Galapagos islands: why Darwin’s finches differ in beak size


Darwin's finchesAFP reports:

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.

Invasive species on Galapagos: here.

Oil pollution on Galapagos: here.

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29 thoughts on “Galapagos islands: why Darwin’s finches differ in beak size

  1. Evolutionary biology: On Building a Longer Beak

    A classic illustration of nature’s ability to generate
    morphological diversity comes from the finches that inhabit the
    Galapagos Islands. The beak shapes of these finches are
    remarkably diverse, and — as described in new work –
    researchers have uncovered one of the mechanisms involved in
    achieving this. They have compared beak development of…

    Full report at http://scienceweek.com/2006/sw060818.htm

  2. I think you have some strong theories but more proof is needeed to prove it. i am a strong beliver in evolution but some religious beliefs need more proof. if you could just give more info then the rest of the world could have a little less doubt on the subject. Thank you.

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