The evolution of coercive policing in genetically mixed groups: the case of plasmid copy number control

Abstract

Policing is a widespread mechanism regulating cooperation in both human and animal social groups.Policing can promote the evolution and maintenance of cooperation among non-relatives by tying the reproductive success of individuals to the efficiency and success of the group. In this paper, we investigate the evolution of reproductive policing using a multi-scale computational model inspired by the copy number control system of conjugative bacterial plasmids. Our results show that the repression of competition through policing can evolve across a very broad range of migration (plasmid conjugation) rates, improving system-level performance and bringing efficiency gains to the group beyond those achievable by pure self-restraint. Reproductive policing acts to increase genetic relatedness by reducing variation in group size which, in turn, reduces the heterogeneity of the plasmid population. When among-group migration is high, coercive policing strategies are favoured, characterized by high levels of policing coupled with relatively lower obedience. Coercive policing strategies preferentially limit the reproduction of rival lineages while, at the same time, maintaining effective collective reproductive control. Author SummaryThe emergence and maintenance of cooperation is a topic of great importance in evolutionary biology.The evolution of cooperation has been explained in the context of kin selection when there is sufficient genetic relatedness among interacting individuals. When there is insufficient relatedness, the presence of alternative mechanisms, such as mutual policing, can promote the evolution and maintenance of cooperation by tying the reproductive success of individual to the efficiency and success of the group. In this paper, we investigate the evolution of reproductive policing using an agent-based computational model inspired by a simple and elegant biological example: replication control among conjugative plasmids, a class . CC-BY-NC-ND 4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/053579 doi: bioRxiv preprint first posted online May. 22, 2016; 2 of molecular symbionts of bacterial hosts. Our results show that the repression of competition through policing evolves and improves plasmid group performance beyond levels achievable by self-restraint, across a very broad range of migration rates. Under conditions of high migration (frequent conjugation), we observe the evolution of coercive policing strategies that limit the reproduction of rival lineages by investing disproportionately in policing relative to their obedience to the policing trait.

In silico bacteria evolve robust cooperation via complex quorum-sensing strategies

“…2). The resulting hump in signal investment with increased genetic mixing is predicted by a simple analytical game theory model 25 and now has support from two distinct simulation models built with very different biological motivations (this study and 63,66 ), which raises the challenge of why this result has been difficult to pin down experimentally, despite explicit attention 62 . Later in the discussion we return to this point in a general overview of the empirical context, but in short, it appears that the genetics of auto-regulation present an effective mechanistic block to the elaboration of coercive strategies.…”

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.…”

“…3 and also 246 see Fig. 4 in [54]). However, as genetic mixing increases this coercive peak in signaling 247 (policing) fails due to a collapse in obedience / response (Fig.…”

“…Introduction across multiple bacterial systems [17,19,20,24,30,32,[37][38][39][40][41][42][43]. Across these experimental 53 systems, there is evidence that QS systems can limit cooperative investments to high 54 density [19], low mass transfer [21,44] and clonal [30,32] environments -in some cases 55 these responses have demonstrated fitness advantages [19,30,32]. While consistent with 56 theoretical predictions, these results cannot separate whether these functional roles were 57 the drivers of QS evolution, or simply fortuitous byproducts or 'spandrels' [45] of a 58 complex system driven by other ecological pressures.…”

The social lives of viruses and other mobile genetic elements: a commentary on Leeks et al. 2023

“…The resulting model showed strong benefits for policing investments even under a high relatedness scenario (purely vertical transmission), by avoiding over‐ and underexploitation of the shared cellular resource. The addition of horizontal gene transfer to the model can reduce intracellular relatedness and produces more complex social strategies, including coercive high policing / low obedience strategies (Kentzoglanakis et al., 2016).…”