Within the archaeal domain, there is a group of tiny hitchhikers. These organisms are abundant and yet exceptionally small, with mini genomes to match. As a result, they cannot process all of the chemicals they need to survive. To fill in their nutrient gaps, they must latch onto a larger host — often, a fellow archaeal microbe. Understanding how these hosts and hitchhikers coexist is key for understanding their impact on wider ecosystems, but these symbiotic interactions are difficult to study in the lab.
Metagenomics provides new views of these relationships. Recently, researchers used population genomics to find that while archaeal hitchhikers may often act as parasites, in other cases, they likely help their hosts. Learn more here on the JGI website.