Seaports are introduction hotspots for invasive alien species (IAS). This is especially true for rodents, which have accompanied humans around the globe since the earliest days of ocean-going voyages. The rapid spread of IAS soon after arrival in a new environment is facilitated by further human-mediated transport or landscape features, like roads. By measuring genetic diversity and structure to investigate dispersal pathways, we gained insight into the transport, spread and establishment stages of a biological invasion, leveraging the most common rodent species (R. norvegicus) in this setting. We characterized the genetic structure of three Norway rat populations along a busy industrial road used by trucks to access the Port area in Paranaguá city (Brazil). A total of 71 rats were genotyped using 11 microsatellite markers. The results revealed a pattern of gene flow contrary to the expected stepping-stone model along the linear transect, with the two furthest apart populations being clustered together. We hypothesize that the observed outcome is explained by natural dispersal along the corridor being lower than human-mediated transport. The sampled area furthest from the port is a gas station frequented by trucks which are considered the most likely mode of transportation. In terms of management strategies, we suggest more emphasis should be put on cargo surveillance to lower the risk of Norway rat dispersal, not only for biosecurity, but also for sanitary reasons, as this port is a major grain trading point.

海港是外来入侵物种 (IAS) 的引进热点。对于啮齿类动物来说尤其如此，它们从远洋航行的早期开始就伴随着人类环游世界。进入新环境后不久 IAS 的迅速传播是由进一步的以人为媒介的交通或景观特征（如道路）促进的。通过测量遗传多样性和结构来研究传播途径，我们利用最常见的啮齿动物物种（R. norvegicus）深入了解了生物入侵的运输、传播和建立阶段) 在此设置中。我们沿着一条繁忙的工业道路描述了三个挪威老鼠种群的遗传结构，卡车用于进入巴拉那瓜市（巴西）的港口区。使用 11 个微卫星标记对总共 71 只大鼠进行基因分型。结果揭示了一种与沿着线性横断面的预期垫脚石模型相反的基因流动模式，两个相距最远的种群聚集在一起。我们假设观察到的结果是由沿走廊的自然扩散低于人类介导的运输来解释的。距离港口最远的采样区域是卡车经常光顾的加油站，这被认为是最有可能的运输方式。在管理策略方面，我们建议应更加重视货物监控，以降低挪威老鼠扩散的风险，