Suzuki Yukari, Toquenaga Yukihiko
Integrative Environmental Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Ten-Nou-Dai, Tsukuba, Ibaraki 305-8572, Japan.
J Theor Biol. 2005 Jan 21;232(2):191-201. doi: 10.1016/j.jtbi.2004.08.006.
An altruistic individual has to gamble on cooperation to a stranger because it does not know whether the stranger is trustworthy before direct interaction. Nowak and Sigmund (Nature 393 (1998a) 573; J. Theor. Biol. 194 (1998b) 561) presented a new theoretical framework of indirect reciprocal altruism by image scoring game where all individuals are informed about a partner's behavior from its image score without direct interaction. Interestingly, in a simplified version of the image scoring game, the evolutionarily stability condition for altruism became a similar form of Hamilton's rule, i.e. inequality that the probability of getting correct information is more than the ratio of cost to benefit. Since the Hamilton's rule was derived by evolutionarily stable analysis, the evolutionary meaning of the probability of getting correct information has not been clearly examined in terms of kin and group selection. In this study, we applied covariance analysis to the two-score model for deriving the Hamilton's rule. We confirmed that the probability of getting correct information was proportional to the bias of altruistic interactions caused by using information about a partner's image score. The Hamilton's rule was dependent on the number of game bouts even though the information reduced the risk of cooperation to selfish one at the first encounter. In addition, we incorporated group structure to the two-score model to examine whether the probability of getting correct information affect selection for altruism by group selection. We calculated a Hamilton's rule of group selection by contextual analysis. Group selection is very effective when either the probability of getting correct information or that of future interaction, or both are low. The two Hamilton's rules derived by covariance and contextual analyses demonstrated the effects of information and group structure on the evolution of altruism. We inferred that information about a partner's behavior and group structure can produce flexible pathways for the evolution of altruism.
一个利他主义个体必须冒险与陌生人合作，因为在直接互动之前，它不知道这个陌生人是否值得信赖。诺瓦克和西格蒙德（《自然》393卷（1998年a期）573页；《理论生物学杂志》194卷（1998年b期）561页）通过形象评分博弈提出了一种间接互惠利他主义的新理论框架，在该博弈中，所有个体无需直接互动就能从其形象评分中了解到伙伴的行为。有趣的是，在形象评分博弈的一个简化版本中，利他主义的进化稳定性条件变成了与汉密尔顿法则类似的形式，即获得正确信息的概率大于成本与收益之比的不等式。由于汉密尔顿法则是通过进化稳定性分析推导出来的，所以从亲缘选择和群体选择的角度来看，获得正确信息的概率的进化意义尚未得到明确研究。在本研究中，我们将协方差分析应用于双评分模型以推导汉密尔顿法则。我们证实，获得正确信息的概率与因使用伙伴形象评分信息而导致的利他互动偏差成正比。尽管信息在首次相遇时降低了与自私个体合作的风险，但汉密尔顿法则仍依赖于博弈轮次的数量。此外，我们将群体结构纳入双评分模型，以检验获得正确信息的概率是否会通过群体选择影响利他主义的选择。我们通过情境分析计算了群体选择的汉密尔顿法则。当获得正确信息的概率、未来互动的概率或两者都较低时，群体选择非常有效。通过协方差分析和情境分析推导出来的两个汉密尔顿法则证明了信息和群体结构对利他主义进化的影响。我们推断，关于伙伴行为的信息和群体结构可以为利他主义的进化产生灵活的路径。
