How invasive bugs get that way
Manipulation of soil communities enables some introduced species to turn
into 'monsters'
By Stuart Blackman

While most introduced species never become established, some "have just gone
crazy [and] changed, from being nice guys-good citizens coexisting with
other species-into these competitive monsters," according to University of
Montana plant ecologist Ragan Callaway. One secret to invasive species'
success is a knack for manipulating soil organisms in their adoptive habitat
to their own advantage, according to a paper by Callaway and colleagues in
the February 19 Nature (Nature, 427:731-733, February 19, 2004).

The "competitive monster" studied by Callaway and colleagues was spotted
knapweed (Centaurea maculosa), a European native that has spread to all 50
US states since its introduction in the late 1800s. They took a
biogeographic approach, comparing the feedback effects that arise between
the plant and soil microbes when it is grown in soil taken from its native
versus adoptive habitat.

The authors showed that soil microbes from the plant's home range have
stronger inhibitory effects on its growth than do those from its US habitat.
Sterilization of European soil resulted in a 166% increase in plant biomass
compared with a 24% increase following the same treatment of soil from
Montana. Additionally, plants grown in nonsterilized European soil were
smaller if the soil had been precultured with other C. maculosa plants
rather than a European grass species. Conversely, in Montana soil, plants
did better in C. maculosa-primed soil.

Read the rest at BioMedNet
http://www.biomedcentral.com/news/20040220/01

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