CAREER: Elucidating early origins and evolution of Asgard archaea in geothermal environments

About This Grant

Asgard archaea are a group of microbes that hold keys to understanding the diversification of life on Earth, including the origin of eukaryotes. They likely originated in thermal environments such as deep-sea hydrothermal vents or terrestrial hot springs. There is limited documentation of diversity and ecology of Asgard archaea from hot springs in particular. This project will collect samples of microbes from understudied hot springs in the western U.S. and analyze their genomes. New species of Asgard archaea will be identified and characterized. Data from hot spring samples will be compared with those from other habitats to answer questions of origins. Researchers will also study the evolutionary history of eukaryotic signature genes in archaea. This project will train a postdoctoral researcher, graduate and undergraduate students, and high school interns from local schools. A new undergraduate course will provide students with hands-on research experience in microbial ecology and evolution. YouTube videos of the field and laboratory research will be developed as part of outreach to the broader public on diversity of Asgard archaea. This project will collect hot spring sediment samples from the western U.S. to recover and identify novel Asgard archaeal lineages. A combination of amplicon, metagenomic, and metatranscriptomic sequencing will be performed from DNA and RNA extracted from these samples. Amplicon sequencing will be done using archaeal primers that capture most of Asgard archaeal diversity. Near full-length sequencing of amplicons will result in phylogenetically useful information enabling assessment of diversity and abundance in the hot springs. Metagenomic sequencing using both short and long reads of the most abundant archaeal samples will enable reconstruction of near-complete genomes. Metatranscriptomic sequencing will reveal novel lineages that may have been missed due to PCR bias. Phylogenomic and ancestral state reconstructions with the improved representation of lineages from hot spring habitats will shed light on the origins of Asgard archaea in terrestrial or marine geothermal features. Phylogenetic analysis of the eukaryotic signature proteins found in these archaea will also reveal where the genes encoding these proteins first appeared during geologic time. This research will advance our knowledge of diversity and deep evolutionary relationships of Asgard archaea. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.