Evolution in a Big City

大都市裡的演化

譯者: Regina Chu 審譯者: Kuanju Chou

（音樂）

（城市交通）今天我在這裡 想鼓勵你們想一下紐約這個城市

So I'm here today to encourage you to think about New York City,

and not just as one of humanity's greatest achievements,

它不僅是人類最大的成就

but as home to native wildlife

也是原始野生動物 經歷重大演化實驗的家

that are subject to a grand evolutionary experiment.

So take this forested hillside in Northern Manhattan, for example.

就拿這片位於北曼哈頓島 樹木叢生的山坡為例

This is one of the last areas left in the city

這是城內最後一片淨土 乾淨的泉水仍從地面湧出

where there's clean spring water seeping out of the ground.

You could drink this out of your hands and you'd be OK.

你能以手接泉水直接飲用，不會生病

這一小片泉水區 住著龐大數量的暗棕脊口螈

These tiny little areas of seeping water

contain huge populations of northern dusky salamanders.

These guys were common in the city maybe 60 years ago,

以前這些小東西在城內很常見

大約六十年前還有

but now they're just stuck on this single hillside

但現在牠們被困在這片山坡 及史坦頓島上幾個地方

and a few places in Staten Island.

Not only do they suffer the indignity of being stuck on this hillside,

被困在這片山坡上

牠們不僅尊嚴受辱

but we divided the hillside in two

我們還把這片山坡

on two different occasions

在兩個不同的場合一分為二

with bridges crossing from the Bronx into Manhattan.

蓋橋把布朗克斯與曼哈頓島相連

But they're still there, on either side of the bridges,

但牠們還存在那兒

在橋的兩端，你們看到的紅箭頭處

where you see the red arrows -- about 180th Street, 167th Street.

約在 180 街，167 街

My lab has found that if you just take a few segments of DNA

我的實驗室發現，如果你拿幾段

取自這兩處的蠑螈的 DNA 來看

from salamanders in those two locations,

you can tell which side of the bridge they came from.

你能分辨牠們從橋的哪一端來

We built this single piece of infrastructure

我們建造的基礎建設

that's changed their evolutionary history.

改變了牠們的演化歷史

We can go study these guys, we just go to the hillside

我們要研究這些傢伙，你知道， 只要跑去這片山坡就好

we know where they are, we flip over rocks so we can catch them.

我們知道牠們在哪， 我們能翻石頭，我們能抓到牠們

但紐約市還有很多其他的東西

There are a lot of other things in New York City, though,

並不那麼容易捕捉 就像這傢伙，郊狼

that are not that easy to capture, such as this guy, a coyote.

我們在某處的自動相機陷阱上拍到牠

We caught him on an automatic camera trap in an undisclosed location;

地點不能透露，我們不允許討論這地點

I'm not allowed to talk about it yet.

但牠們是第一次遷移進紐約市

But they're moving into New York City for the first time.

牠們是非常靈活、聰明的動物

They're very flexible, intelligent animals.

This is one of this year's pups checking out one of our cameras.

這是一頭今年出生的幼狼 在看我們的相機

And my colleagues and I are very interested in understanding

我的同事和我很有興趣要搞懂

how they're going to spread through the area,

牠們要如何在這片區域拓展

how they're going to survive here and maybe even thrive.

牠們要如何在這裡生存，甚至大量繁殖

And they're probably coming to a neighborhood near you,

牠們還可能去你家附近 如果牠們還沒占領那塊地方

if they're not already there.

Some things are too fast to be caught by hand.

那麼，有些東西跑太快，手抓不到

We can't pick them up on the cameras,

我們無法用相機捕捉

so we set up traps around New York City and the parks.

所以我們其實在整個紐約市 及其公園內設了陷阱

This is one of our most common activities.

這是我們最常見的活動

這是我一些學生及合作者 把陷阱拿出去架好

Here's some of my students and collaborators

getting the traps out and ready.

This guy, we catch in almost every forested area in New York City.

而這個傢伙，在紐約市 有樹林的地方幾乎都能抓到

This is the white-footed mouse --

這是隻白足鼠

not the mouse you find running around your apartment.

這不是那種你偶爾看到 在你的公寓裡跑來跑去的老鼠

This is a native species, been here long before humans.

這是一種原生種 在人類出現前就已在這裡生存

You find them in forests and meadows.

你能在樹林及草原上看到牠們

Because they're so common in forested areas in the city,

因為牠們在都市中 有樹林的地方如此常見

we're using them as a model to understand how species are adapting

我們現在以牠們為模範 來瞭解物種如何適應都市環境

to urban environments.

So if you think back 400 years ago,

那麼，如果你回想 400 年前

the five boroughs would've been covered in forests and other types of vegetation.

這五個城區都還被

森林及其他植物覆蓋

This mouse would've been everywhere [in] huge populations

這種老鼠其實隨處可見

整片土地龐大的老鼠族群基因差異很小

that showed few genetic differences across the landscape.

But if you look at the situation today,

但如果你看看今天的情況

they're just stuck in these little islands of forest scattered around the city.

牠們就只能待在這幾個

城內少數有樹林覆蓋的小塊地區

Just using 18 short segments of DNA, we can pretty much take a mouse

僅僅只用 18 小段 DNA 我們就能拿一隻老鼠

somebody could give us a mouse, not tell us where it was from,

某人給我們一隻老鼠 不讓我們知道是從哪來的

and we could determine what park it came from.

然後我們就能判斷牠是從哪個公園來的 那就是牠們之間演化的差異

That's how different they've become.

You'll notice in the middle of this figure,

你會注意到在這段有顏色的條紋中間

there are some mixed-up colors.

有一些混雜的顏色

There are a few parks in the city that are still connected to each other

這個城市內有幾個公園仍然連接在一起

with strips of forest, so the mice can run back and forth

以帶狀森林方式相連 所以老鼠可以跑來跑去

and spread their genes, so they don't become different.

並散佈牠們的基因 所以牠們沒有差異

But throughout the city, they're mostly becoming different in the parks.

但以整座城市來看 牠們在公園間已變得相當不同

So I'm telling you they're different, but what does that mean?

好，所以我說了牠們不一樣

但這代表什麼意義？ 牠們在生物學上有什麼變化？

What's changing about their biology?

To answer this question,

要回答這個問題

we're sequencing thousands of genes from our city mice

我們為我們城市老鼠 定序了數千個基因

and comparing those to thousands of genes from the country mice,

並與鄉下老鼠的數千個基因比較

so, their ancestors outside of New York City

牠們的祖先在紐約市外圍

in these big, more wilderness areas.

住在這些較大較原始的區域

Now, genes are short segments of DNA that code for amino acids.

那麼，基因是小片段的DNA

是組成胺基酸的密碼

And amino acids are the building blocks of proteins.

而胺基酸是蛋白質組成的元件

那如果某個基因裡有一對鹼基配對變了

If a single base pair changes in a gene,

你就會得到不同的胺基酸

you can get a different amino acid,

這樣就會跟著改變蛋白質的形狀及結構

which will then change the shape and structure of the protein.

如果你改變了某種蛋白質的結構

If you change the structure of a protein,

you often change something about what it does in the organism.

你通常就會改變它在生物體裡的功能

Now if that change leads to a longer life or more babies for a mouse,

那麼如果這種改變會使老鼠的 壽命更長或生更多寶寶

something evolutionary biologists call fitness,

跟演化有關，生物學家就稱之為適存度

then that single base-pair change will spread quickly

那麼那對配對的改變 就會在城市的族群中快速散播

in an urban population.

So this crazy figure is called a Manhattan plot,

所以這張怪怪的圖 其實是叫曼哈頓散佈圖

because it kind of looks like a skyline.

因為它看起來有點像建築物的輪廓

Each dot represents one gene,

那每個點都代表一個基因

and the higher the dot is in the plot,

在這圖上的點愈高

the more different it is between city and country mice.

其在城市與鄉村老鼠間的差異就愈大

The ones kind of at the tips of the skyscrapers are the most different,

這些約在輪廓頂端的是差異最大的

especially those above the red line.

尤其是在紅線之上的那些

And these genes encode for things like immune response to disease,

這些基因是免疫系統 如何對抗疾病等的編碼

because there might be more disease in very dense, urban populations;

因為可能有更多的疾病出現

在密度高的都市族群裡

metabolism, how the mice use energy;

代謝作用，老鼠如何使用能量

and heavy-metal tolerance.

及重金屬耐受性。你們大概可以預測到

You guys can probably predict

that New York City soils are pretty contaminated

紐約市的土壤頗受

with lead and chromium and that sort of thing.

鉛、鉻這類東西汙染

And now our hard work is really starting.

那現在我們辛苦的工作要真正開始了

We're going back into the wilds of New York City parks,

我們要回到紐約市公園的荒地

following the lives of individual mice

追蹤個別老鼠的生活 及看這些基因究竟如何在他們身上運作

and seeing exactly what these genes are doing for them.

And I would encourage you guys to try to look at your parks in a new way.

而我鼓勵大家試著 以新的方式看你家附近的公園

我不會變成第二個查爾斯·達爾文

I'm not going to be the next Charles Darwin,

but one of you guys might be, so just keep your eyes open.

但在座之一可能會 所以千萬要睜大你的眼睛，謝謝

Thank you.

（掌聲）

(Applause)

（音樂）