Mzilikazi Nomakwezi, Lovegrove Barry G
School of Botany and Zoology, University of KwaZulu-Natal, Private Bag X01, Scottsville, South Africa.
Physiol Biochem Zool. 2004 Mar-Apr;77(2):285-96. doi: 10.1086/381470.
Under laboratory conditions, rock elephant shrews, Elephantulus myurus, use daily torpor under both short and long photoperiod acclimation. However, use of heterothermy often differs under field and laboratory conditions. We investigated the use of torpor in free-ranging elephant shrews from May 2001 to May 2002. The elephant shrews were capable of daily torpor throughout the year, with torpor most prevalent during winter. We recorded two torpor bouts during early summer (November). We recorded a total of 467 torpor bouts during the year. The mean torpor minimum body temperature (Tbmin) for the whole year was 15.3 degrees +/-4.4 degrees C, and the mean bout length was 8.6+/-3.5 h. These values were in the range expected for daily heterotherms. However, there was some marginal overlap with hibernation characteristics; a few torpor bouts were longer than 24 h in duration, and Tbmin decreased below 10 degrees C. Torpor was highly correlated with low ambient temperature and photoperiod. Torpor was also correlated with invertebrate abundance after controlling for photoperiod effects. During the year in which this study was conducted, the rainfall was 14% below long-term average. Historical rainfall records show that summer rainfall during strong El Nino years is up to 40% below the long-term average. During these drought years, the frequency of summer torpor may be higher, highlighting the need for long-term physiological data in free-ranging animals.
在实验室条件下，岩象鼩（Elephantulus myurus）在短期和长期光周期适应下都会每日进入蛰伏状态。然而，在野外和实验室条件下，异温性的使用情况往往有所不同。我们在2001年5月至2002年5月期间对自由放养的象鼩的蛰伏情况进行了调查。象鼩全年都能够每日进入蛰伏状态，蛰伏在冬季最为普遍。我们在初夏（11月）记录到了两次蛰伏发作。全年共记录到467次蛰伏发作。全年蛰伏时的平均最低体温（Tbmin）为15.3摄氏度+/-4.4摄氏度，平均发作时长为8.6+/-3.5小时。这些数值处于每日异温动物预期的范围内。然而，与冬眠特征存在一些边缘重叠；少数蛰伏发作持续时间超过24小时；最低体温降至10摄氏度以下。蛰伏与低环境温度和光周期高度相关。在控制光周期影响后，蛰伏也与无脊椎动物的丰富度相关。在进行本研究的这一年，降雨量比长期平均水平低14%。历史降雨记录显示，强厄尔尼诺年的夏季降雨量比长期平均水平低达40%。在这些干旱年份，夏季蛰伏的频率可能更高，这凸显了获取自由放养动物长期生理数据的必要性。
