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SSS 2012-01-24

时间:2012-02-17 06:44来源:互联网 提供网友:gmeng   字体: [ ]
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 This is Scientific American Sixty Seconds Science, I'm Sophie Bushwick, got a minute?

When Mexican tetra fish moved into darker caves long ago, they evolved to deal with the dark by becoming albino and going blind. A new research shows that the changes various cavefish  populations  went through occurred repeatedly. A massive textbook example of convergent1 revolution. The studys in the journal  BioMed Central Evolutionary2 Biology.
To determine how the dark-dwelling fish evolved their sightlessness, researchers  tested the DNA3 of 11 Mexican cavefish populations; they compared the genes4 with those of the tetra populations that lived out in the light. Originally researches had believed that all of the cave populations were descended5 from a single group of tetra fish that went underground and then went blind.  But the cavefish genes told a different story: the 11 populations had  five separate evolutionary origins, with different groups independently experiencing and selecting an eyeless mutation6. Although the surfacing cave-dwelling fish frequently mix, interbreeding has not eradicated7 cavefish blindness, which means that evolution is actively8 selecting blindness, perhaps  because investing bodily resources in sight is a waste of energy in the dark.
Thanks for the minute for Scientific American Sixty Seconds Science, I'm Sophie Bushwick.

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1 convergent PZDyF     
adj.会聚的
参考例句:
  • A curved-inwards wall has a convergent effect on wall spray.凹型壁面对碰壁喷雾有聚集作用。
  • If a sequence is not convergent,it is divergent.如果一个序列不收敛,我们称它发散。
2 evolutionary Ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • Life has its own evolutionary process.生命有其自身的进化过程。
  • These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
3 DNA 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
4 genes 01914f8eac35d7e14afa065217edd8c0     
n.基因( gene的名词复数 )
参考例句:
  • You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因,所以能够活得很长。 来自《简明英汉词典》
  • Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪
5 descended guQzoy     
a.为...后裔的,出身于...的
参考例句:
  • A mood of melancholy descended on us. 一种悲伤的情绪袭上我们的心头。
  • The path descended the hill in a series of zigzags. 小路呈连续的之字形顺着山坡蜿蜒而下。
6 mutation t1PyM     
n.变化,变异,转变
参考例句:
  • People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
  • So far the discussion has centered entirely around mutation in the strict sense.到目前为止,严格来讲,讨论完全集中于围绕突变问题上。
7 eradicated 527fe74fc13c68501cfd202231063f4a     
画着根的
参考例句:
  • Polio has been virtually eradicated in Brazil. 在巴西脊髓灰质炎实际上已经根除。
  • The disease has been eradicated from the world. 这种疾病已在全世界得到根除。
8 actively lzezni     
adv.积极地,勤奋地
参考例句:
  • During this period all the students were actively participating.在这节课中所有的学生都积极参加。
  • We are actively intervening to settle a quarrel.我们正在积极调解争执。
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