scholarly journals Cheater suppression and spite through quorum sensing

2021 ◽  
Author(s):  
Alexander S Moffett ◽  
Peter J Thomas ◽  
Michael Hinczewski ◽  
Andrew W Eckford
Keyword(s):  
Population Dynamics ◽  
Quorum Sensing ◽  
Public Good ◽  
Bacterial Population ◽  
Extinction Time ◽  
Population Extinction ◽  
Good Production ◽  
Alternative Sources ◽  
Demographic Noise ◽  
The Cost

The evolutionary consequences of quorum sensing in regulating bacterial cooperation are not fully understood. In this study, we reveal unexpected consequences of regulating public good production through quorum sensing on bacterial population dynamics, showing that quorum sensing can be a "spiteful" alternative to unregulated production. We analyze a birth-death model of bacterial population dynamics accounting for public good production and the presence of non-producing cheaters. Our model demonstrates that when demographic noise is a factor, the consequences of controlling public good production according to quorum sensing depend on the cost of public good production and the presence of alternative sources of the fitness benefits provided by public goods. When public good production is inexpensive, quorum sensing is a spiteful alternative to unconditional production, in terms of the mean population extinction time. When costs are higher, quorum sensing becomes a selfish strategy for the producing strain, both stabilizing cooperation and decreasing the risk of population extinction.

scholarly journals Optimal strategy for public good production is set by balancing intertemporal trade-off between population growth rate and carrying capacity

2021 ◽  
Author(s):  
Manasi S. Gangan ◽  
Marcos M. Vasconcelos ◽  
Urbashi Mitra ◽  
Odilon Camara ◽  
James Q Boedicker
Keyword(s):  
Growth Rate ◽  
Quorum Sensing ◽  
Public Goods ◽  
Public Good ◽  
Cell Density ◽  
Carrying Capacity ◽  
Cellular Growth ◽  
Logistic Growth ◽  
Trade Off ◽  
Good Production

Public goods are biomolecules that contribute to the community welfare. Their production can benefit populations in many ways, such as by providing access to previously unutilized resources. However, public good production has often been energetically costly, resulting in a reduction in the cellular growth rate. To reduce this cost, populations have evolved strategies to regulate biosynthesis of public good. Among these cell densities dependent regulation of public goods, as accomplished by quorum sensing, is a widely studied mechanism. Given that the fitness costs and benefits of public good production must be balanced, adoption of quorum sensing as a regulatory pathway by bacterial cells may have parallels with several economic principles that are used to study optimal investment decisions. Here, we explore the regulation of a public good, whose benefit is an increase in the carrying capacity, through experimental measurements of growth for engineered strains of Escherichia coli and analysis of those results using a modified logistic growth model. By varying the cell density at which the production of the public good was activated, we showed sharply-peaked optimum population fitness. Analysis further revealed that cell density associated with maximum public good benefits was determined by the trade-off between the cost of public good production, in terms of reduced growth rate, and benefits received from public good, in the form of increased carrying capacity. Moreover, our model showed that cells with luxRI quorum sensing seem to upregulate public good expression when the benefits from the production was immediate. These results demonstrate a case where a biological system apparently has evolved to optimize the timing of public good production to account for short-term costs and delays in reaping a future benefit.

scholarly journals Sharing the Cost of a Public Good without Subsidies

2009 ◽  
Vol 11 (1) ◽  
pp. 1-8 ◽  
Author(s):  
MARC FLEURBAEY ◽  
YVES SPRUMONT
Keyword(s):  
Public Good ◽  
The Cost

scholarly journals Host-pathogen Immune Feedbacks Can Explain Widely Divergent Outcomes from Similar Infections

2021 ◽  
Author(s):  
Stephen Ellner ◽  
Nicolas Buchon ◽  
Tobias Doerr ◽  
Brian P Lazzaro
Keyword(s):  
Bacterial Population ◽  
Dynamic Models ◽  
System Response ◽  
Chronic Infections ◽  
Host Immune Responses ◽  
Lethal Infection ◽  
Negative Feedbacks ◽  
Immune System Response ◽  
Natural Result ◽  
The Cost

A longstanding question in infection biology is why two very similar individuals, with very similar pathogen exposures, may have very different outcomes. Recent experiments have found that even isogenic \emph{Drosophila melanogaster} hosts, given identical inoculations of some bacterial pathogens at suitable doses, can experience very similar initial bacteria proliferation but then diverge to either a lethal infection or a sustained chronic infection with much lower pathogen load. We hypothesized that divergent infection outcomes are a natural result of mutual negative feedbacks between pathogens and the host immune response. Here we test this hypothesis \emph{in silico} by constructing process-based dynamic models for bacterial population growth,host immune induction, and the feedbacks between them, based on common mechanisms of immune system response. Mathematical analysis of a minimal conceptual model confirms our qualitative hypothesis that mutual negative feedbacks can magnify small differences among hosts into life-or-death differences in outcome. However, explaining observed features of chronic infections requires an extension of the model to include induced pathogen modifications that shield themselves from host immune responses at the cost of reduced proliferation rate. Our analysis thus generates new, testable predictions about the mechanisms underlying bimodal infection outcomes.

Rational Choice with Deontic Constraints

2001 ◽  
Vol 31 (3) ◽  
pp. 361-388 ◽  
Author(s):  
Joseph Heath
Keyword(s):  
Public Good ◽  
Rational Choice ◽  
Free Rider ◽  
Household Tasks ◽  
Household Organization ◽  
State Of Nature ◽  
The Cost ◽  
Sticking Point

Anyone who has ever lived with roommates understands the Hobbesian state of nature implicitly. People sharing accommodations quickly discover that buying groceries, doing the dishes, sweeping the floor, and a thousand other household tasks, are all prisoner's dilemmas waiting to happen. For instance, if food is purchased communally, it gives everyone an incentive to overconsume (because the majority of the cost of anything anyone eats is borne by the others). Individuals also have an incentive to buy expensive items that the others are unlikely to want. As a result, everyone's food bill will be higher than it would be if everyone did their own shopping. Things are not much better when it comes to other aspects of household organization. Cleaning is a common sticking point. Once there are a certain number of people living in a house, cleanliness becomes a quasi-public good. If everyone ‘pitched in’ to clean up, then everyone would be happier. But there is a free-rider incentive—before cleaning, it's best to wait around a bit to see if someone else will do it. As a result, the dishes will stack up in the sink, the carpet will get grungy, and so on.

scholarly journals The consequences of polyandry for population viability, extinction risk and conservation

2013 ◽  
Vol 368 (1613) ◽  
pp. 20120053 ◽  
Author(s):  
Luke Holman ◽  
Hanna Kokko
Keyword(s):  
Population Dynamics ◽  
Extinction Risk ◽  
Population Level ◽  
Female Fitness ◽  
Male Care ◽  
Negative Effect ◽  
Adverse Environmental Conditions ◽  
The Cost ◽  
Cost Of Sex ◽  
Population Fitness

Polyandry, by elevating sexual conflict and selecting for reduced male care relative to monandry, may exacerbate the cost of sex and thereby seriously impact population fitness. On the other hand, polyandry has a number of possible population-level benefits over monandry, such as increased sexual selection leading to faster adaptation and a reduced mutation load. Here, we review existing information on how female fitness evolves under polyandry and how this influences population dynamics. In balance, it is far from clear whether polyandry has a net positive or negative effect on female fitness, but we also stress that its effects on individuals may not have visible demographic consequences. In populations that produce many more offspring than can possibly survive and breed, offspring gained or lost as a result of polyandry may not affect population size. Such ecological ‘masking’ of changes in population fitness could hide a response that only manifests under adverse environmental conditions (e.g. anthropogenic change). Surprisingly few studies have attempted to link mating system variation to population dynamics, and in general we urge researchers to consider the ecological consequences of evolutionary processes.

Microbial population dynamics and profiling of quorum sensing agents in membrane bioreactor

2016 ◽  
Vol 113 ◽  
pp. 66-73 ◽  
Author(s):  
Hira Waheed ◽  
Imran Hashmi ◽  
Sher Jamal Khan ◽  
Sang Ryoung Kim ◽  
Muhammad Arshad ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Quorum Sensing ◽  
Membrane Bioreactor ◽  
Microbial Population ◽  
Microbial Population Dynamics

Bacterial population dynamics in a meromictic lake.

1997 ◽  
Vol 63 (6) ◽  
pp. 2181-2188 ◽  
Author(s):  
P Tuomi ◽  
T Torsvik ◽  
M Heldal ◽  
G Bratbak
Keyword(s):  
Population Dynamics ◽  
Bacterial Population ◽  
Meromictic Lake
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