Invasive Species
Introduced into an ecosystem where
they out-compete native (endemic)
species for resources, such as nutrients,
light, physical space, water or food.
Common traits:
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Fast growth
The ability to reproduce both asexually and sexually
Rapid reproduction
High dispersal ability
Phenotypic plasticity (the ability to alter one’s growth form
to suit current conditions)
Tolerance of a wide range of environmental conditions
(generalist)
Ability to live off of a wide range of food types (generalist)
Association with humans
Other successful invasions
Zebra Mussels
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Zebra mussels made their debut in
North America in 1988, after they
hitched a ride in ballast water of ships
from their native Russia.
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A mussel may sound like the most nonthreatening creature in the ocean, but
the zebras are an exception: They've
spread from Lake St. Clair (near
Detroit) to the Mississippi River and
the Great Lakes, edging out native
clams and mussels, clogging industrial
intake valves, changing the migratory
patterns of local ducks, and bloodying
feet of beach goers (they are really
sharp).
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And while edible, they store toxins and
therefore are not recommended for
eating.
Cane Toad
• Setting cane toads loose in
Australia seemed like a good idea
at the time: The amphibians were
supposed to help combat pests in
sugarcane fields, and they did.
• But they didn't stop there: They
became a threat to all of the native
species in their paths, affecting the
entire country's biodiversity as they
moved west toward the national
parks region.
• The country is now working on a $7
million, 15-year plan to rein them
in.
Rats
• Rats: The original stowaway. These
rodents have been hiding in ships for
generations, and changing the
ecosystems where they land.
• For example: They were the first
invasive species to arrive on Macquarie
Island, and efforts to rebuff them -which included introducing cats -- only
made things worse; the cats -- and the
rabbits later introduced for food -- have
since "resulted in the annihilation of two
native bird species and the stripping of
Macquarie Island's vegetation.“
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• Estimated cost of fixing this "ecosystem
meltdown": $16 million.
Gypsy Moths
• The gypsy moth was introduced into
the United States in 1868 by a French
scientist living in Medford,
Massachusetts, to try to make a silk
caterpillar hybrid, that could resist
diseases.
• When some of the moths escaped
from his lab, they found suitable
habitat and started to multiply. Gypsy
moth is now one of the most
notorious pests of hardwood trees in
the eastern United States
• The species can decimate entire trees,
stripping them of their leaves and
affecting forests and native wildlife.
Starlings
•
There are 200 million in North America
descended from 60 to 100 birds released in
Central Park, New York in an attempt to
introduce every bird species mentioned in the
works of William Shakespeare to North America
in 1890, and this turned into a terrible
environmental disaster.
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Starlings are among the worst nuisance species
in North America. The birds travel in enormous
flocks; pose danger to air travel; disrupt farms;
spreads disease to other animals, "usurps
nesting sites," and causes $800 million in crop
damage each year.
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Corrosive droppings on structures cause
hundreds of millions of dollars of yearly
damage. In 2008 the U.S. government
poisoned, shot or trapped 1.7 million, the most
of any nuisance species.
Kudzu
• An invasive plant is nothing you
can't handle with a pair of garden
shears, right? When it comes to
kudzu, wrong. This Japanese vine,
originally planted as a way of
preventing soil erosion, does its
job a little too well.
• According to The Nature
Conservancy, it also "grows out of
control, smothers native plants,
and even uproots native trees by
the sheer force of its weight.“
Brown Tree Snake
• As one of the most expensive invasive
species ever, according to Daily Finance,
the brown tree snake is a lot more
imposing than it looks.
• In the 1950s, the reptiles stowed away
on military planes to end up in Guam
where they took over the previously
snake-free island.
• Now Guam is believed to be home to
13,000 of the snakes -- which were also
the culprits behind the demise of the
now extinct-in-the-wild Micronesian
kingfisher bird.
Mountain Pine Beetles
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Mountain pine beetles usually only grow to
about 1/3 of an inch, but these tiny pests
can have a huge impact with their tree-killing
capabilities.
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The beetles kill the trees by boring through
the bark into the phloem layer on which they
feed and in which eggs are laid.
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They already cover 3.6 million acres of forest
in Northern Colorado and Southern
Wyoming alone, and also live throughout
Canada.
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They're even a threat to massive grizzlies,
since the beetles eat white bark pine -which is also a main source of prehibernation food for the bears in
Yellowstone.
References:
• http://www.treehugger.com/galleries/2011/0
1/10-invasive-species-that-changed-theworld-forever.php?page=11
• http://en.wikipedia.org/wiki/Invasive_species