Why does a zebra have stripes? 斑馬為何有斑紋

Victoria Gill, BBC News

White stripes could have been a result of natural selection

媒體英語(yǔ)會(huì)帶大家一起學(xué)習(xí) BBC 撰稿人在報(bào)道世界大事時(shí)常用到的單詞和短語(yǔ)。

科學(xué)家們稱(chēng)他們已經(jīng)揭開(kāi)了斑馬身上為何有黑白條斑紋的秘密。這篇刊登在《自然生物學(xué)期刊上》的文章說(shuō)斑紋有掩護(hù)作用，因?yàn)槔ハx(chóng)不喜歡斑紋。

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There have been many theories to explain the zebra's unmistakable stripes. Scientists have suggested that each zebra has a unique pattern that lets other animals recognise it. Or that the mass of black and white in a vast herd provides confusing camouflage that puts off predators.

But this team set out to test exactly what effect the stripes had on a zebra's most irritating and ubiquitous enemy - the blood-sucking horsefly.

As part of their experiment the team put sticky horse models - one white, one black and one zebra-striped - into a fly-infested field. When they collected the flies that had landed and stuck to each of the models, they found that the model zebra attracted by far the fewest flies.

The researchers think that zebras had a black-coated ancestor, which evolved its white stripes in an evolutionary arms race, with an insect that's become the biting, disease-carrying scourge of most horse herds.

Glossary 詞匯表 （點(diǎn)擊單詞收聽(tīng)發(fā)音）

• horsefly馬蠅
• fly-infested充滿(mǎn)蒼蠅的
• ancestor祖先
• evolved進(jìn)化
• scourge天災(zāi)/瘟疫