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http://online1.tingclass.net/voaspe/…/20160321sa_science.mp3
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🎁 中英文稿：
Monarch butterflies are famous for their long haul to Mexico—a migration of more than 2,500 miles. But far more impressive is a species of dragonfly, Pantala flavescens. It's commonly known as a "globe skimmer," and it lives up to its name, migrating between 9,000 and 11,000 miles.
帝王蝶，因其長途跋涉到墨西哥而出名——遷徙距離超過2500英里。但是更令人印象深刻的是一種蜻蜓：Pantala flavescens。這種蜻蜓全球奔波，並且實至名歸，它們遷移的距離從長達9000到11000裡。
"Being really good at gliding, being able to take advantage of winds, being able to track rainy seasons, having short developmental times, because the larvae can develop very, very quickly,"—all those factors, according to Rutgers evolutionary biologist Jessica Ware, suggest the dragonflies may actually be one huge global population of interbreeding insects.
它們非常擅長滑行，善於利用風力，能夠監測雨季，發育時間極短，因為幼蟲能夠很快的發育成熟——根據羅格斯大學進化生物學家Jessica Ware的建議，根據這些因素，這類蜻蜓數量在全球範圍內，是雜交繁殖的昆蟲中最多的。
To test that idea, Ware and her colleagues sequenced DNA from dragonflies collected in Guyana, Japan, Korea, India, Canada and the United States. And since the genes they sequenced tend to mutate very quickly, if the populations were not interbreeding you'd expect to see differences from region to region. Instead, they found dragonflies in Japan that were more closely related to ones from Guyana than their own Japanese cousins. And that pattern of cross-continental similarities held true around the world. "This is a really compelling story that this is a species of the entire planet, of the Earth—it's not regional. The region is the planet." The results appear in the journal PLoS ONE.
為了證實這個觀點，她和同事們對圭亞那、日本、韓國、印度、加拿大和美國的蜻蜓樣本中的DNA進行了序列測定。並且因為基因突變的很快，所以，如果沒有進行雜種繁殖，基因測序的結果應該是具有區域差異性的特點。可是調查結果顯示，來自於日本的蜻蜓標本和來自於圭亞那蜻蜓親緣關係更近一些，比和其它來自於日本的蜻蜓標本還近呢。而這種跨大陸的樣本之間的相似性在全世界範圍內的樣本中是確實存在的。這是引人注目的一件事，也就是說這個物種是全世界全地球範圍內生存的——可不是區域性的，它的生存範圍是整個地球。該研究結果已發表在《公共科學圖書館》雜誌上。
As a truly global species, though, how will it react to global change? "If anything, climate change might just affect where it's able to set up these other populations, like in Canada. Maybe it'll be able to still establish and breed slightly north of where it is now. But I doubt it would necessarily change its routes dramatically." It's too early to know for sure—we’ll just have to see which way the wind blows.
作為全球性物種，這種蜻蜓對全球氣候變化又會作出怎樣的反應？如果這種影響確實存在，氣候變化影響它們在一個地區建立種群，那麼該地區就是加拿大。或許它在現在棲息地偏北一點的地方繁衍。但是我懷疑它有必要對遷移路線做出重大調整。現在來講還為時尚早——我們將來還是要看看天氣的情況才能做出判定。
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