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托福official37阅读第2篇Direct Species Translocation题目解析

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Direct Species Translocation
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It is becoming increasingly common for conservationists to move individual animals or entire species from one site to another. This may be either to establish a new population where a population of conspecifics (animals or plants belonging to the same species) has become extinct or to add individuals to an existing population. The former is termed reintroduction and the latter reinforcement. In both cases, wild individuals are captured in one location and translocated directly to another.

Direct translocation has been used a wide range of plants and animals and was carried out to maintain populations as a source of food long before conservation was a familiar term. The number of translocations carried out under the banner of conservation has increased rapidly, and this has led to criticism of the technique because of the lack of evaluation of its efficacy and because of its potential disadvantages. The nature of translocation ranges from highly organized and researched national or international programs to ad hoc releases of rescued animals by well- intentioned animal lovers. In a fragmented landscape where many populations and habitats are isolated from others, translocations can play an effective role in conservation strategies; they can increase the number of existing populations or increase the size, genetic diversity, and demographic balance of a small population, consequently increasing its chances of survival.

Translocation clearly has a role in the recovery of species that have substantially declined and is the most likely method by which many sedentary species can recover all or part of their former range. However, against this is the potential for reinforcement translocations to spread disease from one population to another or to introduce deleterious or maladaptive genes to a population. Additionally, translocation of predators or competitors may have negative impacts on other species, resulting in an overall loss of diversity. Last but not least of these considerations is the effort and resources required in this type of action, which need to be justified by evidence of the likely benefits.

Despite the large number of tranlocations that have taken place, there is surprisingly little evidence of the efficacy of such actions. This is partly because many translocations have not been strictly for conservation; neither have they been official nor legal, let alone scientific in their approach. Successful translocations inevitably get recorded and gain attention, whereas failures may never be recorded at all. This makes appraisal of the method very difficult. One key problem is a definition of success. Is translocation successful if the individuals survive the first week or a year, or do they need to reproduce for one or several generations? Whatever the answer, it is clear that a general framework is required to ensure that any translocation is justified, has a realistic chance of success, and will be properly monitored and evaluated for the benefit of future efforts.

An example of apparent translocation success involves the threatened Seychelles warbler. This species was once confined to Cousin Island, one of the Seychelles islands, and reduced to 26 individuals. Careful habitat management increased this number to over 300 birds, but the single population remained vulnerable to local catastrophic events. The decision was taken to translocate individuals to two nearby islands to reduce this risk. The translocations took place in 1988 and 1990, and both have resulted in healthy breeding populations. A successful translocation exercise also appears to have been achieved with red howler monkeys in French Guiana. A howler population was translocated from a site due to be flooded for hydroelectric power generation. The release site was an area where local hunting had reduced the density of the resident howler population. Released troops of monkeys were kept under visual observation and followed by radio tracking of 16 females. Although the troops appeared to undergo initial problems, causing them to split up, all the tracked females settled into normal behavioral patterns.

Unfortunately, the success stories are at least matched by accounts of failure. Reviewing translocation of amphibians and reptiles, researchers C.Kenneth Dodd and Richard A. Siegel concluded that most projects have not demonstrated success as conservation techniques and should not be advocated as though they were acceptable management and mitigation practices.

1.According to paragraph 1, what distinguishes reinforcement from reintroduction of animal species?

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正确答案:B
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【题目翻译】根据第1段,加强与重新引入动物物种有什么区别? A:只有加强抓捕野生动物。 B:唯一的强化是在现有人口中增加个体。 C:只有加强才需要使用同种异体。 D:一旦一个种群灭绝,只有加强才能起作用。 【判定题型】:题目问的是文章中的具体细节信息,故根据题目问法可以判断本题为事实信息题。 【关键词定位】根据关键词“ reinforcement 和 reintroduction”,定位到Passage 1倒数第二句,原句为“he former is termed reintroduction and the latter reinforcement.”,意思是“前者的术语是物种再引入,后者的术语是物种再强化”。 【逻辑分析】本题需要通读第一段。根据第一段第三句可以得知,第一句是reintroduction的定义,第二句是reinforcement的定义。reintroduce指的是把一个物种迁移到另一个地区,reinforcement指的是给一个原有物种已经灭绝或者还没灭绝的时候引入另一个物种群。 【选项分析】 对于选项A和C,文章第一段最后一句说明捕捉动物和conspecifics这个概念是两者都有的。故选项错误。 选项B说的reinforcement涉及到在原有物种的基础上引进新物种正确。选择B。 选项D根据两者的定义,它们都可以帮助物种灭绝的地区。故选项错误。

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