Tomimatsu Hiroshi, Kephart Susan R, Vellend Mark
Departments of Botany and Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.
Mol Ecol. 2009 Sep;18(18):3918-28. doi: 10.1111/j.1365-294X.2009.04341.x. Epub 2009 Sep 1.
Recent human activities have spread numerous plant species across the globe, yet it is unclear to what degree historical human activities influenced plant dispersal. In western North America, Camassia quamash was one of the most important food plants for indigenous peoples, who transported its propagules either intentionally or accidentally. We investigated how human and natural dispersal might have contributed to the current pattern of spatial genetic structure in C. quamash by performing phylogeographical surveys at two geographical scales. We sequenced two noncoding regions of chloroplast deoxyribonucleic acid (DNA) in 226 individuals from 53 populations of C. quamash as well as 126 individuals from 21 populations of the non-food plant Zigadenus venenosus. Contrary to the expectation of anthropogenic transport, C. quamash populations did not exhibit weaker genetic structure than Z. venenosus populations. We also failed to find convincing evidence for signatures of transport. Instead, our data showed strong effects of past glaciation and geographical barriers of the mountains in the Cascade Range, Olympic Peninsula and Vancouver Island. West of the Cascades, the species appears to have largely migrated northward from a southern refugium after deglaciation, whereas few populations having a highly divergent haplotype might have survived in southwestern Washington. Our data suggest that despite substantial ethnobotanical evidence for anthropogenic transport, the current pattern of genetic structure of C. quamash does not show any detectable signatures of transport by indigenous peoples and is better understood as the result of natural dispersal processes.
近期的人类活动已使众多植物物种在全球范围内扩散，然而历史上人类活动对植物传播的影响程度尚不清楚。在北美西部，食用 camass（Camassia quamash）是当地原住民最重要的食用植物之一，他们有意或无意地传播其繁殖体。我们通过在两个地理尺度上进行系统地理学调查，研究了人类和自然传播可能如何促成了食用 camass 当前的空间遗传结构模式。我们对来自食用 camass 的53个种群的226个个体以及来自非食用植物毒蝇伞（Zigadenus venenosus）的21个种群的126个个体的叶绿体脱氧核糖核酸（DNA）的两个非编码区域进行了测序。与人为传播的预期相反，食用 camass 种群的遗传结构并不比毒蝇伞种群的遗传结构弱。我们也未能找到令人信服的传播特征证据。相反，我们的数据显示了过去冰川作用以及喀斯喀特山脉、奥林匹克半岛和温哥华岛山脉的地理屏障的强烈影响。在喀斯喀特山脉以西，该物种似乎在冰川消退后主要从南部避难所向北迁移，而在华盛顿州西南部可能有少数具有高度分化单倍型的种群存活了下来。我们的数据表明，尽管有大量民族植物学证据证明存在人为传播，但食用 camass 当前的遗传结构模式并未显示出任何可检测到的原住民传播特征，将其更好地理解为自然传播过程的结果更为恰当。
