Reproductive character displacement occurs when competition for successful breeding imposes a divergent selection on the interacting species, causing a divergence of reproductive traits. Here, we show that a disputed butterfly taxon is actually a case of male wing colour shift, apparently produced by reproductive character displacement. Using double digest restriction‐site associated DNA sequencing and mitochondrial DNA sequencing we studied four butterfly taxa of the subgenus Cupido (Lepidoptera: Lycaenidae): Cupido minimus and the taxon carswelli, both characterized by brown males and females, plus C. lorquinii and C. osiris, both with blue males and brown females. Unexpectedly, taxa carswelli and C. lorquinii were close to indistinguishable based on our genomic and mitochondrial data, despite displaying strikingly different male coloration. In addition, we report and analysed a brown male within the C. lorquinii range, which demonstrates that the brown morph occurs at very low frequency in C. lorquinii. Such evidence strongly suggests that carswelli is conspecific with C. lorquinii and represents populations with a fixed male brown colour morph. Considering that these brown populations occur in sympatry with or very close to the blue C. osiris, and that the blue C. lorquinii populations never do, we propose that the taxon carswelli could have lost the blue colour due to reproductive character displacement with C. osiris. Since male colour is important for conspecific recognition during courtship, we hypothesize that the observed colour shift may eventually trigger incipient speciation between blue and brown populations. Male colour seems to be an evolutionarily labile character in the Polyommatinae, and the mechanism described here might be at work in the wide diversification of this subfamily of butterflies.

中文翻译：

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丘比特蝴蝶因繁殖性状置换而快速发生色移

当成功育种的竞争对相互作用的物种施加不同的选择，从而导致生殖性状发生分歧时，就会发生生殖性状位移。在这里，我们表明，有争议的蝴蝶类群实际上是雄性机翼颜色偏移的一种情况，显然是由于生殖角色的移位造成的。使用双酶切限制性酶切位点相关的DNA测序和线粒体DNA测序，我们研究了Cupido属（鳞翅目：Lycaenidae）的四个蝴蝶类群：Cupid minimus和taxon carwelli，均以棕色和雌性为特征，此外还有C. lorquinii和C. osiris，有蓝色的雄性和棕色的雌性。出乎意料的是，出租车尽管我们显示出明显不同的男性肤色，但根据我们的基因组和线粒体数据，C。lorquinii和C. lorquinii几乎无法区分。此外，我们报告并分析了C. lorquinii范围内的棕色雄性，这表明棕色形态在C. lorquinii中的发生频率非常低。这些证据强烈表明carswelli与C. lorquinii是同种的，代表具有固定的男性棕色形态的种群。考虑到这些棕色种群与蓝色C. osiris共生或非常接近，并且蓝色C. lorquinii种群从未发生，我们建议分类单元carswelli由于C. osiris的繁殖性状移位，可能失去了蓝色。由于男性颜色对于求爱过程中的具体识别非常重要，因此我们假设观察到的颜色偏移最终可能会触发蓝色和棕色种群之间的初期物种形成。雄色似乎是多虫科中进化上不稳定的特征，此处描述的机制可能在蝴蝶亚科的广泛多样性中起作用。