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.

•Background and Aims Animal-pollinated angiosperms have evolved a variety of signalling mechanisms to attract pollinators. Floral scent is a key component of pollinator attraction, and its chemistry modulates both pollinator behaviour and the formation of plant–pollinator networks. The neotropical orchid genus Gongora exhibits specialized pollinator associations with male orchid bees (Euglossini). Male bees visit orchid flowers to collect volatile chemical compounds that they store in hind-leg pouches to use subsequently during courtship display. Hence, Gongora floral scent compounds simultaneously serve as signalling molecules and pollinator rewards. Furthermore, because floral scent acts as the predominant reproductive isolating barrier among lineages, it has been hypothesized that chemical traits are highly species specific. A comparative analysis of intra- and inter-specific variation of floral scent chemistry was conducted to investigate the evolutionary patterns across the genus.•Methods Gas chromatography–mass spectrometry (GC-MS) was used to analyse the floral scent of 78 individuals belonging to 28 different species of Gongora from two of the three major lineages sampled across the neotropical region. Multidimensional scaling and indicator value analyses were implemented to investigate the patterns of chemical diversity within and among taxonomic groups at various geographic scales. Additionally, pollinator observations were conducted on a sympatric community of Gongora orchids exhibiting distinct floral scent phenotypes.•Key Results A total of 83 floral volatiles, mainly terpenes and aromatic compounds, were detected. Many of the identified compounds are common across diverse angiosperm families (e.g. cineole, eugenol, β-ocimene, β-pinene and terpinen-4-ol), while others are relatively rare outside euglossine bee-pollinated orchid lineages. Additionally, 29 volatiles were identified that are known to attract and elicit collection behaviour in male bees. Floral scent traits were less variable within species than between species, and the analysis revealed exceptional levels of cryptic diversity. Gongora species were divided into 15 fragrance groups based on shared compounds. Fragrance groups indicate that floral scent variation is not predicted by taxonomic rank or biogeographic region.•Conclusions Gongora orchids emit a diverse array of scent molecules that are largely species specific, and closely related taxa exhibit qualitatively and quantitatively divergent chemical profiles. It is shown that within a community, Gongora scent chemotypes are correlated with near non-overlapping bee pollinator assemblies. The results lend support to the hypothesis that floral scent traits regulate the architecture of bee pollinator associations. Thus, Gongora provides unique opportunities to examine the interplay between floral traits and pollinator specialization in plant–pollinator mutualisms.

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Background Nasopharyngeal specimens (NPS) are commonly used for SARS-CoV-2 testing but can be uncomfortable for patients. Self-collected saliva or anterior nasal specimens (ANS) for SARS-CoV-2 detection are less invasive but the sensitivity of these specimen types has not been thoroughly evaluated. Methods During September–November 2020, 730 adults undergoing SARS-CoV-2 testing at community testing events and homeless shelters in Denver provided self-collected saliva and ANS specimens before NPS collection and answered a short survey about symptoms and specimen preference. Specimens were tested for SARS-CoV-2 by rRT-PCR; viral culture was performed on a subset of specimens positive by rRT-PCR. Sensitivity of saliva and ANS for SARS-CoV-2 detection by rRT-PCR was measured against NPS. Subgroup analyses included test outcomes by symptom status and culture results. Results Sensitivity for SARS-CoV-2 detection by rRT-PCR appeared higher for saliva than for ANS (85% vs. 80%) and among symptomatic participants than among those without symptoms (94% vs. 29% for saliva; 87% vs. 50% for ANS). Among participants with culture-positive SARS-CoV-2 by any specimen type, sensitivity of saliva and ANS by rRT-PCR was 94% and 100%, respectively. Saliva and ANS were equally preferred by participants; most would undergo NPS again despite being least preferred. Conclusions Saliva was slightly more sensitive than ANS for SARS-CoV-2 detection by rRT-PCR. Both saliva and ANS reliably detected SARS-CoV-2 among participants with symptoms. Self-collected saliva and ANS offer practical advantages, are preferred by patients, and might be most useful for testing people with COVID-19 symptoms.