Body Insulation of Some Arctic and Tropical Mammals and Birds

Scholander, P. F.; Walters, Vladimir; Hock, Raymond J.; Irving, Laurence

doi:10.2307/1538740

Cited by 526 publications

(258 citation statements)

References 3 publications

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“…S1) (not reported in the original study). The only major deviations of our model from the empirical data were for the northern collared lemming and the least weasel, which required core body temperatures lower than those reported (25) for a close match (32°C vs. 37°C).…”

Section: Resultsmentioning

confidence: 69%

“…Scholander et al (24,25) provided an extensive dataset on the LCTs of a wide range of mammalian taxa ranging in size from 0.05 to 12 kg (Fig. 4A), with small animals such as the white fox (4.5 kg) obtaining LCTs well below Ϫ20°C as a result of their fur properties.…”

Section: Resultsmentioning

confidence: 99%

“…We tested our model predictions in this article against field and laboratory metabolic measurements of a variety of mammalian taxa (12,20,24,25,45) (Figs. 1 and 5 and Fig.…”

Section: Methodsmentioning

confidence: 99%

“…For comparison against the Chappell (12, 45) data we used ratios for a:b,c of 5 for weasels and 3 for other taxa (Table S1), which provided a good match with observed diameters and surface areas. For comparisons against the Scholander et al (24,25) data, no postural data were available and so we used a:b, c ratios of 1.5 Table 1 (curled) and 4.5 (standing) ( Table 1). A key parameter not measured for the individuals used in the Brown and Lasiewski and Scholander et al studies was the thermal conductivity of the fur.…”

Section: Methodsmentioning

confidence: 99%

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Size, shape, and the thermal niche of endotherms

Porter

Kearney

2009

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

229

250

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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: 69%

Section: Resultsmentioning

confidence: 99%

“…We tested our model predictions in this article against field and laboratory metabolic measurements of a variety of mammalian taxa (12,20,24,25,45) (Figs. 1 and 5 and Fig.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Size, shape, and the thermal niche of endotherms

Porter

Kearney

2009

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

229

250

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“…For a reindeer with similarly soaked fur, actual heat loss may be less than observed in this study. Scholander (1950) suggested animals would shake off excess water, restoring some of the trapped air layer and insulation value of their fur. Therefore, the present results for soaked fur samples may be maximums.…”

Section: Simulated Heavy Rainmentioning

confidence: 99%

Rain more important than windchill for insulation loss in Svalbard reindeer fur

Cuyler

Øritsland

2004

Ran

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Heat transfer through dry and wet Svalbard reindeer (Rangifer tarandus platyrhynchus) summer and winter midback fur samples was studied in a wind tunnel. A light wetting water spray simulated heavy fog, mist or light rain, while heavy soaking simulated heavy rain. Wind velocities ranged from 0 to 10 m . s -1 . Calf fur samples were from June, August and March. Adult fur samples were females from August and March. There was no evidence for increased heat loss from lightly wet fur relative to dry fur. Calm air conductance decreased for calf fur (P's < 0.05). Adult fur also decreased, however, the difference was not significant (P > 0.05). Further, wind coefficients and regressions for lightly wet fur were similar or below those for dry fur. A thin water film forming on the fur surface may have caused this. It is unlikely that a light rain, fog or mist would cause increased heat loss for Svalbard reindeer, and no increase of metabolic heat production would be needed to maintain thermoregulation. Only the simulated heavy rain dramatically raised heat loss from the fur samples examined regardless of age or season, e.g., heavy soaking increased calm air conductance for all furs (P's < 0.05). This was likely due to the addition of evaporative heat loss from the fur surface and a reduction in the amount of trapped air within the fur. Windchill was of minor importance, since wind coefficients were generally close to zero, meaning increasing wind velocity only marginally raised heat loss even with the added effect of evaporative heat loss. Rain would cause greater insulation loss than increasing wind velocity in Svalbard reindeer of all ages, with the exception of calves under one month old, which could experience dramatic insulation loss from a combination of heavy rain and windchill. Dry or wet, Svalbard reindeer fur appears to provide better insulation than fur of others of their species.

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Effects of seasonality and fasting on the plasma leptin and thyroxin levels of the raccoon dog (Nyctereutes procyonoides) and the blue fox (Alopex lagopus)

2001

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Plasma leptin and thyroxin concentrations of eleven raccoon dogs and eleven blue foxes were monitored for 6 months. Half of the animals were placed on a 3‐week fast in November. Leptin levels were low in summer, but in October they rose significantly. In November, leptin concentrations decreased rapidly within a week although the body mass of the animals remained stable. There were no significant differences between experimental groups for raccoon dogs, but in blue foxes the fasting group had lower leptin levels than the control group. High thyroxin levels in summer decreased as autumn progressed, but thyroxin concentrations of the fasting groups increased at the end of the fast. Leptin levels of the raccoon dog and the blue fox are not determined only by the fat reserves of the animals, but they seem to reflect the autumnal deposition of fat at the onset of winter. Blue foxes have metabolic rates of active animals during the winter and higher leptin levels in December than raccoon dogs. The superficially hibernating raccoon dogs have low leptin levels after the onset of winter perhaps as an adaptation to fasting. J. Exp. Zool. 289:109–118, 2001. © 2001 Wiley‐Liss, Inc.

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Body Insulation of Some Arctic and Tropical Mammals and Birds

Cited by 526 publications

References 3 publications

Size, shape, and the thermal niche of endotherms

Size, shape, and the thermal niche of endotherms

Rain more important than windchill for insulation loss in Svalbard reindeer fur

Effects of seasonality and fasting on the plasma leptin and thyroxin levels of the raccoon dog (Nyctereutes procyonoides) and the blue fox (Alopex lagopus)

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