Coevolutionary dynamics via adaptive feedback in collective-risk social dilemma game
Figures
![](https://iiif.elifesciences.org/lax:82954%2Felife-82954-fig1-v1.tif/full/617,/0/default.jpg)
Coevolutionary feedback loop of population and risk states in the coupled game system.
The meaning of colors is explained in the legend on the top.
![](https://iiif.elifesciences.org/lax:82954%2Felife-82954-fig2-v1.tif/full/617,/0/default.jpg)
Feedback equation varies with for different values of .
The parameter determines the steepness of the curves. When the value of is small, the function is almost constant or decays linearly by increasing . For larger values, the shape of approaches a step-like form. In this parameter area, the risk level depends sensitively on whether the group cooperation exceeds the threshold value or not.
![](https://iiif.elifesciences.org/lax:82954%2Felife-82954-fig3-v1.tif/full/617,/0/default.jpg)
Representative plot of stable evolutionary outcomes in System I when linear strategy feedback on risk level is assumed.
Different colors are used to distinguish the stability of different equilibrium points in the parameter space (). The blue line indicates that the system undergoes a Hopf bifurcation at . Here, is the real root of the equation , where , and is the interior fixed point where . The dashed curve represents that the value of changes with when . The horizontal dashed line represents that when . The vertical dashed line represents that when .
![](https://iiif.elifesciences.org/lax:82954%2Felife-82954-fig4-v1.tif/full/617,/0/default.jpg)
Coevolutionary dynamics on phase planes and temporal dynamics of System I when linear feedback is considered.
Filled circles represent stable and open circles denote unstable fixed points. The arrows provide the most likely direction of evolution and the continuous color code depicts the speed of convergence in which red denotes the highest speed, while purple represents the lowest speed of transition. On the right-hand side, blue solid line and red dash line respectively denote the fraction of cooperation and the risk level, as indicated in the legend. The first three rows show the coevolutionary dynamics when , , and , respectively. The bottom row shows coevolutionary dynamics when . Parameters are in panel (a). The initial conditions are in panel (b) and in panel (c). in panel (d). The initial conditions are in panel (e) and in panel (f). in panel (g). The initial conditions are in panel (h). , in panel (i). The initial conditions are in panel (j) and in panel (k).
![](https://iiif.elifesciences.org/lax:82954%2Felife-82954-fig5-v1.tif/full/617,/0/default.jpg)
A representative diagram about stable solutions of System II when strategy feedback on risk level is exponential.
We use different colors to distinguish the stability of equilibrium points in the parameter space (). The blue line indicates that the system undergoes a Hopf bifurcation at . Here, is the interior fixed point where . The dashed curve represents that the value of changes with when . The horizontal dashed line represents that when . The vertical dashed line represents that when .
![](https://iiif.elifesciences.org/lax:82954%2Felife-82954-fig6-v1.tif/full/617,/0/default.jpg)
Coevolutionary dynamics on phase planes and temporal dynamics of System II when exponential feedback is assumed.
Filled circles represent stable and open circles denote unstable fixed points. The arrows provide the most likely direction of evolution and the continuous color code depicts the speed of convergence in which red denotes the highest speed, while purple represents the lowest speed of transition. Blue solid line and red dash line respectively denote the fraction of cooperation and the risk level, as indicated in the legend. The first three rows show the coevolutionary dynamics when , , and , respectively. The bottom row shows the case when . Parameters are in panel (a). The initial conditions are in panel (b) and in panel (c). in panel (d). The initial conditions are in panel (e) and in panel (f). in panel (g). The initial conditions are in panel (h). , in panel (i). The initial conditions are in panel (j) and in panel (k).
![](https://iiif.elifesciences.org/lax:82954%2Felife-82954-app1-fig1-v1.tif/full/617,/0/default.jpg)
Coevolutionary dynamics of System I for different values when linear feedback effect of strategy on risk level is considered.
Parameters are , and in left column and in right column. The initial conditions are .
Tables
Notation symbols and meanings in our work.
Symbol | Meaning |
---|---|
Group size | |
Initial endowment | |
Cost of cooperation | |
Risk | |
Collective goal | |
Feedback speed | |
Growth rate of risk with the proportion of defectors | |
Threshold value of cooperation | |
Steepness parameter | |
Frequency of cooperation |