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課程來源:TED
     
Jonathan Drori談每顆花粉都有一個故事
Jonathan Drori: Every pollen grain has a story

 

講者:Jonathan Drori
20102月演講,20104月在TED上線
 
翻譯:陳盈
簡體編輯:洪曉慧
簡繁轉換:劉契良
後制:陳盈
字幕影片後制:謝旻均
 
 
關於此演講
除非患上花粉熱,否則我們很多人都不留意到花粉。但顯微鏡讓我們清楚地看到花粉迷人的顏色和形狀,還有其寬廣的傳播路徑。Jonathan Drori詳細地講述植物在繁殖期產生的這些迷人小顆粒。
 
關於Jonathan Drori
Jonathan Drori在BBC創始網站工作過,在他投身線上文化和教育媒體,並理解我們如何學習的漫長職業生涯中,這是閃亮的一筆。
 
為什麼聽他演講:
Jonathan Drori的工作專注於媒體和學習。他是BBC線上的營運主管,領導創建BBC的線上版本bbc.co.uk(他對此努力津津樂道)。他從BBC的電視部門轉到網路部門,以前是電視編輯和製片人。他製作了很多關於科學、教育和藝術的電視系列片。
他在BBC工作了大約20年,現在是Changing Media有限公司的主管,同時也是一位媒體和教育諮詢師,以及布里斯托大學的客席教授,他也在學校裡研究教育媒體和科學中的誤解。他繼續監製一些非帶狀的電視系列片,包括2004年獲獎的「DNA故事」和2009年的「精子向前衝」。他是皇家植物園和林地信託基金的理事會成員。
(圖片:Lloyd Davis/flickr
「怎樣把Segway的發明者Dean Kamen嚇到說話結巴?告訴他,就像Jon Drori在演講『為什麼我們瞭解的比預想中少』中所做的,很多麻省理工學院畢業生,也像我們這些人一樣,說不出怎麼用電池和電線來讓燈泡發亮」。
-Wired.com
 
Jonathan Drori的英文網上資料:
 
 [TED科技娛樂設計]
已有中譯字幕的TED影片目錄(繁體)(簡體)。請注意繁簡目錄是不一樣的。
 
Jonathan Drori談每顆花粉都有一個故事
謝謝,今天我有兩個任務。首先我希望告訴大家一些關於花粉的事,讓你們相信這不僅是讓人打噴嚏的東西。第二是讓你們相信,每個家庭真要有一部電子掃描顯微鏡。(笑聲)如果一朵花要長出更多花,它就要傳粉。花粉上有雄性性細胞,從一朵花傳到另一朵花,這樣我們就有了遺傳多樣性,或者最起碼它讓植物有遺傳多樣性。最好不要你來幫它傳粉,基本上人類也是那樣。
 
花粉是花粉囊產生的,每個花粉囊能容納十萬顆花粉,很大量。不光是漂亮的花朵有花粉,樹木和草也有,記得我們所有的穀類作物都是草演變而來。
 
這是電子掃描顯微鏡下的一顆花粉,中間的那個小洞我們遲點再講。但那是讓之後的花粉管出來的,非常小的管。那花粉的橫截距是20微米,大約等於一毫米的五十分之一。但不是所有花粉看起來都這麼簡單。
 
這是一種叫Morina的植物,我一直覺得這很沒趣,這是根據Morin這個名字來改的。Morin是一個很進取的法國園丁,就是他在1621年發表了第一個種子目錄。我們還是來看看它的花粉吧。我覺得這很神奇,中間的小孔是留給花粉管的。當花粉找到另一朵Morina花的雌性傳粉點,在正確的物種上,會發生什麼?剛才說過,花粉上有雄性性細胞,如果你確實沒意識到植物有性,那我告訴你,它們的性生活是暴力的、混雜的、很有趣和古怪的。(笑聲)
 
我要講的並不是植物繁殖,而是花粉本身。我聽到有人問,花粉的特性是什麼?首先,我們都知道,它很小,在生物學角度來看,它十分活躍,有花粉熱的人會理解這點。靠風力傳播的植物花粉,例如樹木和草類等的花粉會引致大多數花粉熱。那是因為這些植物會產出非常多的花粉,這樣可以抓住一切機會,把花粉傳到同一物種的另一株植物上。
 
這裏有些例子,你看這些圖片時覺得它們很光滑。這是樹的花粉,靠風力傳播,這張是小無花果樹,也是靠風力傳粉。所以樹木和不漂亮的花很難吸引昆蟲,儘管它們的花粉很好。這是我特別喜歡的一種,花旗松,它有小的氣囊,讓花粉傳得更遠。記住,這是橫截距只有三十微米的東西。
 
如果用昆蟲傳粉的話,效率會更高。這是一條蜜蜂的腿,上面沾有一株錦葵屬植物的花粉。這是一株紅棕櫚,奇異美麗的花,十分豔麗,吸引了很多昆蟲來傳粉。花粉上有些小倒鉤,我們可以看到,那些小倒鉤明顯可以鉤住昆蟲。但我們從這幅圖可以看到一些東西。你可能看到一條分裂線,橫在整顆花粉的赤道位置。如果我們把這顆花粉看作地球,從這裏我就知道,這顆花粉的確已石化。很自豪地說,這顆花粉是在倫敦附近找到的。在五千五百萬年前,倫敦到處都是紅棕櫚,很好玩吧?(笑聲)
 
OK,這就是另一種靠昆蟲傳粉來進化的物種,你從那小倒鉤可以看到,所有這些圖片都是在Kew實驗室裏用電子掃描顯微鏡拍下。這些是藝術家Rob Kessle拍的,並非偶然。我想一個人同時有設計和藝術的眼光並不偶然,就像他那樣可以帶出花粉最美的一面。(笑聲)
 
所有這種多樣性意味著你其實可以看著一顆花粉,然後說出它來自哪個物種。如果你有一個標本,很容易就能看出那顆花粉從哪來。所以,不同的植物種類生長在不同地方,一些花粉會傳得更遠。所以,如果你有一顆花粉標本,理論上就可以知道它來自何方,這就是鑒別花粉的有趣之處。
 
花粉很細小,它落到東西上,粘在那裏,所以不僅每個花粉類型看起來不同,每個環境的植物組合也不同。如果你喜歡,那會是一種不同的花粉信號,或者一種不同的花粉印記,通過觀察一個標本裏不同種類花粉的比例和組合,你可以很精確的說出它來自哪裡。這是一件棉襯衫裏面的一些花粉,跟我現在穿的這件類似。在反覆洗滌之後,很多花粉仍會附在上面。它到過哪裡?四種不同的棲息地可能看起來差不多,但它們的花粉信號很不同。其實這很簡單,這些照片在不同的國家拍的。
 
但花粉鑒定可以很精細。現在這用來追蹤假藥製造的地點,鈔票的來源,古董的出處,看是不是真的來自賣家說的地方。通過殺人嫌疑犯的衣服,可以知道他們去過的地方。事實上在英國,在某個夠小的區域內,你可以讓警犬去找被謀殺的人。所以你可以根據一件衣服圈定方圓約一千米的範圍,那是衣服最近去過的地方,然後讓警犬去搜索。最後,挺沮喪地講講波士尼亞戰爭犯罪,一些人被抓去審判是因為從花粉裏得到證據,顯示出屍體被埋,之後被挖出,又被轉埋到其他地方。
 
我希望我已經讓你們睜開雙眼,抱歉我用了花粉奧秘的視覺雙關。順便說說,這是七葉樹果,這是我們周遭看不到的美。每顆花粉都有一個故事,我們每個人其實都有一個身上花粉印記的故事,感謝Kew的同事,感謝所有孢粉學專家。(掌聲)
 

以下為系統擷取之英文原文

About this talk

Pollen goes unnoticed by most of us, except when hay fever strikes. But microscopes reveal it comes in stunning colors and shapes -- and travels remarkably well. Jonathan Drori gives an up-close glimpse of these fascinating flecks of plant courtship.

About Jonathan Drori

Jonathan Drori commissioned the BBC's very first websites, one highlight in a long career devoted to online culture and educational media -- and understanding how we learn. Full bio and more links

Transcript

Thank you. I have two missions here today. The first is to tell you something about pollen, I hope, and to convince you that it's more than just something that gets up your nose. And, secondly, to convince you that every home really ought to have a scanning electron microscope. (Laughter) Pollen is a flower's way of making more flowers. It carries male sex cells from one flower to another. This gives us genetic diversity, or at least it gives the plants genetic diversity. And it's really rather better not to mate with yourself. That's probably true of humans as well, mostly.

Pollen is produced by the anthers of flowers. Each anther can carry up to 100,000 grains of pollen. So, it's quite prolific stuff. And it isn't just bright flowers that have pollen; it's also trees and grasses. And remember that all our cereal crops are grasses as well.

Here is a scanning electron micrograph of a grain of pollen. The little hole in the middle we'll come to a bit later. But that's for the pollen tube to come out later on; a very tiny tube. So, that is 20 micrometers across, that pollen grain there. That's about a 50th of a millimeter. But not all pollen is quite so simple looking.

This is Morina. This is a plant which I've always thought to be rather tedious, named after Morin, who was an enterprising French gardener, who issued the first seed catalog, actually, in 1621. But anyway, take a look at its pollen. This is amazing, I think. That little hole in the middle there is for the pollen tube. And when the pollen finds its special female spot in another Morina flower, just on the right species, what happens? Like I said, pollen carries the male sex cells. If you actually didn't realize that plants have sex, they have rampant, promiscuous and really quite interesting and curious sex, really. (Laughter)

My story is actually not about plant propagation, but about pollen itself. So, what are pollen's properties, I hear you ask? First of all, pollen is tiny. Yes we know that. It's also very biologically active, as anyone with hay fever will understand. Now, pollen from plants which are wind-dispersed, like trees and grasses and so on, tend to cause the most hay fever. And the reason for that is, they've got to chuck out masses and masses of pollen to have any chance of the pollen reaching another plant of the same species.

Here are some examples. They're very smooth if you look at these pictures of tree pollen that is meant to be carried by the wind. Again, this time, sycamore, wind-dispersed. So, trees, very boring flowers, not really trying to attract insects. Cool pollen though. This one I particularly like. This is the Monterey Pine, which has little air sacks to make the pollen carry even further. Remember, that thing is just about 30 micrometers across.

Now, it's much more efficient if you can get insects to do your bidding. This is a bee's leg, with the pollen glommed onto it from a mallow plant. And this is the outrageous and beautiful flower of the mangrove palm. Very showy, to attract lots of insects to do its bidding. The pollen has little barbs on it, if we look. Now, those little barbs obviously stick to the insects well, but there is something else that we can tell from this photograph, and that is that you might be able to see a fracture line across what would be the equator of this, if it was the Earth. That tells me that it's actually been fossilized, this pollen. And I'm rather proud to say that this was found just near London, and that 55 million years ago London was full of mangrove palms. Isn't that cool? (Laughter)

Okay, so this is another species evolved to be dispersed by insects. You can tell that from the little barbs on there. All these pictures were taken with a scanning electron microscope actually in the lab at Kew Laboratories. No coincidence that these were taken by Rob Kessler, who is an artist. And I think it's no coincidence that someone with a design and an artistic eye like him that has managed to bring out the best in pollen. (Laughter)

Now, all this diversity, means that actually you can look at a pollen grain and tell what species it came from. And that's actually quite handy if you maybe have a sample and you want to see where it came from. So, different species of plants grow in different places. and some pollen carries further than others. So, if you have a pollen sample then, in principle, you should be able to tell where that sample came from. And this is where it gets interesting for forensics.

Pollen is tiny. It gets on to things, and it sticks to them. So, not only does each type of pollen look different, but each habitat has a different combination of plants, a different pollen signature, if you like, or a different pollen fingerprint. By looking at the proportions and combinations of different kinds of pollen in a sample, you can tell very precisely where it came from. This is some pollen embedded in a cotton shirt, similar to the one that I'm wearing now. Now, much of the pollen will still be there after repeated washings. Where has it been? Four very different habitats might look similar but they've got very different pollen signatures. Actually this one was particularly easy. These pictures were all taken in different countries.

But pollen forensics can be very subtle. It's being used now to track where counterfeit drugs have been made, where banknotes have come from, to look at the provenance of antiques and see that they really did come from the place the seller said they did. And murder suspects have been tracked using their clothing, certainly in the U.K., to within an area that's small enough that you can send in tracker dogs to find the murder victim. So, you can tell from a piece of clothing to within about a kilometer or so, where that piece of clothing has been recently, and then send in dogs. And finally, in a rather grizzly way, the Bosnia war crimes. Some of the people brought to trial were brought to trial because of the evidence from pollen, which showed that bodies had been buried, exhumed, and then reburied somewhere else.

I hope I've opened your eyes, if you'll excuse the visual pun, to some of pollen's secrets. This is Horse Chestnut, by the way. There is an invisible beauty all around us, each grain with a story to tell, each of us, in fact, with a story to tell, from the pollen fingerprint that's upon us. Thank you to the colleagues at Kew. And thank you to palynologists everywhere. (Applause)


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