Miyashita Tadashi
Laboratory of Forest Zoology, Faculty of Agriculture, University of Tokyo, Bunkyo-ku, 113, Tokyo, Japan.
Oecologia. 1992 Dec;92(3):339-342. doi: 10.1007/BF00317459.
Population parameters of the orb-web spider Nephila clavata were estimated at two sites with different spider densities (for 2 successive years at the high density site and 1 year at the low density site), and the relationship between survival rate and feeding conditions was examined. The rate of decrease of population density was almost constant over time and nearly the same at the two sites. Daily survival rate (sum of the effects of mortality and emigration) was low during August to early September and increased markedly thereafter. Daily immigration rate (number of immigrants/number of residents) was high during August to early September. Since there were strong negative correlations between survival and immigration rates, low survival rate seems to be caused by a high rate of emigration. Strong positive correlations were found between survival rate and feeding frequency (mean percent observed feeding). Analysis of covariance revealed that the parameters of the regression between survival rate and feeding frequency did not differ significantly among three occasions. These results suggest that feeding condition has a significant influence on dispersal activity of populations in this spider.
在两个蜘蛛密度不同的地点（高密度地点连续两年，低密度地点一年）估算了棒络新妇蜘蛛的种群参数，并研究了存活率与进食条件之间的关系。种群密度的下降速率随时间几乎保持恒定，且在两个地点几乎相同。8月至9月初的日存活率（死亡率和迁出率的综合影响）较低，此后显著增加。8月至9月初的日迁入率（迁入个体数/居民个体数）较高。由于存活率和迁入率之间存在很强的负相关，低存活率似乎是由高迁出率导致的。存活率与进食频率（观察到的平均进食百分比）之间发现了很强的正相关。协方差分析表明，三次观察中存活率与进食频率之间回归的参数没有显著差异。这些结果表明，进食条件对该蜘蛛种群的扩散活动有显著影响。
