Out of Australia
UF researchers help map the movement of the world’s perching birds
Perching birds, which include songbirds, make up the majority of the world’s bird species. These birds — also known by their order name, passerines — comprise more than 6,000 species, including familiar birds like cardinals, warblers, jays and sparrows. Passerines embody more than 60 percent of all feathered friends known to humankind. While much is known about their birdsong, mating rituals, and anatomy, the origin of passerines, which determines how different species developed and their relationship to one another, has never been fully explained or understood.
Previous hypotheses about passerine evolution and diversification purported that perching birds originated from South America. Now a clearer picture of an Old World origin and patterns of movement that were influenced by global climate change, mass extinction or the colonization of new continents has come into focus. This research is published today in the Proceedings of the National Academy of Sciences.
UF professors of biology Edward Braun and Rebecca Kimball were part of a large team led by researchers at Louisiana State University that proved all passerines originated in Australia. That sweet Carolina wren at your feeder actually has a long-lost daddy, 47 million years ago or so, in the land Down Under.
Braun, Kimball, and their collaborators conducted genomic testing using technology that did not exist 10 years ago. They analyzed DNA data from the 137 families of perching birds. Kimball says that working together in a large research group is especially advantageous because each member provided an essential piece to this complex study that used museum samples, some as old as 100 years.
“Previous studies only looked at one or a few genes,” said Braun. “What makes this study unique is one, the broad sampling across the genome, and two, the comprehensive nature in that we captured all major groups of perching birds. The third factor is the integration of the fossil records and biogeography, along with the comprehensive genomic sampling.”
Using this genomic data, as well as knowledge of the Earth’s shifting history when continents were closer to each other, the team discovered that this history was the primary factor in the evolution of passerines. “A lot of people thought that factors that drove movement were radiation, expansion of numbers, things linked to climate change,” said Kimball. “We’ve shown that is less likely.”
“The evolutionary history of perching birds — when they moved, when they diversified was very much shaped by Earth’s history,” said Braun. “They were passengers on parts of the planet. It was the history of the planet that determined when and where they moved.”
“This study showcases the critical importance of museum collections in explaining the living world,” said David Cannatella, a program director at the National Science Foundation, which funded this research. “By integrating modern, cutting-edge analysis of bird specimens with the legacy of natural history, the authors have uncovered valuable insights into how Earth history has influenced species diversity and what it means for the future of life on Earth.”
Sequencing from these passerine genomes is the first paper that will contribute to the Open Wings, a project funded by the National Science Foundation that aims to understand the evolutionary history of all 10,560 named species of birds. Braun and Kimball are both principals on this project. “With Open Wings, our plan is to build on this. Hopefully, we will manage to have this tree to leap out to include all species of birds. That’s a potential for the future,” said Braun. “We need to know the broad brushstrokes before we focus in on every single group.”
Additional Links:
Earth history and the passerine superradiation, PNAS: http://www.pnas.org/cgi/doi/10.1073/pnas.1813206116
OpenWings: http://www.openwings.org/