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科学60秒:寄生虫让我们拥有了“性”?

时间: 2020年05月19日 | 作者: Admin | 来源: 领研网(linkresearcher.com)


 [听力全文]


Sex might seem like one of those little gifts from evolution. But it’s pretty inefficient from an evolutionary perspective. It’d be much easier to reproduce if you could do away with finding the right member of the opposite sex to help you create the next generation. So why did evolution come up with sex?


Biologists have hypothesized that one driving force might have been parasites. Now scientists have had a chance to test that theory. Asexual reproduction leads to clones. Being genetically identical, clones are also weak in the same ways, and thus more likely to all succumb to a parasite. But sex keeps shuffling the genetic deck. 


Well, there’s a snail common in New Zealand lakes that does both—some populations have sex and some reproduce asexually. So researchers spent 10 years monitoring the two populations, and the number of parasites living off both groups. As expected, cloned snails that were plentiful at the beginning of the study suffered big losses as they became infected with parasites. But the sexual snail populations remained stable, results published in the journal American Naturalist. So, next time you’re feeling sexy, thank a parasite.


—Cynthia Graber



 [重难点词汇、短语]


asexual: adj. 无性的;无性生殖的;性冷淡的;无性恋的

succumb: v. 屈服;死;被压垮



 [参考译文]


“性”似乎只是进化过程中诸多馈赠的其中之一,但从进化的角度来看,它的效率很低。如果你不需要找到合适的异性来帮助你生育下一代,那繁殖就会容易得多。那么,为什么会进化出“性”呢?

 

生物学家曾推测,其中一个驱动力可能是寄生虫;而现在,科学家能着手验证这一假设了。无性繁殖产生的克隆体基因相同,正因如此,所有的克隆体会有同样的缺陷,因此更有可能全部被寄生虫瓦解。而有性繁殖则会不停地重组基因。

 

在新西兰的湖泊里,有种常见蜗牛同时拥有两种繁殖技能,它们中的某些群体进行有性繁殖,另一些则进行无性繁殖。研究人员花了10年的时间来监测这两种群体,以及依赖这两个群体生存的寄生虫数量。不出所料,研究初期数量庞大的无性繁殖蜗牛在感染了寄生虫后,群体数量遭受了巨大损失。但是有性繁殖的蜗牛数量保持了稳定。该研究结果发表在《美国博物学家》(American Naturalist)杂志上。所以,下次感受到性感时,感谢下寄生虫吧。


翻译 页一