Question

Why do introduced species often disrupt an ecosystem?

Answer 1

They don't have a natural predator in the ecosystem.
Also, they usually come from a larger continent where there is more, fiercer competition. Natural selection pressure is higher on these species so they become superior and out-compete the indigenous species.

Answer 2

@Nurali UGH thank you thank you ! I finally understand :)

Answer 3

My Pleasure.