Genomes of a feather flock together

Several long-standing questions about the evolutionary history of birds have been answered in a Science paper published by the Avian Phylogenomics Consortium. The paper was one of 28 appearing in several journals, including a special issue of Science, to report the Consortium's first findings.

The Consortium, which includes Wang Jun of China's BGI, who is also affiliated with King Abdulaziz University in Saudi Arabia, sequenced 45 bird genomes and analysed them together with three already published avian genomes to build a phylogeny of birds. Several of the species, including bustard and sandgrouse, came from the Breeding Centre for Endangered Arabian Wildlife in Sharjah. The researchers found strong evidence for a rapid radiation of bird species following the mass extinction that killed the dinosaurs 66 million years ago, rather than an earlier, more gradual diversification of species. 

The new phylogeny also clarifies several evolutionary relationships and the history of various traits; for example, vocal learning evolved independently at least twice in birds. “This tree will affect all bird evolution studies,” says Erich Jarvis of Duke University, lead co-author with Siavash Mirarab of University of Texas at Austin.

None of the trees built using only individual genetic elements matched the tree based on the entire genome. “That means you can’t trust gene trees to give you a species tree. Depending on how closely in time the species being compared diverged, you need many genes, if not most of the genome [to get an accurate species tree],” says Jarvis. In addition, evolutionary convergence makes protein-coding genes the least informative for inferring a tree. “I suspect as more genomes become available for tree analyses, we will be seeing important changes in our view of the tree of life.”

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