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2016年职称英语考试真题理工B级完型填空(文字版)

Source: 恒星英语学习网    2016-05-05  我要投稿   论坛   Favorite  

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2016职称英语考试真题 理工B级完型填空

Warmer climate will bake tropical bugs

  Global warming could cook tropical insects, with uNPRedictable knock-on effects, say researchers who warn that rising temperatures also  threaten tropical frogs, lizards and turtles.

  Temperatures are expected   to increase much faster in temperate and polar regions than in the tropics. But no-one had looked at how warming would affect insects and other cold-blooded animals that had evolved in tropical regions with little temperature variation.

  Curtis Deutsch at the University of California at Los Angeles and colleagues analysed data on insect survival and reproduction for 38 species in different ecosystems, and then estimated how these values would change with predictions of climate change for the 21st century.

  The team found that the reproductive rate of tropical insects tends to peak very close to the temperatures where they normally live, but drops sharply at higher temperatures. This means that cranking up the heat only a small amount can exert a heavy toll, leaving insects unable to reproduce fast enough to keep up their numbers.

  Temperature tolerance

  Temperate insects reproduce well over a broader range, and do not live as close to their thermal limit, so they can reproduce successfully when their climate warms more than in the tropics.

  “Tropical insects do very well in a narrow band of temperatures, but move them above that range and they die,” says team member Josh Tewksbury of the University of Washington in Seattle.

  Frogs, lizards and turtles face similar problems, although not as much data is available on their temperature tolerance, says Deutsch.

  The heart of the problem is temperature tolerance. Temperate-zone insects have evolved to survive the much broader temperature swings of seasonal climates, than have their tropical relatives.

  Important role

  The effect appears worse for animals that live in hot stable climate of the lower levels of tropical forests. Lizards in clear areas can find shade to cool down, but those living in the forest are already in the shade, and there’s not much they can do to get cooler, Deutsch says.

  Too few tropical insects have been studied so far to tell if any particular group will be particularly hard-hit, says Tewksbury. Insects play important roles in forest ecology, including pollination, and eating detritus to recycle carbon.

  The team are now starting to evaluate how temperature affects ecological interactions of insects with other species, including crops such as African corn.

  Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0709472105)

  Climate Change – Want to know more about global warming: the science, impacts and political debate? Visit our continually updated special report.

  Endangered species – Learn more about the conservation battle in our comprehensive special report.

  答案:

  51 threaten

  52 expected

  53 that

  54 on

  55:change

  56;rate

  57;drops

  58:sucessfully

  59;close

  60:range

  61: problem

  62: effect

  63: shade

  64: tell

  65:roles


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