Deep mitochondrial origin outside the sampled alphaproteobacteria.
Level 5 - mechanism / opinion, no new human data
By design analogy, Level 5 (computational phylogenomic and metagenomic analysis; non-clinical basic science)
PubMed 29695865 · doi:10.1038/s41586-018-0059-5
What was done
Researchers expanded genomic sampling of Alphaproteobacteria by binning oceanic metagenome datasets, identifying 12 divergent clades and one sister clade to all Alphaproteobacteria. They conducted phylogenomic analyses structured to control for compositional bias and long-branch attraction artefacts to reassess the evolutionary origin and phylogenetic position of mitochondria.
What was found
The abstract reports no numerical or quantitative metrics. The analyses indicated that mitochondria did not evolve from Rickettsiales or any other sampled alphaproteobacterial lineage, but instead originated from a proteobacterial lineage that branched off prior to the divergence of all currently sampled alphaproteobacteria.
Why it matters
These findings challenge the prevailing paradigm that mitochondria arose directly from an ancestor within the Rickettsiales, requiring a reassessment of hypotheses regarding the metabolic and physiological nature of the mitochondrial ancestor.
Limits
The abstract provides no quantitative support metrics (such as bootstrap values, posterior probabilities, or exact numbers of genomes and metagenomic samples analyzed). Findings remain subject to the limitations of deep-time phylogenetic inference, incomplete environmental taxon sampling, and potential model-misspecification biases.
Cited by
- supports Cellular mitochondria originated as bacterial endosymbionts that integrated into eukaryotic cells and retain their own genome.