In a first breakthrough of its kind, scientists have been able to successfully create an evolutionary tree for birds based on their genomes – and they accomplished this feat with the genes of 48 bird species in order to establish how related they are to one another. The researchers were able to get this done through a data crunching analysis technology that necessitated the use of huge computer power and new algorithms since the whole spectrum of the genomes of tens of birds needed to be mapped and then sequenced.
According to Erich Jarvis of the Howard Hughes Medical Institute and Duke University Medical Center, “It contradicts morphology-based trees. It contradicts mitochondrial trees. It supports more trees based upon nuclear genes, although those trees weren’t highly resolved and this one is.”
In a more detailed analysis that reviewed the research and aspects of its genomic relevance, Jarvis explained at a meeting of Science Writers in Columbus, Ohio, that “We decided we wanted to make a big effort to focus on birds, because each of us had some aspects that we liked about bird biology. But something was practical about that as well. Bird genomes, in terms of genome size, compared to other vertebrate groups like reptiles, amphibians, mammals, they’re on average smaller than other vertebrates. And this allows one to sequence their genomes easier, and also assemble them easier. The reason why: it’s thought that they have less repetitive genome in their genome, but yet a similar complement of genes encoding for proteins…so you can learn a lot about vertebrate biology more easily studying birds than you can in other groups where there’s a lot of this repetitive so-called junk DNA.”
Jarvis was able to list out the discoveries made with the new bird tree as well as variations observed among birds that have the ability for vocal learning and even those that adapt to water and land.
“We can infer at least two independent gains of vocal learning…we’re also supporting two independent gains of water adaptions…and two independent origins of the predatory trait, suggesting that amongst this higher land-bird group that includes songbirds, parrots, hawks, eagles, falcons and so on, a top apex predator was the common ancestor of the higher land birds that most of you know about, including vocal learners.
Jarvis was not done yet, he wanted to give insights into how the genomes of these birds must have evolved since the Cretaceous period some 80 million years ago.
“What’s also different compared to a number of trees that have been dated with fossils, with the whole genome scale dating we are arguing that avian diversity of 95 percent of the species did not occur 80 to 100 million years ago in the Cretaceous Period, but occurred right around the time of the extinction of the dinosaurs [what we call the meteor impact in the Yucatan peninsula], which was an alternative theory…right after that extinction event, we get all orders of birds diverge within 50 million years. And then from there on everybody else speciates.”
Published in the journal Science, this study opens a whole new debate about the genomic spectrum of bird species that was never known or fully understood before.