Santangelo et al., 2022. Global urban environmental change drives adaptation in white clover. Science 375:1275-1281.pdf

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.