60秒科学:Are Parasites to Thank for Sex?（在线收听）

Are Parasites to Thank for Sex?

A study in the journal The American Naturalist implies that parasites helped drive the development of sex, because the shuffling of genes gives sex-produced progeny an advantage over asexual genetic clones. Cynthia Graber reports

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

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

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 advertising, it must be because people are known to succumb to persuasion 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。

shuffle

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 algae.
无性生殖细胞无性生殖细胞，存在于一些藻类植物里