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托福TPO-33 Lecture 3(中)

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First, what we call a chance mutation. A tiny genetic change occurred in that one Notothenioid species.

第一个是我们称为的偶然突变。在那种南极鱼的基因中发生了微小的改变。

Its DNA allowed for the production of a special protein, a protein that prevents the fish from freezing.

它的基因产生了一种特殊的蛋白质,这种蛋白质能保护南极鱼不受冻。

The way this...this anti-freeze protein works is: it binds to any ice crystals that form inside the fish.

这种抗冻蛋白工作的原理是:它会附在鱼类体内的每一个冰晶上。

This binding action prevents the ice crystals from growing larger. And this is what prevents Notothenioids from freezing.

这种粘附能防止冰晶变大。这就能保护南极鱼不受冻了。

南极鱼.jpg

Now, at that time, the waters the Notothenioids inhabited were still not freezing cold, so the protein didn't really make a difference as far as the fish's survival.

在那时候,南极鱼所在水域还没有那么冷,所以这种蛋白对于鱼类生存来说,并没有起很大作用。

But this would change, because in the same period of geologic time there was a shift in the earth's continental plates.

但这很快就会改变,因为在同一地质时期,地球的大陆板块发生了变化。

Continental drift caused Antarctica to move apart from the landmass of South America

大陆漂移导致南极洲从南美大陆中分离出来,

and to drift into the Southern Polar Region. This resulted in a powerful water current encircling Antarctica,

漂流到南极区域。这导致南极洲被一股强水流环绕,

which prevented the Antarctic waters from mixing with warmer water.

阻止了南极洲水域和温度更高的水融合。

So the southern ocean, isolated from that warm airflow from the north, cooled down drastically,

所以,南部海域与来自北方的暖气流隔绝了,大幅度降温,

to the kinds of sub-freezing temperatures we associate with it today.

达到了低于结冰点的温度,也就是今天的温度。

Now, most fish species couldn't survive in this frigid environment and they became extinct.

大部分鱼类在如此寒冷的环境下都无法生存,很快灭绝了。

But that one Notothenioid species, with its unique ability to produce that anti-freeze protein, thrived.

但那种南极鱼,有了独一无二的制造抗冻蛋白的能力,茁壮成长。

It had virtually the entire southern ocean to itself! So? Well, there was little or no competition for food or space.

基本上整个南部海域都是它的了!所以?那儿几乎没有关于食物和生存空间竞争。

You might think of it as...um...as a...a kind of ecological vacuum. And the Notothenioids exploited fully.

你大概能把它当成……一种生态真空。南极鱼充分利用了这一点。

The species migrated into different habitats throughout the southern ocean.

这种鱼迁徙到不同的栖息地,遍布整个南部海域。

And its population increased dramatically, with various sub-populations migrating into different parts of the ocean.

鱼类数量大幅增加,发展出很多不同的亚种,迁徙到海洋的不同区域。

重点单词   查看全部解释    
current ['kʌrənt]

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n. (水、气、电)流,趋势
adj. 流通的

联想记忆
shift [ʃift]

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n. 交换,变化,移动,接班者
v. 更替,移

 
competition [kɔmpi'tiʃən]

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n. 比赛,竞争,竞赛

 
survival [sə'vaivəl]

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n. 生存,幸存者

联想记忆
drift [drift]

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vi. 漂流,漂移,漂泊,吹积,偏离
vt.

 
protein ['prəuti:n]

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n. 蛋白质

 
associate [ə'səuʃieit]

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n. 同伴,伙伴,合伙人
n. 准学士学位获得

联想记忆
continental [.kɔnti'nentl]

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adj. 大陆的

 
environment [in'vaiərənmənt]

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n. 环境,外界

 
mutation [mju:'teiʃən]

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n. 变化,转变,母音变化

 

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