Stewart Alexander J, Parsons Todd L, Plotkin Joshua B
Department of Genetics, Environment and Evolution, University College London, London WC1E 6BT, United Kingdom;
Laboratoire de Probabilités et Modèles Aléatoires, CNRS UMR 7599, Université Pierre et Marie Curie, Paris 75005, France.
Proc Natl Acad Sci U S A. 2016 Nov 8;113(45):E7003-E7009. doi: 10.1073/pnas.1608990113. Epub 2016 Oct 24.
Iterated games provide a framework to describe social interactions among groups of individuals. This body of work has focused primarily on individuals who face a simple binary choice, such as "cooperate" or "defect." Real individuals, however, can exhibit behavioral diversity, varying their input to a social interaction both qualitatively and quantitatively. Here we explore how access to a greater diversity of behavioral choices impacts the evolution of social dynamics in populations. We show that, in public goods games, some simple strategies that choose between only two possible actions can resist invasion by all multichoice invaders, even while engaging in relatively little punishment. More generally, access to a larger repertoire of behavioral choices results in a more "rugged" fitness landscape, with populations able to stabilize cooperation at multiple levels of investment. As a result, increased behavioral choice facilitates cooperation when returns on investments are low, but it hinders cooperation when returns on investments are high. Finally, we analyze iterated rock-paper-scissors games, the nontransitive payoff structure of which means that unilateral control is difficult to achieve. Despite this, we find that a large proportion of multichoice strategies can invade and resist invasion by single-choice strategies-so that even well-mixed populations will tend to evolve and maintain behavioral diversity.
重复博弈提供了一个框架来描述个体群体之间的社会互动。这一领域的工作主要集中在面临简单二元选择（如“合作”或“背叛”）的个体上。然而，真实的个体可能表现出行为多样性，在社会互动中的投入在质量和数量上都会有所不同。在这里，我们探讨获得更多样化的行为选择如何影响群体中社会动态的演变。我们表明，在公共物品博弈中，一些仅在两种可能行动之间进行选择的简单策略可以抵御所有多选择入侵者的入侵，即使惩罚相对较少。更一般地说，获得更多的行为选择会导致更“崎岖”的适应度景观，群体能够在多个投资水平上稳定合作。因此，当投资回报较低时，增加行为选择有助于合作，但当投资回报较高时，它会阻碍合作。最后，我们分析了重复的石头剪刀布博弈，其非传递性的收益结构意味着难以实现单方面控制。尽管如此，我们发现很大一部分多选择策略可以入侵并抵御单选择策略的入侵，因此即使是充分混合的群体也倾向于进化并维持行为多样性。
