【單性魚類的自我繁殖力】

【單性魚類的自我繁殖力】

ATTACK OF THE CLONES: 『生物複製品的攻擊』

CREATURE THAT STARTED AS PET NOW MULTIPLYING OUT OF CONTROL

原先開始時是寵物的生物，現在則己繁殖到失控

Most species of crayfish reproduce the same way that humans do: by having sex. But one species of crayfish that evolved out of the pet trade can do something unique—clone itself—and this ability has led populations of the crustacean to spawn out of control.

大多數種類的小龍蝦繁殖的方式如同人類一樣: 經由交配。但是從寵物買賣中，進化出來的一種小龍蝦，可以做一些獨特的事情--本身自我複製，此種能力導致了甲殼類動物的孵卵生育到失控。

For a study published today in the journal Nature Ecology and Evolution, researchers sequenced the genomes of 11 marbled crayfish, both from the wild and from the pet trade. They found that the genomes in all 11 animals were nearly identical, meaning that they don’t reproduce sexually, and that they are officially a different species than their North American mother species, Procambarus fallax.

對於今天發表在《自然生態學與進化》雜誌上的一項研究，研究人員對11隻大理石螯蝦的基因組，進行了排序， 無論是從野外取得，還是從寵物市場中購得。他們發現，所有11隻動物的基因組幾乎是相同的。這意味著，它們不經由交配繁殖， 而且正式上，它們與北美洲的母種，克氏黃花是完全不同的物種。

The marbled crayfish evolved into a new species out of the pet trade.SINA TÖNGES

大理石螯蝦從寵物交易演變成一個新物種

 “Here we have an evolutionary event that has happened only a very short time ago,” Frank Lyko, head of divisions of epigenetics at the German Cancer Research Center, told Newsweek. “Certainly there will be some changes, genetic changes over time, that will make it more normal. At this specific time point in evolution it’s very unique.”

「在這裡，我們有一個很短時間前發生的進化事件」弗蘭克 Lyko說，他是德國癌症研究中心的遺傳學分部負責人，他告訴新聞週刊：「當然隨著時間的推移，會有一些變化，基因的變化，這將使它更正常。在此進化特定的時間點上，它是非常獨特的」。

Lyko explained that forming a new species usually takes evolution thousands of years or more. However, it was only a few decades ago that the North American species of crayfish entered the pet trade, and now a different, exceptional species has emerged from them.

Lyko 解釋說，要形成一個新物種，通常需要上千年或更多時間的進化。然而, 就在幾十年前， 北美的螯蝦品種，進入了寵物交易市場，現在又出現了不同的、異乎尋常的物種。

The way that this new species formed is exceptional as well. P. fallaxcame to Germany as a pet, sold over the internet and in pet and aquarium stores. But some time between 1990 and 1995, the animals evolved into a new species. The new species had marbled coloring, and people first noticed that it was different from the original species because there was only one sex.

“People wondered, ‘it's only females, where are the males?’” Lyko said.  

這種新物種的形成方式也很特殊。對德國而言，fallaxcame作為寵物，在網上和水族館商店出售。但在1990和1995之間的一段時間，這些動物進化成一個新的品種。新的品種有大理石的顏色，人們首先注意到， 它是不同於原始品種，因為只有一個性別。「人們想知道," 這只是雌性, 雄性在哪裡？ 」Lyko 說。

It turns out that marbled crayfish only exist in female form, spawning clones of themselves two or three times a year in a process called parthenogenesis.

結果是，大理石螯蝦只有雌性形態，每年產卵二至三次，在一個叫做孤雌生殖珐的過程中繁殖。

The marbled crayfish can start with one and then clone itself into millions.RANJA ANDRIANTSOA

大理石龍蝦可以從一個開始，然後自己複製成百萬隻。

Because they spawn so quickly and easily, they’re easy to breed (clone) in captivity. That made them ideal for people selling the animals as pets, but it became a problem for people who only want one in their aquarium.

“You put them into your aquarium and a year later you have hundreds of them,” Lyko explained. No dad required.

因為它們產卵得如此迅速和容易，它們在圈養時就很容易滋生繁衍。這使他們作為寵物出售，是合乎理想的。 但它對於只想要他們生活在水族館的人，就成為一個難題。Lyko 解釋說: 『你把它們放進水族館，一年後你會有數以千計的魚』。不需要雄性魚類的幫忙。

Then what are you going to do? You can kill the others, sell them, or release them into nearby waterways. If the animals were once your pets, you might be inclined to release the extras—which, in turn, can create thousands more rapidly.

那你打算怎麼辦？你可以殺死其他應， 賣掉它們，或者把它們放到附近的水域裡。如果這些動物曾經是你的寵物，你可能會傾向于釋放，這些額外的附加物--反過來, 它可以更快地創造出數以千計的魚。

That’s how the species became invasive to Germany and Madagascar where they were also popular pets. The scientists concluded that there are now millions of this unique but unstoppable creature crawling throughout Madagascar and constantly multiplying.

這就是該魚種如何侵入德國和馬達加斯加， 在那裡他們也是受歡迎的寵物。科學家們得出結論，現在有數以百萬計的這種獨特，但不可阻擋的魚類生物，爬入遍及在整個馬達加斯加島，和不斷繁殖中。

Justin Lai  編譯

02/11/2018