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Journal of Comparative Physiology B

, Volume 180, Issue 5, pp 767–773 | Cite as

Bioenergetics of torpor in the Microbiotherid marsupial, Monito del Monte (Dromiciops gliroides): the role of temperature and food availability

  • Roberto F. Nespolo
  • Claudio Verdugo
  • Pablo A. Cortés
  • Leonardo D. Bacigalupe
Original Paper

Abstract

Torpor is the physiologically controlled reduction of metabolic rate and body temperature experienced by small birds and mammals when facing periods of low temperature and/or food shortage. In this study, we provide a first quantitative description of torpor in the relict marsupial Dromiciops gliroides by: (1) characterizing body temperature (T B) and torpor patterns, (2) evaluating the combined effects of ambient temperature and different levels of food restriction on torpor incidence and (3) exploring the metabolic depression during torpor. D. gliroides exhibited short bouts of torpor on a daily basis, during which T B decreased close to ambient temperature. During the active phase, T B also exhibited pronounced variation (range 34–38°C). In order to evaluate the consistency of torpor, we computed the repeatability of T B. Using the whole dataset, repeatability was significant (τ = 0.28). However, when torpid individuals were excluded from the analysis, repeatability was non-significant: some individuals were more prone to experience torpor than others. Our results indicate that this species also exhibits short bouts of daily torpor, whose depth and duration depends on the joint effects of T A and food availability. At T A = 20°C, the maximum torpor incidence was found at 70–80% food reduction, while at both extremes of the food continuum (100 and 0–10% food reduction) individuals were completely active, although considerable variation in T B was recorded. At T A = 10°C, individuals developed a deep form of torpor that was independent of the amount of food provided. On average, torpid D. gliroides reduced their metabolic rate up to 92% of their active values. In general, our results suggest that T A was the most immediate determinant of torpor, followed by energy availability.

Keywords

Torpor Repeatability Energetics Thermoregulation Dromiciops 

Notes

Acknowledgments

This work was funded by FONDECYT grant No 1090423. Animal maintenance and capture were performed according current Chilean law, and SAG permit No 444-2007. We would like to thank reviewers for comments that greatly improved the manuscript.

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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Roberto F. Nespolo
    • 1
  • Claudio Verdugo
    • 2
  • Pablo A. Cortés
    • 1
  • Leonardo D. Bacigalupe
    • 1
  1. 1.Facultad de Ciencias, Instituto de Ecología y EvoluciónUniversidad Austral de ChileValdiviaChile
  2. 2.Centro de Rehabilitación de Fauna Silvestre (CEREFAS), Facultad de Ciencias VeterinariasUniversidad Austral de ChileValdiviaChile

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