All 18 species of Darwins finches derived from a single ancestral species that colonised the Galapagos about one to two million years ago.
"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. However, these were not able to attract native finches for copulation and thus had to mate within their own new species, making them genetically and reproductively isolated.
Nearly 40 years ago, a graduate student working with the researchers noticed a male bird that was much larger in body and beak size than the species that were known natives on Daphne Major.
This gave rise to a population of finches, about 30 of them, that are distinctively different in appearance and behavior on the island of Daphne Major.
"We didn't see him fly in from over the sea, but we noticed him shortly after he arrived", said Peter Grant, also from Princeton. The research team followed the new species for six generations, taking blood samples for genetic analysis.
Finches on the Galapagos Islands consist of many species known collectively as Darwin's finches, which were first studied by Charles Darwin in the 1830s. Throughout our work on Daphne Major, we were in a position to discern the match up of two birds from varied species and then pursue to observe how speciation occurred.
The researchers involved in this study have noted that such remarkable and fast evolution was made possible by reproductive isolation, which is a critical step in the creation of a new species from interbreeding of two separate species. "Evolution in general can happen very quickly".
The new species, called Big Bird, was observed by British husband and wife researchers Rosemary and Peter Grant, of Princeton University in the U.S., evolving and establishing itself on the island of Daphne Major within the Galapagos from 1981. Prior, the theory primarily relied on fossil records and species hybridisation, though an existing species had never been observed evolving into an entirely new species.
The original breeding pair's offspring were unable to persuade other species to mate with them so bred between themselves. When those babies matured, they couldn't find mates among the local finches, according to the research. The new bird, bigger than the three species living on the island, was a large cactus finch that had apparently flown from an island over 60 miles away.
The study emanates from the work carried out on Darwin's finches which resides on the Galapagos Islands in the Pacific Ocean.