From The Origin of Species to the origin of bacterial flagella

@article{Pallen2006FromTO,
  title={From The Origin of Species to the origin of bacterial flagella},
  author={Mark J. Pallen and Nicholas J. Matzke},
  journal={Nature Reviews Microbiology},
  year={2006},
  volume={4},
  pages={784-790}
}
In the recent Dover trial, and elsewhere, the 'Intelligent Design' movement has championed the bacterial flagellum as an irreducibly complex system that, it is claimed, could not have evolved through natural selection. Here we explore the arguments in favour of viewing bacterial flagella as evolved, rather than designed, entities. We dismiss the need for any great conceptual leaps in creating a model of flagellar evolution and speculate as to how an experimental programme focused on this topic… 
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Proponents of the intelligent design (ID) explanation for how organisms developed claim that the bacterial flagellum (BF) is irreducibly complex. They argue that this structure is so complicated that
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References

SHOWING 1-10 OF 87 REFERENCES
Prokaryotic motility structures.
TLDR
Research on the bacterial flagellum has greatly aided the authors' understanding of not only motility but also protein secretion and genetic regulation systems, and continued study and understanding of all prokaryotic motility structures will provide a wealth of knowledge that is sure to extend beyond the bounds of proKaryotic movement.
Spirochete periplasmic flagella and motility.
TLDR
To better understand spirochete motility on a more molecular level, the proteins and genes involved in motility are being analyzed and unique aspects have already become evident.
Flagellar glycosylation - a new component of the motility repertoire?
TLDR
This review focuses on the structural diversity in flagellar glycosylation systems and demonstrates that as a consequence of the unique assembly processes, the type of glycosidic linkage found on archaeal and bacterialflagellins is distinctive.
Characterization of the fliL gene in the flagellar regulon of Escherichia coli and Salmonella typhimurium
TLDR
FliL does not appear to have a major role in flagellar structure or function and is therefore unlikely to be a component of the motor or switch; the effect on motility caused by truncation of the gene is probably an indirect one.
Diversity in Chemotaxis Mechanisms among the Bacteria and Archaea
TLDR
The Bacillus subtilis chemotaxis system is considerably more complex and appears to be similar to the one that existed when the bacteria and archaea separated during evolution, so that understanding this mechanism should provide insight into the variety of mechanisms used today by the broad sweep of chemotactic bacteria and Archaea.
Regulation of flagella.
...
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