The Evolution of Collective Restraint: Policing and Obedience among Non-conjugative Plasmids

Abstract

The repression of competition by mechanisms of policing is now recognized as a major force in the maintenance of cooperation. General models on the evolution of policing have focused on the interplay between individual competitiveness and mutual policing, demonstrating a positive relationship between within-group diversity and levels of policing. We expand this perspective by investigating what is possibly the simplest example of reproductive policing: copy number control (CNC) among non-conjugative plasmids, a class of extra-chromosomal vertically transmitted molecular symbionts of bacteria. Through the formulation and analysis of a multi-scale dynamical model, we show that the establishment of stable reproductive restraint among plasmids requires the co-evolution of two fundamental plasmid traits: policing, through the production of plasmid-coded trans-acting replication inhibitors, and obedience, expressed as the binding affinity of plasmid-specific targets to those inhibitors. We explain the intrinsic replication instabilities that arise in the absence of policing and we show how these instabilities are resolved by the evolution of copy number control. Increasing levels of policing and obedience lead to improvements in group performance due to tighter control of local population size (plasmid copy number), delivering benefits both to plasmids, by reducing the risk of segregational loss and to the plasmid-host partnership, by increasing the rate of cell reproduction, and therefore plasmid vertical transmission.

In silicobacteria evolve robust cooperation via complex quorum-sensing strategies

“…3). The resulting hump in 248 signal investment with increased genetic mixing is predicted by a simple analytical game 249 theory model [25] and now has support from two distinct simulation models built with 250 very different biological motivations (this study and [51,54]), which raises the challenge 251 of why this result has been difficult to pin down experimentally, despite explicit 252 attention [55]. Later in the discussion we return to this point in a general overview of 253 the empirical context, but in short, it appears that the genetics of auto-regulation 254 present an effective mechanistic block to the elaboration of coercive strategies.…”

“…(S6), depending on whether invoking the 47 auto-regulation mechanism. 48 Computational model of quorum sensing without 49 auto-regulation 50 The computational model of signal dynamics for quorum sensing without 51 auto-regulation is given as below:…”

Reticulate Evolution

“…Kentzoglanakis et al (2013) analyzed the conflict between obedience and deafness to the control mechanism with computer simulations to show that the evolution of plasmid copy-number control mechanisms improves plasmid stability (Kentzoglanakis et al 2013). While the molecules responsible for the initiation of plasmid replication replicates only the plasmid where they are encoded, the inhibitor always constrains the replication of all plasmid molecules, not only the plasmid molecule where it is encoded.…”

Symbiosis Between Non-Transferable Plasmids and Prokaryotic Cells

“…Would it be a good strategy for the "other" plasmids to mutate the receptor of the inhibitor in order to become deaf to it? Kentzoglanakis et al (2013) analyzed the conflict between obedience and deafness to the control mechanism with computer simulations to show that the evolution of plasmid copy-number control mechanisms improves plasmid stability (Kentzoglanakis et al 2013). tend to respond to each other's replication activators and repressors.…”