The last living members of an extinct species - Jan Stejskal

譯者: Lilian Chiu 審譯者: Helen Chang

In the savannahs of Kenya, two female northern white rhinos, Nájin and Fatu,

在肯亞的大草原上，

兩隻母的北白犀，納金和法圖，

munch contentedly on the grass.

津津有味地嚼著青草，十分滿足。

At the time of this video’s publication,

在這支影片發表的同時，

these are the last two known northern white rhinos left on Earth.

牠們是我們所知世界上 最後兩隻北白犀。

Their species is functionally extinct—

牠們所屬的物種 正面臨功能性滅絕，

without a male, Nájin and Fatu can’t reproduce.

沒有公犀牛， 納金和法圖無法繁殖。

And yet, there’s still hope to revive the northern white rhino.

但還是有希望可以拯救北白犀。

How can that be?

怎麼可能？

The story starts about 50 years ago,

故事開始於約五十年前，

when poachers began illegally hunting thousands of rhinos

當時偷獵者開始在非洲各地 非法獵捕數千隻犀牛，

across Africa for their horns.

以取得牠們的角。

This, combined with civil wars in their territory,

這件事，再加上發生在 牠們領土上的內戰，

decimated northern white rhino populations.

讓北白犀的數量大減。

Concerned conservationists began trying to breed them in captivity in the 1970s,

關心此事的保育人士

在 1970 年代開始試圖 在籠裡飼養進行育種，

collecting and storing semen from males.

收集公犀牛的精液並儲存起來。

Only four rhinos were ultimately born through the ambitious breeding program.

這個野心勃勃的繁殖計畫 最終只產出了四隻犀牛。

Nájin, and her daughter Fatu were the last two.

納金和牠的女兒法圖是最後兩隻。

In 2014, conservationists discovered that neither can have a calf.

2014 年，

保育人士發現牠們 都無法懷小犀牛。

Though Nájin gave birth to Fatu, she now has weak hindlegs,

雖然納金生出了法圖， 但牠現在的後腿太弱，

which could harm her health if she became pregnant again.

如果牠再懷孕，會對 牠的健康有不良影響。

Fatu, meanwhile, has a degenerated uterine lining.

至於法圖，牠的子宮內膜退化。

Then, the last northern white rhino male of the species, Sudan, died in 2018.

接著，最後一隻公的北白犀，

名叫蘇丹，在 2018 年死亡。

But there was one glimmer of hope: artificial reproduction.

但還有一線希望：人工繁殖。

With no living males and no females able to carry a pregnancy,

沒有還活著的公犀牛， 也沒有能懷孕的母犀牛，

this is a complicated and risky process to say the least.

再怎麼說這都是個 複雜又冒險的過程。

Though scientists had stored semen, they would have to collect the eggs—

雖然科學家已儲存精液， 他們還得收集卵子——

a complex procedure that requires a female to be sedated for up to two hours.

這個程序很複雜，

要用鎮靜劑讓母犀牛安靜兩小時。

Then, they’d create a viable embryo in the lab—

接著，他們要在實驗室中創造 一個能活下來的胚胎——

something that had never been done before, and no one knew how to do.

以前沒有人做過， 也沒有人知道要怎麼做。

Even that was just the beginning—

那都還只是開端——

a surrogate mother of another rhino species

還需要由另一種犀牛的代理孕母

would have to carry the embryo to term.

帶著這個胚胎一直到足月。

Females of a closely related species, the southern white rhino,

有一種很接近的物種是南白犀，

這些母犀牛成為實驗室中 發展犀牛胚胎的關鍵，

became both the key to developing a rhino embryo in a lab

and the leading candidates for surrogate mothers.

以及代理孕母的主要候選者。

Northern and southern white rhinos diverged about a million of years ago

北白犀和南白犀 在大約一百萬年前分開，

into separate— though still closely-related— species.

成為不同的—— 但仍然很接近的——物種。

They inhabit different regions, and have slightly different physical traits.

牠們居住在不同的地區， 身體特徵有些微的不同。

In a fortunate coincidence, several female southern white rhinos

在一次幸運的巧合中， 有數隻母的南白犀

needed treatment for their own reproductive problems,

因為自己的生殖問題而需要治療，

and researchers could collect eggs as part of that treatment.

在治療時，研究者 可以順便收集卵子。

In Dvůr Králové Zoo in October 2015,

2015 年十月，在杜武洛夫動物園，

experts of IZW Berlin began collecting eggs from southern white rhinos

柏林 IZW 的專家開始收集 母的南白犀的卵子，

and sending them to Avantea, an animal reproduction laboratory in Italy.

再將卵子送到義大利的 Avantea 動物繁殖實驗室。

There, scientists developed and perfected a technique to create a viable embryo.

在那裡，科學家 開發出很完美的技術，

可以創造出能活下來的胚胎。

Once they mastered the technique,

等研究者精通該技術時，

researchers extracted Nájin and Fatu’s eggs on August 22, 2019

便在 2019 年八月二十二日 從納金和法圖身上取得卵子，

and flew them to Italy.

用飛機送往義大利。

Three days later, they fertilized the eggs with sperm

三天後，他們用公的北白犀的精子

from a northern white rhino male.

讓那些卵子受精。

After another week, two of the eggs made it to the stage of development

再過了一週，兩個卵子 成功進入到發展階段，

when the embryo can be frozen and preserved for future.

在此階段，可以將胚胎 冰凍起來保存到未來。

Another collection in December 2019 produced one more embryo.

2019 年十二月又做了一次 採集，再產生出一個胚胎。

As of early 2020, the plan is to collect Nájin and Fatu’s eggs three times a year

2020 年初的計畫是，

如果納金和法圖的健康狀況允許，

一年要收集牠們的卵子三次。

if they’re healthy enough.

In the meantime, researchers are looking for

同時，研究者也在尋找

promising southern white rhino surrogate mothers—

理想的南白犀代理孕母——

ideally who’ve carried a pregnancy to term before.

最適合的是曾經懷孕 到足月生產的犀牛。

The surrogacy plan is somewhat of a leap of faith—

某種程度上，只能帶著最大的信心 去進行這個代理計畫——

southern and northern white rhinos have interbred

北白犀和南白犀曾經雜交過，

both during the last glacial period and more recently in 1977,

包括在末次冰盛期 以及最近一次是 1977 年，

so researchers are optimistic a southern white rhino

所以研究者樂觀認為南白犀

would be able to carry a northern white rhino to term.

能夠懷著北白犀到足月生產。

Also, the two species’ pregnancies are the same length.

此外，這兩種物種的 懷孕期一樣長。

Still, transferring an embryo to a rhino is tricky

不過，因為子宮頸的形狀，

將胚胎轉到犀牛身上是很棘手的。

because of the shape of the cervix.

The ultimate goal, which will take decades,

最終的目標是在數十年後，

is to establish a breeding population of northern white rhinos

建立起一個能夠 自行繁衍的北白犀族群，

in their original range.

在原本的家園生活。

Studies suggest that we have samples from enough individuals

研究指出，我們有足夠的樣本來源，

to recreate a population with the genetic diversity the species had a century ago.

重新創造出的族群能夠具有牠們 在一世紀前所具有的基因多樣性。

Though the specifics of this effort are unique,

雖然這項工作的細節獨特，

as more species face critical endangerment or functional extinction,

但隨著更多物種面臨到 關鍵的絕種危機或功能性滅絕，

it’s also an arena for big questions:

讓這項工作也成為 重大問題的競技場：

do we have a responsibility to try to bring species back from the brink,

我們是否有責任要試圖 把其他物種從絕種邊緣救回來？

especially when human actions brought them there in the first place?

尤其是人類正是造成 牠們面臨絕種的元兇？

Are there limits to the effort we should expend

當我們把這項做法用來拯救 其他受到絕種威脅的動物時，

on saving animals threatened with extinction?

有沒有什麼限制？