The characteristic feature of the ancestral finch was:

Darwin's finches were a good example of

Adaptive radiation in the case of insects is a result of:

Which phenomenon allowed the pouched mammals of Australia to survive due to a lack of competition from any other mammals?

The finches of Galapagos islands provide evidence in favor of:

$A$: During evolution,pouched mammals of Australia survived.
$R$: Due to lack of competition from any other mammal due to continental drift.