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Chickens are closely related to dinosaurs, and other insights from the new bird family tree

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Using statistical techniques to handle genetic data, scientists are learning new things about our fine feathered friends

Tambako The Jaguar

Flamingos and doves are more closely related than they look, a new genetic analysis of birds shows. That's not all: chickens are close relations of dinosaurs, and genetic patterns in the brains of birds that learn new calls show remarkable similarities to humans.

These findings stem from a project that sequenced genes from 48 bird species and then used several months of supercomputing time to analyze relationships. This week, eight papers appear in Science from the effort, which included more than 200 people from 80 labs. More than 20 papers will also be published in separate journals.

"an impressive effort""This is an impressive effort that provides important support for a number of previous assertions that have lacked this extensive genomic information," said Walter Jetz, a biodiversity scientist at Yale University, in an email. He wasn't involved in the project. "As the studies show, capturing more of the genome than traditional approaches allow provides a more rigorous basis" for addressing existing questions, and brings up new ones.

Before now, biologists had relied on other methods to construct family trees. The first trees were made by biologists putting birds that looked alike into groups, says Tandy Warnow, the Founder professor of bioengineering and computer science at the University of Illinois, Urbana-Champaign. As genetic tools became available, biologists began to use them to create trees as well.

depending on what individual gene scientists looked at, the family tree changedThe first genetically-based family trees were made by focusing on the evolution of only one gene. But researchers quickly discovered a problem: different parts of the genome have different evolutionary histories. Depending on what individual gene scientists looked at, the family trees changed.

So Warnow and other researchers came up with a new technique, published in one of the eight Science papers, called statistical binning. Her group used the usual methods to build species trees, and compared them to the method they'd developed. They found the new method led to significantly improved gene trees — and it can be used for other genetic data in the future.

Once the tree had been established, scientists found other things. For instance, birds had an explosive diversification of species right after the dinosaurs went extinct, says Erich Jarvis, a neurobiologist at Duke University and a co-author on several papers. All modern orders of birds formed within a 10 million to 15 million year period following that extinction event about 60 million years ago, he said. That was long after birds lost their teeth, about 116 million years ago, according to one of the Science papers.

Chickens and turkeys appear to be closer to dinosaurs than other birds areChickens and turkeys appear to be closer to dinosaurs than other birds are, having experienced fewer genomic changes, according to a paper published in BMC Genomics.

Another study compared birds to crocodiles, alligators, and gharials — so-called crocodilians, descendants of a lineage of dinosaurs that lived through the mass extinction period. The three types of animals, birds, crocodillians, and dinosaurs, are considered to be archosaurs, a scientific grouping called a clade that arose at least 200 million years ago. So far, scientists have found that crocodilians are evolving more slowly than birds, which in turn are evolving more slowly than mammals.

"Birds are also the living descendants of dinosaurs," says Tom Gilbert, a geneticist at the University of Copenhagen, in a press call. The data trove may help scientists infer more about the now-extinct dinosaur species, he says. Today's bird genetic data helps scientists begin to reconstruct the common ancestor for all archosaurs, according to one of the papers published in Science.

"Birds are living descendants of dinosaurs."Besides helping scientists understand the deep past, today's findings have some implications for humans. Birdsong and human speech share patterns of gene activity, even though they evolved separately. One of the genes involved in birdsong, FOXP2, is also important for those of us vocal learners who don't sport feathers except in hats and boas. The new avian genomes make it easier for scientists to assess vocal learning in birds as compared to humans.

But vocal learning didn't just evolve once among birds, according to one of the Science papers. It seems to have cropped up at least twice, and perhaps three times — in songbirds, parrots, and hummingbirds. Around 55 genes are less active in speech areas in these birds' brains. Birds that don't learn new noises — like pigeons, quails, and doves — don't have the same pattern of gene regulation. Humans do.

As the price of genome sequencing goes down, we can expect to see more studies like this one, says Jeffrey Joy, a post-doctoral researcher who studies animals' family trees at Simon Fraser University in Canada. He wasn't involved in today's research. At BGI, the Chinese organization that sequenced the original 48 genomes, 200 more bird genomes have been sequenced and are waiting to be analyzed, according to a report in Science.

"On balance, it's an amazing contribution," he said in an email. "The data the authors generated provides a crucial resource for studies."