兽类的死亡率

本文共收集了３３种兽类的年均死亡率数据。求得陆生兽类的死亡率和体重的回归模型为： Ｄｔ＝０．６９５－０．０９７３ｌｎ Ｗｔ（ｒ２＝０．８６５，ｐ＜０．００１） Ｄｈ＝０．７３２－０．１００ｌｎ Ｗｈ（ｒ２＝０．８９１，ｐ＜０．００１） Ｄｃ＝０．６１９－０．０９０８ｌｎ Ｗｃ（ｒ２＝０．８６９，ｐ＜０．００１）这里，Ｄｔ、Ｄｈ和 Ｄｃ分别为陆生兽类、食植兽类和食肉兽类的年均死亡率；Ｗｔ、Ｗｈ和 Ｗｃ则分别是它们的体重（公斤）。研究发现：陆生兽类的体重决定了年均死亡率８６％以上的变异：食肉兽类比同样体重的食植兽类的年均死亡率小；飞行兽类比同样体重的陆生兽类的年均死亡率小。兽类死亡率的这一变异规律被认为和能量限制有关。

MORTALITY OF MAMMALS

This present paper deals with the evolutionary strategy of mortality in mammals. It was found that, body mass determined about 86% variations mortality in mammals; the mortality of carnivores was smaller than that of herbivores or seed-eaters, and the mortality of flying mammals was smaller than that of terrestrial ones in terms of the same body mass. The energy limitation hypothesis was suggested to explain the evolutionary strategy of mortality in mammals: in the environments with poor supply of food resources or difficult availability of finding foods, small mortality is favoured by natural selection, and vice versa; because of the implication of body mass by energy budgets, small mortality is also favoured for large mammals, and vice versa.