This study identifies one possible mechanism whereby gene flow is interrupted in populations undergoing evolutionary divergence in sympatry; this is an important issue in evolutionary biology that remains poorly understood. Variation in trophic morphology was induced in three-spined stickleback by exposing them from an early age either to large benthic or to small pelagic prey. At sexual maturity, females given a choice between two breeding males, showed positive assortative mate choice for males raised on the same diet as themselves. The data indicate that this was mediated through a preference for males with trophic morphology similar to that of fish with which the females were familiar (from their pre-testing holding tanks). In trials where the female did not choose the most familiar male, the evidence suggests that either she had difficulty discriminating between two similar males or was positively choosing males with more extreme morphologies (more benthic-like or pelagic-like). This study has shown for the first time that expression of a plastic trait induced at an early age, not only results in specialisation for local foraging regimes but can also play a significant role in mate choice. This is equivalent to an environmentally induced, plastic version of the “magic traits” that promote ecologically-driven divergence in sympatry, hence the proposed descriptor “plastic magic trait”.

中文翻译：

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促进刺鱼生殖隔离的表型可塑性魔法特征？

这项研究确定了一种可能的机制，即基因流在经历进化分歧的群体中被中断；这是进化生物学中仍然知之甚少的一个重要问题。通过将三刺棘鱼从小暴露于大型底栖动物或小型中上层猎物，它们的营养形态发生了变化。在性成熟时，雌性在两个繁殖雄性之间进行选择，对于与自己相同饮食饲养的雄性表现出积极的选择配偶。数据表明，这是通过偏爱具有与雌性熟悉的鱼类（来自它们的预测试储水池）的营养形态相似的营养形态的雄性来调节的。在雌性没有选择最熟悉的雄性的试验中，证据表明，要么她难以区分两个相似的雄性，要么积极选择形态更极端的雄性（更像底栖动物或更像远洋动物）。这项研究首次表明，在幼年时诱导的可塑性特征的表达不仅会导致当地觅食制度的专业化，而且还可以在配偶选择中发挥重要作用。这相当于环境诱导的“魔法特征”的塑料版本，促进了生态驱动的同情分歧，因此提出了“塑料魔法特征”的描述。不仅导致当地觅食制度的专业化，而且还可以在配偶选择方面发挥重要作用。这相当于环境诱导的“魔法特征”的塑料版本，促进了生态驱动的同情分歧，因此提出了“塑料魔法特征”的描述。不仅导致当地觅食制度的专业化，而且还可以在配偶选择方面发挥重要作用。这相当于环境诱导的“魔法特征”的塑料版本，促进了生态驱动的同情分歧，因此提出了“塑料魔法特征”的描述。