北美地区的雪兔－猞猁种群数量10年周期性波动一直是种群生态学中研究的一个热点，并且在生态学教科书中一直被用作猎物-捕食者相互作用形成种群周期振荡的经典案例。中科院动物研究所农业动物生态研究组严川等通过分析长期数据发现：一，与传统的猎物－捕食模型不同，雪兔与猞猁之间存在非对称性的猎物－捕食者效应，即雪兔对猞猁为直接正作用，而猞猁对雪兔的负作用有两年时滞；二，密度制约及猎物－捕食者作用仅能产生阻尼式振荡，而气候的驱动对于周期性波动的产生及持续具有重要作用；三，温度没有直接作用，北半球温度与北大西洋涛动指数通过降雨及降雪负作用于猞猁种群，而南方涛动指数通过降雨正作用猞猁种群；四，气温变暖可能导致近期猞猁周期性波动减弱或消失。
该研究结果说明：猎物-捕食者相互作用不是形成种群周期振荡的充分必要条件，气候对种群周期性波动起着不可或缺的作用；全球气候变暖可导致种群周期波动消失（生物谷Bioon.com）。
生物谷推荐的英文摘要
Global Change Biology doi: 10.1111/gcb.12321
Linking climate change to population cycles of hares and lynx
Yan C， Stenseth NC， Krebs CJ， Zhang Z
The classic 10-year population cycle of snowshoe hares (Lepus americanus， Erxleben 1777) and Canada lynx (Lynx canadensis， Kerr 1792) in the boreal forests of North America has drawn much attention from both population and community ecologists worldwide； however， the ecological mechanisms driving the 10-year cyclic dynamic pattern are not fully revealed yet. In this study， by the use of historic fur harvest data， we constructed a series of generalized additive models to study the effects of density dependence， predation， and climate (both global climate indices of North Atlantic Oscillation index (NAO)， Southern Oscillation index (SOI) and northern hemispheric temperature (NHT) and local weather data including temperature， rainfall， and snow). We identified several key pathways from global and local climate to lynx with various time lags： rainfall shows a negative， and snow shows a positive effect on lynx； NHT and NAO negatively affect lynx through their positive effect on rainfall and negative effect on snow； SOI positively affects lynx through its negative effect on rainfall. Direct or delayed density dependency effects， the prey effect of hare on lynx and a 2-year delayed negative effect of lynx on hare (defined as asymmetric predation) were found. The simulated population dynamics is well fitted to the observed long-term fluctuations of hare and lynx populations. Through simulation， we find density dependency and asymmetric predation， only producing damped oscillation， are necessary but not sufficient factors in causing the observed 10-year cycles； while extrinsic climate factors are important in producing and modifying the sustained cycles. Two recent population declines of lynx (1940-1955 and after 1980) were likely caused by ongoing climate warming indirectly. Our results provide an alternative explanation to the mechanism of the 10-year cycles， and there is a need for further investigation on links between disappearance of population cycles and global warming in hare-lynx system.
