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，可为揭示物种定殖与扩散模式提供关键视角。将景观基因组学（landscape genomics）技术应用于此类研究问题，可获取此前未被记录的、关于物种入侵影响因子的详尽认知。本研究针对入侵性河岸灌木柽柳（Tamarix L.）展开研究，以采自美国西南部25个种群的259个个体为研究对象，通过分析1997个全基因组范围的单核苷酸多态性（Single Nucleotide Polymorphism）标记，解析了其遗传变异的空间格局，以及景观因素对种群遗传相似性的影响。研究结果显示，科罗拉多河与里奥格兰德河流域的柽柳种群存在大范围的空间遗传分化，并在两大河流水系沿线均识别出影响种群遗传相似性的潜在障碍。河流廊道对种群遗传相似性的贡献最为显著；与之相反，低温与水坝可能成为阻碍种群遗传相似性形成的因素。本研究推测，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事件、后续自然选择的作用、扩散障碍以及种群扩张过程中的奠基者效应（founder effect）共同塑造而成。