204年5月25日托福阅读真题+题目+答案：The Long History of Overexploitation
Overexploitation is the overuse by humans of a population of organisms to an extent that threatens the viability of the population or radically alters the natural community in which it lives. There is a tendency to think that overexploitation is a relatively new phenomenon. However, that view is a bit naïve, as we will see in some examples of past overexploitation.
After the most recent glaciation, which was at its height between about 20,000 and 14,000 years ago, the grasslands in central North America harbored an extraordinary array of large animals. The diversity of antelope, horses, cheetahs, giant ground sloths, mammoths, mastodons, and other animals easily rivaled that of the large animal fauna of Africa today. However, about 11,000 years ago, at the end of the Pleistocene epoch, many disappeared; 34 genera of large mammals became extinct in fewer than 1,000 years, while 40 more became extinct in South America. This was a massive die-off when you consider that only 20 large mammal genera had become extinct in North America over the previous three million years.
Is it a coincidence that so many large mammals became extinct shortly after the time that humans, crossing from Siberia to Alaska, probably first arrived in the Western Hemisphere? Paul Martin, an anthropologist, thinks not and has argued in many articles and books that overhunting was primarily responsible for the extinctions. Martin’s critics have argued that the extinctions were primarily the result of significant climate change. If climate change was responsible, we would expect many small mammals, primarily rodents, to have become extinct in the region, too; however, only four North American genera of small animals became extinct at the end of the Pleistocene, compared with 46 genera over the preceding three million years. On the other hand, perhaps small mammals are less susceptible to climate change than large mammals are. We cannot definitely say which answer is correct, and the truth may lie in the middle, but many scientists believe that the end of the Pleistocene saw a massive overkill by the first human inhabitants of the Americas.
The best evidence that overhunting by early people eliminated some species comes from islands. On many remote islands, birds evolved in the absence of mammalian predators, sometimes losing their ability to fly in the process. When people arrived on these islands, they found easy prey. For example, when Polynesians, now known as Maori, arrived in New Zealand about A.D. 1200, the islands had 11 species of moas: flightless birds that ranged in size from as small as a turkey to larger than an ostrich. By the time Europeans colonized the islands in the 1700s, the moas were gone, along with five species of rail and six waterfowl species. The demise of the moas and other birds undoubtedly was hastened by forest clearing and other changes brought about by the Maori, but the abundance of moa remains at Maori village sites makes it clear that hunting was a major factor.
On small islands throughout the Pacific, scores of birds are known to have become extinct after the arrival of Polynesians. In the Hawaiian Islands, 44 species of endemic land birds out of 82 became extinct between the arrival of Polynesians and the arrival of Europeans. Again, habitat changes were undoubtedly important, but it is likely that overhunting was a major problem, especially for various species of flightless geese, ibis, and rail. On Madagascar, the loss was not limited to birds. The arrival of people 1,500 to 2,000 years ago caused the extinctions of two giant tortoises, a bear-sized giant lemur, a small species of hippopotamus, many other mammals, and elephant birds, some of which rivaled the largest moas in size.
Currently, the worst overexploitation may be happening through global overfishing. This is partially disguised by the fact that we are still able to harvest huge quantities of marine species; only on closer inspection does one notice that the predatory fish that used to dominate catches are being replaced by species further down the food chain.
1. The word ”viability” in the passage is closet in meaning to
A. ability to exist
C. rate of growth
D. ability to change
2. According to paragraphs 2 and 3, all of the following are true of the diversity of large mammals in the North American grasslands after the most recent glaciation EXCEPT:
A.It was easily as great as the diversity of large animals in Africa today.
B. It diminished significantly over a period of fewer than 1,000 years.
C. It was probably reduced by both climate change and hunting at the end of the Pleistocene epoch.
D. It was much greater than the diversity of small animal populations during the Pleistocene epoch. Paragraphs2 and 3 are marked with arrows [→]
3. Why does the author mention that “20 large mammal genera had become extinct in North America over the previous three million years”?
A.To give an example of extinction that was caused by overexploitation by humans
B. To cast doubt on the idea that the extinctions at the end of the Pleistocene epoch were unique or notable
C. To provide evidence for the idea that large mammal species were able to flourish in central North America after the glaciation
D. To emphasize the significance of the number of extinctions at the end of the Pleistocene epoch
4. Which of the following statements best describes anthropologist Paul Martin’s views on Pleistocene extinction as explained in paragraph 3?
A.It is a coincidence that so many large mammals became extinct shortly after humans first arrived in the Western Hemisphere.
B. Overhunting was primarily responsible for the extinction of large mammals after the arrival of humans in the Western Hemisphere.
C. The massive extinction of large animal species was due to the severe climate changes at the end of the Pleistocene epoch.
D. The extinction of large mammals was caused by the extinction of small rodents that large animals hunted for food. Paragraph 3 is marked with an arrow [→]
5. 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.
A.We cannot definitely say whether or not a massive overkill happened at the end of the Pleistocene, despite what many scientists believe.
B. We cannot definitely say whether the massive overkill by the first human inhabitants of the Americas occurred in the middle of the end of the Pleistocene.
C. Although it is difficult to know for sure, many scientists believe that the first human inhabitants were responsible for an overkill of mammals at the end of the Pleistocene.
D. Many scientists believe that many of the first human inhabitants of the Americas did not survive the climate changes at the end of the Pleistocene.
10. According to paragraph 5, which of the following did NOT contribute to the extinction of many bird species on Pacific islands?
B. The inability to fly
D. New species of mammals introduced by the Polynesians Paragraph 5 is marked with an arrow [→]
11. The word ” disguised” in the passage is closet in meaning to
D. made worse
12. Which of the following statements is supported by the discussion of fish catches in paragraph 6?
A.Global overfishing has been difficult to recognize because there are so many different species of predatory fish in different areas around the world.
B. Closer inspection of the global fishing industry was undertaken recently because we have not been able to harvest enough fish.
C. Reduced numbers of predatory fish that used to be caught most often are evidence that humans have overexploited these fish.
D. Fish species further down the food chain now prey on species that used to be harvested. Paragraph 6 is marked with an arrow [→]
Paragraph 4 The best evidence that overhunting by early people eliminated some species comes from islands. On many remote islands, birds evolved in the absence of mammalian predators, sometimes losing their ability to fly in the process. When people arrived on these islands, they found easy prey. ■For example, when Polynesians, now known as Maori, arrived in New Zealand about A.D. 1200, the islands had 11 species of moas: flightless birds that ranged in size from as small as a turkey to larger than an ostrich. ■By the time Europeans colonized the islands in the 1700s, the moas were gone, along with five species of rail and six waterfowl species. ■The demise of the moas and other birds undoubtedly was hastened by forest clearing and other changes brought about by the Maori, but the abundance of moa remains at Maori village sites makes it clear that hunting was a major factor.■
13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. Indeed, some evidence suggests that these extinctions occurred long before, perhaps as early as 100 years after Polynesian colonization.
Where would the sentence best fit? Click on a square [■] to add the sentence to the passage.
14. Directions Although it is sometimes thought to be a new phenomenon, overexploitation has many examples in human history. Answer Choices
1.Strong evidence for overexploitation comes from the extinction of many species of flightless birds on Pacific islands after these places were colonized by humans.
2.The fact that only flightless-bird species became extinct on Pacific islands after the arrival of humans could indicate that overexploitation of forest habitats rather than hunting caused the massive overkill.
3.Presently, overexploitation may be worst in the sea, where global overfishing has significantly reduced some predatory-fish population.
4.Although some people attribute the mass extinctions of large animals at the end of the Pleistocene epoch to climate change, many scientists believe them to result from overexploitation by humans.
5.Because of their comparative diversity, marine species are less susceptible to the overexploitation that has affected mammals and birds on land.
6.The fact that most small-rodent species died out during the Pleistocene epoch provides evidence that humans were responsible for the mass extinction of animals during this period.