Self-destructive cooperation mediated by phenotypic noise.
In many biological examples of cooperation, individuals that cooperate cannot benefit from the resulting public good. This is especially clear in cases of self-destructive cooperation, where individuals die when helping others. If self-destructive cooperation is genetically encoded, these genes can only be maintained if they are expressed by just a fraction of their carriers, whereas the other fraction benefits from the public good. One mechanism that can mediate this differentiation into two phenotypically different sub-populations is phenotypic noise. Here we show that noisy expression of self-destructive cooperation can evolve if individuals that have a higher probability for self-destruction have, on average, access to larger public goods. This situation, which we refer to as assortment, can arise if the environment is spatially structured. These results provide a new perspective on the significance of phenotypic noise in bacterial pathogenesis: it might promote the formation of cooperative sub-populations that die while preparing the ground for a successful infection. We show experimentally that this model captures essential features of Salmonella typhimurium pathogenesis. We conclude that noisily expressed self-destructive cooperative actions can evolve under conditions of assortment, that self-destructive cooperation is a plausible biological function of phenotypic noise, and that self-destructive cooperation mediated by phenotypic noise could be important in bacterial pathogenesis.
Ackermann
Martin
M
Institute of Integrative Biology, ETH Zurich, 8092 Zürich, Switzerland. martin.ackermann@env.ethz.ch
Stecher
Bärbel
B
Freed
Nikki E
NE
Songhet
Pascal
P
Hardt
Wolf-Dietrich
WD
Doebeli
Michael
M
D000818:Animals; D005075:Biological Evolution; D003299:Cooperative Behavior; D004195:Disease Models, Animal; D004760:Enterocolitis / Q000382:microbiology; D051379:Mice; D008954:Models, Biological; D010641:Phenotype; D012480:Salmonella Infections / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000472:pathogenicity* / Q000502:physiology*; D013269:Stochastic Processes; D037521:Virulence Factors / Q000502:physiology
D037521:Virulence Factors