The study of phenotypic variation patterns among populations is fundamental to elucidate the drivers of evolutionary processes. Empirical evidence that supports ongoing genetic divergence associated with phenotypic variation remains very limited for marine species where larval dispersal is a common homogenizing force. We present a genome‐wide analysis of a marine fish, Labrus bergylta, comprising 144 samples distributed from Norway to Spain, a large geographical area that harbours a gradient of phenotypic differentiation. We analysed 39,602 biallelic single nucleotide polymorphisms and found a clear latitudinal gradient of genomic differentiation strongly correlated with the variation in phenotypic morph frequencies observed across the North Atlantic. We also detected a strong association between the latitude and the number of loci that appear to be under divergent selection, which increased with differences in coloration but not with overall genetic differentiation. Our results demonstrate that strong reproductive isolation is occurring between sympatric colour morphs of L. bergylta found at the southern areas and provide important new insights into the genomic changes shaping early stages of differentiation that might precede speciation with gene flow.

中文翻译：

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温带海鱼地理结构颜色多态性的基因组景观

人口中表型变异模式的研究对于阐明进化过程的驱动力至关重要。支持与表型变异有关的持续遗传差异的经验证据对于海洋生物来说仍然非常有限，在海洋生物中，幼虫扩散是常见的均化力。我们提出了一种海洋鱼类唇Lab鱼的全基因组分析包括从挪威分发到西班牙的144个样本，这是一个很大的地理区域，具有表型分化的梯度。我们分析了39602个双等位基因单核苷酸多态性，发现在整个北大西洋地区观察到的明显的基因组差异的纬度梯度与表型形态频率的变化密切相关。我们还检测到纬度与似乎在不同选择下的基因座数目之间有很强的关联性，该关联性随颜色差异而增加，但与总体遗传分化无关。我们的结果表明，L的同胞颜色形态之间发生了强烈的生殖隔离。 子 在南部地区发现并提供了重要的新见解，可了解塑造分化的早期阶段的基因组变化，这些变化可能早于形成物种的基因流。