关键词: 种群密度, 密度制约, 皮质酮, 根田鼠

Abstract: The proximate causation of density-dependence is not clear so far. Social stress may be related to density-dependence.To examine this hypothesis,we experimentally investigated the effects of population density on demography and individual corticosterone levels during the breeding period in root voles (Microtus oeconomus). We established replicate root vole populations at high and low densities in 4 field enclosures (50 m × 30 m)at the Haibei Research Station of Alpine Meadow Ecosystem,the Chinese Academy of Sciences,and tested the effects of population density on recruitment rate, survival rate,and rate of population change,as well as on individuals corticosterone level. The results showed that high density caused a lower rate of recruitment and a rate of population change. Significant linear regression relationship between the rate of population change,the rate of recruitment and founder number respectively were found. However,survival rate of founders or offspring were not different between high and low densities. In addition,under high density conditions root voles exhibited an increase in corticosterone level and spleen index. We conclude that the rate of recruitment and rates of change in population is density-dependent,which is only induced by founder numbers. The density dependence is related to social stress responses of individuals. The social stress may be a proximate causation to induce density dependence in population of root voles.

Key words: Corticosterone, Density-dependence, Population density, Root vole