【摘 要】
：
本文总结了橙腹田鼠(Microtus ochrogaster)和草原田鼠(M. pennsylvanicus)25年的种群统计学研究结果和结论.探讨了田鼠种群波动周期性、诱发种群波动以及导致波动期间峰值变
【机 构】
：
Department of Animal Biology
论文部分内容阅读
本文总结了橙腹田鼠(Microtus ochrogaster)和草原田鼠(M. pennsylvanicus)25年的种群统计学研究结果和结论.探讨了田鼠种群波动周期性、诱发种群波动以及导致波动期间峰值变异的因素.并对种群存活值和繁殖活动的作用进行了分析和评价.根据两种田鼠种群波动周期性、波动峰值出现的时间以及特定年份峰值的高度等特征,证明两物种波动均具有不稳定性.两种田鼠存活值的变化是由特定年份是否发生波动以及波动峰值出现的时间决定.增加初始阶段的种群密度及时间长度是造成两种动物种群波动峰值不同的主要原因.橙腹田鼠种群停止增长的原因是存活值降低,而草原田鼠则是繁殖活动减少.据推测,与种群波动初始密度相关的种群死亡率的差异是由捕食者的净效应(Net effect)决定的,调控两种群密度的因素均为非密度的其它生态学因子.由于特定年份田鼠种群捕食压力的不确定性,导致了橙腹田鼠和草原田鼠种群波动的不稳定性.
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