Division of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
Am Nat. 2014 Jan;183(1):108-25. doi: 10.1086/674008. Epub 2013 Nov 12.
When organisms encounter environments that are heterogeneous in time, phenotypic plasticity is often favored by selection. The degree of such plasticity can vary during an organism's lifetime, but the factors promoting differential plastic responses at different ages or life stages remain poorly understood. Here we develop and analyze an evolutionary model to investigate how environmental information is optimally collected and translated into phenotypic adjustments at different ages. We demonstrate that plasticity must often be expected to vary with age in a nonmonotonic fashion. Early in life, it is generally optimal to delay phenotypic adjustments until sufficient information has been collected about the state of the environment to warrant a costly phenotypic adjustment. Toward the end of life, phenotypic adjustments are disfavored as well because their beneficial effects can no longer be fully reaped before death. Our analysis clarifies how patterns of age-dependent plasticity are shaped by the interplay of environmental uncertainty, the accuracy of perceived information, and the costs of phenotypic adjustments with life-history determinants such as the relative strengths of fecundity and viability selection experienced by the organism over its lifetime. We conclude by comparing our results with expectations for alternative mechanisms, including developmental constraints, that promote age-dependent plasticity.
当生物体遇到时间上不均匀的环境时，表型可塑性通常会受到选择的青睐。这种可塑性的程度在生物体的一生中可能会有所变化，但促进不同年龄或生命阶段产生不同可塑性反应的因素仍知之甚少。在这里，我们开发并分析了一个进化模型，以研究生物体如何在不同年龄最佳地收集环境信息并将其转化为表型调整。我们证明，可塑性通常必须以非单调的方式随年龄变化。在生命早期，通常最优的做法是延迟表型调整，直到收集到足够的关于环境状态的信息，以保证进行昂贵的表型调整是合理的。在生命的后期，表型调整也不被看好，因为在死亡之前，它们的有益效果再也无法完全实现。我们的分析阐明了年龄依赖性可塑性的模式是如何由环境不确定性、感知信息的准确性以及表型调整的成本与生活史决定因素（例如生物体在其一生中经历的繁殖力和生存力选择的相对强度）之间的相互作用所塑造的。最后，我们将我们的结果与促进年龄依赖性可塑性的替代机制（包括发育限制）的预期进行了比较。
