Open AccessThe expanding Asgard archaea and their elusive relationships with Eukarya
Author(s) -
Da Cunha Violette,
Gaïa Morgan,
Forterre Patrick
Publication year - 2022
Publication title -
mlife
Language(s) - English
Resource type - Journals
ISSN - 2770-100X
DOI - 10.1002/mlf2.12012
Subject(s) - archaea , evolutionary biology , ancestor , phylogenetic tree , biology , tree of life (biology) , genome , most recent common ancestor , three domain system , topology (electrical circuits) , computational biology , genetics , gene , geography , archaeology , mathematics , combinatorics
Abstract The discovery of Asgard archaea and the exploration of their diversity over the last 6 years have deeply impacted the scientific community working on eukaryogenesis, rejuvenating an intense debate on the topology of the universal tree of life (uTol). Here, we discuss how this debate is impacted by two recent publications that expand the number of Asgard lineages and eukaryotic signature proteins (ESPs). We discuss some of the main difficulties that can impair the phylogenetic reconstructions of the uTol and suggest that the debate about its topology is not settled. We notably hypothesize the existence of horizontal gene transfers between ancestral Asgards and proto‐eukaryotes that could result in the observed abnormal behaviors of some Asgard ESPs and universal marker proteins. This hypothesis is relevant regardless of the scenario considered regarding eukaryogenesis. It implies that the Asgards were already diversified before the last eukaryotic common ancestor and shared the same biotopes with proto‐eukaryotes. We suggest that some Asgards might be still living in symbiosis today with modern Eukarya.