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关联，可为揭示物种定植与扩散模式提供关键研究视角。将景观基因组学（landscape genomics）技术应用于此类科学问题，或可获取此前未被记录的、关于物种入侵驱动因子的精细化认知。本研究以入侵性河岸灌木柽柳（Tamarix L.）为研究对象，针对美国西南部全域采集的25个种群共计259个个体，通过分析1997个全基因组范围的单核苷酸多态性（Single Nucleotide Polymorphism, SNP）标记，解析了其遗传变异的空间分布格局以及景观因子对种群相似性的调控作用。研究结果表明，柽柳种群在科罗拉多河与里奥格兰德河流域之间存在显著的大范围空间遗传分化，并识别出两条河流水系沿线阻碍种群相似性形成的潜在屏障。河流廊道对种群相似性的贡献最为突出；与之相对，低温与水坝或为种群相似性的主要障碍。本研究提出假说：遗传多样性的大范围地理格局，是由不同种群的早期引种事件、后续自然选择作用、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。