and Parks Authority, Fraser Avenue, West Perth, WA 6005, Australia. Electronic address: sean.tomlinson@bgpa.wa.gov.au.
authors.forename: Sean
authors.initials: S
authors.lastname: Tomlinson
mesh_terms: D000465:Algorithms; D000818:Animals; D001315:Australia; D001481:Basal Metabolism; D001833:Body Temperature Regulation; D058865:Introduced Species; D012377:Rodentia / Q000502:physiology*; D013045:Species Specificity; D062125:Thermometry / Q000379:methods; D014870:Water Loss, Insensible
keywords: Basal metabolic rate; Evaporative water loss; Leggadina; Mus; Non-linear scaling; Notomys; Pseudomys; Rattus; Rodentia; Thermoregulation