橙腹田鼠中延缓性密度依赖效应和种群波动

检验了延迟的密度依赖对橙腹田鼠 (Microtusochrogaster)一个波动种群的生存和生殖的影响 ,研究持续了 63个月 ,取样间隔为 3 5天。在研究期间 ,该种群的密度经历了 4次波动 ,每次波动的高峰都在 11月至次年 1月 ,种群数量在冬季下降。生存和生殖都有负面的密度依赖效应 ,最大效应具有 2个月的时滞。种群存活率增长对种群密度最大的正面效应具有 2个月的时滞 ,而对与增加生殖则有 3个月的时滞。内部因素和冬季都可能推延对生殖的密度依赖效应 ,但是本文未能检验这些内部因素的影响。季节性影响看来与对生存的延缓性密度依赖效应无关。负面的延缓性密度依赖效应对生存和生殖的净作用可能在于减少、而不是阻止橙腹田鼠种群波动的幅度

Delayed density-dependent effects and population fluctuations in the prairie vole Microtus ochrogaster

We tested for delayed density-dependent effects on survival and reprod uction in a fluctuating population of the prairie vole Microtus ochrogaster monitored at 3 5-day intervals for 63 months. The population underwent four fluctuations in density during the study; all peaked November-January, with wi n ter declines. Survival and reproduction displayed negative density-dependent e f fects, with an approximate 2-month lag time for maximum effects. There was a 2 - month lag for maximum positive effects of increased survival on population densi ty and a 3-month lag in respect to increased reproduction. Extrinsic factors, w inter, may have been involved in the delayed density-dependent effects on repro d uction, but we could not test for role of intrinsic factors. Seasonal effects d id not appear to be responsible for the delayed density-dependent effects on su rvival. The net effect of the negative delayed density-dependent effects on su rvival and reproduction are suggested to moderate amplitudes, but not prevent, p opulation fluctuations of M ochrogaster