For the past four years, around 200 researchers from 20 countries have combined their expertise to work toward a single massive undertaking: creating the most comprehensive bird family tree ever made. Today, they released the results of that project—comprising eight separate reports—in the journal Science. (About 20 more papers spun off from the research are due to be published in other journals.) Among the findings are insight into bird evolutionary history, surprising relationships between species, and answers about why birds do not have teeth.
The avian tree of life, as it's called, was built from the genomes of 48 bird species representing all major bird lineages. Almost all of the species in the study had never had their genomes sequenced before. All told, the team scrutinized 14,000 genetic regions representing both coding and non-coding sections of DNA. Crunching those data required the combined computing power of nine supercomputers, and the researchers had to develop new statistical methods to handle all the variation found within the genomes. (The scale of this endeavor is one explanation for why an analysis on so massive a scale has never been attempted before, for any animal group.)
According to the researchers' results, most land birds—from goofy parrots to diminutive hummingbirds—trace their heritage back to a carnivore at the very top of the food chain that lived millions of years ago. Birds really had their moment around 65 million years ago, however, when, following the dinosaurs' extinction by about 10 million years, they underwent a "big bang" evolutionary event, giving rise to hundreds of new species from just a few founder lineages. Researchers previously put this event at about 80 million years ago, but now they know it happened more recently than that.
The research also led to some unusual insights, such as the fact that flamingos are closer relatives to pigeons than they are to pelicans and that falcons have more evolutionary affinity with songbirds than they do with eagles or vultures, writes the University of Illionois at Urbana-Champaign. The scientists also found that common bird traits like webbed feet and singing evolved multiple times, in separate events not related to one another. Likewise, water birds evolved independently three different times, Duke University reports. On the other hand, some parts of birds' genomes are shared between all species and date back more than 100 million years—about the same time birds' relatives lost their teeth due to genetic mutations.
All of the data generated from the project are being made publicly available, and the researchers say they hope this effort inspires other similar undertakings. "Only with this scale of sampling can scientists truly begin to fully explore the genomic diversity within a full vertebrate class," Tom Gilbert, a researcher at the Natural History Museum of Denmark and one of the paper authors, told Duke University.