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托福听力练习-科学美国人60秒:"苹果"里的青蛙

2017-04-12 09:39:00来源：科学美国人60秒

点击查看>>科学美国人60秒音频："苹果"里的青蛙

　　科学美国人60秒听力练习："苹果"里的青蛙

　　科学美国人60秒英文文本

　　Scientists discover new species all the time—on the order of 15,000 a year. One of the latest additions to the tree of life is a new type of leopard frog. Which might sound unremarkable, except for where it was found: New York City.

　　But how does a frog go unnoticed in the Big Apple? Well even experts have a hard time telling this new species from its northern and southern cousins on looks alone. But the new guy has a different croak, which raised ecologists' suspicions. So they tracked down four leopard frog populations with the unique call—including one within view of the Statue of Liberty—and took DNA samples.

　　As they suspected, the odd croakers weren't southern or northern leopard frogs, or even a mix. They had a genetic ancestry of their own—earning them new species status. Those results appear in the journal Molecular Phylogenetics and Evolution.

　　The frogs are tough New Yorkers—the center of their range appears to be Yankee Stadium. But the researchers say that the urban amphibians face threats like pesticides and infectious diseases. Not to mention real-life games of Frogger.

　　中文翻译请点击下一页

本文关键字: 托福听力 科学美国人

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