What sequence of events resulted in this region having animals and plants that are different from those found anywhere else?

answer as soon as possible !
this counts for 50% of my grade

Okay, well can we have some more information.  Most likely, this is refering to natural selection.  That is, lets say that there are three types of bunnies in the Arctic.  One of them is white, one is brown, one is black.

With knowing this, which one do you think will survive and repopulate more than the others.

That would be the white one because it blends into the environment, making it hard for predators to find.  There are many factors that can affect this but this is also known as evolution

I believe that the question refers to Australia and to the fact that it's been very isolated and that as a result it has developed a number of species which cannot be found anywhere else.
The series of events here would be 1) the geographical isolation of Australia (it separated from the other lands 99 million years ago) and 2) the frequent changes in climate it experienced which led to population bottlenecks (for example it was initially very warn and then it experienced a colder period)