臺灣產龜殼花屬蛇類之溫度耐受度

Temperature tolerances of Trimeresurus snakes in Taiwan

黃思綿(Szu-Mien Huang)

指導教授 ： 杜銘章

國立臺灣師範大學/理學院/生物學系/碩士(2001年)

摘要

台灣產龜殼花屬（Trimeresurus）三種蛇類中，菊池氏龜殼花（T. gracilis）為台灣特有種，且僅分佈於海拔2000公尺以上的山區；而龜殼花（T. mucrosquamatus）及赤尾青竹絲（T. s. stejnegeri）則分佈在海拔2000公尺以下的地區。從台灣的生物地理來看，侷限分佈在高海拔的物種常是冰河期北方地理區系的孓遺物種，且爬行動物屬於外溫動物，環境溫度會直接影響到牠們的生理反應及行為能力。因此溫度可能是造成這些蛇在海拔上區隔分佈的主要因子之一，本研究並預期菊池氏龜殼花的高溫耐受度比龜殼花及赤尾青竹絲差；而後兩者的低溫耐受度比前者差。
當溫度高或低至使動物失去其正常行為能力時，該溫度點即為臨界溫度。本研究將採得的三種蛇先各自在10℃、20℃和30℃的溫度馴化兩星期，之後再進行臨界高溫（CTMax）和臨界低溫（CTMin）的檢測。CTMax的判斷標準為蛇出現張口行為；而當蛇失去翻正反應時，則記錄該溫度為CTMin。
結果顯示，三種蛇皆可透過馴化的方式提升其CTMax及降低其CTMin。菊池氏龜殼花的CTMax在冬天有低於其他兩種蛇的傾向，但夏天沒有此現象；而赤尾青竹絲的CTMin在冬夏兩季都高於菊池氏龜殼花，但龜殼花的CTMin則不一定高於菊池氏龜殼花，故結果只吻合我的部分預期，進一步檢視高低海拔的溫度資料與三種龜殼花的臨界溫度則發現低海拔的環境高溫（35.2℃）並未達到菊池氏龜殼花的CTMax（36.6℃），而三種蛇類在10℃馴化後雖都無法忍受高海拔冬季的地表低溫（2.7℃），但都能忍受地底下一公尺的溫度（6.1℃），故對環境溫度有立即反應的溫度耐受並不是造成台灣龜殼花屬三種蛇類在不同海拔區隔分佈的原因，然而環境溫度是否會經由長期影響蛇類生理表現而達到限制其海拔分佈的結果，還需進一步的實驗才能釐清。

關鍵字

龜殼花屬 ； 溫度耐受度 ； 海拔分佈 ； 臨界溫度最高值 ； 臨界溫度最低值

並列摘要

There are three species of Trimeresurus snakes in Taiwan. T. gracilis is the endemic species and it can be found only at an altitude above 2000 meters in Taiwan. Whereas, the other species, T. mucrosquamatus and T. s. stejnegeri inhabit under 2000 meters. In Taiwan, the species that restrict at highland are sometimes the glacial relics of the Paleartic zoogeographical region. Reptiles are ectotherms and temperature may directly affect their physiology and behaviors. Therefore, temperature may become one of the major factors that set the distribution limit of Trimeresurus snakes along different altitude in Taiwan. I predict the critical thermal maximum (CTMax) of T. gracilis is lower than that of T. mucrosquamatus and T. s. stejnegeri. On the other hand, the critical thermal minimum (CTMin) of the latters should higher than that of the former.
Critical temperatures are defined as the thermal points at which the locomotory activity of an animal becomes disorganized and it loses its ability to escape from conditions that will promptly lead to its death. From the ecological viewpoint, critical temperatures are the lethal temperatures. Before testing the CTMax and CTMin, all snakes are individually acclimated at 10℃, 20℃ and 30℃ for more than two weeks. The criterion of CTMax is panting, and that of CTMin is losing the righting responses.
When acclimation temperature is higher, both CTMax and CTMin in all three species become higher. The CTMax of T. gracilis is lower than that of T. mucrosquamatus and T. s. stejnegeri in winter, but not in summer. The CTMin of T. s. stejnegeri is higher than that of T. gracilis in both winter and summer. However, the CTMin of T. mucrosquamatus is not always higher than that of T. gracilis. Consequently, my prediction is only partially supported.
The CTMax (36.6℃) of T. gracilis when acclimated at 10℃ is higher than the highest mean temperature （35.2℃） in lowland nearby Chiai City. On the other hand, the CTMin acclimated at 10℃ of all three species are lower than the temperature (6.1℃) that under ground 1 meter nearby Tatachia, Nantou County. So, I conclude that thermal tolerance is not the main factor that set the distribution limit of Trimeresurus in Taiwan.

並列關鍵字

Trimeresurus ； temprature tolerance ； altitudinal distribution ； CTMax ； CTMin

參考文獻

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