Data from: Strong divergence in trait means but not in plasticity across hatchery and wild populations of sea-run brown trout Salmo trutta

There is ample evidence that organisms adapt to their native environment when gene flow is restricted. However, evolution of plastic responses across discrete environments is less well examined. We studied divergence in means and plasticity across wild and hatchery populations of sea-run brown trout (Salmo trutta) in a common garden experiment with two rearing environments (hatchery and a nearly natural experimental stream). Since natural and hatchery environments differ, this arrangement provides an experiment in contemporary adaptation across the two environments. A QST-FST approach was used to investigate local adaptation in survival and growth over the first summer. We found evidence for divergent selection in survival in one year and in body length in both years and rearing environments. In general, the hatchery populations had higher survival and larger body size in both environments. QST in body size did not differ between the rearing environments and constitutive divergence in the means was in all cases stronger than divergence in the plastic responses. These results suggest that in this system constitutive changes in mean trait values are more important for local adaptation than increased plasticity. In addition, ex-situ rearing conditions induce changes in trait means that are adaptive in the hatchery, but potentially harmful in the wild, suggesting that hatchery rearing is likely to be a sub-optimal management strategy for trout populations facing selection in the stream environment.

已有充分研究证据表明，当基因流受限之时，生物会适应其原生栖息环境。然而，针对离散环境下表型可塑性响应的演化过程，现有研究仍相对不足。本研究以洄游型褐鳟（Salmo trutta）的野生种群与孵化场种群为研究对象，通过设置孵化场与近自然实验溪流两种饲养环境的同质园实验（common garden experiment），探究了种群性状均值与表型可塑性的分化情况。由于自然栖息环境与孵化场环境存在显著差异，该实验设计可用于探究两种环境下的当代适应过程。本研究采用QST-FST分析法，针对首个夏季内的存活与生长性状开展局部适应研究。研究结果显示，单一年份的存活性状存在分化选择信号，而体长性状在两年间以及所有饲养环境中均呈现分化选择信号。总体而言，孵化场种群在两种饲养环境中均表现出更高的存活率与更大的体型。体型性状的QST值在不同饲养环境间并无显著差异，且所有情况下的性状均值组成型分化均强于表型可塑性响应的分化。上述结果表明，在本研究系统中，性状均值的组成型变化相较于表型可塑性的提升，对局部适应的贡献更为显著。此外，迁地饲养（ex-situ rearing）条件会诱导性状均值发生变化，这类变化在孵化场环境中具有适应性，但在野生自然环境中却可能产生危害。这表明，对于面临溪流环境选择压力的鳟鱼种群而言，孵化场饲养属于次优的管理策略。