Genetic diversity and population structure of invasive and native populations of Erigeron canadensis L.

Abstract

Invasive alien plants threaten biodiversity across the world. Erigeron canadensis (horseweed) is considered one of the most problematic agricultural weeds and represents a classic example of inter-continental invasion. Here, we studied the genetic diversity and population structure of invasive alien populations from the Jiangsu and Zhejiang Provinces in China and native populations from Alabama, in the USA. Methods: We used ten polymorphic SSR loci to genotype 312 individuals from five native and five invasive populations to estimate the genetic diversity and structure. Important Findings: Invasive populations from Jiangsu and Zhejiang Provinces showed, on average, similar genetic diversity to native populations from Alabama, indicating no severe genetic bottlenecks during the invasion. STRUCTURE revealed low population differentiation and only two genetic groupings were detected in both native and invaded ranges. The high diversity observed in the invasive populations suggested multiple introductions and/or the introduction of genetically diverse propagules during initial colonization. Our study provides new insights towards understanding the invasion dynamics of this globally noxious weed in Eastern China. Preventing gene flow via seed dispersal between invasive and native populations should be examined to prevent the introduction and dispersal of herbicide resistant individuals and inform management practices.

小蓬草入侵地和原产地种群的遗传多样性和种群结构 外来入侵植物对全球生物多样性造成了危害。小蓬草(Erigeron canadensis L.)是危害最为严重的外来农业杂草之一，代表了洲际入侵的典型例子。本研究利用10个多态性SSR位点，分别对采自中国江苏和浙江省的入侵地和采自美国阿拉巴马州的原产地各5个种群、共计312个植株的基因型进行了遗传多样性和遗传结构分析。结果表明，江苏省和浙江省的入侵种群显示出与阿拉巴马州原产地种群相似的遗传多样性，表明入侵期间没有严重的遗传瓶颈。利用STRUCTURE对种群结构的分析结果显示，种群之间分化较低，在原产地和入侵范围内均只仅检测到两个基因群。在入侵种群中观察到的遗传多样性较高，表明在入侵初期可能存在多次引入或引入了遗传背景不同的繁殖体。上述研究为阐明小蓬草这一全球有害杂草在中国东部的入侵动态提供了新的证据。在防除实践中，应注意防范小蓬草入侵种群和本地种群之间的种子基因流传播，阻止除草剂抗性植株的引入和扩散。