Mechanisms underlying patchy distribution pattern and spread of the invasive species

Introduction: Understanding the mechanisms driving patchy distribution patterns is crucial for managing invasive species. This study investigates the multi-vector dispersal dynamics underlying the patchy spread of Methods: We integrated spatial analysis of historical and field‑collected occurrence data, mechanistic simulations, and field experiments to quantify dispersal by wind, vehicles, and animals. A Gamma Generalized Linear Mixed Model (GLMM) was used to attribute variation in empirically derived minimum arrival speeds to different vectors and their interactions. Results: We identified 103 spatially clustered patches with strong directional alignment to roads but not rivers. Wind‑mediated dispersal was limited (<0.12 km/year), whereas vehicle‑ and animal‑mediated epizoochory showed higher potential (0.08-0.58 and 0.44-0.56 km/year, respectively). Statistical models attributed 64.3% of the variance in spread speed to these three vectors, with vehicle dispersal being the most influential single factor. Synergistic interactions among vectors significantly enhanced local, within‑patch spread. However, observed long‑distance, inter‑patch dispersal speeds (up to 1,746 km/year) vastly exceeded the capacity of any natural vector or their synergy, implicating human‑mediated transport of contaminated materials as the primary driver of regional colonization. Discussion: These findings demonstrate that patchy invasions can arise from distinct mechanisms operating at different scales: local synergistic dispersal among natural and anthropogenic vectors, and long‑distance jump dispersal via human activities. Effective management therefore requires dual strategies targeting local vector synergy and regional pathways of human‑assisted spread.