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2008年职称英语理工类教材新增部分内容(八)
发布时间：2008-1-15 15:01:00 浏览次数: 567
13. ‘Hidden’ Species May Be Surprisingly Common (A级)
（替换2007年用书理工类阅读理解第四十八篇：Shrinking Water Supply Poses Threat to Peace）
Cryptic species – animals that appear identical but are genetically quite distant – may be much more widespread than previously thought. The findings could have major implications in areas ranging from biodiversity estimates and wildlife management, to our understanding of infectious diseases and evolution.
Reports of cryptic species have increased dramatically over the past two decades with the advent of relatively inexpensive DNA sequencing technology. Markus Pfenninger and Klaus Schwenk, of the Goethe-Universitat in Frankfurt1, Germany, analyzed all known data on cryptic animal species and discovered that they are found in equal proportions throughout all major branches of the animal kingdom and occur in equal numbers in all biogeographical regions.
Scientists had previously speculated that cryptic species were predominantly found in insects and reptiles, and were more likely to occur in tropical rather than temperate regions. “Species that are seemingly widespread and abundant could in reality be many different cryptic species that have low populations and are highly endangered,” says Pfenninger. Until the genetic information of all species in at least one taxon is thoroughly studied, no one will know just how many cryptic species exist. “ It could be as high as 30%,” Pfenninger says.
“I’m extremely surprised by their results,” says Alex Smith of the University of Guelph2 in Ontario3, Canada. “It’s a call to arms to keep doing the broad kind of genetic studies that we are doing.”
Sampling as many individuals as possible, scientists hope to complete work on all fish and birds in another 5 to 10 years. Once either of these taxonomic groups is completed, Pfenninger says researchers will able to decide how many cryptic species exist throughout the animal kingdom.
Examples of cryptic species include the African elephant. A 2001 study found the elephants were actually two genetically distinct, non-interbreeding species, the African bush elephant and the African elephant. The species are currently listed as vulnerable and threatened, respectively, by the World Conservation Union (WCU)4.
The reclassifications are more than an academic exercise. They define populations that have evolved independently of each other and whose genetic differences can have significant consequences.
In the early 1900s misidentification of mosquito species based on morphology confused attempts to control malaria in Europe. Ultimately, what was thought to be a single species was actually made up of six sibling species, only three of which transmitted the disease. “The basic unit in biology is always the species, and you have to know what you are dealing with,” Pfenninger says. Much previous research is now no longer used, he says, because it is not clear what species was being studied. (428 words)
词汇：
cryptic adj. 隐蔽的；隐藏的
taxon n. （生物的）分类单元
biodiversity n. 生物多样性
taxonomic adj. 分类（学）的
DNA n. 脱氧核糖核酸（deoxyribonucleic acid的缩写）
non-interbreeding adj. 非杂交繁殖
biogeographical adj. 生物地理学的
morphology n. 形态学
malaria n. 疟疾
reptile n. 爬行动物
sibling n. 同胞，同属
temperate adj.（气候）温带的
注释：
1. the Goethe-Universitat in Frankfurt：德国法兰克福大学，即 Johann Wolfgang Goethe-Universitat Frankfurt am Main ，位于美因和莱茵两河汇流处的法兰克福。
2. the University of Guelph：圭尔夫大学。该校成立于1964年，是一所公立的综合性大学。在2005年加拿大综合类大学评比中，圭尔夫大学名列第3名，是全加拿大最著名的高等学府之一。
3. Ontario：安大略。加拿大中东部的一个省。
4. the World Conservation Union：世界自然保护联盟。全球最大、最重要的自然保护网络机构， 它集合了82个国家、111个政府机构、800多个非政府组织以及来自181个国家的约1万多名科学家和专家，形成了世界环保领域里独一无二的全球性合作关系。
练习：
1. Which of the following about the significance of the research on cryptic species is NOT true?
A) The results of the research can help the development of many other research areas.
B) The results of the research can help the development of biodiversity estimates.
C) The results of the research can help our understanding of infectious disease evolution.
D) The results of the research can help our understanding of “survival of the fittest.”
2. What was scientists’ understanding of cryptic species?
A) They occurred in equal numbers in all biogeographical regions.
B) They were mostly found in insects and reptiles.
C) They were likely to be in tropical rather than temperate regions.
D) Both B and C.
3. Do scientists know how many cryptic species exist?
A) Not yet.
B) Yes, they do.
C) They will know the answer in another one or two years.
D) They will never know the answer.
4. Which of the following about the African bush elephant and the African elephant is true?
A) The WCU are interbreeding those elephants.
B) They are interbreeding species.
C) They are two genetically distant species.
D) They depend on each other for survival.
5. People were confused in their attempts to control malaria in Europe in the early 1900s, because scientists
A) identified only one mosquito species instead of six species.
B) thought only three mosquito species transmitted disease.
C) thought there was only one mosquito species.
D) did not know what species was being studied.
答案与题解：
1. D 短文的第一段第二句的大意是，研究结果为广泛的研究领域提供启示，包括生物多样性研究，还能帮助我们理解传染疾病及其演变。所以，选项 A、B、C 都是正确的，它们不是答案。选项 D 的“适者生存”的内容文章中没有提及，因此是本题的答案。
2. D 短文的第二段第二句描述的是科学家目前的研究结果，第三段描述的是科学家在这之前对于cryptic species的理解。本题用的是过去式，问的是过去的状况，因此，答案在第三段中，B和C是答案，所以D是正确选择。
3. A 第三段和第五段提供了答案。第三段的最后一句中的Until …, no one will know just how many cryptic species exist. 其意思就是人们目前还不了解。第五段的最后一句也说明了研究者目前对此尚未了解。
4. C 答案在第六段中。该段举了非洲大象为例，说明什么是 cryptic species。第六段的句子 “A 2001 study found the elephants were actually two genetically distinct, non-interbreeding species”是选择 C 的依据。选项 A 不对， the WCU 并没有杂交繁殖这两种象。选项 B 不对，短文说这两种象是非杂交物种。选项 D 的内容短文中找不到。
5. A 短文最后一段告诉我们，由于对蚊子种类不了解，20世纪初期疟疾曾肆虐欧洲，最终，科学家才了解到蚊子这一物种不是由一个种类而是由六个种类组成。所以，应该选择 A。
14. Why Humans Walk On Two Legs (A级)
（替换2007年用书理工类阅读理解第四十九篇：Retinal Prosthesis Helps the Blind Regain Eyesight）
A team of scientists that studied chimpanzees trained to use treadmills has gathered new evidence suggesting that our earliest apelike ancestors started walking on two legs because it required less energy than getting around on all fours.
"When our earliest ancestors started walking on two legs, they took the first steps toward becoming human," said lead researcher Michael Sockol of UC Davis1. "Our findings help answer why." Sockol worked for two years to find an animal trainer willing to coax adult chimps to walk on two legs and to "knucklewalk" on all fours on the sort of treadmill found in most gyms.
The five chimps also wore face masks used to help the researchers measure oxygen consumption. While the chimps worked out, the scientists collected metabolic and other data that allowed them to calculate which method of locomotion used less energy and why. The team gathered the same information for four adult humans walking on a treadmill.
The researchers found that human walking used about 75 percent less energy and burned 75 percent fewer calories than quadrupedal and bipedal2 walking in chimpanzees. They also found that for some but not all of the chimps, walking on two legs was no more costly than knucklewalking.
"We were prepared to find that all of the chimps used more energy walking on two legs - but that finding wouldn't have been as interesting," Sockol said. "What we found was much more telling. For three chimps, bipedalism3 was more expensive, but for the other two chimps, this wasn't the case. One spent about the same energy walking on two legs as on four. The other used less energy walking upright." These two chimps had different gaits and anatomy than their knucklewalking peers.
Taken together, the findings provide support for the hypothesis that anatomical differences affecting gait existed among our earliest apelike ancestors, and that these differences provided the genetic variation which natural selection could act on when changes in the environment gave bipeds an advantage over quadrupeds.
Fossil and molecular evidence suggests the earliest ancestors of the human family lived in forested areas in equatorial Africa in the late Miocene era some 8 to 10 million years ago, when changes in climate may have increased in distance between food patches. That would have forced our earliest ancestors to travel longer distances on the ground and favored those who could cover more ground using less energy.
"This isn't the complete answer," Sockol said. "But it's a good piece of a puzzle humans have always wondered about: How and why did we become human? And why do we alone walk on two legs?" (435 words)
词汇：
chimpanzee n. 黑猩猩（又作chimp）
calorie n. 卡（路里），小卡
biped n 二足动物
treadmill n. 踏轮；踏车；单调工作
gait n. 步态，步法
coax v. 哄，哄劝
anatomic adj. 解剖（学）的
knucklewalk v. 用膝关节走路
quadruped n. 四足动物
metabolic adj.（新陈）代谢的
Miocene n.& adj. 中新世（的）
locomotion n. 运动（力）
注释：
1. UC Davis ：加州大学戴维斯分校。UC是University of California (加利福尼亚大学)的缩写，该校有多个分校，UC Davis是其中一个。Davis以前是UC Berkeley分校的农学院，后来独立出来。Davis是一个大学城，很小的城市，Davis校园基本就构成了这个城市。
2. quadrupedal and bipedal：quad-：构词词素，是"四"的意思；bi-:构词词素，是"二"的意思；ped-：构词词素，是"脚"的意思；-al是构成形容词的后缀，表示"．．．的"。因此，quadrupedal意为"四足动物的"，bipedal意为"二足动物的"。
3. bipedalism：系bipedal（二足动物的）的对应名词，这里后缀-ism表示"特征"、"特性"。
练习：
1. What did Michael Sockol and his team find out in their study of chimpanzees?
A) The evidence why chimpanzees can be trained to use treadmills.
B) The evidence why our apelike ancestors came to walk on four legs.
C )The evidence why our apelike ancestors came to walk on two legs.
D) The evidence why chimpanzees can be trained to walk on two legs.
2. Which of the following best interprets the meaning of"While the chimps worked out, …."(the first sentence of the third paragraph)?
A) While the chimps worked in the lab….
B) While the chimps exercised in the gym….
C) While the chimps tried to figure out what they should do….-
D) While the chimps tried to understand the instructions….
3. What was the result of the finding, according to Paragraph 5?
A) Three chimps used more energy walking on two legs.
B) One chimp used less energy walking on two legs.
C) One chimp used about the same energy walking on two legs as on four.
D) All of the above.
4. What was true of the hypothesis of the research?
A) Our apelike ancestors were anatomically different but had the same gaits.
B) Bipeds with natural selection had an advantage over quadruped.
C) Our apelike ancestors could adapt to different climate changes due to genetic variation.
D) Bipeds had an advantage over quadrupeds due to changes in the environment.
5. What does fossil and molecular evidence tell us about our earliest ancestors.
A) They experienced more climate changes than we do today.
B) Due to changes in climate, they were forced to travel between food patches.
C) They could cover more ground than their quadrupedal peers because they used less
energy.
D)They could travel longer distances on the ground than those who could use less energy.
答案与题解：
1. C 短文的第一段直接回答了这个问题。
2. B worked out在此是"运动，锻炼"的意思，所以选择 B。
3. D 第五段的第三、第四和第五句提供了答案。bipedalism was more expensive的意思是：两足行走消耗更多的体能。walking upright的意思是：直立行走，即两足行走。
4. B 第六段告诉了我们研究的两个假设：猿人祖先在解剖学意义上存在着差异，这一
差异影响了它们的步态；这些差异在自然选择的过程中决定了遗传变异，而环境变化使得两足行走的猿人比起四足行走的猿人更有优势。A、C、D都不是正确的说法，只有B在该段中被提到。
5. C 倒数第二段提供了问题的答案。travel longer distances用的是比较级，这里是将两足行走的猿人与上文中四足行走的猿人做比较。those who could cover more ground using less energy指的是上文提到的与四足行走的猿人相比，体能消耗较小的两足行走猿人。其他选择都不是正确说法。
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