Gainesville, Florida
November 20, 2008
Plants that range northward
because of climate change may be better at defending themselves
against local enemies than native plants.
So concludes a team of scientists including a
University of Florida
geneticist. The team's findings, reported in today's online
edition of Nature, suggest that certain plants could become
invasive if they spread to places that were previously too cold
for them.
"This paper is the first to suggest that the mechanisms that aid
invasive species when they move from one continent to the next
may actually work within continents when climate change
gradually extends the distributional range of a species," said
Koen J.F. Verhoeven, an evolutionary biologist at The
Netherlands Institute of Ecology. "Plants may be able to outrun,
so to speak, their enemies from the southern range."
Often, exotic plants and animals are introduced to new
continents or geographic regions by travelers and commerce.
Separation from their natural enemies can drive their invasive
success in the new range. But, increasingly, the distribution of
many species is shifting because of climate change and changes
in land use.
Led by scientists Tim Engelkes, Elly Morriën and Wim van der
Putten of The Netherlands Institute of Ecology, with
collaborators from the University of Florida, Wageningen
University and Leiden University, the researchers compared
exotic plant species that had recently established in
Millingerwaard, a nature preserve in The Netherlands, with
related native plant species from the same area.
"We set out to see whether the native and exotics responded
differently to natural enemies such as herbivores or
microorganisms in the soil," said Lauren McIntyre, an associate
professor of molecular genetics and microbiology in UF's College
of Medicine and a member of the UF Genetics Institute. "UF
helped develop a statistical model that took into account the
experimental design and had good power to detect the effects of
herbivory."
Scientists grew six exotic and nine native plant species in pots
with field-collected soil from the Millingerwaard area, allowing
natural soil pathogenic microbes to accumulate in the pots. Then
they removed the plants and replanted the soils with the same
plant species.
The growth of native plants was reduced far more than the growth
of exotic species, indicating natives were more vulnerable to
natural soil-borne microbes.
In addition, all plant species were exposed to North African
locusts and a widespread species of aphid. These herbivores were
not expected to show a preference for either the native or the
exotic species. But they preferred the native plants and left
the exotic ones relatively alone.
Researchers say the findings help to better assess the
ecological consequences of climate change. The success of exotic
plants expanding their range in response to warmer climates may
be comparable to invasive exotic plant species that arrive from
other continents, representing an additional threat to
biodiversity. |
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