Colunga-Garciamarin P, May-Pat F
Am J Bot. 1997 Nov;84(11):1449.
Extant variants of henequen (Agave fourcroydes Lem.) and wild populations of its putative ancestor A. angustifolia Haw. were grown in the Mexican state of Yucatan for 10 yr under homogeneous conditions. A statistical and numerical analysis of their patterns of morphological variation was performed as part of broader research to provide evidence of its genetic diversity, evolutionary relationships and changes under human selection. A comparison with results of a similar analysis under natural growing conditions was also made. The study indicated the following. (1) Under natural growth conditions, the three putative wild ecotypes are morphologically distinct, but under uniform conditions only populations growing in Tropical subdeciduous forest may be distinguished from the other two, thus indicating the probable existence of only two ecotypes: one growing in Coastal dunes and Tropical subdeciduous forest, and the other growing in Tropical deciduous forest. (2) This last ecotype is the most similar to cultivated variants. Within its populations, the most similar to the cultivated is that known as Chelem White, gathered by artisans for its textile use. (3) The cordage-cultivated Sac Ki and Yaax Ki differ from wild populations in four syndromes of domestication: gigantism, greater fibrosity, less thorniness, and less reproductive capacity. The lower cv of their characteristics compared with those of wild populations suggest less genetic diversity. (4) Kitam Ki is probably a textile-cultivated variant of recent introduction and/or a variant in which the artificial selection process has had different direction and intensity. (5) Improved growth conditions in the botanic garden resulted in a decreased cv, an increase in size and fiber content, and a reduction of thorniness for both wild and cultivated variants. Given that wild populations with desirable characteristics exist and that these characteristics are highly plastic and respond positively to cultivation, then selection and cultivation of populations such as those from Tropical deciduous forest may well have been the path taken by the ancient Maya during henequen domestication.
剑麻（Agave fourcroydes Lem.）的现存变种及其假定祖先狭叶龙舌兰（A. angustifolia Haw.）的野生种群在墨西哥尤卡坦州的同质条件下种植了10年。作为更广泛研究的一部分，对它们的形态变异模式进行了统计和数值分析，以提供其遗传多样性、进化关系以及在人工选择下变化的证据。还与在自然生长条件下进行的类似分析结果进行了比较。该研究表明如下情况。（1）在自然生长条件下，三种假定的野生生态型在形态上是不同的，但在统一条件下，只有生长在热带半落叶林中的种群可以与其他两个种群区分开来，因此表明可能只存在两种生态型：一种生长在沿海沙丘和热带半落叶林中，另一种生长在热带落叶林中。（2）最后这种生态型与栽培变种最为相似。在其种群中，与栽培品种最相似的是被工匠们采集用于纺织的“切莱姆白”。（3）用于制作绳索的栽培品种“萨克基”和“亚克斯基”在四个驯化综合征方面与野生种群不同：巨型化、纤维更粗、刺更少以及繁殖能力更低。与野生种群相比，它们特征的较低变异系数表明遗传多样性较低。（4）“基塔姆基”可能是近期引入的用于纺织的栽培变种和/或人工选择过程具有不同方向和强度的变种。（5）植物园中改善的生长条件导致野生和栽培变种的变异系数降低、尺寸和纤维含量增加以及刺减少。鉴于存在具有理想特征的野生种群，并且这些特征具有高度可塑性且对栽培有积极反应，那么古代玛雅人在剑麻驯化过程中很可能选择并培育了诸如来自热带落叶林的那些种群。
