The news is likely to upset Young Earth Creationists, who reject the evolution of new species by natural selection, and this one especially stings because the species observed evolving in real time was a new type of Galapagos finch.
"From generation 2 onwards the lineage behaved as an independent species", researchers from Princeton and Sweden's Uppsala University wrote as they reported their findings in the journal Science. 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.
"We didn't see him fly in from over the sea, but we noticed him shortly after he arrived". These new unnamed birds were called simply Big Birds because they were larger than the native species. This shows how important geographical isolation is when it comes to creating new species. The peculiar tale takes place on a remote island in the Galapagos chain tucked away in the Pacific Ocean, and it's helping scientists to understand how new species can form much faster than we typically imagine. "He was so different from the other birds that we knew he did not hatch from an egg on Daphne Major", Peter Grant told Phys.org.
Researchers have generally assumed that this process could have take thousands of years, but as a result of the unique circumstances on Daphne Major, it happened in just two generations.
Blood and DNA samples enabled researchers to discover that the unusual new bird was actually a large cactus finch of the species Geospiza conirostris from Española island, more than 100 km (62.14 miles) away from Daphne Major.
After reaching maturity, the new Big Birds attempted to find mates of their own only to be met with a big problem.
It reports that researchers saw the finches mixing with other birds to create a third species, in what is thought to be the first example of speciation observed directly in the field. The hybrid birds couldn't replicate the song of the native finches, and that, combined with their difference in size, prevented them from attracting mates. Cactus finches have bigger body and beak as compared to other finch species living on the island at the time.
Ironically, the discovery was published on the eve of the anniversary of the publication of Charles Darwin's magnum opus titled "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life", which was released in 1859 and largely inspired by his time on the Galapagos Islands. Instead, he settled on one of the three finch species on the island.