Invasive alien species are terrible

Massive vines that blanket the southern United States,climbing as high as 100 feet as they uproot trees and swallow buildings.A ravenous snake that is capable of devouring an alligator.Rabbit populations that eat themselves into starvation.These aren't horror movie concepts.They're real stories,but how could such situations exist in nature?All three are examples of invasive species,organisms harmful not because of what they are,but where they happen to be.