### Seasonal dynamic of population survival and its mechanism in Mongolian gerbils (Meriones unguiculatus) in the Inner Mongolia agro-pastoral ecotone

LIU Wei 1,2，  ZHONG Wenqin 1， WANG Dehua 1,2

1. (1 State Key Lab of Integrated Management of Pest Insects and Rodent, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China)
（2 University of Chinese Academy of Science, Beijing 100049, China)
• Online:2020-12-01 Published:2020-12-03

### 内蒙古农牧交错带长爪沙鼠种群存活的季节格局及其动态机制

1. (1中国科学院动物研究所,农业虫鼠害综合治理研究国家重点实验室，北京 100101)
（2中国科学院大学，北京 100049）
• 通讯作者: 王德华 E-mail: wangdh@.ioz.ac.cn
• 基金资助:
国家自然科学基金项目（31872232）

Abstract:

Understanding differential and integral effects of climate and population density on vital rates e.g. survival, helps elucidate the ecological and demographic mechanisms underlying animal population dynamics.  The Mongolian gerbil (Meriones unguiculatus) is one of dominate rodents widely distributed in semi-arid, typical steppes, and desert grasslands in north of China.  We studied population dynamics of gerbils under semi-natural conditions using monthly capture–mark-recapture methods from October 2000 to 2004 in agro-pastoral ecotone of south-central Inner Mongolia, China. We used Cormack–Jolly–Seber (CJS) models to estimate apparent survival probability, and analyzed the difference of survival between males and females, or the survival seasonal variations.  Additionally, we used multistate （MS）models to test the difference of survival between adults with reproducing or reproduced strata and the sexually immature young.  Our results showed that the best approximating CJS model included the significant effect of full time（t）or season (month)- dependence on survival but not the effect of sex. These demonstrated that apparent survival probabilities displayed seasonal fluctuations of a lower apparent survival in summer compared to the rest of the year, and undistinguished survival between females( 0.788±0.013) and males (0.781±0.013）in the absence of limitation of environmental factors.  Our results also showed that the best and competition approximating MS model included age state (or stratum)-specific effect on apparent survival of
gerbils with a monthly (or seasonal) patterns. It may reflect the important life-history strategies adapting to the semi-arid or desert environment in Mongolian gerbils, Furthermore, there was evidence that population density negatively influenced survival with a time lag of 1 month in M. unguiculatus.  Considering the extrinsic environmental factors, increases in monthly total precipitation reduced the apparent survival of gerbils.  Moreover, these effects of population density-dependent and precipitation on the survival of female and male gerbils are different.  Therefore, we suggested that weather conditions may mainly mediate the change of habitable environment, supporting the optimum habitat hypothesis, and integrate density-dependent feedback to shape the different response of survival models between female and male gerbils.  These processes might construct an adaptive sexual-structure of population, and then affect the change of the other population parameters, consequently population growth rates. Pronounced a primary mechanism to regulate the small mammal’s population dynamic in northern high latitudes.