Am Nat. 2020 Apr;195(4):717-732. doi: 10.1086/707561. Epub 2020 Mar 4.
Adaptation is often described in behavioral ecology as individuals maximizing their inclusive fitness. Under what conditions does this hold, and how does this relate to the gene-centered perspective of adaptation? We unify and extend the literature on these questions to class-structured populations. We demonstrate that the maximization (in the best-response sense) of class-specific inclusive fitness obtains in uninvadable population states (meaning that all deviating mutants become extinct). This defines a genuine actor-centered perspective on adaptation. But this inclusive fitness is assigned to all bearers of a mutant allele in a given class and depends on distributions of demographic and genetic contexts. These distributions, in turn, usually depend on events in previous generations and are thus not under individual control. This prevents, in general, envisioning individuals themselves as autonomous fitness maximizers, each with its own inclusive fitness. For weak selection, however, the dependence on earlier events can be neglected. We then show that each individual in each class appears to maximize its own inclusive fitness when all other individuals exhibit inclusive fitness-maximizing behavior. This defines a genuine individual-centered perspective of adaptation and justifies formally, as a first-order approximation, the long-heralded view of individuals appearing to maximize their own inclusive fitness.
适应通常在行为生态学中被描述为个体最大化其适合度。在什么条件下可以实现这一点，以及这与适应的以基因为中心的观点有何关系？我们将这些问题的文献统一并扩展到具有阶层结构的群体中。我们证明，在不可入侵的种群状态下（即所有偏离的突变体都会灭绝），特定阶层的适合度最大化（在最佳反应意义上）。这定义了一种真正的以行动者为中心的适应观点。但是，这种适合度被分配给给定阶层中具有突变等位基因的所有携带者，并且取决于人口统计和遗传背景的分布。这些分布反过来通常取决于前几代的事件，因此不受个体控制。这通常阻止将个体自身视为自主的适应最大化者，每个个体都有自己的适合度。然而，对于弱选择，可以忽略对早期事件的依赖。然后，我们表明，当所有其他个体都表现出最大化适合度的行为时，每个阶层的每个个体似乎都在最大化自己的适合度。这定义了一种真正的以个体为中心的适应观点，并在一阶近似意义上正式证明了个体似乎最大化自己适合度的长期以来的观点。
