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在印度次大陆的亚热带地区,秋天冷而干燥,春天湿润。变温性果蝇所具有的抗干燥性有助于其度过较为干旱的气候条件。Drosophila jambulina具有体色二型性。已有研究表明,随湿度变化,D.jambulina热带种群始终保持体色多型性,这与热条件下体色黑化相反,且该热带物种中体色分化频率随季节性变化,这符合黑化-干燥假说。但是两种色型的D.jambulina产生这类气候适应的机理尚不明了。为了检验干燥相关性状生理基础的分化与对气候条件的色型特异性适应相关这一假说,我们利用分别在17℃和25℃、低湿(40%RH)和高湿(80%RH)条件下饲养获得的两种色型的D.jambulina,检测了其水分平衡对相对湿度、温度、及温湿度相互作用的反应。我们发现,在低相对湿度下,两种温度下饲养的深色型果蝇的生理和脱水性状数值显著高于浅色型。对两种色型果蝇的水分收支情况进行的比较分析表明,在低相对湿度下,深色型果蝇的含水量较高、水分损失率较低、抗脱水能力较强,使其具有更强的抗干燥性。在干燥胁迫过程中,两种色型的果蝇均以碳水化合物作为代谢燃料,但是在低湿条件下,深色果蝇中贮存碳水化合物的含量明显要高。而且,在两种湿度条件下,这两种色型果蝇之间的总能量收支显著不同。据此认为,D.jambulina的水分平衡相关性状表现出的色型特异性分化与其对湿热生境的适应相关。
In the sub-tropical Indian subcontinent, autumn is cold and dry, wet in spring. The anti-drying properties of variable-temperature flies help them weather more dry climatic conditions. Drosophila jambulina has body color dichroism. It has been shown that with the change of humidity, the D.jambulina tropical population always maintains the stereotypical pleomorphism, which is opposite to that of body color blackening under hot conditions, and the frequency of body color differentiation in this tropical species changes seasonally, which is in line with blackening - Drying hypothesis. However, the mechanism by which these two types of D.jambulina produce such climate adaptation is not known. In order to test the hypothesis that the physiological basis of dry-related traits is related to the color-specific adaptation to climatic conditions, we used a series of experiments at 17 ° C and 25 ° C, low humidity (40% RH) and high humidity (80% RH) D.jambulina, two color-type reared, was tested for its moisture balance response to relative humidity, temperature, and temperature-humidity interactions. We found that the physiological and dehydration traits of dark-colored flies kept at both temperatures were significantly higher than those of light-colored at low relative humidity. The comparative analysis of the moisture budget of the two color Drosophila showed that at low relative humidity, the dark color Drosophila had higher water content, lower moisture loss rate and stronger resistance to dehydration, Greater resistance to drying. During the dry stress, both types of fruit flies use carbohydrates as metabolic fuels, but the content of stored carbohydrates in dark flies is significantly higher under low humidity conditions. Moreover, under both humidity conditions, the total energy expenditure between the two color flies is significantly different. Therefore, it is concluded that the color-specific differentiation of D.jambulina’s water balance-related traits is related to its adaptation to hot and humid habitat.