Energetics and genetics across the prokaryote-eukaryote divide

Area of Science:

• Evolutionary Biology
• Cell Biology
• Genomics

Background:

• Complex life is exclusively eukaryotic, originating from a single common ancestor.
• Prokaryotes, despite metabolic diversity, lack morphological complexity evolution.
• The eukaryotic cell likely arose from a singular endosymbiotic event between prokaryotes.

Purpose of the Study:

• To propose a novel hypothesis for the origin of the eukaryotic cell.
• To explain the unique evolutionary trajectory of eukaryotes compared to prokaryotes.
• To elucidate the driving forces behind eukaryotic complexity and the evolution of sex.

Main Methods:

• This study presents a theoretical framework based on existing evolutionary and cell biology principles.
• It synthesizes evidence from genomics, cell energetics, and evolutionary history.
• The approach involves analyzing the selective pressures and genetic consequences of endosymbiosis.

Main Results:

• Endosymbiosis led to reductive evolution of endosymbionts into mitochondria, enabling massive bioenergetic expansion.
• This energetic transformation removed prokaryotic genome size constraints, permitting significant host genome expansion.
• A high mutation rate, driven by gene/intron transfer from endosymbionts, facilitated genome duplication and the emergence of a proto-sexual cycle.

Conclusions:

• The combination of bioenergetic expansion, relaxed genome constraints, and high mutation rates drove eukaryotic evolution.
• These factors explain the unique origin of eukaryotes and the absence of transitional forms.
• The study posits that these conditions favored the evolution of sex in eukaryotes, unlike in prokaryotes.