Researchers from Harvard University and the University of Toronto have sequenced a near-complete genome from a little bush moa – a flightless bird endemic to New Zealand that went extinct after the island was first settled by humans in the 1200s.
The digitized DNA blueprint, extracted from a single toe bone, will enhance our understanding of how moas are related to other birds, what they were like in life, and how – and potentially why – moas evolved their wingless bodies from winged ancestors.
Reaching heights of 50 to 90 centimeters (1.6 to 3 feet), the forest-dwelling bush moa was sizable by our standards, yet was the littlest of the nine known species in the moa family. Back when male scientists traveled the globe, collecting specimens and sketching out animal family trees, it was simply assumed that the emu-shaped herbivores were related to emus, cassowaries, and other birds lacking wings. Thus, these creatures were lumped into a group called ratites and their skeletons were displayed together in museums worldwide.
But our assumed groupings were thrown into disarray when DNA sequencing technology burst onto the scene. A 2014 study (also by co-author Allan Baker) that examined part of the moa genome showed that the birds were actually more closely related to tinamous, a family of South American winged birds.
To better understand the newly mysterious moas, we needed more genetic information. And although a good few moa remains exist, it’s not as simple as grinding up a bone and separating out the nucleotides. DNA molecules have a 521-year half-life, meaning that more than half of the bonds between the base pairs are broken in even the most recently deceased specimens (about 700 years old).
Thankfully, obtaining large quantities of fragmented DNA is now possible, thanks to high-throughput sequencing (HTS) technology. Other researchers have used HTS to sequence near-complete versions of the Neanderthal, Denisovan, and woolly mammoth genomes.
In the current study, available online but not yet published in a peer-reviewed journal, the team used HTS to read 900 million base pairs of DNA in the toe bone. After referencing an emu genome, they were able to arrange the chaotic AGTC patterns into roughly an 85 percent complete map of the genome.
“The other 15 percent is in their data but is difficult to organize using the emu genome,” Ben J. Novak, a de-extinction scientist who helped sequence the passenger pigeon genome, said to Stat News. “The fact that they could get a genome from a little bush moa toe bone is a big deal, since now we might be able to use their data to do other extinct bird species.”
After analyzing the little bush moa’s reconstructed genes, the authors found new evidence in support of the recent hypothesis that wing loss among ratites actually occurred multiple times independently, rather than the flightless birds all evolving from one flightless ancestor.
Future investigations on ratite evolution will be able to use this valuable genomic data as a resource.
[H/T: Stat News]
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