Wed Aug 2
PARIS – Scientists have discovered the reason for a phenomenon that supported Charles Darwin’s theory of evolution — the varied shape of finches’ beaks — according to the journal Nature.
When the British naturalist Darwin disembarked on the Pacific archipelago of the Galapagos Islands in 1835, he found 14 separate species of finch, which were distinguishable by a key feature — the shape of their beaks.
Although all are descended from a common ancestor, their beaks vary from the long, pointed one of the so-called cactus finch, to the ground finch‘s deep, wide protuberance.
The different shapes and lengths reflect differences in the species’ diet.
The cactus finch uses its long beak to pick out insects hiding in plants, while the ground finch uses its wide one to scoop morsels from the ground.
So a team of scientists based in the United States sought to discover what gave the beaks their different shapes.
Using a genetic analysis technique called DNA microarray analysis to study the differences between five species of finch, they found that the longer, pointed beaks contained more calmodulin, a protein molecule that binds calcium in cells.
To confirm their findings, the team — led by Clifford Tabin of Harvard Medical School in Boston, Massachusetts –, used genetic manipulation to increase the level of calmulodin in the beaks of chicken embryos.
The chickens were born with pointy beaks that were 10-percent longer than normal.
Genome sequencing clarifies the evolution of Darwin’s finches and their beaks: here.
Invasive species on Galapagos: here.
Oil pollution on Galapagos: here.