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自然界中的“养殖户”

When Ants Domesticated Fungi

If you visit the tropical forests of Central and South America,
如果你去参观中美洲和南美洲的热带森林
you might be lucky enough
那你可能会足够幸运地
to spot a parade of leaf-cutter ants,
看到一群切叶蚁在
tirelessly carrying food back to their nests.
不知疲倦地抬着食物返回它们的巢穴
But did you know that those ants aren’t taking
但你是否知道 那些蚂蚁把叶子带回家
those leaf-cuttings home to eat?
并不是为了吃?
Because I did not know that
因为连我也不知道
The fact is, they physically can’t survive on plant material.
事实是 它们根本不能靠植物生存
Instead, the ants use those leaves to feed the gardens of fungi
反而 这些叶子是它们用来投喂生长在
that they grow in their colonies,
蚁群中的真菌的食物
which are their primary source of food.
这些真菌是其主要的食物来源
And both the age and the sophistication of these little farms
这些小农场 无论其年代还是精密程度
put our own farms to shame.
都让人类的农场黯然失色
While we’ve been farming for around 10,000 to 12,000 years,
尽管人类进行农业生产的时间约有1万到1.2万年
the ancestors of these ants
但这些蚂蚁的祖先
have been doing it for around 60 million years.
进行此项工作的时间则是6000万年左右
And over that time,
而且在此期间
they’ve been through many of their own agricultural revolutions
它们已经经历了许多次农业革命
that have changed not just how they farm,
这些革命不仅改变了蚂蚁的农作方式
but also the very biology of their fungi that they grow,
而且也改变了蚂蚁自身以及
and the biology of the ants themselves.
它们所培育的真菌的生物特性
So when, and how,
那蚂蚁在何时 又是如何
and why did ants start … farming?
以及为什么开始务农的呢?
It looks like the relationship between ants and fungi
蚂蚁和真菌的关系看起来似乎是
may have emerged from the ashes of a famously devastating extinction event.
在一场著名的毁灭性事件的灰烬中诞生的
Now these ants didn’t start out as fungus-farmers.
这些蚂蚁一开始并不是真菌养殖者
For much of their history,
在大部分历史中
they did what most ants still do today:
它们做的事今天大多数蚂蚁仍在干:
they go out into the world and eat the things they find,
它们到外面吃它们找到的食物
which also is how I go through life.
这也是人类的生活方式
But everything changed for them when they started farming.
但当它们开始养殖时 一切都变了
And this transition happened only once
这种变革在一种名为真菌小蚂蚁的
– in the subgroup known as the Attini.
子群中只发生过一次
Because they’re teeny ants,
因为它们极其微小
that’s not why they call them that actually
事实上 它们得此称呼并非源于此
There are more than 250 species of these ants, all of them in the western hemisphere
这些蚂蚁有250多个种类 都在西半球
and all of them fungus farmers
并且它们都是真菌养殖者
But not all of these Attine ants farm the same way.
但不是所有的真菌蚂蚁的养殖法都相同
Most practice what some researchers have called ‘lower agriculture’
大部分蚂蚁进行的是一些研究人员所说的“低等农业”
– the system with the least complex farms,
这个系统具有最不复杂的农场体系
which is thought to have been the first to evolve.
被认为是第一个进化的系统
In this system, the fungi aren’t fully dependent on the ants.
在此系统中 真菌不完全依靠蚂蚁生存
They’re what are known as facultative symbionts-
它们被称为兼性共生体
they can survive without the ants
即没有蚂蚁 它们也能生存
and interbreed with other, wild fungi.
还能与其他野生真菌杂交
So they’re not really fully ‘domesticated’,
因此 实际上它们不完全是“养殖的”
and if they end up disappearing from the colony somehow,
如果它们最终以某种方式从蚁群里消失
the ants can just replace them with wild versions of the cultivated fungi species
蚂蚁可以用培养的野生真菌代替它们
But, other ants – including the leaf-cutters
但其他蚂蚁——包括切叶蚁在内
– practice higher agriculture.
则实行高等农业
In these colonies, the fungi are obligate symbionts –
在这些蚁群里 真菌是专性共生物
they’re completely dependent on their ant farmers,
它们完全依赖蚂蚁农夫
they can’t survive in the wild,
它们无法在野外生存
and they can’t interbreed with free-living fungi.
也不能与自生真菌异种繁殖
They’ve been fully domesticated by ants, which I think is strange.
它们被蚂蚁完全驯化了 我认为这很奇怪
but just like with us,
但就像我们一样
farming is even a part of the ants’ culture
养殖是蚂蚁文化的一部分
– if you can call it that.
如果能如此说的话
Like, when young queens of these ant species
例如 当这些蚂蚁物种的年轻蚁后
leave their families to start new colonies,
要离开家族去建立新蚁群时
they take a piece of fungus with them to start their own gardens,
它们会带走一块真菌来建设自己的花园
passing these strains down from queen to queen across generations.
一代又一代蚁后将菌株传承下去
So how did this relationship between ants and fungus actually start?
那实际上蚂蚁和真菌之间的关系是如何开始的呢?
And how did it evolve over time into
随着时间的推移 它是如何演变成
the different agricultural systems we see today?
我们今天看到的不同农业系统的?
Well, the fossil record has only given us some pieces of the story.
嗯 化石记录只给了我们一些故事的片段
Mainly because, while we do have lots of fossils of ants
主要因为尽管我们确实有大量蚂蚁化石
– many trapped in amber –
但很多被困于琥珀中
they can’t easily tell us how those ants actually lived
它们无法轻易告诉我们蚂蚁的实际生活方式
But there is some extremely rare fossil evidence
然而 有一些罕见的化石证据表明
of fungus-farming in ancient Attine ants in the form of nests
古代真菌蚂蚁种植了真菌
that contain traces of fungus filaments.
其巢穴中有少许真菌丝
But these are from relatively recently,
不过 这些化石是相对较近期的
like around 5 to 10 million years ago.
大约在500万到1000万年前
This means that, to dig deeper into
这意味着 要深入挖掘
the origins of fungus- farming in ants,
蚂蚁种植真菌的起源
we’ve had to find another way to study them.
我们必须找到别的方法去研究
Enter the field of phylogenomics – or using genomic data to
应用系统基因组学 即用基因组数据
reconstruct an organism’s evolutionary history.
重建微生物的进化历史
In a paper published in 2017 ,
在2017年发表的一篇论文中
researchers at the Smithsonian tried to
史密森博物馆的研究人员试图
trace the history of fungus- farming in ants
利用蚂蚁的基因组 跨越远古时代
across deep time, using their genomes.
追溯蚂蚁种植真菌的历史
They compared the DNA of more than a hundred
他们对比了100多种
different ant species from around the Western Hemisphere –
来自西半球的不同种类蚂蚁的DNA
some that practiced higher agriculture,
发现一些实行高等农业生产
some that practiced lower agriculture,
一些实行低等农业生产
and some that didn’t farm at all.
还有一些根本不养殖
By comparing their genetic relatedness,
通过比较它们的遗传亲缘关系
and how long ago the different groups diverged from one another,
以及根据每个基因谱系积累的突变
based on the mutations that each lineage had accumulated,
推算出来的不同群体间分离的时间
they could reconstruct their evolutionary family tree.
研究人员得以重建它们的进化家谱
And this revealed some intriguing clues about
这提供了一些有趣的线索 即关于
where, when and why
每个农业系统的演变最初
each agricultural system first evolved.
是在何时 何地 又是因何发生的
The tree seemed to suggest that
这家谱似乎表明
the Attini which contains all fungus-farming ant species,
真菌蚂蚁含概所有养殖真菌的蚂蚁品种
originally emerged in the rainforests of South America
它们最早出现于约6000万前的
around 66 million years ago.
南美洲的热带雨林中
And almost immediately,
几乎立刻地
they diversified really quickly – radiating into many different groups.
这些蚂蚁非常迅速地分化 辐射出许多不同的种群
By 61 million years ago,
到6100万年前
they had established themselves as lower agriculturalists
它们让外界接受了它们是“低等农学家”
– full-time fungus farmers.
也就是全职的真菌养殖户
And if this time period rings a bell,
大家若感觉这段时期听起来耳熟
there’s a good reason for that.
那是有原因的
This was the direct aftermath of the K-Pg mass extinction –
这是白垩纪——古近纪大灭绝带来的直接后果:
with the asteroid and the volcanism
小行星撞击地球 火山爆发
and the end of the reign of the dinosaurs.
恐龙统治终结
– the non-avian dinosaurs anyway.
反正非鸟恐龙是完全消失了
And the fact that the origin of fungus-farming in ants
蚂蚁种植真菌的起源
lines up with a period of global ecological chaos
与全球生态混乱的时期相吻合
is probably not a coincidence.
这一事实可能并非巧合
After all, the impact must’ve caused
毕竟 这种撞击肯定造成了
all kinds of environmental mayhem,
各种环境的混乱不堪
including a sort of nuclear winter
包括一种核冬天
in which clouds of dust and ash blocked out sunlight.
在这一时期中 尘埃和火山灰挡住了阳光
This would have been catastrophic for photosynthesizers like
这对于进行光合作用的生物 例如
plants at the base of the food chain
处于食物链底端的植物
and for species that relied on them.
以及依赖植物生存的物种都是灾难性的
But! Fungi are decomposers and don’t rely on sunlight for growth.
然而!真菌是分解者且不依靠阳光来生长
So they might actually have thrived
因此 它们在这些条件下
in these conditions.
可能真的生机勃勃
The dark, humid, post-K-Pg world,
黑暗 潮湿 后白垩纪——古近纪世界
filled with dead and decaying organisms,
充满了死亡和腐烂的有机体
would’ve been a paradise for fungi.
这会是真菌的天堂
The earliest Attine ants, on the other hand,
另一方面 最早的真菌蚂蚁
would have had a much harder time.
它们的日子会更难过
Suddenly, foraging for food would have been a real challenge,
突然间 觅食会成为一个真正的挑战
at least above ground.
至少地面上是如此
So it’s easy to imagine why Attine ants might’ve begun
因此 容易想像到真菌蚂蚁为何会开始
harnessing fungi as their sole food source.
用真菌作为它们唯一的食物来源
It’s a stable and reliable crop they could grow underground,
这是种稳定可靠的收成 可在地下养殖
perfectly suited to the apocalypse!
非常适合大灾变环境!
And this changed not just their lifestyle,
并且这不仅改变了它们的生活方式
but elements of their biology too.
也改变了它们的生理要素
Research has shown that Attine ants lost the ability
研究表明 真菌蚂蚁在进化的早期
to produce an important amino acid
就失去了产生一种
called arginine very early on in their evolution.
叫作精氨酸的重要氨基酸的能力
And ever since then,
自那之后
they’ve been totally reliant on fungi to get that amino acid!
它们就完全依靠真菌来获得那种氨基酸了
This may explain why we’ve yet to find
这也许能解释为何我们还未找到
a single example of an Attine ant species that’s stopped farming.
停止养殖的真菌蚂蚁的个例
They literally can’t survive without their crops.
没有培植的真菌 它们的确无法生存
So, while the evidence is kind of circumstantial,
因此 尽管证据有点间接
it’s at least plausible that the devastation of the K-Pg
但至少我们似乎有理由认为白垩纪——古近纪大灭绝事件
was the catalyst for the first agricultural revolution in Attine ants
是真菌蚂蚁进行第一次农业革命的诱因
– transitioning from foragers to farmers.
——这使它们从觅食者转变为养殖者
But it wasn’t until 30 million years later
但直到3000万年之后
that one group of ants experienced their second agricultural revolution
一群蚂蚁才开始了它们的第二次农业革命
– transitioning from lower to higher agriculture.
这次是由低等农业向高等农业转变
The researchers found the genetic signal of this transition
研究人员发现 这种转变的基因信号
at somewhere between 27 million to 31 million years ago,
出现在大约3100万至2700万年前之间
in the early Oligocene epoch.
就在渐新世早期
This is when the group of ants that practice higher agriculture seems to have emerged
这时候 实行高等农业的蚁群似乎出现了
and branched off from the other Attines.
并从其他真菌蚂蚁中分离出来
And just like the ants’ first agricultural revolution,
就像蚂蚁的第一次农业革命一样
the timing of this one matched up with a period of environmental upheaval.
这次革命的时机与环境剧变的时期相一致
This was the aftermath of the Terminal Eocene Event
这是始新世末期事件的后果
that took place as the name suggests
顾名思义
at the end of the eocene epoch around 34 million years ago.
就发生在约3400万年前的始新世末期
For reasons we still don’t fully understand,
由于一些我们依旧不全然了解的原因
the planet went through a period of global cooling at this time,
地球在这时经历了一段全球变冷的时期
which allowed drier, less humid habitats to expand.
这使得更干燥 不太潮湿的栖息地增多
And some Attine ants left the rainforests of South America
接着 为寻找这些更干燥的栖息地
for these drier habitats and brought their fungi with them,
一些真菌蚂蚁带着真菌离开了南非热带雨林
which may have spurred a radical shift in their relationship.
这促使双方关系发生了根本性的改变
After all, dry habitats are pretty inhospitable to fungi.
毕竟 干燥的栖息地相当不适合真菌生存
So researchers think that, in these new environments,
因此 研究人员认为 在这些环境下
the fungi became completely dependent on the ants for survival.
真菌变得完全依赖蚂蚁而活
They couldn’t live outside of the well-tended, humid, underground gardens of the ant colony.
它们离不开被照料的 潮湿的蚁群地下花园
And, over time, they became reproductively isolated from their free-living relatives,
随时间的推移 它们在繁殖上与其自生亲属隔离
which had largely remained in the rainforests.
这些亲属大部分留在了热带雨林
This marked the switch from facultative to obligate symbiosis in the fungi,
这标志着真菌从兼性共生到专性共生的转变
and from lower to higher agriculture in the ants
且蚂蚁务农也从较低级转变为较高级
These fungi are now found only in higher Attine ant colonies ,
我们现在只在高等真菌蚁群发现这些真菌
and they’ve developed some specific adaptations
它们已经在这种完全被驯化的生活中
in this fully domesticated existence.
发展出了一些特定的适应能力
For example, they have nutrient-rich structures called gongylidia
例如 它们有一种营养丰富的结构 叫做菌丝球
that can be efficiently harvested and eaten by the ants.
营菌丝球能被蚂蚁有效地采摘然后吃掉
These structures aren’t seen in wild fungi
这些结构是在野生真菌
or in lineages grown by ants that practice lower agriculture.
或是在被较低等农业蚁养殖的菌系中看不到的
And this relationship seems to have reached new heights in the leaf-cutter ants.
且这种关系在切叶蚁中似乎达到了新高度
This group is represented by around 50 species,
这一群组大约有50个物种
which are widespread in South America, Central America,
广泛分布于南美洲 中美洲
Mexico, and some southern parts of the US.
墨西以及美国南部的部分区域
And the researchers’analysis suggests that
而且 研究人员的分析表明
the leaf-cutters were the most recent group of higher agriculturalists to evolve,
切叶蚁是最新进化的更高级别的“农学家群体”
emerging around 18 to 19 million years ago.
大约出现在1900至1800万前
They have incredibly complex colonies, with big fungal gardens,
它们有非常复杂的群落和大规模的真菌花园
and even sophisticated hygiene practices
甚至有先进的卫生措施
to protect their fungal crops from disease.
来保护其真菌作物不得病
Like, there are certain areas of their nests where they leave their waste,
比如 它们会把排泄物弃于巢穴的某些区域
to keep it away from their gardens.
让其远离真菌花园
And some ants even have bacteria on them
一些蚂蚁身上甚至有
that produce antimicrobial compounds,
能产生抗菌化合物的细菌
which help protect the fungus from pathogens! I kinda wish I had that!
有助于保护真菌免受病原体的伤害 我也想有!
And unlike other Attines,
不同于其他只是收集
which usually just collect whatever dead plant and animal material they can find,
自己能找到的所有死亡动植物残骸的真菌蚁
leaf-cutter ants source only the finest,
切叶蚁只获取最好的
freshest biomass – cutting it straight off the plant.
最新鲜的生物质——直接从植物上切下来
*chef’s kiss*
厨师之吻
In fact, leaf-cutters get through so much plant material
事实上 切叶蚁能获取的植物食材非常多
they’re considered the dominant herbivore of the neotropics
因此它们被认为是新热带地区的主要食草动物
– harvesting more total plant material
收获的植物食材总量
than any other animal group.
超过任何其他动物群体
So in a way,
因此 在某种程度上
the leaf-cutter ants have kind of brought fungus-farming full-circle.
切叶蚁似乎让真菌养殖绕了一圈又返回到原点
What may have started as a way to survive
在白垩纪——古近纪大灭绝后 原本可能是为了
without plants after the K-Pg mass extinction
在没有植物的情况也能活下去的真菌养殖
has now come all the way back around to
现在又回到了
depending on plants for the system to keep going.
依赖植物来维持生命系统的状态
If the story of the Attine ants tells us anything,
真菌蚂蚁的故事告诉我们
it’s never to underestimate their ability to innovate over time.
永远不要低估——与时俱进 不断创新
Through 60 million years of evolution,
经过6000万年的进化
facing challenge after challenge in the form of global environmental change,
面对全球环境变化带来的一个又一个挑战
the ants and their fungi adapted, adjusted, and thrived.
蚂蚁和其真菌已适应 调整并蓬勃发展了
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视频概述

说起蚂蚁,相信我们所有人都不陌生,因为它们对于我们来说是那么司空见惯,甚至觉得它们平淡无奇!但,你听说过会养殖的蚂蚁吗?它们有自己的种植花园,有自己的养殖方法,它们是怎么做到的?你不想知道吗?本期视频将为您展开一个新奇的世界,向您介绍这迷人的“小养殖户”们!

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视频来源

https://www.youtube.com/watch?v=-XuPtW8lBCM

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