Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, campus Morelia, Apartado Postal 27-3 (Santa María de Guido), Morelia, Michoacán, México.
Ann Bot. 2010 Sep;106(3):483-96. doi: 10.1093/aob/mcq143.
The Tehuacán Valley in Mexico is a principal area of plant domestication in Mesoamerica. There, artificial selection is currently practised on nearly 120 native plant species with coexisting wild, silvicultural and cultivated populations, providing an excellent setting for studying ongoing mechanisms of evolution under domestication. One of these species is the columnar cactus Stenocereus pruinosus, in which we studied how artificial selection is operating through traditional management and whether it has determined morphological and genetic divergence between wild and managed populations.
Semi-structured interviews were conducted with 83 households of three villages to investigate motives and mechanisms of artificial selection. Management effects were studied by comparing variation patterns of 14 morphological characters and population genetics (four microsatellite loci) of 264 plants from nine wild, silvicultural and cultivated populations.
Variation in fruit characters was recognized by most people, and was the principal target of artificial selection directed to favour larger and sweeter fruits with thinner or thicker peel, fewer spines and pulp colours other than red. Artificial selection operates in agroforestry systems favouring abundance (through not felling plants and planting branches) of the preferred phenotypes, and acts more intensely in household gardens. Significant morphological divergence between wild and managed populations was observed in fruit characters and plant vigour. On average, genetic diversity in silvicultural populations (H(E) = 0.743) was higher than in wild (H(E) = 0.726) and cultivated (H(E) = 0.700) populations. Most of the genetic variation (90.58 %) occurred within populations. High gene flow (Nm(FST) > 2) was identified among almost all populations studied, but was slightly limited by mountains among wild populations, and by artificial selection among wild and managed populations.
Traditional management of S. pruinosus involves artificial selection, which, despite the high levels of gene flow, has promoted morphological divergence and moderate genetic structure between wild and managed populations, while conserving genetic diversity.
墨西哥的特瓦坎谷是中美洲主要的植物驯化地区。在那里，近 120 种本地植物与野生、造林和栽培种群共存，同时进行人工选择，为研究驯化过程中正在进行的进化机制提供了极好的环境。其中一种物种是柱状仙人掌 Stenocereus pruinosus，我们研究了人工选择是如何通过传统管理发挥作用的，以及它是否导致了野生和管理种群之间的形态和遗传分化。
对三个村庄的 83 户家庭进行了半结构式访谈，以调查人工选择的动机和机制。通过比较 264 株植物的 14 个形态特征和种群遗传学（四个微卫星位点），对 9 个野生、造林和栽培种群的变异模式进行了研究，以研究管理效应。
大多数人都认识到果实特征的变异，并且主要是人工选择的目标，目的是选择更大、更甜、果皮更薄或更厚、刺更少、果肉颜色不是红色的果实。人工选择在农林复合系统中起作用，有利于受青睐的表型的丰度（通过不砍伐植物和种植树枝），并且在家庭花园中作用更强烈。在果实特征和植物活力方面，观察到野生和管理种群之间存在显著的形态差异。平均而言，造林种群的遗传多样性（H(E) = 0.743）高于野生种群（H(E) = 0.726）和栽培种群（H(E) = 0.700）。大多数遗传变异（90.58%）发生在种群内部。在几乎所有研究的种群之间都发现了高基因流（Nm(FST) > 2），但在野生种群之间受到山脉的限制，在野生和管理种群之间受到人工选择的限制。
S. pruinosus 的传统管理涉及人工选择，尽管基因流水平较高，但仍促进了野生和管理种群之间的形态分化和适度的遗传结构，同时保持了遗传多样性。
