Understanding how complex eukaryotic cells emerged from prokaryotic ancestors represents a major challenge in biology. A main point of contention in refining eukaryogenesis scenarios revolves around the exact relationship between Archaea and eukaryotes. In new research, scientists from the University of Texas at Austin and elsewhere generated 63 new Asgard archaea genomes from samples obtained from 11 locations around the world. By analyzing the enlarged genomic sampling of Asgard archaea using state-of-the-art analyses, they firmly place eukaryotes as a clade nested within the Asgard archaea, similar to how birds are one of several groups within a larger group called dinosaurs, sharing a common ancestor. By revealing key features regarding the identity, nature and physiology of the last Asgard archaea and eukaryotes common ancestor, their results represent important, thus far missing pieces of the eukaryogenesis puzzle.
“No fossils of eukaryotes have been found from farther back than about 2 billion years ago, suggesting that before that, only various types of microbes existed,” said co-senior author Dr. Brett Baker, a researcher in the Department of Integrative Biology at the University of Texas at Austin.
“So, what events led microbes to evolve into eukaryotes? That’s a big question. Having this common ancestor is a big step in understanding that.”
In their study, Dr. Baker and colleagues identified the closest microbial relative to all complex life forms on the tree of life as a newly described order called the Hodarchaeales.
Hodarchaeales, found in marine sediments, are one of several subgroups within the larger group of Asgard archaea.
The Asgard archaea evolved more than 2 billion years ago, and their descendants are still living.
Some have been discovered in deep sea sediments and hot springs around the world, but so far only two strains have been successfully grown in the lab.
To identify them, the researchers collect their genetic…
Read the full article here