种群密度调节是种群生态学的核心内容，过去的研究多限于外源性假说（例如食物和气候假说）和内源性假说（例如内分泌调节假说、遗传调节假说和行为领域假说），但有关肠道微生物在鼠类种群调节上的机制研究比较缺乏。随着高通量测序技术的发展，研究发现肠道微生物在宿主的生长、存活（免疫）和繁殖等方面上发挥了重要的调控作用。我们认为外因（食物、降雨和放牧）和内因（社会压力）均可通过肠道微生物的作用从而共同调节种群波动。外因通过改变动物的食物影响肠道微生物群落，而内因通过改变动物行为和激素影响肠道微生物群落。最终，肠道微生物通过影响个体适合度进而达到调节种群的作用。本项目结合野外观测实验和室内验证实验，研究布氏田鼠(Lasiopodomys brandtii) 肠道微生物对种群密度的响应及调控机制，探讨肠道微生物在种群动态中的作用。该研究有望为丰富发展鼠类种群调节理论和鼠类控制提供新的思路和方法。

Population regulation has always been a key theme in population ecology. Both extrinsic factors (e.g., food, predation and climate) and intrinsic factors, (e.g., social stress and dispersal behaviors) have been used to explain population fluctuations. Although gut microbes play a key role in individual’s growth, survival and reproduction, the role of gut microbes in population regulation is still poorly understood. We hypothesize that extrinsic and intrinsic factors can influence the gut microbes’ community and in turn these changes in gut microbes should regulate the population density by mediating individual’s growth, survivals and reproduction. In this study, by using both field enclosure and laboratory studies, we want to reveal the mechanisms of gut microbes in regulating the population of Brandt’s voles (Lasiopodomys brandtii) and provide novel theories or methods in population regulation and control of small rodents.