Unveiling the avian tree of life

The finding that birds flourished after the dinosaurs disappeared from the earth is just one outcome of a massive project on sequencing the genomes of birds.

For the past four years, an international consortium of 200 researchers has been working on sequencing the genomes of 48 different birds. This has resulted in the creation of what is the most reliable avian tree of life to date.

The consortium - who call themselves the Avian Phylogenomics Group - analysed at least one genome from every major bird lineage to generate a dataset representing a wide range of avian evolutionary diversity.

Taken together, the results reveal how some of the earliest branches on the avian family tree diverged, helping to answer some long-standing questions about the common ancestor of birds, crocodilians and dinosaurs.

The findings support that birds rapidly evolved during the 10 to 15 million years following the mass extinction that included the dinosaurs 66 million years ago, giving rise to the 10,500 bird species known today.

The studies also shed new light on the evolution of avian sex chromosomes, new candidate genes associated with vocal learning as well as skeletal development to be light and aerodynamic, evolutionary processes that led to birds losing their teeth and the rapid evolution of 15 pigmentation genes associated with plumage for mating display.

Instead of studying a few genes at a time, trying to infer species’ relationships over the past 100 million years or so - as many previous studies have done - this project examined whole genomes to get a clearer picture of avian evolution.

One publication highlights recent progress in tracing the origin of birds from theropod dinosaurs, focusing especially on recent fossil finds of feathered dinosaurs of northeastern China. Current research on developmental biology and functional anatomy is integrated with the paleontological record to show how key features of birds, such as feathers, wings and flight, originated and evolved, radiating from their dinosaur forebears.

The Avian Phylogenomics Group arose out of the Genome 10K Project, founded in 2009 to unveil animal diversity through genomics.

Findings from this research have been announced in several scientific publications, including Science magazine, Genome Biology and GIGA Science.

Image credit: ©stockvault/Tony Ryta