Global urban environmental change drives adaptation in white clover

Abstract

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.

A global meta-analysis reveals higher variation in breeding phenology in urban birds than in their non-urban neighbours

“…Urbanisation has been associated with shifts in mean phenotypic values across a wide range of organisms (Alberti et al 2017;Merckx et al 2018;Santangelo et al 2022), including birds, which show smaller body sizes and generally lower life-history trait values in urban habitats (Chamberlain et al 2009;Sepp et al 2018;Thompson et al 2022). Our analyses expand the spatial, temporal and phylogenetic coverage of previous meta-analyses of the avian literature (Chamberlain et al 2009;Sepp et al 2018), and agree on their findings.…”

“…The extent to which mean phenotypic shifts represent adaptive responses to urbanisation in birds, either via genetic changes or plasticity, or are maladaptive, is mostly unknown (Lambert et al . 2020; see Santangelo et al . (2022) for evidence of adaptive phenotypic shifts in urban plants).…”

“…2017; Merckx et al . 2018; Santangelo et al . 2022), including birds, which show smaller body sizes and generally lower life-history trait values in urban habitats (Chamberlain et al .…”

Phenology of plant reproduction, foliar infection, and herbivory change along an urbanization gradient

“…Contrastingly, in an analysis of herbarium samples of three woody species and one understory herb collected over 112 years in the northeastern United States, urbanization was negatively correlated with insect abundance and herbivory (Meineke et al, 2019). Other evidence for changes in herbivory pressure with urbanization comes from clines in production of an antiherbivore chemical defense (hydrogen cyanide, HCN) in white clover (Johnson et al, 2018; Santangelo et al, 2022). Specifically, 75 of 160 cities around the world show clines in white clover HCN production along urban–rural transects, and most clines (62 of 160 cities) are in the direction of decreasing HCN production with urbanization (Santangelo et al, 2022).…”

“…Other evidence for changes in herbivory pressure with urbanization comes from clines in production of an antiherbivore chemical defense (hydrogen cyanide, HCN) in white clover (Johnson et al, 2018; Santangelo et al, 2022). Specifically, 75 of 160 cities around the world show clines in white clover HCN production along urban–rural transects, and most clines (62 of 160 cities) are in the direction of decreasing HCN production with urbanization (Santangelo et al, 2022). However, as for plant–pathogen interactions, so few studies have directly quantified rates of herbivory on herbaceous plants across urbanization gradients that the generality of such trends across plant species are unknown.…”