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Updated: Nov 3, 2025

Using Phylogenetic Analysis to Investigate Eukaryotic Gene Origin

Using Phylogenetic Analysis to Investigate Eukaryotic Gene Origin

Published on: August 14, 2018

Dating Alphaproteobacteria evolution with eukaryotic fossils.

Sishuo Wang¹, Haiwei Luo^2,3,4

¹Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, SAR, Hong Kong.

Nature Communications

|June 4, 2021

Summary

Alphaproteobacteria originated ~1900 million years ago, with early Rickettsiales interacting with unicellular eukaryotes before animals emerged. This new dating method uses endosymbiosis for robust bacterial evolution timelines.

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Published on: September 20, 2016

Area of Science:

Microbiology
Evolutionary Biology
Genomics

Background:

Alphaproteobacteria are crucial microbial lineages in marine and terrestrial ecosystems.
Understanding their evolutionary timescale is vital for co-evolutionary studies with eukaryotes and Earth systems.
The scarcity of bacterial fossils limits traditional dating methods.

Observation:

Mitochondria, which evolved from an alphaproteobacterial lineage, were used as a calibration point for divergence times.
Alphaproteobacteria are estimated to have originated approximately 1900 million years ago.
Major clades of Alphaproteobacteria diverged rapidly after their origin.

Findings:

The Rickettsiales order, comprising obligate intracellular bacteria with animal hosts, predates animal emergence by ~700 million years.
The origin of Rickettsiales coincides with the emergence of eukaryotes, suggesting early interactions with unicellular eukaryotes.
The mitochondria-based dating approach is more robust to calibration uncertainties than methods using cyanobacterial fossils.

Implications:

This study suggests a novel approach for dating the bacterial tree of life using endosymbiotic events.
Early Rickettsiales likely engaged in significant interactions with early eukaryotic hosts.
Revisiting previous bacterial evolution dating methods that rely on modern host divergence times is recommended.