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341.
Torpor and basking in a small arid zone marsupial 总被引:3,自引:3,他引:0
The high energetic cost associated with endothermic rewarming from torpor is widely seen as a major disadvantage of torpor.
We tested the hypothesis that small arid zone marsupials, which have limited access to energy in the form of food but ample
access to solar radiation, employ basking to facilitate arousal from torpor and reduce the costs of rewarming. We investigated
torpor patterns and basking behaviour in free-ranging fat-tailed dunnarts Sminthopsis crassicaudata (10 g) in autumn and winter using small, internal temperature-sensitive transmitters. Torpid animals emerged from their resting
sites in cracking soil at ∼1000 h with body temperatures as low as 14.6°C and positioned themselves in the sun throughout
the rewarming process. On average, torpor duration in autumn was shorter, and basking was less pronounced in autumn than in
winter. These are the first observations of basking during rewarming in S. crassicaudata and only the second direct evidence of basking in a torpid mammal for the reduction of energetic costs during arousal from
torpor and normothermia. Our findings suggest that although overlooked in the past, basking may be widely distributed amongst
heterothermic mammals. Therefore, the energetic benefits from torpor use in wild animals may currently be underestimated. 相似文献
342.
Many mammals save energy during food shortage or harsh weather using controlled reductions in body temperature and metabolism
called torpor. However, torpor slows offspring growth, and reproductive individuals are thought to avoid using it because
of reduced fitness resulting from delayed offspring development. We tested this hypothesis by investigating torpor during
reproduction in hoary bats (Lasiurus cinereus, Vespertilionidae) in southern Canada. We recorded deep, prolonged torpor bouts, which meet the definition for hibernation,
by pregnant females. Prolonged torpor occurred during spring storms. When conditions improved females aroused and gave birth
within several days. Our observations imply a fitness advantage of torpor in addition to energy conservation because reduced
foetal growth rate could delay parturition until conditions are more favourable for lactation and neonatal survival. 相似文献
343.
While other research has reported on the concentrations of (129)I in the environment surrounding active nuclear fuel reprocessing facilities, there is a shortage of information regarding how the concentrations change once facilities close. At the Hanford Site, the Plutonium-Uranium Extraction (PUREX) chemical separation plant was operating between 1983 and 1990, during which time (129)I concentrations in air and milk were measured. After the cessation of chemical processing, plant emissions decreased 2.5 orders of magnitude over an 8-year period. An evaluation of (129)I and (127)I concentration data in air and milk spanning the PUREX operation and post-closure period was conducted to compare the changes in environmental levels. Measured concentrations over the monitoring period were below the levels that could result in a potential annual human dose greater than 1 mSv. There was a measurable difference in the measured air concentrations of (129)I at different distances from the source, indicating a distinct Hanford fingerprint. Correlations between stack emissions of (129)I and concentrations in air and milk indicate that atmospheric emissions were the major source of (129)I measured in environmental samples. The measured concentrations during PUREX operations were similar to observations made around a fuel reprocessing plant in Germany. After the PUREX Plant stopped operating, (129)I concentration measurements made upwind of Hanford were similar to the results from Seville, Spain. 相似文献