雜交、演化 外來植物更猖獗 - 生態環境討論

http://e-info.org.tw/node/20115

科學家新報告 探究外來種利甘草強盛之謎
摘譯自2007年2月27日ENS伯林頓，佛蒙特報導；郭啟彬編譯；蔡麗伶審校
最新的利甘草(reed canarygrass)研究報告發現，一種新的機制可以解釋為何有些植物會
在移植到新的地區時變得具有侵略性。在其原生地歐洲，利甘草並不會排擠其他植物或擴
張領域。但是在十九世紀中葉引進美國時，利甘草變得非常猖獗，扼殺了其他溼地本土植
物的生存空間。這種草已經被10州視為侵略性物種，並且還在蔓延中。

2月27日出版的《國家科學院院刊》中一份研究報告指出，這種草的侵略性並非來自於單
一種種類，而是來自於從歐洲各區域不同草種被引進的歷史。數十年來，美國農人和其他
人種植利甘草作為家畜的飼料，或作為水土保持及廢水處理之用；他們將利甘草遠遠帶離
法國、捷克和芬蘭等原生地。

研究人員認為，這些多元的引進方式和之後的混種，創造出一種生物性優勢。由於從歐洲
大陸吸收了多元的基因，在美國出現的新品種具有更高的基因多樣性，並且比它們在大西
洋對岸的兄弟品種更具有潛在的優勢。

「這並不是你從法國帶了一些草種到美國，然後它們就突然變得具有侵略性，」該研究的
協同作者、佛蒙特大學植物生物學副教授莫洛夫斯基（Jane Molofsky）說道，「而是你
帶了一些植物，然後又從另一個地方帶了一些過來，之後它們重新在這裡結合並形成更強
悍的東西，基因上的巨星。」研究人員認為，這使得利甘草所帶來的麻煩具有更深層的含
意，因為侵略性的物種可以以極快的速度繼續演化下去。



Reed Canarygrass Mellow in Europe, Aggressive in America
BURLINGTON, Vermont, February 27, 2007 (ENS)
A new study of reed canarygrass has led to the discovery of a novel mechanism
that explains why some plant species become aggressive when introduced in new
territory. In its native European range, reed canarygrass does not push out
other species or expanding its terrain. But, first introduced into the United
States in the mid-19th century, it has run rampant, choking out native plants
in wetlands. The grass is now considered an invasive pest in about ten states
and its range is growing.

According to research published in the Feb. 27 edition of the Proceedings of
the National Academy of Sciences," the invasive power of this grass, comes
not from any one individual plant, but from this history of multiple
introductions from different regions of Europe. Over decades, U.S. farmers
and others have planted the grass as livestock feed, for erosion control, and
for wastewater treatment, taking plants from places as far apart as France,
the Czech Republic and Finland.

These multiple introductions, and subsequent interbreeding, create a kind of
biological stacked deck, the researchers said. By drawing on genetic variety
from across the European continent, new strains have emerged in the United
States with higher genetic diversity and more potentially advantageous
qualities than their species brethren across the Atlantic.

"It's not that you're taking the ones in France and moving them to the US and
they're suddenly invasive," said study coauthor Jane Molofsky, associate
professor of plant biology at the University of Vermont. "It's that you move
some plants, and then you move some from somewhere else and they recombine
here to form something better, genetic superstars." This has significance far
beyond the headache of reed canarygras, the researchers concluded, showing
that invasive species can evolve extremely rapidly.

全文及圖片詳見
http://www.ens-newswire.com/ens/feb2007/2007-02-27-09.asp#anchor3


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