School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Am Nat. 2013 Aug;182(2):147-56. doi: 10.1086/670943. Epub 2013 Jun 27.
Disentangling individual selection from kin selection is one of the greatest challenges of evolutionary biology. Even solitary organisms that do not interact directly with conspecifics may interact indirectly with them through competition for resources. As a result, traits that appear to affect individual fitness alone can also modify the fitness of relatives nearby and thus may evolve partially through these cryptic indirect fitness effects. Here we develop a method to quantitatively separate direct and indirect fitness consequences when some microbes become dormant, while neighbors of the same genotype remain active. Dormant microbes typically survive stresses that kill metabolically active cells, but dormancy also has a social side effect, sparing resources that may be used by nondormant individuals for growth. In structured populations, spared resources may be preferentially consumed by nondormant clonemates, providing an indirect benefit. Without population structure, however, exploitation by a never-dormant competitor imposes an indirect fitness cost on dormant cells. Cryptic indirect fitness effects may play a significant role in the evolution of many ostensibly asocial traits.
从亲缘选择中分辨个体选择是进化生物学面临的最大挑战之一。即使是那些不与同种个体直接相互作用的独居生物，也可能通过对资源的竞争与它们间接相互作用。因此，那些似乎仅影响个体适合度的特征，也可能会改变附近亲属的适合度，因此可能会通过这些隐藏的间接适合度效应部分进化。在这里，当一些微生物进入休眠状态而同一基因型的邻居仍然活跃时，我们开发了一种定量分离直接和间接适合度后果的方法。休眠微生物通常能在杀死代谢活跃细胞的压力下存活，但休眠也有一个社会副作用，它会节省资源，这些资源可能被非休眠个体用于生长。在结构化种群中，休眠微生物的非休眠克隆体可能会优先消耗这些节省下来的资源，从而提供间接利益。然而，如果没有种群结构，从不休眠的竞争者的利用会给休眠细胞带来间接的适合度成本。隐藏的间接适合度效应可能在许多表面上非社会性特征的进化中发挥重要作用。
