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5 December 2013 11:26 am ,
Vol. 342 ,
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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How Weeds Go Wild
20 February 2004 (All day)
It may not make great action footage for nature documentaries, but plants are in constant battle with each other--for space, light, water--and with soil pathogens that threaten to kill or stunt them. Now it's becoming clear just how important this subterranean struggle can be. Plants that escape their natural soil-borne enemies, and strike up alliances with friendly microbes, can become aggressive invaders.
The idea was first proposed 2 years ago by John Klironomos of the University of Guelph in Canada based on greenhouse experiments that suggested invasive weeds thrive when they're transplanted into soil lacking the pathogens that plague them in their native environment (ScienceNOW, 2 May 2002).
New research by Ragan Callaway of the University of Montana, Missoula, and colleagues strengthens that conclusion. The group studied spotted knapweed (Centaurea maculosa), a European plant that is now a pervasive weed in the western United States. First, they planted seeds in sterilized and nonsterilized soil from both continents. Plants in pathogen-free soil from North America grew up to 148% more than those in the nonsterilized U.S. soil. But the European plants improved much more--up to 900% when they faced no pathogens compared to when they grew in untreated soil from Europe. That suggests knapweed in Europe is held back by soil pathogens even more than is the invasive knapweed in the U.S.
Enemies clearly matter, and that's especially true in the old country. When the researchers grew knapweed in French soil, it fared better in soil that had been previously planted with bunchgrass than with knapweed--presumably because the bunchgrass soil had not accumulated knapweed-specific pathogens. But it appears that enemies aren't the whole story. Montana soil showed the opposite pattern: Knapweed planted in soil that had grown knapweed did better there than in once-grassy soil, the team reports in the 19 February issue of Nature. They think that invasive knapweed has not only escaped its natural pathogens in Montana but is modifying the soil to its own advantage, perhaps by cultivating helpful mycorrhizal fungi.
"This suggests that the contribution of soil organisms in invasiveness is two-fold: [Invasives] escape from the bad guys and [get] help from the good guys," notes Wim Van der Putten of the Centre for Terrestrial Ecology in Heteren, The Netherlands. He and others recently published similar findings on black cherry plants. Figuring out exactly which pathogens are responsible will be an important next step, adds Klironomos.