As described in this case, firstly G.fuliginosa species of bird were live on Los hermanos island solely thus they didn't face any competition.
Darwin's finches are a group of birds that diversified after they migrated from South America to the Galapagos Islands. They each evolved on separate islands separated by large bodies of water. They are therefore an example of allopatric speciation. Repeated volcanic eruptions have helped shape the rugged mountainous landscape of the Galapagos Islands.
The Galapagos Islands are known for their diversity of flora and fauna. Many species are endemic and cannot be found anywhere else in the world. The Galapagos Islands lie on either side of the equator in both the northern and southern hemispheres. These islands are located at the confluence of her three currents in the Pacific Ocean creating an area where warm and cold waters converge.
