Classifying birds by plumage and other anatomical features served scientists well over the centuries, but genetic analyses have opened up a world of detail about avian family ties. An international group of researchers recently developed a tree based on the full genomes of 48 species, representing every major bird lineage—the most thorough genetic study of a large branch on the tree of life to date. The massive effort, with more than 200 collaborators, includes investigations of the emergence and disappearance of teeth, the origin of vocal learning, and the timing of the explosion of bird diversity.
The new tree confirms many past observations, such as the common ancestor of the core landbirds. It also resolves some controversial links. Who might have guessed, for instance, that pigeons and flamingos are close cousins?
Credit: Jen Christiansen; Sources: “Whole-genome analyses resolve early branches in the tree of life of modern birds,” by Erich D. Jarvis et al., in Science, Vol. 346; December 12, 2014 (left tree); “Higher-order phylogeny of modern birds (Theropoda, Aves: Neornithes) based on comparative anatomy,” Part II: “Analysis and discussion,” by Bradley C. Livezey and Richard L. Zusi, in Zoological Journal of the Linnean Society, Vol. 149, No. 1; January 2007 (right tree)
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More classification notes:
In addition to 48 bird genomes, the researchers sequenced three crocodilian genomes to pinpoint early descendent relationships.
The separation of penguins, pelicans and ibis from flamingos and grebes (and pigeons) implies that the waterbird trait evolved independently multiple times.
Because of how quickly both land birds and waterbirds evolved, the data suggests that the original ancestors might have been birds that lived along the coastline.
Chickens share the most DNA with the first bird ancestor, closely followed by hoatzin and emu.