Data from: Population genomic analyses reveal a history of range expansion and trait evolution across the native and invaded range of yellow starthistle (Centaurea solstitialis)

Identifying sources of genetic variation and reconstructing invasion routes for non-native introduced species is central to understanding the circumstances under which they may evolve increased invasiveness. In this study, we used genome-wide single nucleotide polymorphisms to study the colonization history of Centaurea solstitialis in its native range in Eurasia and invasions into the Americas. We leveraged this information to pinpoint key evolutionary shifts in plant size, a focal trait associated with invasiveness in this species. Our analyses revealed clear population genomic structure of potential source populations in Eurasia, including deep differentiation of a lineage found in the southern Apennine and Balkan Peninsulas and divergence among populations in Asia, eastern Europe, and western Europe. We found strongest support for an evolutionary scenario in which western European populations were derived from an ancient admixture event between populations from eastern Europe and Asia, and subsequently served as the main genetic ‘bridgehead’ for introductions to the Americas. Introductions to California appear to be from a single source region, and multiple, independent introductions of divergent genotypes likely occurred into the Pacific Northwest. Plant size has evolved significantly at three points during range expansion, including a large size increase in the lineage responsible for the aggressive invasion of California's interior. These results reveal a long history of colonization, admixture, and trait evolution in C. solstitialis, and suggest routes for improving evidence-based management decisions for one of the most ecologically and economically damaging invasive species in the western United States.

鉴定外来引入物种的遗传变异来源并重建其入侵路径，是解析该物种演化出更强入侵性的核心机制的关键环节。本研究利用全基因组单核苷酸多态性（genome-wide single nucleotide polymorphisms），对黄星蓟（Centaurea solstitialis）在欧亚大陆原生分布区的定殖历史及其入侵美洲的过程展开研究。我们依托该数据精准定位了该物种与入侵性相关的核心目标性状——植株体型的关键演化转变。分析结果显示，欧亚大陆潜在源种群具有清晰的种群基因组结构：分布于南亚平宁半岛与巴尔干半岛的谱系存在深度遗传分化，亚洲、东欧及西欧的种群间亦存在遗传分化。本研究为下述演化场景提供了最有力的支持：西欧种群起源于东欧与亚洲种群间的古老基因混合事件，随后成为向美洲扩散的主要遗传桥头堡。传入加利福尼亚的种群似乎仅来自单一源区域，而多个独立的异型基因型引入事件则大概率发生于美国太平洋西北地区。在分布范围扩张过程中，植株体型共发生了三次显著的演化转变，其中驱动加利福尼亚内陆地区恶性入侵的谱系出现了体型的大幅增长。本研究结果揭示了黄星蓟漫长的定殖、基因混合与性状演化历史，并为针对美国西部生态与经济危害最为严重的入侵物种之一制定循证管理决策提供了可行路径。