Data from: Global population divergence and admixture of the brown rat (Rattus norvegicus)

Native to China and Mongolia, the brown rat (Rattus norvegicus) now enjoys a worldwide distribution. While black rats and the house mouse tracked the regional development of human agricultural settlements, brown rats did not appear in Europe until the 1500s, suggesting their range expansion was a response to relatively recent increases in global trade. We inferred the global phylogeography of brown rats using 32 k SNPs, and detected 13 evolutionary clusters within five expansion routes. One cluster arose following a southward expansion into Southeast Asia. Three additional clusters arose from two independent eastward expansions: one expansion from Russia to the Aleutian Archipelago, and a second to western North America. Westward expansion resulted in the colonization of Europe from which subsequent rapid colonization of Africa, the Americas and Australasia occurred, and multiple evolutionary clusters were detected. An astonishing degree of fine-grained clustering between and within sampling sites underscored the extent to which urban heterogeneity shaped genetic structure of commensal rodents. Surprisingly, few individuals were recent migrants, suggesting that recruitment into established populations is limited. Understanding the global population structure of R. norvegicus offers novel perspectives on the forces driving the spread of zoonotic disease, and aids in development of rat eradication programmes.

褐家鼠（Rattus norvegicus）原产于中国与蒙古国，如今已遍布全球各地。尽管黑家鼠与小家鼠始终伴随人类农业聚落的区域扩张而同步扩散，但褐家鼠直至16世纪才现身欧洲，这表明其种群范围扩张是对近代全球贸易增长的响应。本研究借助32千个单核苷酸多态性位点（Single Nucleotide Polymorphisms, SNPs），解析了褐家鼠的全球系统地理学（phylogeography）特征，在5条扩散路径中共检出13个进化簇。其中1个进化簇源自向南扩散至东南亚的种群支系。另有3个进化簇源于两次独立的向东扩散事件：一次是从俄罗斯向阿留申群岛扩散，另一次则抵达北美西部区域。向西扩散的种群率先殖民欧洲，随后借此快速扩散至非洲、美洲及澳大拉西亚区域，该路径下共检出多个进化簇。采样位点内部及位点间呈现出极高精度的精细聚类结构，这凸显了城市生境异质性对伴人生啮齿动物遗传结构的塑造程度。令人意外的是，近期发生迁移的个体极少，这表明已建立的种群其种群补充过程受到显著限制。阐明褐家鼠的全球种群结构，可为揭示驱动人畜共患病传播的核心因素提供全新视角，同时也有助于鼠类根除防控方案的研发。