Campus News

UGA scientists help sequence bird, crocodilian genomes

Using new computational methods developed by UGA researchers Liang Liu, Travis Glenn and others, an international team of scientists has shed light on an obscure period of avian evolution and further untangled the bird family tree.

Members of the Avian Phylogenomics Consortium, composed of 200 researchers from 80 institutions and 20 countries, have sequenced and analyzed the genomes of 48 species of birds and three species of crocodiles to better understand the fundamental evolutionary events that led to feathers, flight and song.

The consortium simultaneously published 28 papers-eight papers in a special issue of Science and 20 more in Genome Biology, GigaScience and other journals.

Glenn, an associate professor of environmental health science in the College of Public Health; Liu, an assistant professor in the statistics department and the Institute of Bioinformatics in the Franklin College of Arts and Sciences; and John Finger Jr., a doctoral student in the Interdisciplinary Toxicology Program and the College of Public Health, were co-authors on two of the eight papers published in Science.

The first of these two papers, “Whole genome analyses resolve the early branches to the tree of life of modern birds,” creates the most reliable tree of life for birds to date.

Statistical tools developed by Liu were used to analyze the genome-scale DNA sequences at the center of this new research. These new methods provide more robust results than traditional approaches.

Along with revealing the evolutionary relationships of major groups of birds, the team also showed that protein-coding DNA, long thought to be among the best regions to use for such research, actually is biased and thus indicates the wrong relationships. Ultraconserved elements, or UCEs, and introns-­nonprotein coding DNA strands-­produce much more reliable results.

In the second Science paper, “Three crocodilian genomes reveal ancestral patterns of evolution among archosaurs,” Glenn, Finger and colleagues also used UCEs to compare the rate of molecular evolution of all major groups of tetrapods, the superclass of four-limbed vertebrates that includes amphibians, reptiles, birds and mammals.

The team’s findings not only revealed that crocodilians evolved at remarkably slower rates compared to other tetrapods, but allowed the researchers to reconstruct the genome of the ­archosaurs, the early ancestors of birds, crocodiles and dinosaurs.