Urban rat races: spatial population genomics of brown rats (Rattus norvegicus) compared across multiple cities

Urbanization often substantially influences animal movement and gene flow. However, few studies to date have examined gene flow of the same species across multiple cities. In this study, we examine brown rats (Rattus norvegicus) to test hypotheses about the repeatability of neutral evolution across four cities: Salvador, Brazil; New Orleans, USA; Vancouver, Canada; New York City, USA. At least 150 rats were sampled from each city and genotyped for a minimum of 15,000 genome-wide SNPs. Levels of genome-wide diversity were similar across cities, but varied across neighborhoods within cities. All four populations exhibited high spatial autocorrelation at the shortest distance classes (&lt; 500 m) due to limited dispersal. Coancestry and evolutionary clustering analyses identified genetic discontinuities within each city that coincided with a resource desert in New York City, major waterways in New Orleans, and roads in Salvador and Vancouver. Such replicated studies are crucial to assessin...城市化通常会显著影响动物的活动与基因流。然而，截至目前，鲜有研究针对同一物种在多个城市间的基因流展开探讨。本研究以褐家鼠（Rattus norvegicus）为研究对象，旨在验证中性进化的可重复性假说，研究覆盖四座城市：巴西萨尔瓦多、美国新奥尔良、加拿大温哥华以及美国纽约市。本研究从每座城市中至少采集150只褐家鼠样本，并对其开展全基因组范围至少15000个单核苷酸多态性（Single Nucleotide Polymorphism, SNP）的基因分型。四座城市的全基因组多样性水平整体相近，但城市内部不同街区间存在差异。由于扩散能力有限，四个种群在最短距离组（<500米）中均表现出显著的空间自相关。共祖分析与进化聚类分析均发现，各城市内部存在遗传间断现象：纽约市的遗传间断与资源匮乏区域重合，新奥尔良的则与主要水道重合，而萨尔瓦多和温哥华的则与道路网络重合。此类重复性研究对于评估