Evolution in a Big City

大城市的演化

翻译人员: Li Huayang 校对人员: Geoff Chen

（音乐）

（城市交通）今天我在这裡 想鼓励你们想一下纽约这个城市

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

它不仅是人类最大的成就

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

but as home to native wildlife

也是原始野生动物 经歷重大演化实验的家

that are subject to a grand evolutionary experiment.

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

就拿这片位於北曼哈顿岛 树木丛生的山坡為例

This is one of the last areas left in the city

这是城内最后一片净土 乾净的泉水仍从地面涌出

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饮用，不会生病

这一小片泉水区 住著庞大数量的暗棕脊口螈

These tiny little areas of seeping water

contain huge populations of northern dusky salamanders.

以前这些小东西在城内很常见

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

大约六十年前还有

but now they're just stuck on this single hillside

但现在牠们被困在这片山坡 及史坦顿岛上几个地方

and a few places in Staten Island.

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

被困在这片山坡上

牠们不仅尊严受辱

but we divided the hillside in two

我们还把这片山坡

on two different occasions

在两个不同的场合一分為二

with bridges crossing from the Bronx into Manhattan.

盖桥把布朗克斯与曼哈顿岛相连

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

但牠们还存在那儿

在桥的两端，你们看到的红箭头处

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

约在 180 街，167 街

我的实验室发现，如果你拿几段

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

取自这两处的蠑螈的 DNA 来看

from salamanders in those two locations,

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

你能分辨牠们从桥的哪一端来

We built this single piece of infrastructure

我们建造的基础建设

that's changed their evolutionary history.

改变了牠们的演化歷史

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

我们要研究这些傢伙，你知道 只要跑去这片山坡就好

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

我们知道牠们在哪 我们能翻石头，我们能抓到牠们

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

但纽约市还有很多其他的东西

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

并不那麼容易捕捉 就像这傢伙，郊狼

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

我们在某处的自动相机陷阱上拍到牠

I'm not allowed to talk about it yet.

地点不能透露，我们不允许讨论这地点

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

但牠们是第一次迁移进纽约市

牠们是非常灵活、聪明的动物

They're very flexible, intelligent animals.

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

这是一头今年出生的幼狼 在看我们的相机

And my colleagues and I are very interested in understanding

我的同事和我很想要搞懂

how they're going to spread through the area,

牠们要如何在这片区域拓展

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

牠们要如何在这裡生存，甚至大量繁殖

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

牠们还可能去你家附近 如果牠们还没占领那块地方

if they're not already there.

那麼，有些东西跑太快，手抓不到

Some things are too fast to be caught by hand.

我们无法用相机捕捉

We can't pick them up on the cameras,

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

所以我们其实在整个纽约市 及其公园内设了陷阱

This is one of our most common activities.

这是我们最常见的活动

Here's some of my students and collaborators

这是我一些学生及合作者 把陷阱拿出去架好

getting the traps out and ready.

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

而这个傢伙，在纽约市 有树林的地方几乎都能抓到

This is the white-footed mouse --

这是隻白足鼠

not the mouse you find running around your apartment.

这不是那种你偶尔看到 在你的公寓裡跑来跑去的老鼠

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

这是一种原生种 在人类出现前就已在这裡生存

You find them in forests and meadows.

你能在树林及草原上看到牠们

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

因為牠们在都市中 有树林的地方如此常见

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

我们现在以牠们為模范 来瞭解物种如何适应都市环境

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.

这五个城区都还被

森林及其他植物覆盖

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

这种老鼠其实随处可见

整片土地庞大的老鼠族群基因差异很小

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况

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

牠们就只能待在这几个

城内少数有树林覆盖的小块地区

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

仅仅只用 18 小段 DNA 我们就能拿一隻老鼠

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

某人给我们一隻老鼠 不让我们知道是从哪来的

and we could determine what park it came from.

然后我们就能判断牠是从哪个公园来的 那就是牠们之间演化的差异

That's how different they've become.

你会注意到在这段有顏色的条纹中间

You'll notice in the middle of this figure,

there are some mixed-up colors.

有一些混杂的顏色

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

这个城市内有几个公园仍然连接在一起

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

以带状森林方式相连 所以老鼠可以跑来跑去

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

并散佈牠们的基因 所以牠们没有差异

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

但以整座城市来看 牠们在公园间已变得相当不同

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

好，所以我说了牠们不一样

但这代表什麼意义？ 牠们在生物学上有什麼变化？

What's changing about their biology?

To answer this question,

要回答这个问题

we're sequencing thousands of genes from our city mice

我们為我们城市老鼠 定序了数千个基因

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

并与乡下老鼠的数千个基因比较

so, their ancestors outside of New York City

牠们的祖先在纽约市外围

in these big, more wilderness areas.

住在这些较大较原始的区域

那麼，基因是小片段的DNA

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

是组成胺基酸的密码

And amino acids are the building blocks of proteins.

而胺基酸是蛋白质组成的元件

那如果某个基因裡有一对硷基配对变了

If a single base pair changes in a gene,

you can get a different amino acid,

你就会得到不同的胺基酸

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

这样就会跟著改变蛋白质的形状及结构

If you change the structure of a protein,

如果你改变了某种蛋白质的结构 你通常就会改变它在生物体裡的功能

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

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

那麼如果这种改变会使老鼠的 寿命更长或生更多宝宝

something evolutionary biologists call fitness,

跟演化有关，生物学家就称之為适存度

then that single base-pair change will spread quickly

那麼那对配对的改变 就会在城市的族群中快速散播

in an urban population.

So this crazy figure is called a Manhattan plot,

所以这张怪怪的图 其实是叫曼哈顿散佈图

because it kind of looks like a skyline.

因為它看起来有点像建筑物的轮廓

Each dot represents one gene,

那每个点都代表一个基因

and the higher the dot is in the plot,

在这图上的点愈高

the more different it is between city and country mice.

其在城市与乡村老鼠间的差异就愈大

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

这些约在轮廓顶端的是差异最大的

尤其是在红线之上的那些

especially those above the red line.

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

这些基因是免疫系统 如何对抗疾病等的编码

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

因為可能有更多的疾病出现

在密度高的都市族群裡

metabolism, how the mice use energy;

代谢作用，老鼠如何使用能量

and heavy-metal tolerance.

及重金属耐受性。你们大概可以预测到

You guys can probably predict

that New York City soils are pretty contaminated

纽约市的土壤颇受

with lead and chromium and that sort of thing.

铅、铬这类东西污染

And now our hard work is really starting.

那现在我们辛苦的工作要真正开始了

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

追踪个别老鼠的生活

following the lives of individual mice

及看这些基因究竟如何在牠们身上运作

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.

而我鼓励大家试著 以新的方式看你家附近的公园

我不会变成第二个查尔斯·达尔文

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

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

但在座之一可能会 所以千万要睁大你的眼睛，谢谢

Thank you.

（掌声）

(Applause)

（音乐）