Changes in body temperature influence the scaling of and aerobic scope in mammals

Gillooly, James F.; Allen, Andrew P.

doi:10.1098/rsbl.2006.0576

Cited by 26 publications

(37 citation statements)

References 20 publications

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“…First, as Gillooly & Allen (2007) themselves admit, their postulated effect of temperature on metabolic rate can explain only approximately 50% or less of the difference in b between the resting and maximally active conditions, if the most current and comprehensive datasets on mammals are examined (resting bZ0.68; active bZ0.87: see table 1). This is true even if the athletic species are removed from the sample (the scaling exponent for MMR is still relatively high: 0.85; Weibel et al 2004).…”

Section: Discussionmentioning

confidence: 99%

Effects of metabolic level on the body size scaling of metabolic rate in birds and mammals

2008

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Metabolic rate is traditionally assumed to scale with body mass to the 3/4-power, but significant deviations from the '3/4-power law' have been observed for several different taxa of animals and plants, and for different physiological states. The recently proposed 'metabolic-level boundaries hypothesis' represents one of the attempts to explain this variation. It predicts that the power (log-log slope) of metabolic scaling relationships should vary between 2/3 and 1, in a systematic way with metabolic level. Here, this hypothesis is tested using data from birds and mammals. As predicted, in both of these independently evolved endothermic taxa, the scaling slope approaches 1 at the lowest and highest metabolic levels (as observed during torpor and strenuous exercise, respectively), whereas it is near 2/3 at intermediate resting and coldinduced metabolic levels. Remarkably, both taxa show similar, approximately U-shaped relationships between the scaling slope and the metabolic (activity) level. These predictable patterns strongly support the view that variation of the scaling slope is not merely noise obscuring the signal of a universal scaling law, but rather is the result of multiple physical constraints whose relative influence depends on the metabolic state of the organisms being analysed.

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Section: Discussionmentioning

confidence: 99%

Effects of metabolic level on the body size scaling of metabolic rate in birds and mammals

2008

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“…In some cases, these deviations have been predicted by MTE in multicellular plants (West et al 1999b, Enquist et al 2007) and animals (West et al 1997). For example, with respect to mammals, Gillooly and Allen (2007) recently showed that the steeper size‐dependence of maximum metabolic rate is attributable to greater increases in muscle temperature for large mammals (e.g.>6°C for a horse) than for small mammals (e.g.<1°C for a rat) during exercise. In other cases, deviations from ¾ power scaling are expected, but have not yet been integrated into the theory.…”

Section: Individual‐level Mechanismsmentioning

confidence: 99%

The mechanistic basis of the metabolic theory of ecology

Allen¹,

Gillooly²

2007

Oikos

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We welcome the opportunity to respond to . We hope that this exchange will help to clarify some of the strengths and weaknesses of the Metabolic theory of ecology (MTE), and will point towards fruitful areas for future research.The MTE has been formulated based on the premise that the structure and dynamics of ecological communities are inextricably linked to individual metabolism. The individual metabolic rate is the rate at which an organism takes up energetic and material resources from the environment, transforms them into useable forms, and allocates them to the fitness-enhancing processes of survival, growth, and reproduction. Interactions between organisms and their environment (including other organisms) are therefore constrained by metabolic rate. Physiologists have long known that there are three primary factors that control metabolic rate: body size, body temperature, and resource availability. MTE builds on this earlier work by providing a quantitative framework to better understand how these three variables combine to affect metabolic rate, and how metabolic rate, in turn, influences the ecology and evolution of populations, communities, and ecosystems (Brown et al. 2004).Gillooly et al. (2001) developed a model for the scaling of metabolic rate that combines the effects of body size and temperature (West et al. 1997, Gillooly et al. 2002, Charnov and Gillooly 2003, Brown et al. 2004. The model leads to a single equation for individual metabolic rate:where b o is a normalization constant, M is body mass, and T is absolute temperature in degrees Kelvin. The size-dependence, M 3/4 , is attributed to geometric constraints on the delivery of energy and materials to cells through biological distribution networks (West et al. 1997). The Boltzmann-Arrhenius term, e (E=kT ; characterizes the exponential effect of temperature, where E is the average activation energy of the respiratory complex (Â0.65 eV), and k is Boltzmann's constant (8.62 )10(5 eV K (1 ) (Gillooly et al. 2006). This simple analytical expression yields quantitative predictions on metabolic rate that are supported by empirical data for a broad assortment of taxonomic groups (Gillooly et al. 2001). raise issues with the MTE that deserve attention and/or clarification. These issues can be divided into two major points of contention: (1) they argue that the proposed mechanisms underlying the size-and temperature-dependencies of individual metabolic rate in Eq. 1 are invalid; and (2) that attempts to link individual metabolic rate to higher levels of biological organization (populations, communities, ecosystems) using MTE are overly simplistic and should therefore be abandoned. Here we respond to these criticisms, and then conclude by discussing the philosophical issues that underlie them. Points of contention

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“…An example of when the choice of FAS or AAS may affect interpretation of results is when aerobic scope is compared across a range of body sizes and life stages (Bishop 1999;Gillooly and Allen 2007;Glazier 2009;Weibel and Hoppeler 2005). Relatively few studies have quantified changes in both SMR and MMR over orders of magnitude of body sizes for a single species (Brett 1965;Clark et al 2012;Killen et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Exploring key issues of aerobic scope interpretation in ectotherms: absolute versus factorial

Halsey

Killen

Clark

et al. 2018

Rev Fish Biol Fisheries

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Aerobic scope represents an animal's capacity to increase its aerobic metabolic rate above maintenance levels (i.e. the difference between standard (SMR) and maximum (MMR) metabolic rates). Aerobic scope data can be presented in absolute or factorial terms (AAS or FAS, respectively). However, the robustness of these calculations to noise or variability in measures of metabolic rate can influence subsequent interpretations of patterns in the data. We explored this issue using simple models and we compared the predictions from these models to experimental data from the literature. First, we investigated the robustness of aerobic scope calculations as a function of varying SMR when MMR is fixed, and vice versa. While FAS is unexpectedly robust to variability in SMR, even in species with low aerobic scopes, AAS is less sensitive to variation in SMR than is FAS. However, where variation in MMR is the main concern, FAS is more robust than AAS. Our findings highlight the equal importance of minimising variability in MMR, rather than just the variability in SMR, to obtain robust aerobic scope estimates. Second, we analysed metabolic rate accounting for locomotor speed and body mass for swimming fish. The interactions among these factors in relation to AAS and FAS are complex and the appropriate metric is dependent on the specific ecophysiological context of the research question. We conclude with qualified recommendations for using and interpreting AAS and FAS.

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Changes in body temperature influence the scaling of and aerobic scope in mammals

Cited by 26 publications

References 20 publications

Effects of metabolic level on the body size scaling of metabolic rate in birds and mammals

Effects of metabolic level on the body size scaling of metabolic rate in birds and mammals

The mechanistic basis of the metabolic theory of ecology

Exploring key issues of aerobic scope interpretation in ectotherms: absolute versus factorial

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