Evidence suggests that natural populations can evolve to better tolerate the novel environmental conditions associated with urban areas. Studies of adaptive divergence in urban areas often examine one or a few traits at a time from populations residing only at the most extreme urban and nonurban habitats. Thus, whether urbanization drives divergence in many traits simultaneously in a manner that varies with the degree of urbanization remains unclear. To address this gap, we generated seed families of white clover (Trifolium repens) collected from 27 populations along an urbanization gradient in Toronto, Canada, grew them in a common garden, and measured 14 phenotypic traits. Families from urban sites had evolved later phenology and germination, larger flowers, thinner stolons, reduced cyanogenesis, greater biomass and greater seed set. Pollinator observations revealed near-complete turnover of pollinator morphological groups along the urbanization gradient, which may explain some of the observed divergences in floral traits and phenology. Our results suggest that adaptation to urban environments involves multiple traits.

有证据表明，自然种群可以进化以更好地耐受与城市地区相关的新环境条件。对城市地区适应性分化的研究通常一次检查仅居住在最极端的城市和非城市栖息地的人群的一种或几种特征。因此，城市化是否以随城市化程度不同的方式同时驱动许多特征的分化仍不清楚。为了解决这一差距，我们从加拿大多伦多城市化梯度的 27 个种群中收集了白三叶草 ( Trifolium repens )的种子家族，将它们种植在一个公共花园中，并测量了 14 个表型性状。来自城市的家庭进化出较晚的物候和发芽、更大的花、更薄的匍匐茎、减少的氰化、更大的生物量和更大的结籽。传粉媒介的观察揭示了传粉媒介形态群体沿着城市化梯度几乎完全更替，这可能解释了观察到的花性状和物候学的一些差异。我们的结果表明，对城市环境的适应涉及多种特征。