Why do foreign plant and animal species only become invasive in their new habitats?


Why do foreign plant and animal species only become invasive in their new habitats?

In: Biology

Each habitat (ecosystem) is balanced by default; from plants to animals, the system has found a way to sustain all it’s population.

When a sudden change occurs, such as introducing a foreign species, a new members needs to be placed in the balance. Simplifying, it’ll need something to eat and something that eats it to become part of the ecosystem.

Species become invasive when they find a way to feed in the new system but have no other beings feeding from them.

They evolved in a given habitat in conjunction with other species that kept them in check. For example, rabbits have natural predators in Europe. Predator and prey evolved together which ultimately kept their population balanced. More predators caused rabbits to evolve to be more fertile so that they can reproduce quickly. But their numbers are kept limited by the predators, whose population increased as their prey species of rabbits increased. Then you go and release rabbits in Australia, which doesn’t have a significant predator species to eat the rabbits, so they breed outrageously fast and become a plague in Australia.

Only? They don’t. All those palm trees in LA? They’re not indigenous to the area. Not destabilizing the ecosystem, though. Though the same can’t be said for all the human transplants…

In a natural environment everything is in balance. Plants which are poisonous to most species have animals which have adapted to eat them.
Once they are taken away to another area, there’s nothing that can eat them to keep them under control.

Nature also has a distribution system with tornadoes, hurricanes, and tsunamis able to bring species to a new location.