Population cycles revisited
Population cycles revisited
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DOI：
10.2307/1382705
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发表时间：
1996-02-01
影响因子：
1.7
通讯作者：
Krebs, CJ
中科院分区：
文献类型：
--
作者：
Krebs, CJ
小型哺乳动物种群的周期性波动或循环已被广泛研究，但对其原因仍存在很大争议。田鼠和旅鼠的循环是由内在和外在因素的综合作用产生的，问题是要准确地定义这些因素是如何相互作用的。空间行为是田鼠和旅鼠种群调节的一个关键组成部分，栅栏效应最能说明这一点。我们不知道是什么机制导致了社会行为的变化。现在人们认为，最有可能的原因是母体效应或压力造成的表型变化，但关于遗传对间距的影响的研究太少，而且我们对田鼠和旅鼠中与亲缘关系有关的社会行为几乎一无所知。捕食和食物供应可能是参与循环种群动态的外在因素。单因素实验表明，食物短缺本身似乎并不是一个必要的因素周期，也没有捕食，但食物和捕食之间的相互作用可能是一个关键变量，了解外在因素如何影响田鼠周期。雪鞋野兔的周期是由捕食和食物供应之间的相互作用引起的，可能是通过风险敏感的觅食整合的。间隔行为不是野兔周期的一个组成部分，因为雪鞋野兔与田鼠和旅鼠不同，没有已知形式的间隔行为，可以产生社会死亡率。因此，田鼠和旅鼠的短期周期似乎与雪鞋兔的长期周期有不同的解释。在某些地方，旅鼠可能被锁在低密度的捕食者坑中。实验排除捕食者提高了成年人的生存在人口的领旅鼠，但不足以让他们逃脱捕食坑，因为损失的青少年。旅鼠的循环种群是否也落入捕食者坑在低阶段仍有待确定。低阶段并不是在每个周期中都发生，而且特别难以解释。当我们定义明确的替代假设并对实地种群进行实验操作时，在分析周期波动方面取得了最迅速的进展。在这些小型哺乳动物身上还有很多工作要做。
Periodic fluctuations or cycles in populations of small mammals have been widely studied, but much controversy still exists about their causes. Cycles of voles and lemmings are produced by the integrated effects of intrinsic and extrinsic factors, and the problem is to define accurately how these interact. Spacing behavior is a key component of population regulation in voles and lemmings, and this is illustrated most dramatically by the fence effect. We do not know which mechanisms produce changes in social behavior. Phenotypic changes produced by maternal effects or stress are now believed most likely, but there has been too little work done on genetic effects on spacing and we know almost nothing about kin-related social behavior in voles and lemmings. Both predation and food supply may be the extrinsic factors involved in cyclic population dynamics. Single-factor experiments suggest that food shortage by itself does not seem to be a necessary factor for cycles nor does predation, but the interaction between food and predation could be a key variable in understanding how extrinsic factors affect cycles of voles. Cycles of snowshoe hares are caused by an interaction between predation and food supplies, possibly integrated through risk-sensitive foraging. Spacing behavior is not a component of cycles of hares because snowshoe hares differ from voles and lemmings in having no known form of spacing behavior that can produce social mortality. The short-term cycle of voles and lemmings thus seems to have a different explanation from the long-term cycle of snowshoe hares. In some places, lemmings may be locked in a predator-pit at low density. Experimental exclusion of predators improved survival of adults in a population of collared lemmings, but was not sufficient to allow them to escape the predator-pit because of losses of juveniles. Whether cyclic populations of lemmings also fall into a predator-pit in the low phase remains to be determined. The low phase does not occur in every cycle and it is particularly difficult to explain. Progress in analyzing cyclic fluctuations has been made most rapidly when we define clear alternative hypotheses and carry out experimental manipulations on field populations. Much remains to be done on these small mammals.