How underlying mechanisms bias evolution toward predictable outcomes remains an area of active debate. In this study, we leveraged phenotypic plasticity and parallel adaptation across independent lineages of Trinidadian guppies (Poecilia reticulata) to assess the predictability of gene expression evolution during parallel adaptation. Trinidadian guppies have repeatedly and independently adapted to high‐ and low‐predation environments in the wild. We combined this natural experiment with a laboratory breeding design to attribute transcriptional variation to the genetic influences of population of origin and developmental plasticity in response to rearing with or without predators. We observed substantial gene expression plasticity, as well as the evolution of expression plasticity itself, across populations. Genes exhibiting expression plasticity within populations were more likely to also differ in expression between populations, with the direction of population differences more likely to be opposite those of plasticity. While we found more overlap than expected by chance in genes differentially expressed between high‐ and low‐predation populations from distinct evolutionary lineages, the majority of differentially expressed genes were not shared between lineages. Our data suggest alternative transcriptional configurations associated with shared phenotypes, highlighting a role for transcriptional flexibility in the parallel phenotypic evolution of a species known for rapid adaptation.

中文翻译：

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并行适应过程中的非并行转录差异

潜在的机制如何将进化偏向可预测的结果仍是一个有争议的领域。在这项研究中，我们在特立尼达孔雀鱼（Poecilia reticulata）的独立世系中利用表型可塑性和平行适应）以评估平行适应过程中基因表达进化的可预测性。特立尼达孔雀鱼已反复独立地适应野外的高捕食和低捕食环境。我们将此自然实验与实验室育种设计相结合，以将转录变异归因于有或没有捕食者的饲养对起源种群和发育可塑性的遗传影响。我们观察到大量的基因表达可塑性，以及不同人群之间表达可塑性的演变。在群体内表现出可塑性的基因在群体间的表达上也更有可能不同，而群体差异的方向则更有可能与可塑性相反。虽然我们发现来自不同进化世系的高捕食和低捕食种群之间差异表达的基因发生了比预期更多的重叠，但大多数差异表达的基因并未在谱系之间​​共享。我们的数据表明与共享表型相关的替代转录构型，突显了转录灵活性在已知快速适应性物种的平行表型进化中的作用。