EvoLudoLab: Continuous Snowdrift Game - Branching
Along the bottom of the applet there are several buttons to control the execution and the speed of the simulations - for details see the EvoLudo GUI documentation. Of particular importance are the parameters button and the data data views pop-up list along the top. The former opens a panel that allows to set and change various parameters concerning the game as well as the population structure, while the latter displays the simulation data in different ways.
Note: The shades of grey of the payoff scale are augmented by blueish and reddish shades indicating payoffs for mutual cooperation and defection, respectively.
Continuous Snowdrift game: Branching
Driven by selection and mutation, the population first converges to the convergent stable intermediate level of investments \(x^* = 0.6\). However, since \(x^*\) is not evolutionarily stable, adjacent strategies can invade leading to evolutionary branching, i.e. separating the population into two phenotypic clusters of high and low investing individuals. This process provides a quite natural explanation for the emergence of discrete strategies such as cooperators and defectors.
The parameters are set to \(b_0 = -1.4, b_1 = 6, c_0 = -1.6, c_1 = 4.56\) with players imitating better strategies proportional to the payoff difference and an initial traits/investment of \(0.2 \pm 0.05\) in a population of \(5'000\) individuals. Mutations occur with a probability of 1% and the standard deviation of the Gaussian distributed mutations is \(0.01\).
|Snapshot of the spatial arrangement of strategies.|
|Time evolution of the strategy frequencies.|
|Snapshot of strategy distribution in population|
|Time evolution of the strategy distribution|
|Snapshot of the spatial distribution of payoffs.|
|Time evolution of average population payoff bounded by the minimum and maximum individual payoff.|
|Snapshot of payoff distribution in population.|
|Degree distribution in structured populations.|
|Message log from engine.|
The list below describes only the few parameters related to the continuous snowdrift game. Follow the link for a complete list and descriptions of all other parameters e.g. referring to update mechanisms of players and the population.
- Benefit/Cost Functions
- A variety of different combinations of cost and benefit functions can be selected.
- Benefit \(b_0,\ b_1\)
- Two parameters for the benefit function. Note that not all functions require both.
- Cost \(c_0,\ c_1\)
- Two parameters for the cost function. Note that not all functions require both.
- Mean invest
- Mean trait value of initial population.
- Sdev invest
- Standard deviation of initial population. If set to negative values, the population will be initialized with uniform distributed traits.