The study of phenotypic evolution in island birds following colonization is a classic topic in island biogeography. However, few studies explicitly test for the role of selection in shaping trait evolution in these taxa. Here, we studied the Azores woodpigeon (Columba palumbus azorica) to investigate differences between island and mainland populations, between females and males, and interactions between geographical origin and sex, by using spectrophotometry to quantify plumage colour and linear measurements to examine external and skeletal morphology. We further tested if selection explains the observed patterns by comparing phenotypic differentiation to genome‐wide neutral differentiation. Our findings are consistent with several predictions of morphological evolution in island birds, namely differences in bill, flight and leg morphology and coloration differences between island and mainland birds. Interestingly, some plumage and morphological traits that differ between females and males respond differently according to geographical origin. Sexual dimorphism in colour saturation is more pronounced in the mainland, but this is driven by selection on female plumage coloration. Differences in flight morphology between females and males are also more pronounced in the mainland, possibly to accommodate contrasting pressures between migration and flight displays. Overall, our results suggest that phenotypic differentiation between mainland and island populations leading to divergent sexual dimorphism patterns can arise from selection acting on both females and males on traits that are likely under the influence of natural and sexual selection.

中文翻译：

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选择是亚速尔群岛斑鸠表型分化的基础

殖民后岛屿鸟类的表型进化研究是岛屿生物地理学的经典课题。然而，很少有研究明确测试选择在这些分类群中塑造性状进化的作用。在这里，我们研究了亚速尔群岛木鸽（Columba palumbus azorica），通过使用分光光度法来量化羽毛颜色和线性测量来检查外部和骨骼形态，以研究岛屿和大陆种群之间、雌性和雄性之间以及地理起源和性别之间的相互作用的差异. 我们通过比较表型分化与全基因组中性分化来进一步测试选择是否解释了观察到的模式。我们的发现与岛屿鸟类形态进化的几个预测一致，即喙的差异，岛屿和大陆鸟类的飞行和腿部形态和颜色差异。有趣的是，雌性和雄性之间不同的一些羽毛和形态特征会根据地理起源做出不同的反应。色彩饱和度的性别二态性在大陆更为明显，但这是由对雌性羽毛着色的选择驱动的。在大陆，雌性和雄性之间飞行形态的差异也更加明显，可能是为了适应迁徙和飞行显示之间的对比压力。总体而言，我们的研究结果表明，大陆和岛屿种群之间的表型差异导致了不同的性别二态性模式，可能是由于在自然和性选择的影响下，对雌性和雄性进行了选择。