Department of Bioscience, Aarhus University, Building 131, 8000, Aarhus C, Denmark,
J Comp Physiol B. 2014 Feb;184(2):167-77. doi: 10.1007/s00360-013-0788-6. Epub 2013 Oct 24.
Geographic variation in cold tolerance and associated physiological adaptations were investigated in the freeze tolerant enchytraeid Enchytraeus albidus (Oligochaeta). Specimens from Svalbard, Greenland (Nuuk), Iceland (Hólar and Mossfellsbær) and continental Europe [Norway (Bergen), Sweden (Kullen) and Germany] were reared in the laboratory in a common-garden experiment. The aim was to test for variations in minimum lethal temperature, freeze duration tolerance, carbohydrate reserves and metabolic rate among the populations. Cold tolerance was related to environmental temperature of the respective location. Populations from the coldest climatic regions were able to tolerate freezing down to at least -15 °C and endured being frozen at -5 °C for 27-48 days, respectively. Populations from milder climates had a lower freeze duration tolerance (about -9 °C) and endured -5 °C for a shorter period (between 9 and 16 days). Glucose accumulation and glycogen reserves varied significantly between populations, but was not related directly to cold tolerance. Metabolic rate varied significantly between populations, but was not significantly related to cold tolerance. The metabolic rates at -2 °C of frozen and unfrozen worms from Germany and Svalbard were tested. The metabolic depression due to freezing of these populations was relatively small (<50 %), suggesting that the large carbohydrate accumulations may also be important as fuel during long-term freezing at moderately low temperatures. Differences in metabolic depression may partly explain the difference in cold tolerance of these two populations, however, the mechanisms behind local adaptation to low winter temperatures in these enchytraeid populations seem more complex than earlier studies have indicated.
抗寒性的地理变异及其相关的生理适应在耐寒的真蚓科（Enchytraeus albidus）中进行了研究。来自斯瓦尔巴群岛（挪威）、格陵兰（努克）、冰岛（霍拉和莫斯费尔斯拜尔）和欧洲大陆（挪威卑尔根、瑞典库伦和德国）的标本在实验室中进行了共同饲养实验。目的是测试种群之间的最低致死温度、冻结持续时间耐受性、碳水化合物储备和代谢率的变化。耐寒性与各自位置的环境温度有关。来自最寒冷气候区的种群能够耐受至少-15°C的冻结，并能耐受-5°C长达 27-48 天的冻结。来自较温暖气候区的种群具有较低的冻结持续时间耐受性（约-9°C），并且在-5°C下的耐受时间较短（9-16 天）。葡萄糖积累和糖原储备在种群之间存在显著差异，但与抗寒性没有直接关系。代谢率在种群之间存在显著差异，但与抗寒性没有显著关系。测试了来自德国和斯瓦尔巴群岛的冷冻和未冷冻蠕虫在-2°C 时的代谢率。这些种群由于冻结而导致的代谢抑制相对较小（<50％），这表明大量碳水化合物的积累也可能在中低温下长期冻结期间作为燃料很重要。代谢抑制的差异可能部分解释了这两个种群抗寒性的差异，然而，这些真蚓种群对冬季低温的适应的机制似乎比早期研究表明的更为复杂。
