http://www.nature.com/news/2007/070305/full/070305-6.html
Published online: 7 March 2007; | doi:10.1038/news070305-6
Did a 'light' genome help birds take flight?
A smaller genome evolved in dinosaurs, long before birds learned to fly.Lucy Odling-Smee
| Tyrannosaurus rex may have had the genetic 'lightness' to permit flight, long before their descendents took to the skies. NHPA |
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A
study of dinosaur genomes hints that the early evolution of a smaller
genome might have been necessary for later vertebrates to take to the
skies.
Birds
have long been known to have much smaller genomes than mammals and
reptiles living on the ground. And a small genome has been linked to
both small cell size and high metabolic rate: the lower
volume-to-surface ratio of small cells, which don't have much DNA to
pack inside, can allow for faster transport of nutrients and signals
across the membrane. Thus, some suggest that the energetic demands of
flight require birds to have a 'light' genome.
But which came first: flying birds or the smaller genome?
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