Evolution of cooperation by phenotypic similarity
Tibor Antal, Hisashi Ohtsuki, John Wakeley, Peter D. Taylor, and Martin A. Nowak
PNAS May 26, 2009, vol. 106, no. 21, p8597–8600 doi:10.1073 / pnas.0902528106
C’est con, d’un côté financer l’UIP et Jean Staune qui passe son temps à dire que la sélection naturelle ne peut donner des comportements coopératifs et de l’autre financer des études qui démontrent comment la sélection naturelle peut favoriser les comportements coopératifs. N’est-ce pas que c’est con Jean, qu’ils paient pour montrer que tu as tort ! Les mecs de la JTF sont relativement bons pour se tirer des balles au pied.
The emergence of cooperation in populations of selfish individu- als is a fascinating topic that has inspired much work in theoretical biology. Here, we study the evolution of cooperation in a model where individuals are characterized by phenotypic properties that are visible to others. The population is well mixed in the sense that everyone is equally likely to interact with everyone else, but the behavioral strategies can depend on distance in phenotype space. We study the interaction of cooperators and defectors. In our model, cooperators cooperate with those who are similar and defect otherwise. Defectors always defect. Individuals mutate to nearby phenotypes, which generates a random walk of the population in phenotype space. Our analysis brings together ideas from coalescence theory and evolutionary game dynamics. We obtain a precise condition for natural selection to favor cooperators over defectors. Cooperation is favored when the phenotypic mutation rate is large and the strategy mutation rate is small. In the optimal case for cooperators, in a one-dimensional phenotype space and for large population size, the critical benefit-to-cost ratio is given by b/c = 1 + 2/√3. We also derive the fundamental condition for any two-strategy symmetric game and consider high-dimensional phenotype spaces.
