The relative importance of photoperiod and temperature as cues for seasonal acclimation of thermoregulation in pouched mice (Saccostomus campestris: Cricetidae) from southern Africa

G. T.H. Ellison, J. D. Skinner, A. Haim

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of short photoperiod and cold on metabolism and thermoregulation was investigated in pouched mice (Saccostomus campestris: Cricetidae) from three localities in southern Africa which experience contrasting climatic conditions. Mice were initially acclimated to long photoperiod (14L: 10D) at 25°C, followed first by a decline in photoperiod (to 10L: 14D) and then by a fall in temperature (to 10°C). Minimum observed metabolic rate (≡basal metabolic rate) was unaffected by the decline in photoperiod but increased significantly following cold acclimation. Because minimal thermal conductance remained constant throughout the study the increase in minimum observed metabolic rate caused a decline in lower critical temperature to around 26°C. In contrast to minimum observed metabolic rate, regulatory non-shivering thermogenesis improved significantly following the decline in both photoperiod and temperature. However, pouched mice from the warmest locality were significantly less responsive to photoperiod than those from the other two localities whose survival might depend upon their ability to accurately predict seasonal changes in temperature. Neither photoperiod nor temperature had any effect on body mass, yet pouched mice from the most arid locality, where food supply might be unpredictable, were significantly smaller and had lower total energy requirements than those from areas experiencing higher annual rainfall. These results indicate that S. campestris displays considerable geographical variation in energy requirements together with differences in the use of photoperiod as an anticipatory cue for predicting the onset of winter. These differences appear to be related to the availability of energy and the relative severity of climatic conditions in each locality.

Original languageEnglish
Pages (from-to)740-746
Number of pages7
JournalJournal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
Volume162
Issue number8
DOIs
StatePublished - Dec 1992
Externally publishedYes

Keywords

  • Geographical variation
  • Photoperiod
  • Pouched mouse, Saccostomus campestris
  • Seasonal acclimation
  • Thermoregulation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry
  • Physiology
  • Animal Science and Zoology
  • Endocrinology

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