Reassessment of the Lineage Fusion Hypothesis for the Origin of Double Membrane Bacteria
Author(s)Swithers, Kristen S.; Fournier, Gregory P.; Green, Anna G.; Gogarten, J. Peter; Lapierre, Pascal
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In 2009, James Lake introduced a new hypothesis in which reticulate phylogeny reconstruction is used to elucidate the origin of Gram-negative bacteria (Nature 460: 967–971). The presented data supported the Gram-negative bacteria originating from an ancient endosymbiosis between the Actinobacteria and Clostridia. His conclusion was based on a presence-absence analysis of protein families that divided all prokaryotes into five groups: Actinobacteria, Double Membrane bacteria (DM), Clostridia, Archaea and Bacilli. Of these five groups, the DM are by far the largest and most diverse group compared to the other groupings. While the fusion hypothesis for the origin of double membrane bacteria is enticing, we show that the signal supporting an ancient symbiosis is lost when the DM group is broken down into smaller subgroups. We conclude that the signal detected in James Lake's analysis in part results from a systematic artifact due to group size and diversity combined with low levels of horizontal gene transfer.
DepartmentMassachusetts Institute of Technology. Department of Biological Engineering; Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Public Library of Science
Swithers, Kristen S. et al. “Reassessment of the Lineage Fusion Hypothesis for the Origin of Double Membrane Bacteria.” Ed. Jonathan H. Badger. PLoS ONE 6 (8) (2011): e23774. © 2011 Swithers et al.
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