Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697-2525, USA.
J Evol Biol. 2010 Jun 1;23(6):1245-50. doi: 10.1111/j.1420-9101.2010.01986.x. Epub 2010 Mar 24.
An individually costly act that benefits all group members is a public good. Natural selection favours individual contribution to public good [corrected] only when some benefit to the individual offsets the cost of contribution. Problems of sex ratio, parasite virulence, microbial metabolism, punishment of noncooperators, and nearly all aspects of sociality have been analysed as public goods shaped by kin and group selection. Here, I develop two general aspects of the public goods problem that have received relatively little attention. First, variation in individual resources favours selfish individuals to vary their allocation to public goods. Those individuals better endowed contribute their excess resources to public benefit, whereas those individuals with fewer resources contribute less to the public good. Thus, purely selfish behaviour causes individuals to stratify into upper classes that contribute greatly to public benefit and social cohesion and to lower classes that contribute little to the public good. Second, if group success absolutely requires production of the public good, then the pressure favouring production is relatively high. By contrast, if group success depends weakly on the public good, then the pressure favouring production is relatively weak. Stated in this way, it is obvious that the role of baseline success is important. However, discussions of public goods problems sometimes fail to emphasize this point sufficiently. The models here suggest simple tests for the roles of resource variation and baseline success. Given the widespread importance of public goods, better models and tests would greatly deepen our understanding of many processes in biology and sociality.
对所有群体成员都有益但个体成本较高的行为就是公共物品。自然选择只在个体贡献对公共物品的收益足以抵消贡献成本时，才会有利于个体的公共物品贡献。性比问题、寄生虫毒力、微生物代谢、对非合作者的惩罚，以及几乎所有社会性的方面，都被分析为受亲缘选择和群体选择塑造的公共物品。在这里，我提出了公共物品问题的两个普遍方面，这两个方面相对较少受到关注。首先，个体资源的变化有利于自私的个体来改变他们对公共物品的分配。那些资源更充裕的个体将其多余的资源贡献出来，以获得公共利益，而资源较少的个体则较少地贡献于公共物品。因此，纯粹的自私行为导致个体分层为上层阶级，他们对公共利益和社会凝聚力有很大的贡献，而下层阶级对公共利益的贡献则很少。其次，如果群体的成功绝对需要公共物品的生产，那么有利于生产的压力就相对较高。相比之下，如果群体的成功在很大程度上取决于公共物品，那么有利于生产的压力就相对较弱。从这个角度来看，很明显，基线成功的作用是很重要的。然而，关于公共物品问题的讨论有时没有充分强调这一点。这里的模型提出了对资源变化和基线成功作用的简单测试。鉴于公共物品的广泛重要性，更好的模型和测试将极大地加深我们对生物学和社会性许多过程的理解。
