For the first time scientists have observed evolutionary changes in real-time due to competition for resources
They have found that in just two decade’s the finch species – Geospiza Fortis – discovered by Charles Darwin on one of the Galapagos Islands has evolved a smaller beak size to better equip itself to eat small seeds.
Scientists report in the journal Science that the arrival of a new, larger species of finch 20 years ago triggered the change.
Co-author of the study Peter Grant of Princeton University said: “The recent immigrant species had almost eaten the supply of food themselves, so they almost went extinct. The resident species, the species that was there before the new species arrived, underwent a large shift toward small size in beaks.”
Typically, the small members of the species can’t crack larger seeds. But with the depletion of the larger seeds due to the arrival of the new species, the small-beaked population – which could reach the smaller feed and needed less food to meet its daily energy needs – had a better survival rate.
This type of evolutionary change is known as character displacement. “It’s a very important one in studies of evolution because it shows that species interact for food and undergo evolutionary change, which minimises further evolution,” Grant said. “It has not been possible to observe the whole process from start to finish in nature.”