The Lemming Cycle at Baker Lake, Northwest Territories, During 1959-62.
The Lemming Cycle at Baker Lake, Northwest Territories, During 1959-62.
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西北地区贝克湖的旅鼠循环，1959-62 年。
DOI：
10.2307/2401682
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发表时间：
1966
期刊：
影响因子：
--
通讯作者：
C. Krebs
中科院分区：
文献类型：
--
作者：
A. Watson;C. Krebs
一项为期四年的研究，涵盖了一个周期的棕色和不同的旅鼠的数量已进行了贝克湖，基瓦廷，西北。人们试图通过捕捉和活体捕捉技术以及对大约4,000只动物的详细尸检来详细描述周期中的事件，并从中确定什么样的解释符合观察结果。1959年夏季，人口从很低的数字开始增长，1959年冬季，人口出现了巨大的增长。在1960年的高峰夏季，几乎没有进一步的增长。在1960- 1961年冬季，主要研究区的降水量出现了大幅下降，这种下降一直持续到1961年夏季。在1961- 1962年的冬季，变化不大，1962年夏季又开始了增长阶段。繁殖中的两个变化与这个周期有关--繁殖季节长度的变化和性成熟时体重的变化。冬季繁殖期处于上升期而非下降期，夏季繁殖期缩短，处于高峰期而有所下降。幼雄鱼在上升期的夏季成熟，但不在高峰期或下降期;幼雌鱼在上升期和下降期的夏季成熟，但不在高峰期。死亡率的主要变化是很高的少年死亡率在夏季下降。动物质量的变化不仅表现在这些繁殖和死亡率的变化上，而且还表现在与增加或减少的夏季相比，成年动物的平均体重在高峰夏季增加了20- 30%。考虑了外在因素的作用。没有大范围的栖息地破坏，也没有任何证据表明动物数量或质量的食物短缺。捕食者，疾病，也不是寄生虫似乎是观察到的死亡率变化的原因。也考虑了内在因素的作用。夏季肾上腺和脾脏重量与月经周期无明显关系。皮肤上的创伤量表现出强烈的季节性变化，并不是一个简单的函数的密度。从这些观察中得出的结论是，这种旅鼠周期不能用传统的外在因素（如食物供应）来充分解释，而是它本质上是一种自我调节现象。克里斯蒂安提出的压力假说也被拒绝作为对这些事件的充分解释。这些结果完全支持奇蒂的观点，即人口在密度变化过程中质量发生变化。在人口的行为变化可能构成旅鼠周期的关键，和奇蒂的建议，这些波动可能代表了遗传多态性，涉及侵略行为是没有反驳这些数据。
A four-year study covering one cycle in numbers of the brown and varying lemmings has been carried out at Baker Lake, Keewatin, N.W.T. An attempt was made to describe the events of the cycle in detail by snap-trapping and live-trapping techniques and by detailed autopsies on about 4,000 animals and from this to determine what explanations would fit the observations. Increase began from very low numbers in the summer of 1959 with tremendous population growth occurring over the winter of 1959>--60. Little further increase occurred in the peak summer of 1960. A great decline occurred over the winter of 1960--1, and this decline continued through the summer of 1961 on the Main Study Area. Little change occurred over the winter of 1961-2 and the phase of increase began again in the summer of 1962. Two changes in reproduction were associated with this cyclc-changes in the length of the breeding seasoIi and in the weight at sexual maturity. Winter breeding occurred in the period of increase but not in the decline, and a shortened summer breeding season occurred in the peak and to some degree in the decline. Young male Lemmus matured in the summers of increase but not in the peak or in the decline; young females matured in the increase and decline summers but not in the peak. The major change in mortality was a very high juvenile mortality in the summer of the decline. Changes in the quality of the animals were manifested not only by these reproductive and mortality changes but also by a 20--30 per cent increase in mean body weights of the adults in the peak summer compared with the increase or decline summers. The role of the extrinsic factors is considered. There was no widespread destruction of the habitat, or any 'evidence of quantitative or qualitative food shortage in the animals of the decline. Neither predators, disease, nor parasites seemed to be the cause of the observed changes in mortality. The role of the intrinsic factors is also considered. Summer adrenal and spleen weights showed no clear relationship to the cycle. The amount of wounding on skins showed strong seasonal changes and was not a simple function of density. It was concluded from these observations that this lemming cycle could not be adequately explained by the conventional extrinsic factors such as food supply, but rather that it is essentially a self-regulatory phenomenon. The stress hypothesis proposed by Christian was also rejected as an adequate explanation of these events. The idea of Chitty that populations change in quality during changes in density was fully supported by these results. Behavioural changes in the population may constitute the crux of the lemming cycle, and Chitty's suggestion that these fluctuations may represent a genetic polymorphism involving aggressive behaviour is not refuted by these data.