title: Social Evolution Selects for Redundancy in Bacterial Quorum Sensing.
abstract: Quorum sensing is a process of chemical communication that bacteria use to monitor cell density and coordinate cooperative behaviors. Quorum sensing relies on extracellular signal molecules and cognate receptor pairs. While a single quorum-sensing system is sufficient to probe cell density, bacteria frequently use multiple quorum-sensing systems to regulate the same cooperative behaviors. The potential benefits of these redundant network structures are not clear. Here, we combine modeling and experimental analyses of the Bacillus subtilis and Vibrio harveyi quorum-sensing networks to show that accumulation of multiple quorum-sensing systems may be driven by a facultative cheating mechanism. We demonstrate that a strain that has acquired an additional quorum-sensing system can exploit its ancestor that possesses one fewer system, but nonetheless, resume full cooperation with its kin when it is fixed in the population. We identify the molecular network design criteria required for this advantage. Our results suggest that increased complexity in bacterial social signaling circuits can evolve without providing an adaptive advantage in a clonal population.
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Eran
authors.initials: E
authors.lastname: Even-Tov
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Shira Omer
authors.initials: SO
authors.lastname: Bendori
authors.affiliation: Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America.
authors.forename: Julie
authors.initials: J
authors.lastname: Valastyan
authors.affiliation: Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Ke
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Shaul
authors.initials: S
authors.lastname: Pollak
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Tasneem
authors.initials: T
authors.lastname: Bareia
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Ishay
authors.initials: I
authors.lastname: Ben-Zion
authors.affiliation: Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America.|Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America.
authors.forename: Bonnie L
authors.initials: BL
authors.lastname: Bassler
authors.affiliation: Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Avigdor
authors.initials: A
authors.lastname: Eldar
mesh_terms: D001412:Bacillus subtilis / Q000502:physiology*; D005075:Biological Evolution; D008957:Models, Genetic; D053038:Quorum Sensing; D012641:Selection, Genetic; D014733:Vibrio / Q000502:physiology*