Population genomics reveals genetic structure and dispersal sources of the invasive herb Solanum rostratum in northern China

IntroductionThe invasion of Solanum rostratum is causing severe damage to grassland ecosystems in northern China, with the species now spreading rapidly through ongoing emergence of new populations. To prevent further expansion, it is urgent to understand its dispersal patterns and identify the sources of new invasions. This study tested two hypotheses: (i) new invasions originate from established populations that serve as anthropogenic dispersal hubs, and (ii) gene flow is asymmetric, reflecting patterns consistent with human-mediated jump dispersal.MethodsWe integrated population genomics and invasion history by analyzing genome-wide single nucleotide polymorphisms (SNPs) from 261 individuals across 30 populations. Populations were categorized as early-invaded (long-established), mid-invaded (moderately recent), or newly invaded based on county-level invasion records. Phylogenetic relationships, population structure, gene flow patterns, and dispersal networks were reconstructed using phylogenetic, clustering, and gene flow analyses to trace evolutionary relationships and potential dispersal routes.ResultsPhylogenetic analysis resolved seven major monophyletic groups (A–G), while population structure analysis inferred seven ancestral gene pools (P1–P7), with strong concordance between the two independent datasets. Early-invaded populations exhibited clear spatial genetic differentiation. In contrast, newly invaded populations showed genetic admixture with ancestries overlapping multiple gene pools, indicating multiple origins and supporting a mixed dispersal pattern involving both local spread and long-distance jump dispersal. Specifically, new invasions in the Xilin Gol (XL) grassland were traced to agricultural regions in Zhangjiakou (ZJ) and Chifeng (CF). Gene flow and network analyses identified these early-invaded agricultural regions as key dispersal hubs supplying migrants to newly invaded areas. Source populations exhibited higher genetic diversity (Ne, Ho, He, Fis, π), whereas newly invaded populations showed reduced diversity, consistent with founder effects.DiscussionThese findings confirm the hypothesis of asymmetric, human-mediated jump dispersal and clarify the invasion genetic architecture of S. rostratum. By identifying agricultural regions as critical dispersal hubs, this study provides precise targets for early management interventions, offering actionable insights to prevent further expansion and enhance grassland biosecurity.