Imprints of racism: Cities create challenging environments for many nonhuman species, and the presence of nonhumans in cities influences the health and well-being of the humans with which they share the environment. Distinct urban conditions are created by landscape modification, but the history of this transformation is not equal across urban environments. Schell et al. review how systematic racist practices such as residential segregation, enacted in part through redlining, have led to an unequal distribution of “nature” within cities. These inequities continue to play out in both the ecological processes of cities and the welfare of their residents. Science , this issue p. eaay4497
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.