Natalia A S Przelomska, Rudy A Diaz, Fabio Andrés Ávila, Gustavo A Ballen, Rocío Cortés-B, Logan Kistler, Daniel H Chitwood, Martha Charitonidou, Susanne S Renner, Oscar A Pérez-Escobar, Alexandre Antonelli
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引用次数: 0
Abstract
South American coca (Erythroxylum coca and E. novogranatense) has been a keystone crop for many Andean and Amazonian communities for at least 8,000 years. However, over the last half-century, global demand for its alkaloid cocaine has driven intensive agriculture of this plant and placed it in the center of armed conflict and deforestation. To monitor the changing landscape of coca plantations, the United Nations Office on Drugs and Crime collects annual data on their areas of cultivation. However, attempts to delineate areas in which different varieties are grown have failed due to limitations around identification. In the absence of flowers, identification relies on leaf morphology, yet the extent to which this is reflected in taxonomy is uncertain. Here, we analyze the consistency of the current naming system of coca and its four closest wild relatives (the "coca clade"), using morphometrics, phylogenomics, molecular clocks, and population genomics. We include name-bearing type specimens of coca's closest wild relatives E. gracilipes and E. cataractarum. Morphometrics of 342 digitized herbarium specimens show that leaf shape and size fail to reliably discriminate between species and varieties. However, the statistical analyses illuminate that rounder and more obovate leaves of certain varieties could be associated with the subtle domestication syndrome of coca. Our phylogenomic data indicate extensive gene flow involving E. gracilipes which, combined with morphometrics, supports E. gracilipes being retained as a single species. Establishing a robust evolutionary-taxonomic framework for the coca clade will facilitate the development of cost-effective genotyping methods to support reliable identification.
至少在 8000 年前,南美洲古柯(Erythroxylum coca 和 E. novogranatense)一直是许多安第斯和亚马逊社区的主要作物。然而,在过去的半个世纪里,全球对可卡因生物碱的需求推动了这种植物的集约化种植,并将其置于武装冲突和森林砍伐的中心。为了监测古柯种植园地貌的变化,联合国毒品和犯罪问题办公室每年都会收集古柯种植面积的数据。然而,由于识别方面的限制,划定不同品种种植区域的尝试都以失败告终。在没有花朵的情况下,识别依赖于叶片形态,但这在分类学中的反映程度并不确定。在这里,我们利用形态计量学、系统发生组学、分子钟和种群基因组学分析了古柯及其四种近缘野生植物("古柯支系")当前命名系统的一致性。我们将古柯最近的野生近缘植物 E. gracilipes 和 E. cataractarum 的命名模式标本包括在内。对 342 份数字化标本馆标本的形态计量学分析表明,叶片形状和大小不能可靠地区分物种和变种。不过,统计分析表明,某些品种的叶片更圆、更倒卵形,可能与古柯的微妙驯化综合症有关。我们的系统发生组数据表明,涉及 E. gracilipes 的基因流非常广泛,结合形态计量学,支持将 E. gracilipes 保留为一个物种。为古柯支系建立一个强大的进化-分类框架将有助于开发具有成本效益的基因分型方法,以支持可靠的鉴定。
期刊介绍:
Molecular Biology and Evolution
Journal Overview:
Publishes research at the interface of molecular (including genomics) and evolutionary biology
Considers manuscripts containing patterns, processes, and predictions at all levels of organization: population, taxonomic, functional, and phenotypic
Interested in fundamental discoveries, new and improved methods, resources, technologies, and theories advancing evolutionary research
Publishes balanced reviews of recent developments in genome evolution and forward-looking perspectives suggesting future directions in molecular evolution applications.