Herbarium specimens reveal a historical shift in phylogeographic structure of common ragweed during native range disturbance

Invasive plants provide ample opportunity to study evolutionary shifts that occur after introduction to novel environments. However, although genetic characters pre-dating introduction can be important determinants of later success, large-scale investigations of historical genetic structure have not been feasible. Common ragweed (Ambrosia artemisiifolia L.) is an invasive weed native to North America that is known for its allergenic pollen. Palynological records from sediment cores indicate that this species was uncommon before European colonization of North America, and ragweed populations expanded rapidly as settlers deforested the landscape on a massive scale, later becoming an aggressive invasive with populations established globally. Toward a direct comparison of genetic structure now and during intense anthropogenic disturbance of the late 19th century, we sampled 45 natural populations of common ragweed across its native range as well as historical herbarium specimens collected u...入侵植物为研究物种被引入新生境后所发生的进化转变提供了绝佳的研究契机。然而，尽管引入前的遗传特征可作为物种后续入侵成功的重要决定因素，但此前大规模开展历史遗传结构的研究并不具备可行性。普通豚草（Ambrosia artemisiifolia L.）是原产于北美洲的入侵性杂草，其花粉的致敏性广为人知。沉积物岩芯（sediment cores）的孢粉记录（Palynological records）显示，该物种在欧洲殖民北美洲之前并不常见；随着殖民者大规模砍伐森林，豚草种群迅速扩张，后续更成为极具侵略性的入侵物种，在全球范围内建立起种群。为直接对比当前与19世纪末强烈人为干扰时期的遗传结构，我们在其原生分布范围内采集了45个天然种群的样本，同时收集了……的标本馆历史标本。