Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale.

Context. Fragmentation in agricultural landscapes is considered as a major threat to biodiversity. Thus, ecological corridors are deployed at multiple scales to increase connectivity. However, there is limited consensus about their efficiency, especially for plants.Objectives. We assimilated existing knowledge to assess whether and how landscape connectivity impacts plant communities.Methods. We reviewed published literature across more than 20 years, providing an overview on the influence of connectivity on plant communities.Results. We found that landscape connectivity has a varying and complex influence on the composition and diversity of plant communities (i.e. community taxonomic structure), due to the multiplicity of factors that modulate its effect. Our understanding of how of landscape connectivity impacts the dispersal of plants is improved by using biological traits (i.e. community functional structure). Finally, we showed that landscape connectivity promotes actual dispersal between connected communities.Conclusions. This review emphasises the pertinence of trait-based and actual dispersal approaches to improve our understanding and ability to predict the effect of connectivity loss on plant communities, allowing us to identify new prospects for future research.