Key to flight loss in birds
Since
Darwin's era, scientists have wondered how flightless birds such as emus,
ostrich, kiwi, and others are related, and for decades the assumption was that
they must all share a common ancestor. A team of Harvard researchers
believes they may now have part of the answer. Based on precision analysis
of the genomes of more than a dozen flightless birds, including an extinct moa,
a team of researchers found that while different species show wide variety in
the protein-coding portions of their genome, they appear to turn to the same
regulatory pathways when evolving flight loss - reduced forelimbs, and
loss of the 'keel' in their breastbone that anchors flight muscles. While
the protein-coding genes appear to be responsible for adaptations in diet,
feather function and environment, the regulatory regions seem to play a
key role in the body-scaling changes that go along with flight loss. In the
absence of an enhancer, proteins are not expressed during early limb
development stage resulting in flightless birds.
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