Study of Darwin’s finches reveals that new species can develop in as little as two generations

Morgan Kelly ・ High Meadows Environmental Institute

Princeton University researchers B. Rosemary Grant and Peter Grant, along with researchers from Uppsala University in Sweden, have found that a new species of Darwin’s finches developed in as little as two generations, which provides direct genetic evidence of a novel way in which new species arise. The Grants have been studying the evolution of Darwin’s finches on the small island of Daphne Major in the Galápagos Islands for the last four decades.

The arrival of a strange bird to a remote island in the Galápagos Islands archipelago 36 years ago has provided direct genetic evidence of a novel way in which new species arise.

Researchers from Princeton University and Uppsala University in Sweden reported in the journal Science Nov. 23 that the newcomer belonging to one species mated with a member of another resident species on the island, giving rise to a new species that today consists of roughly 30 individuals.

The direct observation this new species occurred during field work conducted on Darwin’s finches carried out over the last four decades on the small Galápagos island of Daphne Major by B. Rosemary Grant and Peter Grant, a wife-and-husband team of scientists from Princeton. The remote location of Daphne Major has enabled researchers to study the evolution of biodiversity due to natural selection under pristine conditions.

“The novelty of this study is that we can follow the emergence of new species in the wild,” said B. Rosemary Grant, a senior research biologist, emeritus, and a senior biologist in the Department of Ecology and Evolutionary Biology. “Through our work on Daphne Major, we were able to observe the pairing up of two birds from different species and then follow what happened to see how speciation occurred.”

In 1981, a graduate student working with the Grants on Daphne Major noticed the newcomer, a male that sang an unusual song and was much larger in body and beak size than the three resident species of birds on the island.

“We didn’t see him fly in from over the sea, but we noticed him shortly after he arrived. He was so different from the other birds that we knew he did not hatch from an egg on Daphne Major,” said Peter Grant, the Class of 1877 Professor of Zoology, Emeritus, and a professor of ecology and evolutionary biology, emeritus.