Question

How does the introduction of invasive species, such as the brown tree snake, upset the stability of an ecosystem?

Answer 1

When ever any new species is introduced it affects the ecosystem because organisms that live there have to learn what that thing eat and does. they will need to know if they should be scared of this thing or not.  

Answer 2

The invasive species are the species who are present in a non native ecosystem. The invasion of These species disturbs the environment of particular system by increasing the competition or destroying the vital component of the ecosystem.

The invasive species like brown tree snake exhaust the food of the other animals present in the ecosystem, as they are capable eating almost every type of food. Due to the presence of the brown tree snake, the competition for food increasing, which result in disappearance of many native species. Other invasive species can feed on the native species and cause decrease in their number, so, the invasive species disturb the ecological balance in the ecosystem.