On the origin of mitosing cells: A historical appraisal of Lynn Margulis endosymbiotic theory

摘要

Highlights ? Margulis’ scheme on eukaryogenesis by endosymbiosis was not a mere revival of old ideas. ? Her coherent evolutionary narrative provided testable hypotheses and specific predictions. ? Genome analyses strengthen the role of endosymbiosis in eukaryogenesis. ? The role of symbiosis in evolutionary innovation expands the Darwinian foundations. ? Margulis endosymbiotic scenario stands as a lasting scientific contribution. Abstract Although for a long-time symbiosis was considered to be quite rare and with no role in evolutionary processes, Lynn Margulis demonstrated that endosymbiotic events played a key role in the origin and evolution of eukaryotic cells. Starting with her seminal assay in the Journal of Theoretical Biology in 1967 (authored as Lynn Sagan), her lifelong work on eukaryogenesis and the role of symbiosis in evolution stands as a valid and authoritative contribution to science. As was quick to acknowledge, she was not the first to discuss the significance of symbiosis to explain the origin of mitochondria and chloroplasts, but no one else had done it to her extent and depth, nor had anyone provided a variety of testable hypotheses. While it is true that some of her proposals were incomplete or mistaken, morphological, biochemical and geochemical evidence together with phylogenomic analyses of mitochondria, chloroplasts and eukaryotic nuclear genomes have demonstrated the validity of her evolutionary scheme, as well that of her specific predictions on the chimeric nature of genomes and the mosaicism of metabolic pathways in eukaryotic cells.