But QS genes may also be selected in non-cooperators, allowing exploitation of cooperative strains and lowering the frequency of cooperation.
Dispersal rate had a stronger effect on the frequency of cooperation under disassortative mating than assortative mating; disassortative mating allowed cue-dependent cooperation to persist even in relatively unstructured populations.
The frequency of cooperation in the 32-person groups fell to 28%.
However, the role of a broad range of population bottlenecks has yet to be considered; it is likely that the frequency of cooperation will increase with decreasing population bottleneck size.
Comparison with the corresponding cases without the possibility of QS (Fig. 1, left column) immediately shows that the QS functions of signalling and responding are selected in a large part of the parameter space and that they have a positive effect on the relative frequency of cooperation in the population.
At steady state, the frequency of cooperation is about 0.3, the frequency of punishment is close to zero, and there is no correlation across groups.
Figures 2 and 3 examine the effects of the model's parameters on recognition locus diversity and the frequency of cooperation at equilibrium.
Punishment does not substantially increase the frequency of cooperation within groups because the transmission bias is weak, so punishment cannot create an inclusive fitness benefit, and does not increase in frequency.
The number of recognition alleles present was positively related to both diversity and the frequency of cooperation, up to an asymptote (as in [ 17]); this effect was especially pronounced under disassortative mating.
We also investigated the effects of dominance at the behaviour locus, but found that the phenotype of heterozygotes (h) had no effect on the equilibrium recognition locus diversity or the frequency of cooperation.
