Answer:
The island are isolated from the rest of the world and human interaction rate it's lower than other places
Step-by-step explanation:
Those species are endemic from the Galapagos Islands, just like almost every island in the world, human interaction becomes harder due to hard access to the island and the competition between species is unaltered because of the lack of humans in the area.
Natural selection is still working there like the moment when Darwin visited those islands. Another example of islands with that characteristics are Australia and Madagascar.