Thermodynamic Equilibria of Animals with Environment

Porter, Warren P.; Gates, David M.

doi:10.2307/1948545

Cited by 732 publications

(525 citation statements)

References 26 publications

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“…5). Climate space is typically considered in the four dimensions of air temperature, wind speed, radiation, and humidity (26). However, the inclusion of a morphometric axis in the climate space diagrams in Fig.…”

Section: Resultsmentioning

confidence: 99%

Size, shape, and the thermal niche of endotherms

Porter

Kearney

2009

Proc. Natl. Acad. Sci. U.S.A.

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218

232

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A key challenge in ecology is to define species' niches on the basis of functional traits. Size and shape are important determinants of a species' niche but their causal role is often difficult to interpret. For endotherms, size and shape define the thermal niche through their interaction with core temperature, insulation, and environmental conditions, determining the thermoneutral zone (TNZ) where energy and water costs are minimized. Laboratory measures of metabolic rate used to describe TNZs cannot be generalized to infer the capacity for terrestrial animals to find their TNZ in complex natural environments. Here, we derive an analytical model of the thermal niche of an ellipsoid furred endotherm that accurately predicts field and laboratory data. We use the model to illustrate the relative importance of size and shape on the location of the TNZ under different environmental conditions. The interaction between body shape and posture strongly influences the location of the TNZ and the expected scaling of metabolic rate with size at constant temperature. We demonstrate that the latter relationship has a slope of approximately 1 ⁄2 rather than the commonly expected surface area/volume scaling of 2 ⁄3. We show how such functional traits models can be integrated with spatial environmental datasets to calculate null expectations for body size clines from a thermal perspective, aiding mechanistic interpretation of empirical clines such as Bergmann's Rule. The combination of spatially explicit data with biophysical models of heat exchange provides a powerful means for studying the thermal niches of endotherms across climatic gradients.biophysical ecology ͉ functional traits ͉ lower critical temperature ͉ metabolic scaling ͉ thermoneutral zone T he ecological niche reflects the interaction between an organism and its environment and how that interaction affects its fitness (1, 2). An understanding of a species' niche requires knowledge of its traits (morphology, physiology, and behavior) and how that species interacts with its habitat to construct environments (2). This two-way interaction between organism and environment is also key to understanding how a species' traits, and hence its niche, evolves (3, 4). A species' energy and water balance are key determinants of its niche, reflecting both its requirements for life (Grinnellian niche) and its impact on the other species with which it interacts (Eltonian niche). Here, we illustrate how biophysical principles can be used to link variation in the size, shape, and other functional traits of organisms with environmental data to predict the thermal niches of endotherms. Such a model can be conceived as a mechanistic depiction of the Hutchinsonian niche, a hypervolume describing conditions suitable for survival, growth, and reproduction along trait and environmental axes. Biophysical models provide a way to calculate spatially explicit null models of selective pressures on functional traits from the perspectives of energy and water conservation (5).Basal metabolic rate ...

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Section: Resultsmentioning

confidence: 99%

Size, shape, and the thermal niche of endotherms

Porter

Kearney

2009

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

218

232

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“…A research field known as 'Biophysical Ecology' has developed to represent the 'climatic' niches of organisms in 'climate space' (Porter and Gates 1969). These models define the combinations of environmental variables that are suitable for survival and reproduction for a species, and have been applied at the scale of landscapes to predict the distribution, temperature, energy and water relations of organisms (Kearney and Porter 2009).…”

Section: Incorporating Abiotic Factorsmentioning

confidence: 99%

The nature of nutrition: a unifying framework

Simpson

Raubenheimer

2011

Aust. J. Zool.

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Abstract. We present a graphical approach, which we believe can help to integrate nutrition into the broader biological sciences, and introduce generality into the applied nutritional sciences. This 'Geometric Framework' takes account of the fact that animals need multiple nutrients in changing amounts and balance, and that nutrients come packaged in foods that are often hard to find, dangerous to subdue and costly to process. We then show how the Geometric Framework has been used to understand the links between nutrition and relevant aspects of the biology of individual animals. These aspects include the physiological mechanisms that direct the nutritional interactions of the animal with its environment, and the fitness consequences of these interactions. Having considered the implications of diet for individuals, we show that these effects can translate into the collective behaviour of groups and societies, and in turn ramify throughout food webs to influence the structure of ecosystems.

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“…Thermal Suitability.-The dynamics of thermal suitability were modeled using published models of mass-energy balance equations (Porter and Gates, 1969;Porter et al, 2002), with some modifications. We used on-site microclimatic data, available US 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Department of Defense GIS datasets, and principles of biophysical ecology (McCullough and Porter, 1971;Gates, 1980;Campbell and Norman, 1998) to develop a model of the relative amount of time habitat was suitable or unsuitable to horned lizard activity via operative temperature (Appendix A).…”

Section: Niche Variablesmentioning

confidence: 99%

“…Organisms are sensitive to their surrounding thermal landscape (Porter and Gates, 1969), and they routinely make decisions that trade-off with other behaviors, such trade-offs resulting from energetic costs and benefits (Huey and Slatkin 1976;Hertz et al, 1993;Angilletta, 2001;Guthery et al, 2005). Including spatially-explicit thermal data, which represent environmental conditions faced by organisms in the decision-making process of habitat selection, should increase the predictive power of model outputs.…”

Section: Introductionmentioning

confidence: 99%