Abstract
Urban environments represent key models for understanding plant adaptation under Anthropocene conditions. Here, we investigated karyotypic evolution and vegetation structure of spontaneous herbaceous communities across 100 plots (1 m 2 ) in ten cities in Paraíba, Brazil. Species were classified by origin (native vs. alien plants), and chromosome numbers were determined for all taxa. A total of 8,779 individuals representing 39 species, 32 genera, and 18 families were recorded. Although native and alien species showed similar richness, alien plants exhibited substantially higher Importance Value Index (IVI), indicating stronger ecological dominance. Polyploidy occurred in 61.5% of species, including those with the highest IVIs, suggesting association between genome duplication and urban ecological success. Our results indicate that widely dispersed and polyploid plants possess enhanced adaptive capacity, providing insights into evolutionary responses of urban floras and potential survival strategies under ongoing environmental change in the Anthropocene.