新浪博客

托福TPO29--阅读2解析Competition

2013-09-15 11:05阅读：

http://blog.sina.cn/dpool/blog/u/3228153435

Louise_wy原创
Competition

When several individuals of the same species or of several different species depend on the same limited resource, a situation may arise that is referred to as competition. The existence of competition has been long known to naturalists; its effects were described by Darwin in considerable detail. Competition among individuals of the same species (intraspecies competition), one of the major mechanisms of natural selection, is the concern of evolutionary biology. Competition among the individuals of different species (interspecies competition) is a major concern of ecology. It is one of the factors controlling the size of competing populations, and in extreme cases it may lead to the extinction
of one of the competing species. This was described by Darwin for indigenous New Zealand species of animals and plants, which died out when competing species from Europe were introduced.
竞争是什么：同一物种的个体或者几种物种依靠有线的资源，便会产生竞争。同物种间的竞争是自然选择的主要机制之一，不同物种间的竞争则是生态学的重要因素



  1. The phrase “     mechanisms of natural selection” in the passage is closest in meaning to
    1. types of natural selection mechanism是机制的意思，也以理解为way（方式
    2. dangers of natural selection
    3. problems natural selection solves
    4. ways natural selection works √


2. According to paragraph 1, what is one effect of competition among individuals of different species?
    1. It results in the eventual elimination of the resources for which they are competing.
    2. It leads to competition among individuals of the same species.
    3. It encourages new species to immigrate to an area.
    4. It controls the number of individuals in the competing populations. √

3. The word “indigenous ” in the passage is closest in meaning to
    1. native √
    2. rare
    3. most
    4. numerous

4. In paragraph 1, why does the author mention what happened in New Zealand?
    1. To indicate that Darwin understood the importance of competition
    2. To illustrate that competition can lead to the extinction of species √
    3. To identify where the idea of competition among species first arose
    4. To argue against the idea that the process of selection is a natural occurrence 应该是证实

No serious competition exists when the major needed resource is in superabundant supply, as in most cases of the coexistence of herbivores (plant eaters). Furthermore, most species do not depend entirely on a single resource. If the major resource for a species becomes scarce, the species can usually shift to alternative resources. If more than one species is competing for a scarce resource, the competing species usually switch to different alternative resources. Competition is usually most severe among close relatives with similar demands on the environment. But it may also occur among totally unrelated forms that compete for the same resource, such as seed-eating rodents and ants. The effects of such competition are graphically demonstrated when all the animals or all the plants in an ecosystem come into competition, as happened 2 million years ago at the end of the Pliocene, when North and South America became joined by the Isthmus of Panama. North and South American species migrating across the Isthmus now came into competition with each other. The result was the extermination of a large fraction of the South American mammals, which were apparently unable to withstand the competition from invading North American species – although added predation was also an important factor.
竞争发生的条件： 需要的自然资源很丰富。有些动物有备选资源。竞争就不是很激烈。竞争也有激烈的时候：occur1 occur2 举例，南美洲很大一部分生物灭绝，是因为在物种入侵的情况下无法生存，同样，猎食行为也导致了南美洲动物的灭绝。



5. According to paragraph 2, competition is not usually a significant factor among two coexisting species when
    1. one of the species has only recently moved into the territory of the other 不涉及领地，而是食物
    2. the species are closely related to each other 没说
    3. the population of one species is much larger than that of the other
    4. both of the species are herbivores 后面的in case of √

6. The word “graphically ” in the passage is closest in meaning to
    1. vividly √
    2. frequently
    3. broadly
    4. typically

7. In paragraph 2, why does the author talk about what happened as a result of North and South America becoming joined as the Isthmus of Panama?
    1. To make the point that predation can have as much effect on species survival as completion does 没说主要是说自然资源的竞争，猎食只是文中一笔带过
    2. To show how the ability to switch to an alternative resource can give a species a competitive advantage 这句话就是矛盾的
    3. To account for the current species composition of North and South America
    4. To provide an example of the serious effects of competition between unrelated species √证明前文



To what extent competition determines the composition of a community and the density of particular species has been the source of considerable controversy. The problem is that competition ordinarily cannot be observed directly but must be inferred from the spread or increase of one species and the concurrent reduction or disappearance of another species. The Russian biologist G. F. Gause performed numerous two-species experiments in the laboratory, in which one of the species became extinct when only a single kind of resource was available. On the basis of these experiments and of field observations, the so-called law of competitive exclusion was formulated, according to which no two species can occupy the same niche. Numerous seeming exceptions to this law have since been found, but they can usually be explained as cases in which the two species, even though competing for a major joint resource, did not really occupy exactly the same niche.



竞争对环境内生物的组成和物种的密度的影响：有争议。 原因--竞争不能直接被观察到的。GFG开始做实验了，都是一个实验里有两种生物的，然后让两种生物依靠一种自然资源，其中一种就挂掉了，基于实验和观察，所谓的竞争定律就出现了，就是没有两种生物可以只依靠一个生态环境。但是对于这条定论又有很多例外，但这些里外都可以解释得通：他们其实并没有完全的竞争一个生态环境。



8. Paragraph 3 supports the idea that Gause’s experiments were important because they
    1. provided a situation in which competition could be removed from the interaction between two species 哪里有remove
    2. showed that previous ideas about the extent to which competition determines the composition of a community were completely mistaken 原先的想法，也就是竞争在多大程度上决定了一个社区的组成的想法并没有错，文中说的是那些例外错了
    3. helped establish that competition will remove all but one species from any given ecological niche√，两个物种只有一个能剩下来
    4. offered evidence that competition between species is minimal when there is an overabundance of a single food source 这是前文说的

9. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
    1. Apparent exceptions to this law usually involve cases in which two species compete for the same major resource but occupy slightly different niches.√，他们也有自己的代替的环境
    2. Although it may appear that two species always have different niches, many exceptions show that species compete with each other. 反例怎么能证明观点
    3. Cases in which two species not only compete for a shared resource but also occupy similar niches are considered exceptions to this law.这就是反例的内容 ，不是解释为什么反例是错的
    4. Cases in which the two species do not occupy the same niche yet still compete for the same resource are believed to be exceptions to this law. 这不是反例





Competition among species is of considerable evolutionary importance. The physical structure of species competing for resources in the same ecological niche tends to gradually evolve in ways that allow them to occupy different niches. Competing species also tend to change their range so that their territories no longer overlap. The evolutionary effect of competition on species has been referred to as “species selection;” however, this description is potentially misleading. Only the individuals of a species are subject to the pressures of natural selection. The effect on the well-being and existence of a species is just the result of the effects of selection on all the individuals of the species. Thus species selection is actually a result of individual selection.

竞争带来的物种进化： 为了适应别的生态环境，动物的机体开始进化。为了使生态环境不重合，他们改变或者扩大领地。物种的进化的过程中的效果叫做物种选择，但这个描述大体上是错误的，只有每个物种的个体才受到自然选择的压力。影响一个物种的因素实际上是所有形象个体的因素的结果。（国家的繁荣是经济繁荣，人们素质，科技水平，军事力量等等的总和，物种的生存成长是每个个体生存成长的总概论。）


10. According to paragraph 4, how does competition affect evolution?
    1. It results in the evolution of physical structures that allow the species to compete with each other more effectively. 不是为了和别的尽争，而是适应新环境
    2. It results in the evolutionary extinction of all but one of the competing species.不一定，有些转移了生态环境
    3. It results in the competing species evolving in such a way that they no longer compete for the same resources. √
    4. It results in the competing species evolving to become so much like each other that the competition between them eventually disappears. 不是让他们更像。。。。

11. According to paragraph 4, “species selection” is a misleading term because it
    1. overemphasizes the role of selection pressures in species extinction
    2. suggest that selection pressures directly influence whole species 不是直接，是间接 √
    3. does not make a distinction between species extinction and species evolution进化是上一段说的
      D) suggests that extinction always results whenever there is competition





Competition may occur for any needed resource. ¢ In the case of animals it is usually food; in the case of forest plants it may be light; in the case of substrate inhabitants it may be space, as in many shallow-water bottom-dwelling marine organisms. ¢ Indeed, it may be for any of the factors, physical as well as biotic, that are essential for organisms. ¢ Competition is usually the more severe in the denser the population. ¢ Together with predation, it is the most important density-dependent factor in regulating population growth.


竞争的条件--竞争任何可能的自然资源： 比如动物竞争食物，植物竞争阳光，居民，或是水下生物竞争土地。数量越密集竞争越激烈。有猎食行为的情况，对于控制数量增长，是非常重要的影响密度的因素。


全文：
想要介绍竞争，开篇先提出他的概念是什么，然后它的分类，大体让读者了解了一下。
想说明一个现象，那么这个现象分析的方式就通过存在和不存在展开。所以在第二段说了它不存在的情况是什么，存在的情况是什么。最后开始说他的影响，从生物的组成和物种的密度的影响和物种进化来说。最后强调了一下它发生的条件--任何自然资源，因为是强调，所以这一段的位置不是很规范。




12. The word “regulating” in the passage is closest in meaning to
    1. controlling √
    2. explaining
    3. observing
    4. stopping

13. Look at the four squares [¢ ] that indicate where the following sentence could be added to the passage.

That is, as the density of a population increases, competition has a greater impact and leads to greater mortality.



Where does the sentence best fit? D 是解释上一句话

14. Prose Summary

When necessary resources are limited, competition can occur among individuals of the same species or of different species.

Answer Choices:

    1. Competition can eliminate a species, but since most species do not depend on a single resource, competition is often reduced by switching to alternative resources倒数第二段说的√
    2. Experiments and field observations have established that competition between species is strong enough to prevent two species from occupying the same ecological niche. 不是阻止他们竞争，而是不让他们共存
    3. Competition between individuals of the same species is usually for food whereas competition between species is usually for habitat. 不对，应该是都有
    4. Competition between a pair of species tends to lessen over time because the species tend to evolve to occupy different ecological niches and ranges. 第四段√
    5. Investigation of the ecological role of competition is difficult because ordinarily the competition cannot be observed directly and must be inferred from its presumed effects.不能直接观察到，文中说推断 √
    6. Competition is usually strongest when the density of the competing
populations is the same. 密度大竞争大


我的更多文章

下载客户端阅读体验更佳

APP专享