How does geographic isolation hinder or facilitates the evolutionary process?

Question

I'mm working on a assignment and i need ot know what the answer to this is

Answer 1

It facilitates the process since mutations are much more likely to be passed on to a greater percentage of individuals, due to the smaller gene pool, and any useful mutation is more likely to become established, thereby developing at first a sub-species, and after longer isolation, a new species.

Answer 2

the best example is australia - where their animal kingdom is totally different fr the rest of the world.  kangaroo, platypus, dingo, the insects etc.  its just fantastic.  even the koala [variation] is different. where do u get a lazy friendly bear