By JONATHAN
FOWLER
Associated Press Writer
GENEVA
(AP)--What links the 1840s Irish potato famine to the brown tree snake and the
harmless-sounding strawberry guava? The answer, says a conservation group, is
simple--they are all part of an alien invasion.
``If you live in Europe
and you order a plate of fries and ketchup you'll be dining on two alien species,''
said Jeffrey A. McNeely, Chief Scientist at the World Conservation Union. ``Potatoes
and tomatoes are nonnative plants first imported from South America.''
Shifting
plants and animals around the globe can certainly enrich your diet.
But
moving any species from its natural habitat can also have a drastic impact on
its new environment and its inhabitants, said McNeely, whose group has published
a guide to ''100 of the World's Worst Invasive Alien Species'' later this month.
In the distant past the earth's mountains and oceans acted as formidable
natural barriers to all but the toughest species. But human migration allowed
different species--whether animal, plant or humble virus--to hitch a ride.
McNeely
cites the Irish potato famine as a classic example of species invasion. The fungus
which caused the staple food of the rural Irish to rot in the ground arrived on
ships from North America.
Ironically many of the Irish who escaped the
famine settled in Australia, carrying with them cats and rabbits, many of which
soon ran wild and in turn devastated native animal and plant life there.
The
brown tree snake, a native of Australia, is believed to have hitchhiked to Guam
on military aircraft in the 1940s. It is infamous for having wiped out the island's
native forest birds.
The well-intentioned introduction of an alien species
can also have serious consequences.
The strawberry guava, introduced from
Brazil to Hawaii for its edible fruit, is now one of the state's worst pests,
invading natural areas and shading out other vegetation.
McNeely said
the problem is getting worse as world trade expands. ``No one wants to export
problems, but more and freer global trade allows alien species to go further and
in greater numbers,'' he said.
``After habitat loss, this biological invasion
constitutes the greatest threat to biodiversity, and it has already had devastating
consequences for the planet,'' said McNeely.
Beyond the economic impact
of an invasion, conservationists say saving biodiversity is important because
we do not know today which plant and animal species will be useful in the future.
Exporting countries have a responsibility to ensure--as much as they can--that
unwanted invaders don't make it into freight crates, he said. ``They have to make
sure there aren't any free riders.'' |
