Data from: Population genomic analysis suggests strong influence of river network on spatial distribution of genetic variation in invasive saltcedar across the southwestern US

Understanding the complex influences of landscape and anthropogenic elements that shape the population genetic structure of invasive species provides insight into patterns of colonization and spread. The application of landscape genomics techniques to these questions may offer detailed, previously undocumented insights into factors influencing species invasions. We investigated the spatial pattern of genetic variation and the influences of landscape factors on population similarity in the invasive riparian shrub saltcedar (Tamarix L.) by analyzing 1,997 genome-wide SNP markers for 259 individuals from 25 populations collected throughout the southwestern US. Our results revealed a broad-scale spatial genetic differentiation of saltcedar populations between the Colorado and Rio Grande river basins and identified potential barriers to population similarity along both river systems. River pathways most strongly contributed to population similarity. In contrast, low temperature and dams likely served as barriers to population similarity. We hypothesize that large-scale geographic patterns in genetic diversity resulted from a combination of early introductions from distinct populations, the subsequent influence of natural selection, dispersal barriers, and founder effects during range expansion.解析塑造入侵物种种群遗传结构的景观与人为因素的复杂影响，有助于深入理解物种的定殖与扩散模式。将景观基因组学技术应用于此类研究问题，或可揭示此前未被记录的、关于物种入侵影响因子的精细化认知。我们通过对美国西南部25个种群的259个个体的1997个全基因组单核苷酸多态性（Single Nucleotide Polymorphism, SNP）标记进行分析，探究了入侵河岸灌木柽柳（Tamarix L.）的遗传变异空间格局，以及景观因子对种群相似性的影响。研究结果显示，柽柳种群在科罗拉多河与里奥格兰德河流域之间存在大范围的空间遗传分化，并识别出两条河流水系沿线阻碍种群相似性的潜在屏障。河流通路对种群相似性的贡献最为显著；与之相反，低温与水坝或可成为种群相似性的阻碍因子。我们提出假说：遗传多样性的大范围地理格局，是由源自不同种群的早期引种、后续自然选择的影响、扩散屏障以及种群扩张过程中的奠基者效应共同作用形成的。