ISSN:
1432-136X
Keywords:
Circadian rhythms
;
Activity
;
Metabolism
;
Photoresponsivity
;
Pouched mouseSaccostomus campestris
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract The daily activity and energy metabolism of pouched mice (Saccostomus campestris) from two localities in southern Africa was examined following warm (25 °C) and cold (10 °C) acclimation under long (LD 14:10) and short (LD 10:14) photoperiol. There was no differential effect of photoperiod on the daily activity or metabolism of pouched mice from the two localities examined, which suggests that reported differences in photoresponsivity between these two populations were not the result of differences in daily organisation. Neverthe-less, there was a significant increase in metabolism at 10 °C, irrespective of photoperiod, even though seven cold-acclimated animals displayed bouts of spontaneous torpor and saved 16.4–36.2% of their daily energy expenditure. All but one of these bouts occurred under short photoperiod, which suggests that short photoperiod facilitated the expression of torpor and influenced the daily energy metabolism of these individuals. As expected for a noctureal species, the amount of time spent active increased following acclimation to short photoperiod at 25 °C. However, there was a reduction in mean activity levels under short photoperiod at 10 °C, possibly because the stimulation of activity by short photoperiod was masked by a reduction in activity during bouts of spontaneous torpor. Cold temperature clearly had an overriding effect on the daily activity and metabolism of this species by necessitating an increase in metabolic heat production and eliciting spontaneous torpor which overrode the effect of short photoperiod on activity at an ambient temperature of 10 °C.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00714572
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