A Darwin's finch immigrated to an island in the Galapagos archipelago and began a new line of finch species with the local finch. Researchers found that evolution of the new species developed in just two generations.
In 1981, a graduate student working in Daphne Major in the Galapagos Islands noticed a new bird singing an unusual song and was much larger in beak and body size compared to the three resident finches of the island. The research team, immediately recognizing that it was not native to the island because he looked quite distinct from the others, took blood samples which revealed that the bird was a cactus finch of the G. conirostris species originally from Española Island.
Because the G. conirostris was so far away from home, he was unable to return to his home island and instead mated with one of three native finch species in Daphne Major. Soon, their offspring resulted in a hybrid species that is distinct from the three resident species in beak size and shape. Because of their difference in size and song from the other species, they had no other choice but to reproduce among themselves, thus creating the "Big Bird" species line.
Evolution Of Darwin's Finches
It is assumed that the process of evolution and the creation of new species take a long time but in the case of the Big Birds, researchers found that the new species was created just after two generations. They are distinct from the three original residents of Daphne Major in beak size and structural features, giving them a unique and competitive edge.
All 18 species of Darwin's finches came from a single species in the Galapagos Islands about 2 million years ago. Since then, they have diversified in the same way that the Big Birds did, and resulted in different species with different beak sizes and features, allowing them to utilize the different food sources with the other species.
Researchers believe that this kind of development has happened among Darwin's finches many times during the course of the species' evolution, though a majority of such lineages have since gone extinct. In the case of the Big Birds, researchers believe that the new line has a good potential for success. As it stands, there are now 30 Big Birds in Daphne Island.
"Charles Darwin would have been excited to read this paper," said Leif Andersson of Uppsala University, the Swedish University of Agricultural Sciences, and Texas A&M University, coauthor of the study.
The study is published in the journal Science.