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Mechanisms of density dependence in fluctuating vole populations.

田鼠种群波动中的密度依赖性机制。

基本信息

批准号：
14340240
负责人：
SAITOH Takashi
金额：
$ 8.77万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14340240/
关键词：
Rodents The grey-sided vole Clethrionomys rufocanus population Periodicity Cycle Density dependence Seasonality Synchronism

项目摘要

It is essential to analyze the relationship between seasonal and annual dynamics in order to understand multi-annual cycles observed in small mammal populations. Based on recent advances in time-series analyses of ecological dynamics using statistical and mathematical models, we analyzed the seasonal and annual density dependence structure in 189 populations of the gray-sided vole (Clethrionomys rufocanus Sundevall, 1846) in Hokkaido, Japan. Annual direct density dependence was strong in almost all populations. In contrast, delayed density dependence was generally weak, although clear delayed density dependence was detected in some of the studied populations. Although seasonal density-dependence was observed both in winter and summer, direct density dependence was much more profound during winter, thus, winter density dependence contributed most to the overall annual direct density dependence. We found no correlation between the seasonal components of annual delayed density dependence ; however corresponding seasonal components for annual delayed density dependence were positively correlated. We conclude that winter conditions influence the strength of annual direct density dependence most profoundly and that direct density dependence during summer and winter may be generated by different mechanisms, whereas delayed density dependence seems to be generated by a common mechanism.Annual density dependence was stronger in north-eastern populations than in south-western ones for both direct and delayed density dependence. The temperature of Hokkaido becomes lower toward north-east, because Hokkaido Island is heavily influenced by warm (west) and cold (east) sea currents. Thus this geographic gradient that populations in areas with longer winter exhibit stronger density dependence well corresponds to the above results that density dependence is stronger in winter than in summer.

为了理解在小型哺乳动物种群中观察到的多年周期，分析季节和年度动态之间的关系是至关重要的。根据统计和数学模型在生态动力学时间序列分析方面的最新进展，分析了日本北海道189个灰边田鼠种群的季节和年密度依赖结构。几乎所有种群的年直接密度依赖性都很强。相反，延迟密度依赖一般很弱，尽管在一些被研究的人群中检测到明显的延迟密度依赖。尽管冬季和夏季都观察到了季节密度依赖性，但冬季的直接密度依赖性要严重得多，因此，冬季密度依赖性对整个年度直接密度依赖性的贡献最大。我们发现，年延迟密度依赖的季节成分之间没有相关性；然而，相应的年度延迟密度依赖的季节成分是正相关的。我们得出结论：冬季条件对年直接密度依赖强度的影响最大，夏季和冬季的直接密度依赖可能是由不同的机制产生的，而延迟密度依赖似乎是由共同的机制产生的。无论是直接密度依赖还是延迟密度依赖，东北部种群的年密度依赖性都强于西南部种群。北海道的温度向东北方向变低，因为北海道岛受到温暖(西)和冷(东)海流的严重影响。因此，冬季较长地区的种群表现出较强的密度依赖性的这种地理梯度很好地对应了上述结果，即冬季的密度依赖性强于夏季。