刺鼠(Niviventer coxingi)及高山白腹鼠(Niviventer culturatus)溫度生理與其海拔分佈之比較

Abstract

溫度生理的適應是影響動物海拔分佈的因數之一，其中能代表溫度生理的特質包括基礎代謝率(Basal metabolic rate, BMR)、溫度中性區(Thermal neutral zone, TNZ)及耐受溫度(Critical temperature)等。刺鼠(Niviventer coxingi)與高山白腹鼠(Niviventer culturatus)同屬於囓齒目(Rodentia)中的鼠科(Muridae)白腹鼠屬(Niviventer)，刺鼠主要分佈於中低海拔，而高山白腹鼠則出現在中高海拔地區。本實驗之目的是比較刺鼠與高山白腹鼠溫度生理的異同，並討論其對兩種鼠類海拔分佈的影響。 實驗對象主要是1998年九月到2000年四月間不同季節取自南投梅峰的高山白腹鼠與臺北陽明山的刺鼠，另外亦有從觀霧、棲蘭、阿里山及梅蘭林道等中海拔地區捕捉零星個體，共84隻刺鼠與高山白腹鼠，測量的項目包括代謝率，TNZ及CTmax (maximum critical temperature)等。 實驗結果發現高山白腹鼠的代謝率有明顯的季節性變化，而刺鼠代謝率的季節變化不明顯；春夏季時高山白腹鼠的代謝率較刺鼠低，但秋冬時高山白腹鼠的代謝率會高過刺鼠。刺鼠的TNZ範圍較寬(8℃)，高山白腹鼠較窄(6℃)，且TNZ高點都以刺鼠為高，呈現出刺鼠的溫度適應性較強及高山白腹鼠較不適應高溫環境的特徵，在CTmax與體溫的比較上，刺鼠也表現出對高溫有較佳的適應能力。由此推測環境溫度過高對高山白腹鼠來說是一項限制因數。

Thermal physiology, e.g. basal metabolic rate (BMR), thermal neutral zone (TNZ) and critical temperature, can be an important factor that influence the altitudinal distribution of animals. In Taiwan, Niviventer coxingi lives at low to middle altitude, whereaver N. culturatus a congener lives at high to middle altitude. They may live sympatrically at altitude of l500?2000m. This study was designed to compare their thermal physiology and to examine how this may affect in their altitudinal distribution. The animals used in this study were captured at Nantou Hsien Mei-feng farm (N. culturatus) and Yangmeanshan (N. coxingi) in different seasons from Sept 1998 to Apr. 2000. A few others were captured in Kuan-wu, Chilan, Alishan and Meilan. Altogether 84 rats were used. This animals were measured for their metabolic rate, TNZ and CTmax (maximum critical temperature). The results indicated that the BMR varies significantly with season in N. culturatus but not in N. coxingi. In spring and summer, the BMR of N. culturatus is lower than that of N. coxing, but it is reverse in fall and winter. The TNZ of N. coxingi (8℃) are wider than N. culturatus(6℃), and the high temperature of TNZ in N. coxingi is always higher than that of N. culturatus .These results indicate that N. coxingi can adapt to higher temperature, but not N. culturatus . Some results were shown in CTmax and body temperature. According to these results, the high environment temperature may be a limiting factor in altitudinal distribution of N. culturatus.