Thermal acclimation and non-shivering thermogenesis in three species of South American rodents: a comparison between arid and mesic habitats

Nespolo, Roberto F.; Opazo, Juan C.; Bozinovic, Francisco

doi:10.1006/jare.2000.0778

Cited by 22 publications

(15 citation statements)

References 34 publications

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“…Among them, responses to warm experimental treatments include: lowered energy intake with no elevation-related differences (Hammond et al, 2001), increase in body weight and decrease in maximum and resting metabolic rate (Novoa et al, 2005;Nespolo and Rosenmann, 1997;Nespolo et al, 1999Nespolo et al, , 2001Antinuchi and Bush, 2000). As for Phyllotis, there is evidence of decrease in energy intake (Bozinovic and Nespolo, 1997), slowdown of digestion turnover time (Naya et al, 2005) and depressed thermogenic capacity when acclimated to 30 • C (Nespolo et al, 2001). Our results under this thermal treatment are strongly consistent with a decrease in energy expenditure, a slowdown in passage and digestive rates, a relatively small amount of feces produced and therefore an increase in the proportion of energy extracted from food.…”

Section: Discussionmentioning

confidence: 98%

Acclimating to thermal changes: Intraspecific variation in a small mammal from the Andes Mountains

Sassi

Novillo

2015

Mammalian Biology

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a b s t r a c tAmbient temperature strongly affects an ecosystem's characteristics as well as the attributes of individuals, eventually determining the distribution of populations and species. Phenotypic plasticity plays a central role in the administration of energy under thermal variation through traits underlying energy acquisition and expenditure. A powerful approach to assess acclimation ability to environmental variation is studying relevant traits along natural geographic gradients. Our goal was to assess and quantify in the small rodent Phyllotis xanthopygus, changes in traits relevant to energy balance in response to its thermal landscape. We compared energy intake and digestibility by animals from sites at different elevations under different temperatures in the laboratory. Results showed an increase in energy acquisition rates by the lower-elevation individuals to cope with low temperatures, while high-elevation animals appeared unaffected by this treatment. After acclimating to warmer conditions, all individuals showed a similar decrease in energy intake, irrespective of their origin site. We also assessed thermal conductance in individuals from different elevations and found that animals from higher sites exhibited lower heat loss rates. Our evidence suggests that heat conservation differences could in part account for differences among high and low elevation animals in the ability to cope with low temperatures. The lack of plasticity under the warm thermal treatment conforms to recent reports of high conservatism on the upper limit of the thermoneutral zone. P. xanthopygus displays intraspecific variation in the response to temperature, and we propose that this is highly relevant to model its chances in a warming environment.

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Section: Discussionmentioning

confidence: 98%

Acclimating to thermal changes: Intraspecific variation in a small mammal from the Andes Mountains

Sassi

Novillo

2015

Mammalian Biology

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“…This value is surprising, because it is similar to the smallest known value in mammals, which is found in the shrew Suncus ethruscus (0.23 μm), and similar to that of Mus musculus (0.29 μm) (Gehr et al, 1981). Since P. darwini is not a very small mammal and probably does not have particularly high energetic requirements compared to other mammals (see Nespolo et al 2001), we considered the possibility that the values measured were artificially diminished by the methods. In this case, the fixative and buffer used in this study would have produced a thickness barrier 6-24% thinner than the combination used by Gehr et al (1981( , for small mammals (Maina, 2002a).…”

Section: Figmentioning

confidence: 88%

Interplay between the morphometry of the lungs and the mode of locomotion in birds and mammals

et al. 2007

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We studied the lung diffusion parameters of two species of birds and two species of mammals to explore how structural and functional features may be paralleled by differences in life style or phylogenetic origin. We used two fast-flying species (one mammal and one bird), one running mammal and one bird species that flies only occasionally as models. The harmonic mean thickness of the air-blood barrier was very thin in the species we studied. An exception was the Chilean tinamou Notoprocta perdicaria, which only flies occasionally. It showed an air-blood barrier as thick as that of flightless Galliformes. We found that the respiratory surface density was significantly greater in flying species compared to running species. The estimated values for the oxygen diffusion capacity, D t O 2 follow the same pattern: the highest values were obtained in the flying species, the bat and the eared dove. The lowest value was in N. perdicaria. Our findings suggest that the studied species show refinements in their morphometric lung parameters commensurate to their energetic requirements as dictated by their mode of locomotion, rather than their phylogenetic origin. The air-blood barrier appears to be thin in most birds and small mammals, except those with low energetic requirements such as the Chilean tinamou. In the species we studied, the respiratory surface density appears to be the factor most responsive to the energetic requirements of flight.

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“…One approach often used in acclimation experiments is to acclimate for a 'standard' period (e.g. Heimer and Morrison, 1978;Nespolo et al, 2001a). That approach (with the implicit assumption of consistent response rates) could generate misleading conclusions if the kinetics of acclimation differed between individuals or among groups or species (see above).…”

Section: Individual Variation In V O∑max and Ventilatory Traitsmentioning

confidence: 99%

Cold-acclimation inPeromyscus: temporal effects and individual variation in maximum metabolism and ventilatory traits

Rezende

Chappell

Hammond

2004

Journal of Experimental Biology

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SUMMARYThermal acclimation in small endotherms provides an excellent model for the study of physiological plasticity, as energy requirements can be easily manipulated and the results are relevant for natural conditions. Nevertheless,how physiology changes throughout acclimation, and how individuals vary in their response to acclimation, remain poorly understood. Here we describe a high temporal-resolution study of cold acclimation in the deer mouse Peromyscus maniculatus. The experimental design was based on repeated measures at short intervals throughout cold acclimation, with controls(maintained at constant temperature) for measurement artifacts. We monitored body mass, maximum metabolic rate in cold exposure and ventilatory traits(respiratory frequency, tidal and minute volume and oxygen extraction) for 3 weeks at 23°C. Then, half of the individuals were held for 7 weeks at 5°C. Body mass was differently affected by cold acclimation depending on sex. Maximal metabolism(V̇O2max)increased significantly during the first week of cold acclimation, `overshot'after 5 weeks and dropped to a plateau about 34% above control values at week 7. Similarly, ventilatory traits increased during cold acclimation, though responses were different in their kinetics and magnitude. Body mass, maximum metabolism, and most ventilatory traits were repeatable after 7 weeks in control and cold-acclimated animals. However, repeatability tended to be lower in the cold-acclimated group, especially while animals were still acclimating. Our results show that acclimation effects may be under- and/or overestimated,depending on when trials are performed, and that different traits respond differently, and at different rates, to acclimation. Hence, future studies should be designed to ensure that animals have attained steady-state values in acclimation experiments.

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Thermal acclimation and non-shivering thermogenesis in three species of South American rodents: a comparison between arid and mesic habitats

Cited by 22 publications

References 34 publications

Acclimating to thermal changes: Intraspecific variation in a small mammal from the Andes Mountains

Acclimating to thermal changes: Intraspecific variation in a small mammal from the Andes Mountains

Interplay between the morphometry of the lungs and the mode of locomotion in birds and mammals

Cold-acclimation inPeromyscus: temporal effects and individual variation in maximum metabolism and ventilatory traits

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