Friday, December 12, 2014
New Family Tree Illuminates 'Big Bang' in Bird Evolution After Dinosaur Extinction
The biggest takeaway from the eight studies published Thursday in the journal Science is the way genetic codes can be used to answer wide-ranging questions. Scientists are using birds' DNA, for instance, both for research on the brain and learning and to reconstruct what an ancient ancestor of birds and dinosaurs might have looked like.
Researchers mapped the complete set of DNA instructions, or genomes, of 45 bird species representing every group of living birds, as well as representatives of all three groups of crocodilians—the closest living bird relatives. To produce the new family tree, scientists combined this information with previously published sequences for zebra finches and domestic turkeys and chickens.
Most of our notions of how DNA evolves over time come from studying the genetic instruction books of mammals, says Ed Green, a genome scientist at the University of California, Santa Cruz.
Adding the genomes of birds and crocodilians—the American alligator, saltwater crocodile, and Indian gharial—now allows scientists to better understand how these groups are related, he says.
The new study finds the rate of change in birds' DNA took off 66 million years ago when most dinosaurs went extinct. The surviving dinosaurs then radiated into a constellation of species that led to about 95 percent of birds on the planet today, says Erich Jarvis, a neurobiologist at Duke University in Durham, North Carolina. (See how "Birds Evolved From Dinosaurs Slowly—Then Took Off.")
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