十種生物的奇特繁殖方式(上)

No matter how it's done, reproduction is weird, often wonderful and sometimes scary. Back in 2000, Bill Joy, chief scientist at Sun Microsystems, wrote an article in Wired magazine titled "Why the Future Doesn't Need Us." In it, he predicted that a catastrophic development was just around the corner: self-replicating robots. Once that eventuality had been reached, he feared, human life as we know it would shortly become irrelevant.

且不論動物們是怎麼做到的，它們繁衍後代的方式的確是千奇百怪。多數奇妙有趣，有些卻讓人毛骨悚然。遙想2000年時，太陽計算機系統公司的首席科學家比爾·喬伊曾在《連線》雜誌上發表了一篇題爲《未來不需要我們》的文章，他預言自我複製機器人的產生這一災難性變革近在眼前；他擔心自我複製機器人面世之時，就是人類消亡之日。

But you don't have to look to the future for examples of strange reproductive possibilities. In ancient Greece, Zeus, god of thunder and head honcho on Olympus, had a memorable encounter with childbirth. One day Zeus had a liaison with one Metis, goddess of craftiness. Too late, he remembered a prophecy that predicted Metis's children would be more powerful than their father. Worried about the consequences, he quickly swallowed his lover whole. Of course, it was too late — she was already pregnant. Sometime later, having developed a phenomenal headache, he got one of his fellow gods to chop his skull open with an axe. Out jumped his new daughter, Athena, goddess of wisdom, in full battle gear. All this might sound improbable, but it's no stranger than some of the bizarre ways organisms are self-replicating in real life, right now.

但若只是想找尋一些奇葩的繁衍方式，大可不必翹首未來，從過去的故事中即可窺知一二。傳說在古希臘，司掌雷電的奧林匹斯山主神宙斯，有過一次難忘的分娩經歷。某日宙斯臨幸了慧聰女神墨提斯，事後他才憶起蓋亞和烏拉諾斯的預言——墨提斯將生下比自己更強的孩子。他心生懼怕，於是把墨提斯整個吞進了肚子。可惜爲時已晚，墨提斯此時已經懷孕。不久，宙斯頭痛難忍，便命令手下的神用斧頭劈開他的頭顱，他的女兒——全身武裝的智慧女神雅典娜便跳了出來。這一切聽起來簡直像是無稽之談，即便如此，這也絕不會比現實生活中有些生物自我繁殖的方式更加奇怪。那接下來就讓我們一起來看看吧。

inal Dragons

10.孤雌生殖的蜥蜴

Maybe it's because the reproductive process is so strange that humans have been telling stories about virgin births since storytelling began. The most famous of these tales is, of course, the one about the birth of Jesus Christ whose mother, Mary, is said to have conceived while still a virgin.

或許正是因爲繁衍後代如此神奇，“處女生育”的故事纔會層出不窮，流傳至今。其中最出名的莫過於耶穌的降生，傳說他的母親——聖母瑪麗亞懷孕時就是處女。

While it's technically possible for a woman to produce a virgin birth, it's incredibly unlikely. On the other hand, parthenogenesis (the scientific term for virgin birth) is common among other creatures in nature. Hammerhead sharks, komodo dragons, mole salamanders, and an assortment of other reptiles, fish and insects can all produce offspring without mating. It all starts with something called a "germ cell." This germ cell splits in two, and then each of those halves splits again. Now you've got four reproductive cells, called gametes. Three gametes are discarded. The remaining gamete contains half the chromosomes necessary to create a new individual. In sexual reproduction, a female gamete and a male gamete fuse, creating a complete set of chromosomes. But in parthenogenesis, the female gamete, or egg, contains a complete set of chromosomes and is able to stimulate itself to grow. Incredibly, there are species of insects that go back and forth between parthenogenesis and sexual reproduction, depending on which method works best for the environment they're in at the time (e.g., is there a mate available?). Then there's something called cyclic parthenogenesis in which organisms such as water fleas alternate back and forth between mating and non-mating reproduction. As yet, nobody's found any examples of parthenogenesis in mammals, but it's been artificially induced in rabbits, among other critters, with the help of temperature control and chemicals. No luck with humans so far...

儘管處女生育在技術上可行，但人們還是很難相信這個事實。不過在自然界，生物體的孤雌生殖（處女生育的學名）十分普遍，錘頭鯊、科莫多巨蜥、摩爾蠑螈和其他種類的爬行動物、魚類以及昆蟲都可以不經交配，直接繁殖。這一切的過程都始於“生殖細胞”。這種細胞可以一分二，然後二分四。我們把得到的這四個生殖細胞叫做“配子”，其中的三個將被棄置，剩下一個則包含創造新生命所需的一半染色體。在有性生殖中，一個雌配子和一個雄配子結合，就可以合成一套完整的染色體組。但在孤雌生殖中，一個雌配子，或稱爲一顆卵子，即包含整套生物體所需的染色體，並能刺激自身生長，最終成爲新的個體。令人難以置信的是，不少昆蟲能夠從容遊走於孤雌生殖和有性生殖之間，選擇哪種繁殖方式完全取決於當時的環境（例如是否能找到異性交配）。此外，還有一些生物遵循所謂的“週期性孤雌生殖”規律，例如水蚤就是交替進行孤雌生殖和有性生殖的。截至目前，自然界中尚未發現任何哺乳動物進行孤雌生殖的例子。但是通過溫度控制和化學控制，已經成功實現人工誘導兔子以及其他小動物進行孤雌繁殖。但人類至今無緣於此。

sing Nemo

9.雄雌變換的尼莫魚

Let's not confuse parthenogenesis with hermaphroditic reproduction! They're not the same at all. In parthenogenesis, the female gamete does all the work single-handedly. Hermaphrodites, however, are remarkable for being able to produce both male and female gametes. That's because they have both male and female reproductive organs.

別把雌雄同體和孤雌生殖搞混了！這是兩個完全不同的概念。孤雌生殖是指雌配子能獨自完成所有生殖工作，而雌雄同體的奧妙則在於生物體同時擁有雄性生殖器官和雌性生殖器官，可以同時產生雌配子和雄配子。

In some species, like certain flowers, snails and fish, hermaphroditism is common. Sometimes an organism might start off male and turn female; sometimes they might start off female and turn male; and sometimes they remain both sexes throughout their lifespan. Remember Nemo and his dad in "Finding Nemo"? It turns out a sequel is warranted because there's a lot of drama in the reproductive lives of clownfish. Socially, clownfish like to hang out in sea anemones where two large breeders, a male and a female, are in charge of a group of smaller male clownfish who don't reproduce. But say, for instance, the female breeder dies. In that case, the large male switches its sex to become the dominant female while the biggest of the small males quickly bulks up to take on the role of sexually mature male breeder. Come on Pixar — "Becoming Nema" is a hit waiting to happen.

有些物種的雌雄同體現象十分普遍，比如某些品種的花、蝸牛和魚類。它們中有些生而爲雄，卻可在日後變爲雌性；也有些生而爲雌，卻可在後天轉爲雄性。有些物種終其一生，都會同時具備雙性特徵。還記得《海底總動員》裏的尼莫和他的父親嗎？這部電影出個續集還是很有必要的，你都不知道小丑魚的繁殖是多麼的有趣！一般而言，小丑魚喜愛成羣結隊穿梭於海葵之間，除了領頭的一對成年雄性和雌性小丑魚負責生育外，其餘均爲不能生育的年幼雄魚。但比如說，領隊的雌魚去世了，那麼領隊的雄魚就會變性，成爲領隊的雌性，同時，這羣年幼的雄魚裏最強壯的那條就會迅速成長、成熟，成爲領隊雄性，擔當生育大任。皮克斯！快放大招把！我們都等不及想看續集里尼莫的父親突然變成母親了，那一定是個大賣點！

ch Piracy

8.偷盜卵子的雄蛙

Clutch piracy is a breeding strategy that involves frogs sporting eye patches and wielding cutlasses while swigging rum.

竊卵是一種繁殖策略，但乍一聽還以爲是青蛙蒙上運動眼罩，痛飲朗姆酒後手拿刺刀變身江洋大盜去偷盜卵子。

Actually, no it's not. It does involve frogs, but they're naked and they live in the Pyrenees, not Barbados. Their lack of clothes is important — high in the Pyrenees, the nights are so chilly that frogs, who typically like to mate under the cover of darkness, are forced to get busy on sunny afternoons instead. Thanks to this local peculiarity, researchers were able to keep a close eye on the process and observed a weird deviation from the usual ho-hum external fertilization they expected to see. External fertilization is the preferred reproductive strategy of many fish and amphibians. The female lays a "clutch" of eggs in the water and then a male deposits some sperm on them. Frogs like to make sure this process is accomplished without delay. Typically when a female frog is ready to lay her eggs, she lets a male climb on her back and give her a big bear hug. She releases her egg clutch, and the male immediately fertilizes it. However, his sperm might fertilize only a percentage of the eggs in the clutch. High in the ponds of the Pyrenees, frog romance works a little differently. Male frogs vastly outnumber the females. Because they often can't find a female to mate with, gangs of piratical males have taken to hunting for freshly laid egg clutches. As soon as they find them, they do their best to fertilize any of the unfertilized eggs that are left. Researchers have found clutches with as many as four different fathers!

事實上並非如此。這確實與蛙類有關，但它們一種是生活在比利牛斯山脈而非巴巴多斯山脈，且皮膚裸露的蛙類。他們“衣不蔽體”這一特點至關重要——因爲在高高的比利牛斯山上，長夜如此寒涼，這些本喜好在夜幕籠罩下“造人”的蛙類，不得不將此事安排在陽光燦爛的午後。多虧了此地得天獨厚的地理條件，研究者們才能密切觀察這一蛙類的受精過程，從而發現了這與他們平日裏早已司空見慣的體外受精方式並不相同。體外受精是魚類和兩棲動物首選的繁殖方式。雌性動物在水中產下一“窩”卵，接着雄性動物再將精子排在卵子上。青蛙們想要確保此過程不被延誤，因此當雌蛙準備產卵時，就會讓雄蛙爬到她的背上，給她一個大大的熊抱。雌蛙排完卵後雄蛙立刻使其受精。然而，這樣的受精率可能只有1%左右。在高高的比利牛斯山上的池塘裏，青蛙們的浪漫情事卻有所不同。這裏雄蛙的數目遠超過雌蛙，所以經常找不到配偶，這就迫使雄蛙海盜團伙不得不到處尋找新產下的卵。一旦找到卵堆，他們就會竭盡全力給其中的未受精卵受精。研究者們曾發現一個卵堆中的受精卵竟有4個父親！

al Deception

7.“勾引”蜜蜂的蜂蘭花

Most flowers have an I-pat-your-back-you-pat-mine relationship with the pollinators that help them reproduce. Bees, butterflies and hummingbirds, for instance, get a delicious sip of nectar in return for carrying some grains of pollen from one flower to the next. Once this happens, the receiving flower can start the process of making the seeds that will grow into new flowers.

大多數花兒和幫助它們繁殖的傳粉者之間都保持着互幫互助的關係。例如蜜蜂、蝴蝶、蜂鳥等動物，都會在爲花兒傳粉的同時吮吸一口甜美的花蜜作爲回報。此後，受粉的花朵就能逐漸結出種子，這些種子最終又能長成新植株。

But certain species of orchids find this strategy old hat, not to say downright boring. With pollinators hopping from one flower to its neighbor, orchids worry about inbreeding. Well, as far as we know, they don't actually worry, but evolution has resulted in a far more novel — in fact truly bizarre — method of self-replicating for these organisms. In mountainous regions of the Mediterranean, there's a species called Ophrys apifera, better known as the bee orchid. In an incredible trompe l'oeil effect, the flower looks precisely like the rear of a female bee with its head buried in a blue-petalled flower. Not only that, Ophrys mimics the scent of said female bee, and it's even a little furry to add to the sensory illusion. This deception is so perfect that even its seeming imperfections turn out to be advantageous. Male bees, seduced by the floral wizardry, fall to mating so vigorously with the flowers that they dislodge pollen packs pre-loaded with a special adhesive that sticks to their backs. But according to plan, the deception only lasts so long. After some frantic efforts at achieving erotic bliss, the bee wises up to the fact that he's been had and staggers away in a fit of frustration. He'll wander a fair distance collecting his wits before he falls for the trick again and, if all goes well for perfidious Ophrys, unwittingly deposits his pollen payload in another bee orchid flower. The bee's frustration plays into the orchid's reproductive strategy, as the distance traveled while the bee was cooling his temper prevents inbreeding. Of course, bees aren't the only ones seduced by orchid magic — think of all the orchid plants flowering on windowsills the world over.

這種繁殖方式雖說不上無聊透頂，但某些品種的蘭花卻嫌棄它過於老套。傳粉者們在臨近的花朵間不停地忙碌着，但蘭花們卻擔心近親交配的發生。儘管我們知道他們並不會真的爲此擔心，但生物進化已然催生了更爲新穎（實際上超級怪異）的自我繁殖方式，以適應這些生物的需求。在地中海沿岸的山區，有一種植物叫蜂蘭花，而人們更喜歡叫它蜜蜂花。在視覺陷阱的效應下，這種花看起來真的很像把頭埋入藍色花瓣中，只留背部在外的雌蜂。此外，蜂蘭花還能釋放與雌蜂類似的氣味，甚至還長有絨毛，使其看起來毛茸茸的，更加深了這種感官錯覺。這種騙術如此完美，甚至使它那外觀上的缺陷都轉變成了優點。被蜂蘭花的幻術吸引而來的雄蜂爭先恐後地與花朵交配，預先帶有特殊粘性的花粉便會粘在雄蜂背上。但是按照原計劃，騙術只能維持這麼久。雄峯在爲了滿足性慾對蜂蘭花實施了殘暴的摧殘後，才意識到自己上當了，於是帶着失落，步履蹣跚地離開。雄蜂會飛行很長的一段距離來“療傷”，直到下次掉入陷阱。對始作俑者蜂蘭花來說，如果一切順利，雄蜂負載的花粉就能不知不覺地落在另一朵花上。於蜂蘭花而言，雄峯的失落正中下懷，因爲雄蜂在冷靜的過程中飛得越遠，就越能防止蜂蘭花的近親交配。當然，想想看那開在窗臺上千姿百態的蘭科植物，全世界有那麼多種類的蘭花，蜜蜂並不是唯一一種被它們的魔法吸引的動物。

i-gendered Mating

6.多種性別的四膜蟲

Next time you cool off in a lake, try not to think about the fact that you might be surrounded by furry single-celled microbes engaging in some truly peculiar reproductive behavior. Actually, for the most part, Tetrahymena is quite a chaste creature that uses the virginal method of parthenogenesis to populate its fresh-water environs.

下次你在湖邊乘涼時，請儘量忘記以下事實——n多毛茸茸的單細胞微生物正在你周圍進行一些非常奇異的繁殖活動。事實上，多數情況下四膜蟲是一種非常純潔的生物，它們採用貞潔的孤雌生殖方式在其生存的淡水中產下自己的後代。

But parthenogenesis doesn't create the kind of genetic variation that can help organisms adapt to changing surroundings. So when times are tough, Tetrahymena can actually switch on a dormant sex drive to help it survive. That's when things get very interesting. If you think keeping track of gender politics is complicated, consider the fact that this little creature has no fewer than seven genders! Scientists have imaginatively termed these genders Types I through VII. A Type I can't mate with another Type I, but not to worry — it can choose from among any one of the remaining six genders. The new baby Tetrahymena get all the genetic info necessary to become any one of the seven possible types. Then, through a random process, their DNA gets pruned down to a single gender. Pretty complicated stuff for a microscopic microbe!

但是孤雌生殖不能產生遺傳變異，而遺傳變異有助於生物體適應環境變化。因此，當週邊環境變得不適宜生存時，四膜蟲會啓動一直休眠的性慾，以幫助自己存活。那時，事情就變得非常有趣了。如果你覺得研究性別政治已經非常複雜了，那就想想吧，這個小小的微生物竟然有不少於7種的性別！富有想象力的科學家們將這7種性別稱爲類型1至類型7。兩個個性別都爲類型1的四膜蟲無法交配，但是別擔心，它可以與另外6種性別中任一種交配。新形成的四膜蟲攜帶了父代全部的基因，因而它們也能轉變爲7種性別中的任一種。然後，經過隨機選擇，它們的DNA組將被修剪，最終只保留一種性別。對極其微小的微生物而言，這真真是一件相當複雜的事。

審校：suyiee 來源：前十網