The new archaeal order Lutiacidiplasmatales reveals convergent evolution in Thermoplasmatota

Abstract

The archaeal Terrestrial Miscellaneous Euryarchaeota Group (TMEG) has been identified in various environments, and the single genome investigated thus far suggests that these organisms are anaerobic sulfite reducers. We assembled 35 new TMEG genomes that, based on genome analysis, appear to possess aerobic and facultative anaerobic lifestyles and may oxidise rather than reduce sulfite. We propose naming this order (representing 16 genera) "Lutiacidiplasmatales" due to their occurrence in various acidic environments and placement within the phylum Thermoplasmatota. A phylum-level analysis revealed that Thermoplasmatota evolution had been punctuated by several periods of high levels of novel gene family acquisition. Several essential metabolisms, such as aerobic respiration and acid tolerance, were likely acquired independently by divergent lineages through convergent evolution rather than inherited from a common ancestor. Ultimately, this study describes the terrestrially prevalent Lutiacidiciplasmatales and indicates convergent evolution as an important evolutionary driving force in archaeal lineages with complex histories.