Daphne Major Island, one of the most restricted islands in the Galapagos, is home to two species of Finches. It was whilst studying Finches that Charles Darwin came up with his theory of Evolution. Originally the island was populated by a medium ground finch which fed on large and small seeds. Then, in the early 80s, a breeding population of large ground finches arrived on the island.
The result was that the medium ground finches were now competing with the large ground finches for the limited food source. The large ground finches feed solely on the larger seeds of the Tribulus plant and are able to break open the seedpods and eat the seeds faster than the medium ground finch. Meanwhile, the medium ground finches with smaller beaks can get to the smaller seeds whilst the medium ground finches with larger beaks have to compete with the stronger large ground finches for the bigger seeds.
A study by Peter Grant from Princeton University over the past three decades has revealed that the medium ground finches with larger beaks have been dying off and that the species has now evolved smaller beaks so as to not compete with the large ground finch which now resides on the island. This is a perfect example of evolution in action re-enforcing Darwin’s theory 175 years after he visited the islands himself.