Alright! <span>In
most cases it will induce nutrition or sth. like that to the ecosystem
because it's simply going to be eaten or die or whatever. Just a large
amount of animals will be able to survive. They need to be lucky enough
to stand the environment (temperature & stuff) and they need to be
able to find food and water sources.
In this rare case (I heard it's less than 10%) it might have the luck to
have no natural foes so it can spread. The fact that they might not
have any natural foes might cause a strong reduction of their food
source. So if you have a big ape that keeps on eating dodos and its
population keeps on growing and there's nothing that stops it... then
one day there will be no dodos left. You see, an alien species usually
will not be specialized on one prey, (or food source) because if they
were so specialized, they'd be specialized on a food source that you can
find at their homes and not at their new environment. (so they would
have died out in advance already). So they're likely to survive a little
longer.
You have the cats and camels in Australia for example... there are huge
masses of them and there are no real natural enemies to "stop" them.
You see, in the usual case there will always be a balance.
Imagine a fox only eats rabits... once there are no rabbits left, the
population of foxes will shrink because there's almost no food.
Population of rabbits will grow again which makes it possible for foxes
to find food easily which will increase their population and as a
consequence decrease the population of rabbits ;)
So in the end it is still possible that a balance will be established...
but in the worst case it might just create an irreversable unbalance.
And... it has usually never been a good idea to invent another species
as a natural foe of the other one.</span>
