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.