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谢谢地瓜MM 更新了这么多好东东啊！ 这个穴居动物的进化原因综合各个版本，我认为你的理解才是最正确的！ 下面这个版本，我认为第1段理解反了，应该是气候开始变热吧，她写得是变冷！ 因为后面拿了夏威夷来质疑，所以推测前面第1段应该是讲变热。
版本770 V44 穴居动物的进化原因。提出两种理论pleistocene effect theory，还有一个adaptive shift theory。 第一个P理论主要是说因为古代时候有段时间气候一直变冷，一开始变冷，有些动物为了适应环境就慢慢住在离cave比较近的地方（大意），比较容易适应寒冷，也为他们之后住进cave里做准备。接下来天气更冷了，只有进化到住进洞里才不会冻死。那些适应的好的于是就成了穴居动物 stygobites。 第二种理论主要是用来解释热带地区尤其是夏威夷地区的穴居动物进化的。haworth认为在这些地区没有p理论说到的那种突然的天气变化，因此是动物自己变的。
作者接着说，其实两种理论都有缺失，不能完全成立。两种都没有解释。。。（这里忘记了）
不好意思，网上找了很久没找到原文。下面是比较接近的内容，大概说了一下两种理论。
Those highly specialized animals iliving entirely in the groundwater environment, and absent in surface waters, are called stygobites. 接下来说stygobites都有什么习性，包括哪些动物（记得有说蛇）。
There are two main theories of cave colonization and troglobite evolution: 1. the pleistocene effect theory (Barr and Holsinger), 2. the adaptive shift theory (Howarth).
The Pleistocene effect has been the most widely accepted model for the evolution of terrestrial troglobites until quite recently, During cold glacial climates, the cooler, wetter conditions south of the continental ice masses of Europe, Asia and America favoured the spread of invertebrates inhabiting both temperate forest ecosystems and caves. With the ameliorations of climate, those taxa that survived were those living in caves as the forest ecosystmes changed radically. Ultimately geographic and genetic isolation in these cave rerugia produced adaptive radiation and the evolution of distinct troglobites. In favor of this theory are the close affinities between closed forest and cave taxa, the present distributions of taxa in mountain areas separated by deep valleys, and former wider distributions evidenced from the fossil record.
The second theory, that of adaptive shift, was advanced by Howarth to explain the origin of troglobites in the Hawaiian lava tubes, but many have much wider applicability. This theory does not rely on climate change; rather it proposes that partially adapted ancestral species moved into cave niches almost continuously. These may have been species out-competed in surface environments. Thus the availability of food is the keystone of this theory, and troglobite evolution has been continual rather than episodic.
这是关于第一种P理论的补充知识（没有在考试文章出现，不过对理解有帮助）The pioneering studies of cave life were predominantly carried out in the karst areas of Europe and North America, areas directly or closely associated with regions repeatedly covered by ice during the Pleistocene. Hence, the effects of glaciation came to dominate the debate about both the distribution and the origin of troglobitic animals. The classic view of the evolution of terrestrial troglobite is, in essence, that climatic instability in the surface environment - especially changes to cold and arid conditions associated with the onset and retreat of Pleistocene glaciations - led to the extinction of surface populations of species that mostly lived in forest soil and litter. This process disrupted interbreeding between the various troglophilic populations and permitted adaptation to the cave conditions in the now-isolated cave populations.
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我再继续想点JJ...昨天实在困,也累..
发表于 2008-11-29 15:09:00
