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骡子为什么不能生宝宝

Why Can't Mules Have Babies?

你好 这是艾米丽
Hi, this is Emily.
不同种的动物之间很少激动 而它们这么做时 又很少繁殖
Animals of different species rarely get it on, and when they do, they rarely produce
后代
offspring.
比狮虎 斑驴 杂交骆驼 皮弗洛牛还要罕见的 是杂种动物
But even rarer than the ligers, zonkeys, camas, and beefalo of the world are hybrid animals
能够独自生育后代
capable of making babies of their own.
事实上 骡是母马和雄驴的杂交后代
In fact, the idea of a mule – the hybrid progeny of a female horse and a male donkey
它有自己后代是如此难以置信以致于古罗马人过去常采用
– having its own baby is so implausible that the ancient Romans used to employ the
谚语“当骡子产马驹”作为不可能的暗喻 同样的暗喻美国人
saying “when a mule foals” as a metaphor for the impossible — the same way that Americans
说“当猪飞” 土耳其人说“当鱼爬树” 而尼日利亚人
say “when pigs fly”, Turkish people say “when fish climb trees” and Nigerians
说“当鸡有了牙齿”
say “when the chicken has teeth.”
原因如下 为了成功繁殖 动物需要创造可生育的性细胞
Here’s why: in order to successfully reproduce, animals need to create viable sex cells.
正常的体细胞每条染色体各有两个副本 一个来自母亲
Normal body cells have two copies of each chromosome – one from the animal’s mom,
一个来自父亲 有点像两幅完整的牌 它们都可简单地
and one from dad, sort of like two full decks of cards – and both decks can simply be
被复制 然后分裂形成一个新细胞
duplicated and then split off to form a new cell.
但性细胞不同 它们通过将每一组染色体复制 交换
But sex cells are different: they’re produced by taking each set of chromosomes, duplicating them, and then swapping
一些卡片 然后再分裂成四个细胞 每个性细胞
a bunch of cards between decks before breaking them up to form four cells, each with just
又是一副完整的牌
one complete deck of cards.
这种卡片交换在两副牌来自于同种父母时有效
This card-swap works when the decks in each set come from a mom and dad of the same species,
因为他们有着顺序相同的卡片 所以眼色基因与
because they have all the same cards in the same order, so genes for eye-color get swapped
其它眼色基因交换 条纹图案基因与其它条纹图案
with other genes for eye-color, and stripe pattern genes get swapped with stripe-pattern
基因交换
genes.
但杂种动物的细胞里 牌不是相同的 因为其父母
But in the cells of hybrid animals, the decks aren’t identical because they came from parents
是不同种类的 所以眼色基因可能与手爪基因交换或者
of different species, so an eye-color card might get swapped for a paw size card, or
骨髓基因与肾脏基因交换 产生了两种真正怪异的牌
a bone-making gene for a kidney-making gene, producing two really weird decks that give
这就产生了完全没有功能的性细胞
rise to totally non-functional sex cells.
虽然无法解释 但它有时是可能发生的 当一个杂种动物
However, for reasons we really don’t understand, it is sometimes possible for a hybrid animal
完全地跳过卡片交换步骤 并创造了仅仅包含
to skip over the card-swapping step altogether and create new sex cells that contain only
母亲的DNA的新性细胞
the mom’s DNA.
实际上我们只在雌骡上看到它发生:这里有些已证实的
We’ve actually only seen this happen in female mules: there are a handful of documented
事件 骡可以生育出只含母亲DNA的后代
cases in which mules have made babies from eggs containing only their mother’s DNA;
怪诞地 这意味着从基因来看 每只雌骡后代是她半个手足
bizarrely, this means that each female mule’s offspring was genetically also her half-sibling.
所以 虽然猪不会飞 但隔一段时间后 骡却生下了驹
So, while – as far as we know – pigs never fly, every once in a great while, a mule foals.
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拥有一个超过7000个讲座的视频库 它的主讲教授来自一些世界顶尖
with a library of over 7,000 lectures by leading professors from some of the world’s top
学府
institutions.
我已经精读了一个关于基因的课程知道曾经真有
I’ve been perusing a course on genetics and have learned that there actually used
一个克隆人们宠物的公司 这意味着理论上我可以拥有
to be a company that cloned people’s pets, which means that theoretically I could have
一只又老又瞎的我家Yardley猫版本的小猫 但它真的是Yardley吗
a kitten version of my old, blind cat Yardley, except would it be really Yardley?.
想获得伟大的课程+的一个月免费订阅 以及表示对
To get a free one-month trial subscription to The Great Courses Plus and show your support
MinuteEarth的支持 请访问TheGreatCoursesPlus.com/minuteearth或者点击下面说明里的链接
for MinuteEarth, go to TheGreatCoursesPlus.com/minuteearth, or click the link in the description below.
感谢伟大的课程+!
Thanks Great Courses Plus!

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视频概述

形象生动准确地介绍了骡的产生以及解答了有关基因的问题

听录译者

收集自网络

翻译译者

天晴好个秋

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译学馆审核团D

视频来源

https://www.youtube.com/watch?v=6Hfelo_qAw0

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