Study reveals diverse microbial gene sources in early eukaryotic evolution beyond previously identified partners
Researchers analyzing the last eukaryotic common ancestor (LECA) found evidence that eukaryotes acquired genes from multiple bacterial sources beyond the two previously established partners—alphaproteobacteria and Asgard archaea. The study used advanced phylogenetic methods on curated, high-quality proteomes from across the eukaryotic tree of life to minimize reconstruction artifacts. These findings suggest the origin of eukaryotes involved more complex microbial interactions than the current consensus model indicates.
A new analysis of protein families in the last eukaryotic common ancestor identifies at least two major signals of bacterial ancestry distinct from alphaproteobacteria, as well as gene acquisitions apparently mediated by Nucleocytoviricota viruses. The research addresses a longstanding puzzle in evolutionary biology: while the dominant model of eukaryogenesis involves an endosymbiotic relationship between an alphaproteobacterial endosymbiont and an Asgard archaeal host, the reconstructed LECA proteome shows a large dominance of bacterial over archaeal contributions, with only a fraction of bacterial proteins traceable to alphaproteobacteria. To resolve this discrepancy, researchers used state-of-the-art phylogenetic methodologies and compiled carefully curated datasets of representative proteomes, removing low-quality sequences, recent paralogues, and sparsely distributed proteins to minimize artifacts from unsampled lineages and horizontal gene transfer. The findings suggest that eukaryogenesis involved serial interactions with various non-alphaproteobacterial symbionts acting as gene donors, complicating the current consensus model of eukaryotic origins.
Limitations & open questions
The study's own limitations and open questions are not detailed in the excerpt provided. The article does not explicitly state what fraction of LECA proteins remain unassigned to identified sources, nor does it discuss the confidence intervals or statistical support levels for the newly identified bacterial ancestry signals compared to the established partners.
What different sources said
- Nature NewsCenter
Gene ancestries reveal diverse microbial associations during eukaryogenesis
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