布氏田鼠是我国内蒙古东部草原的主要害鼠之一，具有明显的季节性繁殖特征。本研究于2013年采集内蒙古东乌珠穆沁旗草原繁殖盛期（6－7月）和末期（8月）的布氏田鼠，比较了种群组成和繁殖器官的季节特点。结果表明，从繁殖盛期到末期，越冬鼠比例呈现下降趋势，当年鼠比例逐渐上升。不同年龄、性别的布氏田鼠存在明显的繁殖状态上的差异：与当年出生个体相比，越冬鼠参与繁殖时间长，在整个繁殖期都参与繁殖，是繁殖期尤其是繁殖早期种群繁殖的主力；与雄鼠相比，当年出生雌鼠会更多参与繁殖，在6月中旬的繁殖盛期，当年生雌鼠的怀孕率达39％，而当年雄鼠未参与繁殖。这些结果表明，不同性别、不同时期出生的布氏田鼠采取了不同的繁殖策略，体现为各自在种群繁殖中的贡献不同，因此在分析其暴发成灾机制时应考虑种群中性别和年龄组成。%Brandt’s vole (Lasiopodomys brandtii )is one of the main pest rodents with overt characteristics of sea-sonal breeding in eastern Inner Mongolia grassland.In present study,we compared the age structure and reproduc-tive organ weight of Brandt’s voles captured in peak (June to July)and end (August)period of breeding season from East Ujimqin Banner,Xilingol league area of Inner Mongolia.Our results showed that the ratio of overwin-ter voles was decreasing from June to August,while the ratio of newborn individuals was increasing.Reproductive status of Brandt’s voles with different ages and genders showed significant differences.Compared with newborn individuals,overwinter voles keep the high reproductive activity around the whole breeding season especially in early breeding season.Compared with newborn males,more newborn females took part in reproduction and the ratio of pregnant newborn females was higher to 39% in June,while development status of reproductive organs in-dicated no newborn males participated in reproduction at this stage.Those results suggest that Brandt’s voles with different gender and birth time take different reproduction strategies,which give different contributions to popu-lation reproduction.Therefore,the gender and age structure of population should be important factors to be paid more attention during research of rodent outbreak mechanism.
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