年龄对布氏田鼠和长爪沙鼠能量代谢的影响

能量代谢对动物的存活和繁殖等生活史特征具有重要的调控作用.布氏田鼠(Lasiopodomys brandtii)和长爪沙鼠(Meriones unguiculatus)是内蒙古草原同域分布的两种啮齿动物,前者的体重和野外寿命要明显小于后者,这符合寿命随体型增大而增加的一般规律.本研究进一步探讨了随年龄增加,两种动物的能量代谢特征的改变.发现布氏田鼠的非颤抖性产热能力随年龄增加而降低,而长爪沙鼠的非颤抖性产热能力随年龄增加而保持稳定.布氏田鼠的摄食能力和身体脂肪储备随年龄增加而降低;而长爪沙鼠摄食能力不随年龄改变,脂肪储备则随年龄增加而增加.长爪沙鼠的基础代谢水平低于布氏田鼠,其繁殖成熟时间更长.本研究推测,这些随年龄而变的生理特征反映了两种动物不同的生活史对策:布氏田鼠更倾向于尽快繁殖,其他与生存相关的生理指标随年龄增加而迅速降低,而长爪沙鼠更倾向于将能量投资到较晚期的存活和繁殖.

Effect of Age on Energy Metabolism in Brandt＇s Voles （Lasiopodomys brandtii） and Mongolian Gerbils （Meriones unguiculatus）

Energy metabolism plays important roles in regulating life-history traits of animals, such as survival, reproduction and longevity. Previous studies have demonstrated the positive relation between body size and life span in Brandt＇s voles （Lasiopodomys brandtii） and Mongolian gerbils （Meriones unguiculatus）, both of which are distributed in the Inner Mongolian grasslands in China. With smaller body size, Brandt＇s voles exhibit higher metabolic rate and shorter life span than Mongolian gerbils. Thus, it is of great interest to explore the age-dependent effects on energy metabolism and life-history traits in these two species. In this study, we further investigated the effect of age on their energy metabolism. We found that nonshivering thermogenesis （NST） in Brandt＇s voles declined with age, while NST in Mongolian gerbils could hold steady. Similar decreasing patterns of food-intake and body fat content were also found in elder Brandt＇s voles. However, food-intake did not change in elder Mongolian gerbils, and their body fat storage increased with age. In addition, Mongolian gerbils exhibited lower resting metabolic rate （RMR） and later sexual maturity than Brandt＇s voles. These differences in physical characteristics imply that the two species developed distinct life-history strategies： Brandt＇s voles favored speeding up sexual maturity, at the cost of other physiological indexes that could affect survival with age. In contrast, Mongolian gerbils preferred late-maturing and extending lifespan.