城市化在全球加速,改造景观,给生物体带来新的挑战,塑造表型和影响健康。据称,城市个体的类胡萝卜素着色更暗淡,与非城市同行相比,所谓的“城市迟钝”现象。然而,在种内水平,这种概括出奇的不一致,通常基于对单个城市/非城市人口的比较或来自有限地理区域的研究。这里,我们结合了相关性,常见鸣鸟的实验和荟萃分析数据,伟大的山雀Parus少校,调查欧洲城市和森林人口中基于类胡萝卜素的羽毛颜色。我们发现,正如预测的那样,城市个体比森林个体苍白,尽管城市与森林的颜色对比存在很大的人口特异性差异。使用一个焦点区域(马尔默,瑞典),我们揭示了羽毛颜色差异背后的特定种群过程,这不太可能是遗传或早期生活条件的结果,而是环境因素在出生后起作用的结果。最后,我们的荟萃分析表明,城市沉闷现象在文献中得到了很好的确立,对于大山雀,基于类胡萝卜素的羽毛性状不断变化,特别是类胡萝卜素色度,对人为干扰的反应。总的来说,我们的研究结果为“城市暗淡”现象的均匀性提供了证据,但也强调了对色彩的影响程度取决于当地的城市特征。未来的长期重复研究,涵盖更广泛的物种和饲喂行会,对于进一步理解这种现象的生态进化影响至关重要。
Urbanisation is accelerating across the globe, transforming landscapes, presenting organisms with novel challenges, shaping phenotypes and impacting fitness. Urban individuals are claimed to have duller carotenoid-based
colouration, compared to their non-urban counterparts, the so-called \'urban dullness\' phenomenon. However, at the intraspecific level, this generalisation is surprisingly inconsistent and often based on comparisons of single urban/non-urban populations or studies from a limited geographical area. Here, we combine correlational, experimental and meta-analytical data on a common songbird, the great tit Parus major, to investigate carotenoid-based plumage
colouration in urban and forest populations across Europe. We find that, as predicted, urban individuals are paler than forest individuals, although there are large population-specific differences in the magnitude of the urban-forest contrast in
colouration. Using one focal region (Malmö, Sweden), we reveal population-specific processes behind plumage
colouration differences, which are unlikely to be the result of genetic or early-life conditions, but instead a consequence of environmental factors acting after fledging. Finally, our meta-analysis indicates that the urban dullness phenomenon is well established in the literature, for great tits, with consistent changes in carotenoid-based plumage traits, particularly carotenoid chroma, in response to anthropogenic disturbances. Overall, our results provide evidence for uniformity in the \'urban dullness\' phenomenon but also highlight that the magnitude of the effect on
colouration depends on local urban characteristics. Future long-term replicated studies, covering a wider range of species and feeding guilds, will be essential to further our understanding of the eco-evolutionary implications of this phenomenon.