北美托福机经英文版原文(2)

　　1. 英国工业发展时期灰蛾子和黑蛾子数量的增减。
　　核心观点是：污染严重使树木变黑，此时黑蛾子隐蔽效果变好；另一方面，灰蛾子被吃得多。这个理论涉及到一个科学家的实验以及资料获取，学术界关于这个还是有争议的，所以作者使出杀手锏：1965年英国通过环保法案以后，灰蛾子的数量又上来了，于是科学家的理论就从反方向得到证实。
　　辞汇题：detecting。
　　How did peppered moths change because of the Industrial Revolution?
　　The Industrial Revolution caused pepper moths to adapt to a darker color because of the soot and ash everywhere so that they could hide from predators better, which made the black to gray moth ratio pull towards black. After the Industrial Revolution was over however then the black peppered moths numbers started to decrease and the grayish peppered moths number began to increase. This is evidence of adaptation.
　　The English moth, Biston betularia, is a frequently cited example of observed evolution. In this moth there are two color morphs, light and dark (typica and carbonaria). H. Kettlewell found that dark moths constituted less than 2% of the population prior to 1848. Then, the frequency of the dark morph began to increase. By 1898, the 95% of the moths in Manchester and other highly industrialized areas were of the dark type, their frequency was less in rural areas. The moth population changed from mostly light colored moths to mostly dark colored moths. The moths' color was primarily determined by a single gene. So, the change in frequency of dark colored moths represented a change in the gene pool. This change was, by definition, evolution.
　　The increase in relative abundance of the dark type was due to natural selection. The late eighteen hundreds was the time of England 's industrial revolution. Soot from factories darkened the birch trees the moths landed on. Against a sooty background, birds could see the lighter colored moths better and ate more of them. As a result, more dark moths survived until reproductive age and left offspring. The greater number of offspring left by dark moths is what caused their increase in frequency. This is an example of natural selection.
　　Populations evolve, not individuals. In order to understand evolution, it is necessary to view populations as a collection of individuals, each harboring a different set of traits. A single organism is never typical of an entire population unless there is no variation within that population. Individual organisms do not evolve, they retain the same genes throughout their life. When a population is evolving, the ratio of different genetic types is changing -- each individual organism within a population does not change. For example, in the previous example, the frequency of black moths increased; the moths did not turn from light to gray to dark in concert.
　　2. 生物多样性
　　从赤道到极地，生物的多样性渐渐减弱。里面谈到海洋里的对比不强烈，因为温差只是在上面几十米，下面都是一个样的黑和冷，所以作者认为，海洋多样性不是由光照和温度产生的。另外一个问题是多食动物generalist和专食动物specialist的区别。作者是通过季节周期性变化，带来食物供应量的变化，然后食物的限制造成两种动物的不同这个方面来谈。
　　3. 欧洲中世纪同业公会制度guild
　　先讲大师master的出道过程，然后是整个行会的排他性。接着是行会和城邦政府怎么样由前提相互支持（垄断）。后来政府看中垄断的大面包于是插手进来分一杯羹。
　　除了政府以外，另一个行会的强劲对手是城外不受法律约束，而且拥有廉价劳动力（农民工）的个体企业。后来行会竞争不过－因为成本拼不过，价格当然也拼不过。同时又遇到一些供应上的困难，所以结果怎么样就…。还有，他们自己本身也有矛盾，主要是master中有些很有野心，想要扩张，简单说就是内忧外患。
　　辞汇题：inevitable，endorse，convince，give rise to，marginally，capacious。

　　以上机经是康老师2011年10月－12月托福预测范围里的。