60秒科学:Are Parasites to Thank for Sex?

Are Parasites² to Thank for Sex?

A study in the journal The American Naturalist³ implies that parasites helped drive the development of sex, because the shuffling⁴ of genes⁵ gives sex-produced progeny⁶ an advantage over asexual genetic⁷ clones. Cynthia Graber reports

[The following is an exact transcript⁸ of this podcast.]

Sex might seem like one of those little gifts from evolution. But it’s pretty inefficient⁹ from an evolutionary¹⁰ 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 genetically¹¹ identical, clones are also weak in the same ways, and thus more likely to all succumb¹² to a parasite¹. But sex keeps shuffling the genetic deck.

Well, there’s a snail¹³ 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 snails¹⁴ that were plentiful¹⁵ 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

perspective

n. 远景,看法,透视
adj. 透视的

Thus we need to create a common perspective, a Singaporean perspective. 
因此我们确实有必要建立一种共识，一种使得大家都能够从新加坡人的角度和观点来看问题的共识。

hypothesize

vi.,vt.假设, 假定

Biologists have hypothesized that one driving force might have been parasites.
生物学家假设寄生虫可能为其中一个动力。

succumb

vi. 屈从, 屈服, 死

If businessmen spend as much as they do on advertising¹⁶, it must be because people are known to succumb to persuasion¹⁷ through the media.
如果说商人们不惜花本钱做广告的话，那一定是因为他们知道人们容易接受新闻媒介所提供的劝告。

shuffle¹⁸

n. 拖着脚走, 曳步, 混乱, 蒙混, 洗纸牌
vt. 拖曳, 马虎地做, 笨手笨脚地穿(脱)衣, 推诿, 洗牌
vi. 拖曳, 马虎地做, 笨手笨脚地穿(脱)衣, 推诿, 洗牌

Don't shuffle the papers together.
不要把文件混在一起。

deck

n. 甲板, (汽车后部的)行李仓
vt. 装饰, 打扮, 装甲板

The captain walked the deck.
船长巡视甲板。

asexually

adv.无性地, 无性生殖地

An asexually produced reproductive cell, such as a zeospore, found in certain algae¹⁹.
无性生殖细胞无性生殖细胞，存在于一些藻类植物里

1 parasite   

n.寄生虫；寄生菌；食客

参考例句：

• The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
• I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫，我要自己养活自己。

2 parasites   

寄生物( parasite的名词复数 )； 靠他人为生的人； 诸虫

参考例句：

• These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的，而与寄生虫无关。
• Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。

3 naturalist   

n.博物学家(尤指直接观察动植物者)

参考例句：

• He was a printer by trade and naturalist by avocation.他从事印刷业，同时是个博物学爱好者。
• The naturalist told us many stories about birds.博物学家给我们讲述了许多有关鸟儿的故事。

4 shuffling   

adj. 慢慢移动的, 滑移的 动词shuffle的现在分词形式

参考例句：

• Don't go shuffling along as if you were dead. 别像个死人似地拖着脚走。 来自英汉文学 - 嘉莉妹妹
• Some one was shuffling by on the sidewalk. 外面的人行道上有人拖着脚走过。 来自英汉文学 - 嘉莉妹妹

5 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

6 progeny   

n.后代，子孙；结果

参考例句：

• His numerous progeny are scattered all over the country.他为数众多的后代散布在全国各地。
• He was surrounded by his numerous progeny.众多的子孙簇拥着他。

7 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

8 transcript   

n.抄本，誊本，副本，肄业证书

参考例句：

• A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
• They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。

9 inefficient   

adj.效率低的，无效的

参考例句：

• The inefficient operation cost the firm a lot of money.低效率的运作使该公司损失了许多钱。
• Their communication systems are inefficient in the extreme.他们的通讯系统效率非常差。

10 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

11 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

12 succumb   

v.屈服，屈从；死

参考例句：

• They will never succumb to the enemies.他们决不向敌人屈服。
• Will business leaders succumb to these ideas?商业领袖们会被这些观点折服吗？

13 snail   

n.蜗牛

参考例句：

• Snail is a small plant-eating creature with a soft body.蜗牛是一种软体草食动物。
• Time moved at a snail's pace before the holidays.放假前的时间过得很慢。

14 snails   

n.蜗牛；迟钝的人；蜗牛( snail的名词复数 )

参考例句：

• I think I'll try the snails for lunch—I'm feeling adventurous today. 我想我午餐要尝一下蜗牛——我今天很想冒险。 来自《简明英汉词典》
• Most snails have shells on their backs. 大多数蜗牛背上有壳。 来自《简明英汉词典》

15 plentiful   

adj.富裕的，丰富的

参考例句：

• Their family has a plentiful harvest this year.他们家今年又丰收了。
• Rainfall is plentiful in the area.这个地区雨量充足。

16 advertising   

n.广告业；广告活动 a.广告的；广告业务的

参考例句：

• Can you give me any advice on getting into advertising? 你能指点我如何涉足广告业吗?
• The advertising campaign is aimed primarily at young people. 这个广告宣传运动主要是针对年轻人的。

17 persuasion   

n.劝说；说服；持有某种信仰的宗派

参考例句：

• He decided to leave only after much persuasion.经过多方劝说，他才决定离开。
• After a lot of persuasion,she agreed to go.经过多次劝说后，她同意去了。

18 shuffle   

n.拖著脚走，洗纸牌；v.拖曳，慢吞吞地走

参考例句：

• I wish you'd remember to shuffle before you deal.我希望在你发牌前记得洗牌。
• Don't shuffle your feet along.别拖着脚步走。

19 algae   

n.水藻，海藻

参考例句：

• Most algae live in water.多数藻类生长在水中。
• Algae grow and spread quickly in the lake.湖中水藻滋蔓。