Eukaryogenesis From FECA to LECA: Radical Steps Along the Way

Area of Science:

• Evolutionary biology
• Genomics
• Cell biology

Background:

• The origin of eukaryotes (eukaryogenesis) remains a complex puzzle.
• The roles of the host (Asgard archaea) and endosymbiont (alphaproteobacteria) are under investigation.
• Understanding the Last Eukaryotic Common Ancestor (LECA) population is crucial.

Purpose of the Study:

• To elucidate the evolutionary trajectory leading to eukaryotes.
• To analyze the dynamic interplay between host and endosymbiont.
• To propose a model for early eukaryotic evolution.

Main Methods:

• Critical analysis of phylogenomic reconstruction presuppositions.
• Synthesis of recent evidence on endosymbiont arrival.
• Examination of pre-symbiotic conditions and genetic factors.

Main Results:

• Evidence supports the early integration of the proto-mitochondrion.
• Pre-symbiotic conditions, including ATP generation and ROS, were critical.
• Horizontal gene transfer (HGT) played a significant role in adaptation.

Conclusions:

• Eukaryotic evolution was driven by mutual adaptations between host and endosymbiont.
• Efficient energy production and genetic exchange were key.
• A revised perspective on eukaryogenesis emphasizes pre-symbiotic factors and HGT.