The origin of eukaryotes: a reappraisal

Area of Science:

• Cell Biology
• Evolutionary Biology
• Genomics

Background:

• The origin of eukaryotic cells remains a central question in biology.
• Two main hypotheses exist: one emphasizing early cellular complexity and another focusing on prokaryotic endosymbiosis.
• The endosymbiotic theory explains the origin of mitochondria and plastids.

Approach:

• Re-examination of existing cell-biological data.
• Analysis of phylogenetic data to infer evolutionary relationships.
• Comparative genomics to understand gene transfer and cellular evolution.

Key Points:

• Eukaryotic cells possess unique features like endocytosis and intracellular digestion.
• The timing of these features relative to endosymbiosis is crucial.
• Phylogenetic and cell-biological evidence increasingly favors a model of early cellular evolution.

Conclusions:

• The hypothesis that eukaryotic cellular features, including endocytosis, preceded endosymbiosis is better supported by current data.
• This suggests a stepwise evolution of complexity in early eukaryotic cells.
• Further research integrating diverse data types will refine our understanding of eukaryotic cell origins.