字神帝國英語天地

今日主題：Small Fish Takes Fast-Evolution Track
鹹魚翻身記

洪欣老師推薦：托福聽力最好的課外教材：60-Second Science
康康精選托福會考的主題，堅持每天精聽一定會進步的哦!!

建議方法：
1. 先聽兩三遍 (不看文稿)
2. 再一句一句聽寫 (每句都要聽寫數遍，直到寫出85%以上的字)
3. 最後check文稿，看哪聽不出來，單字沒背過，還是發音不熟。
4. 堅持天天聽，就能每天進步哦。

MP3音檔 (按右鍵可下載聽)：喜歡的同學，幫忙推或按讚哦~~
http://online1.tingclass.net/voaspe/…/20160110sa_science.mp3

只有音檔怎夠，聽不懂地方，不用怕，康康幫你準備好中英文稿了：

中英文稿：
March 27th, 1964: the world's second-most powerful recorded earthquake hits Alaska.
1964年，3月27日，阿拉斯加發生了世界上第二強大的地震。

"What happened was the whole Gulf of Alaska and Prince William Sound just sort of tilted, and so near shore, near Alaska, that region sank. And then out at sea, the sea floor raised up." Susie Bassham, a molecular biologist at the University of Oregon. "And so things that were submarine platforms before suddenly were lifted above sea level, and then silt could come in and build more island."
“整個阿拉斯加海灣和威廉王子灣發生了傾斜，阿拉斯加附近發生了塌陷。海床升高。”Susie Bassham是俄勒岡州立大學的分子生物學家，她還說到，“海底高地突出海平面，淤泥可以用來建立更多的島嶼。”

And with more island, came new freshwater ponds. Those newly created bodies of water turned out to be the testbed for a natural evolutionary experiment on a finger-sized fish, called the three-spined stickleback. Saltwater fish went in… freshwater fish came out. "Big silvery well-armored fish entered freshwater ponds. And during the last 50 years they changed their size, their coloration, they changed the size of their eyes, the length of their spines, many aspects of their skeletons, feeding structures, swimming structures, and became more stereotypical freshwater fish." But how?
島嶼更多，就會有新的淡水池塘。原來這些新的淡水池塘是用來對一種手指大小的魚——三刺魚——進行自然進化實驗的。這種鹹水魚潛入水底，然後出來的就是淡 水魚。“這種大銀灰色刺魚，進入淡水池塘。在過去的50年，它們的體型、顏色發生了變化。同時眼睛的大小、棘突長度、骨骼的很多方面、進食和游泳結構都發 生了變化，越來越像淡水魚。”但是這是怎麼發生的呢?

Bassham and her colleagues ran statistical analyses on the genomes and body measurements of fish living in those freshwater ponds today. And they found that the saltwater versions of the fish may have actually colonized those freshwater ponds on the study islands at least six times in the last 50 years. They were able to move in and rapidly adapt because the sea-dwelling fish have a sort of "sleeper genome" of freshwater traits, just waiting to be activated.
Bassham和同事們對淡水池塘的魚進行了基因組和身體測量。研究發現，這些鹹魚版的淡水魚在實驗島嶼的淡水池塘至少生活了50年。這中深海魚，能夠快速的適應淡水環境，因為它們具有淡水魚的“休眠基因”。這些基因只是在等待被啟動。

"These are anadromous fish that have been invading freshwater ecosystems over and over and over. And all those freshwater adaptations have trickled back into the sea, allowing the oceanic population, which is believed to be the ancestor of all the freshwater populations, to maintain this huge resource of differently, alternately adapted genotypes that are just waiting to get back into a freshwater system."
這些溯河性魚類在一次又一次的入侵淡水魚生態系統。這些慢慢適應淡水的鹹水魚，回流到大海裡，這可以讓鹹水魚種類多樣化——人們認為鹹水魚是淡水魚的祖先——之後，已經適應大海的鹹水魚再回到淡水系統。

And when they do, it takes just several dozen generations—instead of thousands of years—for this evolution to occur. The findings are in the Proceedings of the National Academy of Sciences.
這種往返的回流過程，需要幾十代來完成——不需要上千年——進化就產生了。該研究結果發表在《美國國家科學學院院刊》上。

Not all species, of course, have a genome that makes it easy to respond to sudden environmental challenges, the kind we’re seeing with climate change. "For instance corals are very adapted to live in a very narrow temperature range. And there is no genetic diversity to call upon there." But there may be a few species, she says, in possession of the kind of genetic toolkit that enables sticklebacks to deal with adversity so swimmingly.
當然，並不是所有種類，都具有快速適應突發環境變化的基因組，我們這是所指的環境變化是指氣候變化。“珊瑚溫差適應範圍很窄，因為它不具有多樣性的溫差基因。”但是有些物種，Bassham稱，刺魚具有此種基因組，因此它能快速適應逆境。