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SSS 2008-03-04

时间:2010-05-13 03:07来源:互联网 提供网友:0922013129   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American’s 60-Second Science, I’m Karen Hopkin. This will just take a minute.

 

For worse or for better, humans are changing the course of evolution. On February 26, we talked about how fishing practices may be driving the evolution of smaller harder-to-catch trout1. And this week brings news that urbanization has influenced the way weeds make seeds. The results appear in the current online edition of the Proceedings2 of the National Academy of Sciences. Scientists in the south of France were studying the sort of weed you see cropping up around the base of trees planted along city sidewalks. The plant called Crepis sancta can make two different kinds of seed, one that's light like a dandelion seed with a feathery little parachute that gets carried by the wind and another that's heavy and just drops to the ground. The scientists compared weeds that were growing in these small urban patches to ones growing in an open field. They found that the urban weeds produce fewer of the fluffy3 seeds than their country cousins which makes evolutional sense because in a city setting drifting seeds are more likely to hit pavement than soil. In the long run though that strategy might not be healthy because plants benefit from spreading their seeds. So that’s bad news for the weeds but may be not so bad news for the sidewalks.

 

Thanks for the minute, for Scientific American’s 60-Second Science, I’m Karen Hopkin.
 


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1 trout PKDzs     
n.鳟鱼;鲑鱼(属)
参考例句:
  • Thousands of young salmon and trout have been killed by the pollution.成千上万的鲑鱼和鳟鱼的鱼苗因污染而死亡。
  • We hooked a trout and had it for breakfast.我们钓了一条鳟鱼,早饭时吃了。
2 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼
3 fluffy CQjzv     
adj.有绒毛的,空洞的
参考例句:
  • Newly hatched chicks are like fluffy balls.刚孵出的小鸡像绒毛球。
  • The steamed bread is very fluffy.馒头很暄。
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TAG标签:   SSS  urbanization
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