Sociality and cheating in bacteria

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Sociality and cheating in bacteria. Lecture 13, Myxobacteria. Evolution of social and coordinated group behavior in bacteria. Swarming motility Quorum sensing Coordinated cell death Sporulation and fruiting body formation Synergistic niche subdivision Production of “ social goods ” etc. - PowerPoint PPT Presentation

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  • Sociality and cheating in bacteriaLecture 13, Myxobacteria

  • Evolution of social and coordinated group behavior in bacteriaSwarming motilityQuorum sensingCoordinated cell deathSporulation and fruiting body formationSynergistic niche subdivisionProduction of social goodsetc

  • All for the benefit of the group, right?Why broadcast a signal for others to profit from your discovery?Why allow foreigners to listen in on your conversation?How would such behavior evolve?

  • Individual selection favoring functions that coordinate groupsInability to produce a beneficial phenotype in small numbersNumbers of neighbors producing a signal may not matter as much as their densityCommon response by several traits to high density or numbers, so selection favors their coordination (and not vice versa)

  • Quorum sensing

  • Modes of communication

  • Evolution of cooperation +/or selfish behaviorSystem: Myxococcus xanthus

    Primary Investigator: Greg Velicer

  • Myxococcus xanthushttp://cmgm.stanford.edu/~kaiserla/about_myxo/about_myxococcus.html Adventurous motility Social motility Gliding motility Development of spores

  • Motility can be A = adventurous or S = socialA motility = dependent upon gliding and slime extrusionS motility = dependent upon type IV pili

  • First experimental evo of Myxo12 populations, 6 RifR, shaking flasks, CTT (rich) media.Inhibits social contact; mass-action

  • But the selfish asocial evolved lineages cheat

  • Cooperation can evolve along multiple pathways

  • Cooperation re-evolves using a new systemcglB = A motility gene

    dsp = fibril producing gene

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