Department of Biology, University of Virginia, Charlottesville, VA 22904, USA.
Evolution. 2010 Sep;64(9):2558-74. doi: 10.1111/j.1558-5646.2010.01012.x.
Interactions among conspecifics influence social evolution through two distinct but intimately related paths. First, they provide the opportunity for indirect genetic effects (IGEs), where genes expressed in one individual influence the expression of traits in others. Second, interactions can generate social selection when traits expressed in one individual influence the fitness of others. Here, we present a quantitative genetic model of multivariate trait evolution that integrates the effects of both IGEs and social selection, which have previously been modeled independently. We show that social selection affects evolutionary change whenever the breeding value of one individual covaries with the phenotype of its social partners. This covariance can be created by both relatedness and IGEs, which are shown to have parallel roles in determining evolutionary response. We show that social selection is central to the estimation of inclusive fitness and derive a version of Hamilton's rule showing the symmetrical effects of relatedness and IGEs on the evolution of altruism. We illustrate the utility of our approach using altruism, greenbeards, aggression, and weapons as examples. Our model provides a general predictive equation for the evolution of social phenotypes that encompasses specific cases such as kin selection and reciprocity. The parameters can be measured empirically, and we emphasize the importance of considering both IGEs and social selection, in addition to relatedness, when testing hypotheses about social evolution.
同种个体之间的相互作用通过两条截然不同但密切相关的途径影响社会进化。首先，它们为间接遗传效应（IGE）提供了机会，即在一个个体中表达的基因影响其他个体中特征的表达。其次，当一个个体中表达的特征影响其他个体的适合度时，相互作用可以产生社会选择。在这里，我们提出了一个多变量特征进化的定量遗传模型，该模型综合了 IGE 和社会选择的影响，以前这两种影响都是独立建模的。我们表明，只要一个个体的繁殖值与它的社会伙伴的表型相关，社会选择就会影响进化变化。这种相关性可以由亲缘关系和 IGE 共同产生，它们在确定进化反应方面具有平行作用。我们表明，社会选择是估计适合度的核心，并推导出一个 Hamilton 规则的版本，展示了亲缘关系和 IGE 对利他主义进化的对称影响。我们使用利他主义、绿胡子、攻击性和武器作为例子来说明我们方法的实用性。我们的模型提供了一个涵盖特定情况（如亲缘选择和互惠）的社会表型进化的通用预测方程。参数可以通过经验测量，我们强调在测试关于社会进化的假设时，除了考虑亲缘关系外，还应考虑 IGE 和社会选择。
