Evolution on the Fly: Galapagos Study Shows Finches Evolved Super Fast
New research proves interbreeding among species can produce new species in as little as two generations. Researchers discovered their proof, a new bird species -- the product of a love affair between a foreigner and local -- on the Galápagos Islands.
For decades, scientists have been studying Darwin's finches on the Galápagos Islands off the west coast of South America. The remote islands offer an ideal setting in which to study evolution and adaptation.
Some 36 years ago, a Princeton graduate student noted the arrival of a new bird on the island of Daphne Major -- a larger male, different from the other species on the archipelago.
"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," Peter Grant, a professor of ecology and evolutionary biology at Princeton, said in a news release.
Researchers captured the bird and collected a blood sample. After being released, scientists observed the specimen mating with a local female, a medium ground finch of the species Geospiz fortis.
In the decades since, scientists have tracked the development of the lineage produced by the odd pair.
In the latest study, scientists analyzed the blood of the original male and determined him to be a large cactus finch of the species Geospiza conirostris. He arrived from Española island, 62 miles to the southeast.
Genetic analysis of the six generations of the "Big Bird" lineage suggests a new species formed within just two generations. The new species now consists of 30 individuals.
Until now, scientists thought the formation of a new species took much longer.
In addition to being genetically unique, the new bird species also boasts a beak all its own.
"It is very striking that when we compare the size and shape of the Big Bird beaks with the beak morphologies of the other three species inhabiting Daphne Major, the Big Birds occupy their own niche in the beak morphology space," said Sangeet Lamichhaney, a postdoctoral fellow at Harvard University. "Thus, the combination of gene variants contributed from the two interbreeding species in combination with natural selection led to the evolution of a beak morphology that was competitive and unique."
It's likely new species of Darwin's finches have, through history, regularly emerged just as the Big Bird lineage did. Though most may ultimately become extinct, some may account for the species scientists know today.
Scientists detailed their discovery of the new finch species in the journal Science.
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Image credit: Princeton/Photo courtesy of P.R. Grant.
Dr. Arv Edgeworth:
Posted: 2017-11-28 @ 5:13pm PT
Forgive my skepticism but, how is one species of finch mating with a different species of finch, and producing a new species of finch, an example of evolution?
I understand my ancestry is English, Irish, and American Indian. Would not English, Irish, French, Chinese, etc. be different species of humans? If an Englishman married a Chinese lady and they had a child; how is that different from the example of the finches? If the finches are evidence of evolution, why aren’t human species cross-breeding considered evidence of evolution? What makes them different? I just don’t see it.
Also, why is the finch speciation even considered an example of evolution? Mutations apparently were not involved, nor survival of the fittest. To me, I would be more interested in how many species of finch were originally on the islands, how they got there, and is there any evidence of anything causing any of those finches to produce a species heading in the direction of becoming something like a non-finch? Or for that matter, coming from some form of non-finch, whatever that might be.