Ornithologists Publish Most Comprehensive Avian Tree of Life

The most comprehensive and accurate avian tree of life has been published in the current issue of the journal Nature.

Phylogeny of birds. The five major, successive, neoavian sister clades are: Strisores (brown), Columbaves (purple), Gruiformes (yellow), Aequorlitornithes (blue), and Inopinaves (green). Background colors mark geological periods. Ma - million years ago; Ple - Pleistocene; Pli - Pliocene; Q. - Quaternary. Clade numbers refer to the plot of estimated divergence dates. Illustrations of representative bird species are depicted by their lineages. Figure continues below from the green arrow at the bottom of the top panel. Image credit: Richard O. Prum et al., doi: 10.1038/nature15697.

Phylogeny of birds. The five major, successive, neoavian sister clades are: Strisores (brown), Columbaves (purple), Gruiformes (yellow), Aequorlitornithes (blue), and Inopinaves (green). Background colors mark geological periods. Ma – million years ago; Ple – Pleistocene; Pli – Pliocene; Q. – Quaternary. Clade numbers refer to the plot of estimated divergence dates. Illustrations of representative bird species are depicted by their lineages. Figure continues below from the green arrow at the bottom of the top panel. Image credit: Richard O. Prum et al., doi: 10.1038/nature15697.

“Cardinals and woodpeckers evolved from a hawk-like ancestor and most of the world’s water birds also appear to be a close-knit group, indicating one bird group quickly adapted to aquatic environments after most of the dinosaurs died out at the end of the Cretaceous period.”

These are among hundreds of other stories that make up the history of birds revealed in a genomic analysis of almost 200 species by a team of scientists from Yale University, Florida State University, North Carolina Museum of Natural Sciences and Cornell University.

According to the scientists, all modern birds evolved from the only three dinosaur lineages.

“This represents the beginning of the end of avian phylogeny. In the next five or 10 years, we will have finished the tree of life for birds,” said lead author Prof. Richard Prum, of Yale University.

In the last ten years, the historical origins of ostriches and their relatives, the emus, have been well established, as it has for ducks, chickens and their relatives.

But the evolutionary history of 90 percent of contemporary birds in a group called Neoaves has remained unclear.

Phylogeny of birds. The five major, successive, neoavian sister clades are: Strisores (brown), Columbaves (purple), Gruiformes (yellow), Aequorlitornithes (blue), and Inopinaves (green). Background colors mark geological periods. Ma - million years ago; Ple - Pleistocene; Pli - Pliocene; Q. - Quaternary. Clade numbers refer to the plot of estimated divergence dates. Illustrations of representative bird species are depicted by their lineages. Image credit: Richard O. Prum et al., doi: 10.1038/nature15697.

Phylogeny of birds. The five major, successive, neoavian sister clades are: Strisores (brown), Columbaves (purple), Gruiformes (yellow), Aequorlitornithes (blue), and Inopinaves (green). Background colors mark geological periods. Ma – million years ago; Ple – Pleistocene; Pli – Pliocene; Q. – Quaternary. Clade numbers refer to the plot of estimated divergence dates. Illustrations of representative bird species are depicted by their lineages. Image credit: Richard O. Prum et al., doi: 10.1038/nature15697.

The early ancestors of thousands of these species appeared to have evolved suddenly within a few million years after the extinction the non-avian dinosaurs.

The research also reveals fascinating relationships among the living birds within the group.

For instance, other than the ducks and the cranes, most of the world’s water birds are closely related – suggesting they radiated out across the planet in aquatic niches following the extinction of dinosaurs and did not, as previously thought, evolve from multiple independent lineages.

“The highly visual hummingbirds apparently evolved from nocturnal species of bird,” Prof. Prum explained.

“The ancient common ancestor of the cardinal and woodpecker in your garden was a vicious, hawk-like predator.”

The results also indicate that Opisthocomus is the most ancient bird lineage (64 million year old) consisting of only a single, extant species – the enigmatic hoatzin (Opisthocomus hoazin).

The completion of the avian tree of life will allow ornithologists to definitively investigate many outstanding questions in the evolutionary history of birds.

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Richard O. Prum et al. A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing. Nature, published online October 7, 2015; doi: 10.1038/nature15697

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