A newly mapped section of the tree of life showcases the genomes of more than 50 microbial species. Researchers say the comprehensive catalogue of genomes–just the first chapter in a larger project–will help them find new genes and predict their functions. The research was published today in the journal Nature.

The planet houses an estimated nonillion–10³⁰–prokaryotic microbes, organisms that lack a cell nucleus. According to a press release from the University of California, Davis, only about a thousand of these have been sequenced to date, mostly those that cause disease or have potential industrial applications, such as producing biofuels.

“That’s like making a map of the world and only mapping three cities,” said Jonathan Eisen, a microbiologist at the UC Davis Genome Center and the U.S. Department of Energy Joint Genome Institute, in the statement. According to the release:

The new study, called the Genomic Encyclopedia of Bacteria and Archaea or GEBA, looks instead at representatives from across the major branches of the family tree of microorganisms.

The study shows that although microbes are known to swap genes with other species (a process called “lateral transfer,”) phylogeny, or position on the family tree, is more important in determining where new genes appear and how they spread.

“Lateral transfer does not shuffle evolutionary innovations in a massive way,” Eisen said. “If there is an innovation in a branch, you tend to find it in the same branch downstream.”