在哥斯達黎加的一家動物園里，人們發(fā)現(xiàn)了首個美洲鱷單性繁殖的案例。這只雌性美洲鱷產下的胎兒與母親的基因相似度達 99.9% 。

The egg was laid by an 18-year-old female American crocodile in Parque Reptiliana in January 2018. The foetus inside was fully formed, but stillborn, so didn't hatch. The mother was obtained by the reptile park when she was just two years old and was kept apart from other crocodiles for her entire life.

2018年1月，一只18歲的雌性美洲鱷在哥斯達黎加的爬行動物公園產下了這顆蛋。當時，蛋內的幼鱷胚胎已完全發(fā)育成型，但因死產而未孵化。這只鱷魚母親在兩歲時被哥斯達黎加爬行動物公園收養(yǎng)，一生都在與其它鱷魚隔離的環(huán)境下生活。

Because of this, the park scientific team contacted US researchers from Virginia Polytechnic, which specialises in such virgin births, known scientifically as parthenogenesis. They analysed the foetus and found that it was more than 99.9 percent genetically identical to its mother, confirming that it had no father.

正因如此，爬行動物公園的科學團隊聯(lián)系了美國弗吉尼亞理工學院的研究人員，該團隊專門研究這種單性生殖現(xiàn)象，科學術語為 “孤雌生殖”。他們對幼鱷胚胎進行了分析，發(fā)現(xiàn)它與其母親的基因相似度超過99.9%，證實了胚胎沒有父親。

Research team hypothesises that this ability was inherited from a common evolutionary ancestor, suggesting that dinosaurs may also have been capable of reproducing in this way.

研究團隊提出了這樣一種假說：這種孤雌生殖能力是從鱷魚和恐龍的一個共同祖先那里遺傳下來的，這表明恐龍可能也有以這種方式繁殖的能力。

詞匯表

foetus 胎兒，胚胎
stillborn 死產的
virgin birth 單性生殖
parthenogenesis 孤雌生殖，單性生殖
genetically （基因）遺傳上地
hypothesises 假設
inherited 遺傳下來的
ancestor 祖先

閱讀理解：請在讀完上文后，回答下列問題。

1. Why didn't the crocodile egg hatch?

2. Why did scientists believe the crocodile foetus had no father?

3. Which other creatures could have reproduced by themselves?

4. Where does the research team think this ability to self-reproduce was inherited from?

答案

1. Why didn't the crocodile egg hatch?

The foetus inside the egg was fully formed, but stillborn.

2. Why did scientists believe the crocodile foetus had no father?

Scientists found that the foetus was more than 99.9 percent genetically identical to its mother, confirming that it had no father.

3. Which other creatures could have reproduced by themselves?

It's possible dinosaurs may also have been capable of reproducing in this way.

4. Where does the research team think this ability to self-reproduce was inherited from?

Research team hypothesises that this ability was inherited from a common evolutionary ancestor.