The biggest project of genetic study of birds, called Avian Phylogenomics Consortium, has started giving results. 29 articles have been published of which 8 on a special issue of the journal “Science” and the other 21 in “Genome Biology”, “GigaScience” and other magazines. This project engaged for four years over two hundred scientists in many institutes of twenty nations that digged deep as never before with the study of the evolution of birds showing how there was a sort of Big Bang after the extinction of the dinosaurs.
The scientists of the Avian Phylogenomics Consortium completely mapped the DNA of 45 species of birds representing all groups of birds. To make further genetic comparisons, they mapped the DNA of representatives of the three groups of crocodiles. This may sound strange but it totally makes sense when you consider the fact that birds and crocodiles are related, the last survivors among the descendants of archosaurs, a group of reptiles which evolved during the Triassic, about 245 million years ago. They dominated the Mesozoic, especially with dinosaurs, but after the great extinction at the end of that geological era only birds and crocodiles remained.
The crocodiles of which DNA was sequenced belonged to the species: American alligator, saltwater crocodile and Indian gharial. The information obtained through these new mapping were added to those already available from previous sequencing of the DNA of other species of birds: zebra finch and domestic turkey and chicken.
We can’t have the DNA of the birds’ dinosaur ancestors nor of the first species of birds but the complete sequencing of the DNA of today’s species makes it possible to get an idea of their evolution and the relationships among different species. Previous studies were based on the analysis of some genes but that provided unsatisfactory results because they were too limited. Today, genetic technologies allowed a study much more complete that will be useful for subsequent research.
According to the new study, the evolution of birds accelerated considerably after the extinction of the dinosaurs. Archaeopteryx is the most famous primitive bird but the discoveries of other fossils revealed that many of its features had evolved in dinosaurs much earlier.
After the great extinction of the dinosaurs, the birds survived started evolving more rapidly to form the existing groups. Their DNA contains about 14,000 genes for each species and to compare them they developed new computer programs that would help the analyzes. In some cases, supercomputers were used because certain analyzes required a lot of resources and a lot of processing power.
This project has already provided interesting results with the published articles but it’s just the beginning. The Avian Phylogenomics Consortium is creating a genetic database that will include additional genetic samples. It will be made public to allow scientists to use its information for other studies. There are still many questions regarding the characteristics of the birds and their evolution but with this project we can expect new answers in the coming years.
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