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SSS 2009-03-12

时间:2010-05-17 06:29来源:互联网 提供网友:木渐浅。   字体: [ ]
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This is Scientific American's 60-Second Science. I'm Adam Hinterthuer. Got a minute?

Farmers fertilize1 their fields to get the maximum meal from their crops. But the effects of these loads of nitrogen and phosphorous extend beyond the field and past the growing season. According to a study published this week by the Proceedings2 of the National Academy of Sciences, these nutrients4 can also drive the evolution of aquatic5 organisms. 

Agricultural fertilizers often drain into aquatic ecosystems6 and spur a frenzy7 of growth. Eventually the growth peaks and crashes as oxygen is consumed faster than it can be replenished8 - a condition called eutrophication. 

Using samples from two European lakes, Swiss researchers studied a century’s worth of eggs buried deep in the sediment9 by two species of Daphnia, a tiny crustacean10. They found that, during periods of high nutrient3 levels, genetically11 distinct hybrid12 species emerged. Those hybrids13 appeared better at surviving eutrophication and soon outnumbered the original species. 

What’s more, the hybrids remained the dominant14 Daphnia species decades after pollution control measures brought nutrient levels back to normal. The scientists say short-term human impacts can leave permanent changes in ecosystems and a species’ genetics. 

You could say we’ve got quite the ‘gene’ thumb.

Thanks for the minute for Scientific American's 60-Second Science. I'm Adam Hinterthuer.

 


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1 fertilize hk5x8     
v.使受精,施肥于,使肥沃
参考例句:
  • Fertilizer is a substance put on land to fertilize it.肥料是施在地里使之肥沃的物质。
  • Reading will fertilize his vocabulary.阅读会丰富他的词汇。
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 nutrient 3vpye     
adj.营养的,滋养的;n.营养物,营养品
参考例句:
  • Magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
  • The roots transmit moisture and nutrient to the trunk and branches.根将水分和养料输送到干和枝。
4 nutrients 6a1e1ed248a3ac49744c39cc962fb607     
n.(食品或化学品)营养物,营养品( nutrient的名词复数 )
参考例句:
  • a lack of essential nutrients 基本营养的缺乏
  • Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》
5 aquatic mvXzk     
adj.水生的,水栖的
参考例句:
  • Aquatic sports include swimming and rowing.水上运动包括游泳和划船。
  • We visited an aquatic city in Italy.我们在意大利访问过一个水上城市。
6 ecosystems 94cb0e40a815bea1157ac8aab9a5380d     
n.生态系统( ecosystem的名词复数 )
参考例句:
  • There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
  • Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样,从雨林到半荒漠等不一而足。 来自辞典例句
7 frenzy jQbzs     
n.疯狂,狂热,极度的激动
参考例句:
  • He was able to work the young students up into a frenzy.他能激起青年学生的狂热。
  • They were singing in a frenzy of joy.他们欣喜若狂地高声歌唱。
8 replenished 9f0ecb49d62f04f91bf08c0cab1081e5     
补充( replenish的过去式和过去分词 ); 重新装满
参考例句:
  • She replenished her wardrobe. 她添置了衣服。
  • She has replenished a leather [fur] coat recently. 她最近添置了一件皮袄。
9 sediment IsByK     
n.沉淀,沉渣,沉积(物)
参考例句:
  • The sediment settled and the water was clear.杂质沉淀后,水变清了。
  • Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。
10 crustacean Mnrzu     
n.甲壳动物;adj.甲壳纲的
参考例句:
  • Seafood is a valuable lobster crustacean section.名贵海珍品龙虾属甲壳科。
  • The illustrious Cuvier did not perceive that a barnacle was a crustacean.大名鼎鼎的居维叶也未看出藤壶是一种甲壳动物。
11 genetically Lgixo     
adv.遗传上
参考例句:
  • All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
  • Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物
12 hybrid pcBzu     
n.(动,植)杂种,混合物
参考例句:
  • That is a hybrid perpetual rose.那是一株杂交的四季开花的蔷薇。
  • The hybrid was tall,handsome,and intelligent.那混血儿高大、英俊、又聪明。
13 hybrids a5030918be299fefcf603b9326766b39     
n.杂交生成的生物体( hybrid的名词复数 );杂交植物(或动物);杂种;(不同事物的)混合物
参考例句:
  • All these brightly coloured hybrids are so lovely in the garden. 花园里所有这些色彩鲜艳的杂交花真美丽。 来自辞典例句
  • The notion that interspecific hybrids are rare is ill-founded. 有一种看法认为种间杂种是罕见的,这种看法是无根据的。 来自辞典例句
14 dominant usAxG     
adj.支配的,统治的;占优势的;显性的;n.主因,要素,主要的人(或物);显性基因
参考例句:
  • The British were formerly dominant in India.英国人从前统治印度。
  • She was a dominant figure in the French film industry.她在法国电影界是个举足轻重的人物。
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