title: Nonlinear temperature effects on multifractal complexity of metabolic rate of mice.
abstract: Complex physiological dynamics have been argued to be a signature of healthy physiological function. Here we test whether the complexity of metabolic rate fluctuations in small endotherms decreases with lower environmental temperatures. To do so, we examine the multifractal temporal scaling properties of the rate of change in oxygen consumptionr(VO2), in the laboratory mouseMus musculus, assessing their long range correlation properties across seven different environmental temperatures, ranging from 0 °C to 30 °C. To do so, we applied multifractal detrended fluctuation analysis (MF-DFA), finding thatr(VO2)fluctuations show two scaling regimes. For small time scales below the crossover time (approximately 102s), either monofractal or weak multifractal dynamics are observed depending on whetherTa< 15 °C orTa> 15 °C respectively. For larger time scales,r(VO2)fluctuations are characterized by an asymptotic scaling exponent that indicates multifractal anti-persistent or uncorrelated dynamics. For both scaling regimes, a generalization of the multiplicative cascade model provides very good fits for the Renyi exponentsτ(q), showing that the infinite number of exponentsh(q)can be described by only two independent parameters,aandb. We also show that the long-range correlation structure ofr(VO2)time series differs from randomly shuffled series, and may not be explained as an artifact of stochastic sampling of a linear frequency spectrum. These results show that metabolic rate dynamics in a well studied micro-endotherm are consistent with a highly non-linear feedback control system.
authors: Facultad de Ciencias, Universidad Santo Tomás, Santiago, Chile; Centro de Investigación e Innovación para el Cambio Climático, Universidad Santo Tomás, Santiago, Chile.
authors: Fabio A
authors: FA
authors: Labra
authors: Centro de Investigación e Innovación para el Cambio Climático, Universidad Santo Tomás, Santiago, Chile; Departamento de Ecología, Center of Applied Ecology & Sustainability (CAPES) and LINC-Global, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors: Jose M
authors: JM
authors: Bogdanovich
authors: Departamento de Ecología, Center of Applied Ecology & Sustainability (CAPES) and LINC-Global, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile , Santiago , Chile.
authors: Francisco
authors: F
authors: Bozinovic
keywords: Endothermy; Long-range correlations; Metabolic rate; Metabolic rate fluctuations; Multifractality; Mus musculus; Physiological complexity