2021年经济学人 性选择和物种形成(1)

Sexual selection and speciation

性选择和物种形成

Choice and determinism

选择和决定论

Just four genes¹ separate two species of South American bird

南美两种鸟类之间只有四种基因的区别

Natural selection, as propounded² in Charles Darwin's master work, "On the Origin of Species", explains how organisms evolve and adapt to their circumstances. Paradoxically, though, it is a bit hazy³ on the actual subject of its title, namely how parent species spin off new, daughter species. Darwin recognised that diverse ecological⁴ niches⁵ encourage speciation (though he did not use those as-yet-uninvented terms). But he did not ask how incipient⁶ daughter species were prevented from remixing before they had properly separated.

“自然选择”由查尔斯·达尔文在其著作《物种起源》中提出，解释了生物如何进化并适应环境。然而矛盾的是，它对标题的实际主题——即母物种是如何衍生出新子代物种——有点含糊不清。达尔文认识到不同的生态位促进了物种形成(尽管他没有使用那些尚未发明的术语)，但他并没有对“如何阻止早期的子物种在它们完全分离之前重新混合”提出疑问。

Somehow, barriers need to be erected⁷ against miscegenation⁸. They might be geographical—fish in different lakes, for example. Or they might be ecological, such as a shift in food preferences causing insects formerly⁹ of the same species to feed in different types of tree. But sometimes species form in circumstances where no such barriers are apparent. That is puzzling.

无论如何，我们需要建立障碍来反对种族通婚。它们可能是地理上的——例如，不同的湖泊里的鱼。或者它们可能是生态的，比如食物偏好的改变导致原来同一物种的昆虫在不同类型的树上觅食。但有时物种是在没有明显障碍的情况下形成的。这是令人费解的。

One established exception to the rule that speciation requires separation is hybridisation. This is a common source of new plant species, but is rarer for animals. It is, though, thought to explain several brightly coloured animal groups, including the cichlid fish of Africa's Great Lakes, the heliconid butterflies of South and Central America, and the southern capuchino seedeaters, a family of songbirds that also live in the New World tropics. Now, Sheela Turbek of the University of Colorado, in Boulder¹⁰, has taken matters a step further, by showing that a process called sexual selection plays a role in what is going on.

杂交是“物种形成需要分离”这一规则的例外，是新植物物种的常见来源，但在动物中相对罕见。然而它被认为可以解释几种颜色鲜艳的动物群体，包括非洲五大湖的丽鲷科鱼类，南美洲和中美洲的螺旋形蝴蝶，以及南部卡普契诺食种子鸟(一种同样生活在新世界热带地区的鸣禽)。目前，来自科罗拉多大学(位于博尔德)的席拉·图尔贝克通过展示一种被称为性选择的过程在正在发生的事情中起着作用使得这一说法更进一步。

Picky, picky

吹毛求疵

Sexual selection, a phenomenon first described scientifically by Darwin, occurs when one sex (usually the female) chooses another (usually the male) on the basis of a distinctive¹¹ genetically¹² derived¹³ characteristic. The classic example is a peacock's tail. But sexual selection could also serve to separate species in what is more-or-less a one-step process, by the sudden appearance of such a characteristic. And that, as she describes in a paper in Science, is what Ms Turbek thinks has happened in the case of the Ibera and tawny-bellied seedeaters.

“性选择”是达尔文首次在科学上描述的一种现象，在一个性别(通常是女性)基于一种独特的遗传特征来选择另一个性别(通常是男性)之时出现。孔雀的尾巴就是比较经典的例子。但是性选择也可以通过这种特征的突然出现，在一个或多或少是一步的过程中分离物种。正如图贝克女士在《科学》杂志上的一篇论文中所描述的那样，这就是她认为发生在伊比利亚和茶色腹食种子动物身上的情况。

These two birds live, among other places, in the San Nicolas Reserve, in Argentina. They forage¹⁴ on the same grasses, breed at the same time, and have breeding territories which may be as close as 50 metres from one occupied by the other species. They are also similar enough to interbreed successfully in captivity¹⁵. But, as far as is known, they never do so in the wild.

这两种鸟生活在阿根廷的圣尼古拉斯保护区。它们在相同的草地上觅食，在同一时间繁殖，它们的繁殖领地大概离其他物种的领地有近50米。它们的相似程度也足以在圈养环境中成功杂交。但据我们所知，野外的它们从不进行杂交。

1 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

2 propounded   

v.提出（问题、计划等）供考虑[讨论]，提议( propound的过去式和过去分词 )

参考例句：

• the theory of natural selection, first propounded by Charles Darwin 查尔斯∙达尔文首先提出的物竞天择理论
• Indeed it was first propounded by the ubiquitous Thomas Young. 实际上，它是由尽人皆知的杨氏首先提出来的。 来自辞典例句

3 hazy   

adj.有薄雾的，朦胧的；不肯定的，模糊的

参考例句：

• We couldn't see far because it was so hazy.雾气蒙蒙妨碍了我们的视线。
• I have a hazy memory of those early years.对那些早先的岁月我有着朦胧的记忆。

4 ecological   

adj.生态的，生态学的

参考例句：

• The region has been declared an ecological disaster zone.这个地区已经宣布为生态灾难区。
• Each animal has its ecological niche.每种动物都有自己的生态位.

5 niches   

壁龛( niche的名词复数 )； 合适的位置[工作等]； （产品的）商机； 生态位（一个生物所占据的生境的最小单位）

参考例句：

• Some larvae extend the galleries to form niches. 许多幼虫将坑道延伸扩大成壁龛。
• In his view differences in adaptation are insufficient to create niches commensurate in number and kind. 按照他的观点，适应的差异不足以在数量上和种类上形成同量的小生境。

6 incipient   

adj.起初的，发端的，初期的

参考例句：

• The anxiety has been sharpened by the incipient mining boom.采矿业初期的蓬勃发展加剧了这种担忧。
• What we see then is an incipient global inflation.因此，我们看到的是初期阶段的全球通胀.

7 ERECTED   

adj. 直立的，竖立的，笔直的 vt. 使 ... 直立，建立

参考例句：

• A monument to him was erected in St Paul's Cathedral. 在圣保罗大教堂为他修了一座纪念碑。
• A monument was erected to the memory of that great scientist. 树立了一块纪念碑纪念那位伟大的科学家。

8 miscegenation   

n.人种混杂；混血

参考例句：

• It was only in 1967 that the United States finally struck down its anti miscegenation laws.直到1967年，美国才废除了反种族通婚的法律。
• In contemporary times,Brazilians have come to regard miscegenation as a defining national trait.在当代，巴西人已经把种族通婚看作是鲜明的国家特征。

9 formerly   

adv.从前，以前

参考例句：

• We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
• This boat was formerly used on the rivers of China.这船从前航行在中国内河里。

10 boulder   

n.巨砾；卵石，圆石

参考例句：

• We all heaved together and removed the boulder.大家一齐用劲，把大石头搬开了。
• He stepped clear of the boulder.他从大石头后面走了出来。

11 distinctive   

adj.特别的，有特色的，与众不同的

参考例句：

• She has a very distinctive way of walking.她走路的样子与别人很不相同。
• This bird has several distinctive features.这个鸟具有几种突出的特征。

12 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

13 derived   

vi.起源；由来；衍生；导出v.得到( derive的过去式和过去分词 )；（从…中）得到获得；源于；（从…中）提取

参考例句：

• Many English words are derived from Latin and Greek. 英语很多词源出于拉丁文和希腊文。 来自《简明英汉词典》
• He derived his enthusiasm for literature from his father. 他对文学的爱好是受他父亲的影响。 来自《简明英汉词典》

14 forage   

n.(牛马的)饲料，粮草；v.搜寻，翻寻

参考例句：

• They were forced to forage for clothing and fuel.他们不得不去寻找衣服和燃料。
• Now the nutritive value of the forage is reduced.此时牧草的营养价值也下降了。

15 captivity   

n.囚禁；被俘；束缚

参考例句：

• A zoo is a place where live animals are kept in captivity for the public to see.动物园是圈养动物以供公众观看的场所。
• He was held in captivity for three years.他被囚禁叁年。