BOB HIRSHON (host):
Watching evolution happen. I’m Bob Hirshon and
this is Science Update.
Scientists have seen evolution in action—in none other than Darwin’s finches. Two decades ago, large ground finches moved to a Galapagos island where medium ground finches lived. The problem was, the large finches ate the same seeds as the medium finches, and they did it faster with their bigger beaks. So scientists predicted that the medium finches’ beaks would evolve to take advantage of smaller seeds. Princeton University evolutionary biologist Peter Grant says that happened during a drought two years ago.
PETER GRANT (Princeton University):
The recent immigrant species had almost eaten the supply of food for themselves, so they almost went extinct. The resident species underwent this large shift towards small size in beaks.
He says this adds to the evidence that competition between species can lead to evolutionary changes.
I’m Bob Hirshon, for AAAS, the science society.