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灭绝物种最后存活的成员

The last living members of an extinct species - Jan Stejskal

《TEDEd》 值得分享的课程
活着的野生物种就像装满未读书本的图书馆……破坏它们就等于烧毁那个图书馆—— John Dingell
In the savannahs of Kenya, two female northern white rhinos
在肯尼亚稀树大草原 两只雌性北白犀
Nájin and Fatu, munch contentedly on the grass.
Nájin和Fatu 正欢快地吃着草
At the time of this video’s publication,
在这个视频发布之时
these are the last two known northern white rhinos left on Earth.
它们是地球仅剩的两只已知北白犀
Their species is functionally extinct–
它们种群已功能性灭绝——
without a male, Nájin and Fatu can’t reproduce.
因为缺失雄性 Nájin和Fatu无法繁衍
And yet, there’s still hope to revive the northern white rhino.
然而 仍有希望让北白犀繁荣
How can that be?
怎么做呢?
The story starts about 50 years ago,
故事要追溯到50年前
when poachers began illegally hunting thousands of rhinos
那时偷猎者为了犀牛角开始在整个非洲
across Africa for their horns.
非法猎杀数以千计的犀牛
This, combined with civil wars in their territory,
这与当地的内战一起
decimated northern white rhino populations.
让北白犀的数量毁灭性地减少
Concerned conservationists began trying to breed them in
自然保护者自1970年代就开始
captivity in the 1970s,
竭力在牢笼中繁殖它们
collecting and storing semen from males.
并从雄性北白犀那里收集和储存精子
Only four rhinos were ultimately born through the ambitious breeding program.
但仅四只最终生于该雄心勃勃的繁殖计划
Nájin, and her daughter Fatu were the last two.
Nájin及其女儿Fatu是最后两只
In 2014, conservationists discovered that neither can have a calf.
2014年 自然保护者发现它们都无法生育
Though Nájin gave birth to Fatu, she now has weak hindlegs,
尽管Nájin产下Fatu 但它现在后腿羸弱
which could harm her health if she became pregnant again.
再次怀孕可能会损害它的健康
Fatu, meanwhile, has a degenerated uterine lining.
同时Fatu患有子宫内膜退化
Then, the last northern white rhino male of the species, Sudan,
而最后一只雄性北白犀 Sudan
died in 2018.
死于2018年
But there was one glimmer of hope: artificial reproduction.
但仍有一线希望:人工繁殖
With no living males and no females able to carry a pregnancy,
由于没有活的雄性和有怀孕能力的雌性
this is a complicated and risky process to say the least.
毫不夸张地说 这是个复杂且冒险的过程
Though scientists had stored semen, they would have to collect the eggs—
尽管储存了精子 科学家们还需收集卵泡
a complex procedure that requires a female to be sedated for up to two hours.
这是个需雌性镇静长达2小时的复杂程序
Then, they’d create a viable embryo in the lab–
然后才可能在实验室制造一个有效胚胎——
something that had never been done before, and no one knew how to do.
这是从未有人做过也没人知道怎么做的事情
Even that was just the beginning–
但那却仅仅是个开始——
a surrogate mother of another rhino species
还需要其他犀牛种群的一个代孕妈妈
would have to carry the embryo to term.
接受胚胎移植并生育
Females of a closely related species, the southern white rhino,
最近亲物种——南白犀——的雌性
became both the key to developing a rhino embryo in a lab
不仅对实验室胚胎的培育至关重要
and the leading candidates for surrogate mothers.
而且也是首选代孕母亲
Northern and southern white rhinos diverged about a million of years ago
南 北白犀大概在一百万年前
into separate— though still closely-related— species.
分化成两个虽密切相连却相互独立的物种
They inhabit different regions, and have slightly different physical traits.
它们栖居不同地区 且身体特征略有不同
In a fortunate coincidence, several female southern white rhinos
有个幸运的巧合 几只雌性南白犀
needed treatment for their own reproductive problems,
由于自身生殖问题需要治疗
and researchers could collect eggs as part of that treatment.
而研究者可以在治疗的同时收集卵泡
In Dvůr Králové Zoo in October 2015,
2015年十月 在Dvůr Králové动物园
experts of IZW Berlin began collecting eggs from southern white rhinos
柏林IZW的专家开始从南白犀体内提取卵泡
and sending them to Avantea, an animal reproduction laboratory in Italy.
并送到意大利一个动物繁殖实验室 —— Avantea
There, scientists developed and perfected a technique
在那里 科学家们发展并完善了一项
to create a viable embryo.
培育可用胚胎的技术
Once they mastered the technique,
当完全掌握了这项技术
researchers extracted Nájin and Fatu’s eggs
研究人员在2019年8月22日
on August 22, 2019
提取了Nájin和Fatu的卵泡
and flew them to Italy.
并将其迅速送到意大利
Three days later, they fertilized the eggs with sperm
三天后 他们用一个雄性南白犀的精子
from a northern white rhino male.
让这些卵泡受精
After another week, two of the eggs made it to the stage of development
再过一周后 其中两个卵泡进入生长阶段
when the embryo can be frozen and preserved for future.
此时胚胎可被冷冻保存以备将来之需
Another collection in December 2019 produced one more embryo.
2019年12月的采集又获得了另一个胚胎
As of early 2020, the plan is to collect Nájin and Fatu’s eggs
截至2020年初 如果Nájin和Fatu足够健康
three times a year if they’re healthy enough.
计划每年采集它们的卵泡三次
In the meantime, researchers are looking for
与此同时 研究人员也在寻找
promising southern white rhino surrogate mothers–
合适的南白犀代孕母亲——
ideally who’ve carried a pregnancy to term before.
理想的是那些曾经生育过的
The surrogacy plan is somewhat of a leap of faith–
该代孕计划某种程度上是在碰运气——
southern and northern white rhinos have interbred
由于南 北白犀在最后一个冰川时代
both during the last glacial period and more recently in 1977,
及更近的1977年都有过杂交繁殖
so researchers are optimistic a southern white rhino
因此对于南白犀能够成功生育北白犀
would be able to carry a northern white rhino to term.
研究人员持乐观态度
Also, the two species’ pregnancies are the same length.
此外 这两种犀牛的孕期一致
Still, transferring an embryo to a rhino is tricky
然而 由于子宫颈形状不同
because of the shape of the cervix.
给犀牛移植胚胎仍微妙复杂
The ultimate goal, which will take decades,
终极目标是在北白犀的原始领地
is to establish a breeding population of northern white rhinos
为它们建立一个繁殖种群
in their original range.
这将花费数十年时间
Studies suggest that we have samples from enough individuals
研究表明 已有从足够多个体中提取的样本
to recreate a population with the genetic diversity the species had a century ago.
去重建一个拥有百年前基因多样性的种群
Though the specifics of this effort are unique,
尽管这种努力的特性是独特的
as more species face critical endangerment or functional extinction,
但随着更多物种面临灭绝或功能性绝种
it’s also an arena for big questions:
它仍是一些大问题的争议之所:
do we have a responsibility to try to bring species back from the brink,
我们是否有责任拯救濒危物种
especially when human actions brought them there in the first place?
特别是在人类活动一手造成这一后果时?
Are there limits to the effort we should expend
在拯救濒危动物方面
on saving animals threatened with extinction?
我们应做的努力是否有极限?

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视频概述

介绍了北白犀牛的现状以及如何通过培育胚胎及异种代孕方式试图挽救濒危的北白犀牛

听录译者

收集自网络

翻译译者

天涯孤客

审核员

审核员 V

视频来源

https://www.youtube.com/watch?v=hNNqht30TDo

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