Thursday, December 11, 2014
Sprouting feathers and lost teeth: scientists map the evolution of birds
A remarkable international effort to map out the avian tree of life has revealed how birds evolved after the mass extinction that wiped out the dinosaurs into more than 10,000 species alive today. More than 200 scientists in 20 countries joined forces to create the evolutionary tree, which reveals how birds gained their colourful feathers, lost their teeth, and learned to sing songs.
The project has thrown up extraordinary similarities between the brain circuits that allow humans to speak and those that give some birds song: a case of common biology being arrived at via different evolutionary routes. Some birds are shown to have unexpectedly close relationships, with falcons more closely related to parrots than eagles or vultures, and flamingoes more closely related to pigeons than pelicans. The map also suggests that the earliest common ancestor of land birds was an apex predator, which gave way to the prehistoric giant terror birds that once roamed the Americas.
“This has not been done for any other organism before,” Per Ericson, an evolutionary biologist at the Swedish Museum of Natural History in Stockholm, told the journal Science. “It’s mind-blowing.” The scientists began their task by analysing fingernail-sized pieces of frozen flesh taken from 45 bird species, including eagles, woodpeckers, ostriches and parakeets, gathered by museums around the world over the past 30 years. From the thawed-out tissue, they extracted and read the birds’ whole genomes. To these they added the genomes of three previously sequenced species. It took nine supercomputers the equivalent of 400 years of processor time to compare all the genomes and arrange them into a comprehensive family tree.
Members of the project, named the Avian Phylogenomics Consortium, published the family tree and their analysis on Thursday in eight main papers in the journal Science, and in more than 20 others in different scientific journals... Read more: