Studying the levels and patterns of genetic diversity of invasive populations is important to understand the evolutionary and ecological factors promoting invasions and for better designing preventive and control strategies. Wild sunflower (Helianthus annuus L.) is native to North America and was introduced, and has become invasive, in several countries, including Argentina (ARG). Here, using classical population genetic analyses and Approximate Bayesian Computation (ABC) modelling, we studied the invasion history of wild sunflower in ARG. We analyzed 115 individuals belonging to 15 populations from ARG (invasive range) and United States (US, native range) at 14 nuclear and three chloroplast simple sequence repeat markers along with 23 phenotypic variables. Populations from ARG showed similar levels of nuclear genetic diversity to US populations and higher genetic diversity in the chloroplast genome, indicating no severe genetic bottlenecks during the invasion process. Bayesian clustering analysis, based on nuclear markers, suggests the presence of three genetic clusters, all present in both US and ARG. Discriminant analysis of principal components (DAPC) detected an overall low population structure between central US and ARG populations but separated two invasive populations from the rest. ABC modelling supports multiple introductions but also a southward dispersal within ARG. Genetic and phenotypic data support the central US as a source of introduction while the source of secondary introductions could not be resolved. Finally, using genetic markers from the chloroplast genome, we found lower population structure in ARG when compared to US populations, suggesting a role for seed-mediated gene flow in Argentina.

中文翻译：

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阿根廷野生向日葵（Helianthus annuus L.）的遗传多样性和种群结构：重建其入侵历史

研究入侵种群的遗传多样性水平和模式对于了解促进入侵的进化和生态因素以及更好地设计预防和控制策略非常重要。野生向日葵 (Helianthus annuus L.) 原产于北美洲，在包括阿根廷 (ARG) 在内的多个国家被引入并具有侵入性。在这里，我们使用经典的种群遗传分析和近似贝叶斯计算 (ABC) 建模，研究了 ARG 中野生向日葵的入侵历史。我们在 14 个核和三个叶绿体简单序列重复标记以及 23 个表型变量上分析了属于来自 ARG（侵入范围）和美国（美国，原生范围）的 15 个种群的 115 个个体。来自 ARG 的种群显示出与美国种群相似的核遗传多样性水平和更高的叶绿体基因组遗传多样性，表明在入侵过程中没有严重的遗传瓶颈。基于核标记的贝叶斯聚类分析表明存在三个遗传簇，均存在于 US 和 ARG 中。主成分判别分析 (DAPC) 检测到美国中部和 ARG 种群之间的总体低种群结构，但将两个入侵种群与其他种群分开。ABC 建模支持多个引入，但也支持 ARG 内的向南扩散。遗传和表型数据支持美国中部作为引入来源，而二次引入的来源无法解决。最后，利用叶绿体基因组的遗传标记，