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首页> 外文期刊>Plant Systematics and Evolution >Extreme genetic depauperation and differentiation of both populations and species in Eurasian feather grasses (Stipa)
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Extreme genetic depauperation and differentiation of both populations and species in Eurasian feather grasses (Stipa)

机译：欧亚羽毛草（Stipa）中种群和物种的极端遗传退化和分化

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A highly selfing breeding system affects gene flow, which may have consequences for patterns of genetic variation and differentiation on both the population and species level. Feather grasses (Stipa spp.) are dominant elements of Eurasian steppes that persist in Central Europe in scattered isolated populations that are of great conservation interest. Cleistogamy is common in the Stipa pennata group, the phylogeny of which is largely unresolved. Intraspecific patterns of genetic variation can be characterised by lack of gene flow due to selfing, but also by large-scale historical migrations and long-term isolation. We analysed both 5 species within the S. pennata group and 33 populations of Stipa pulcherrima sampled across a large part of its range. Using AFLP markers we assessed phylogenetic relationships of the S. pennata group and patterns of genetic variation within and among populations. The S. pennata group formed a consistent clade separated from S. capillata. Stipa pulcherrima was sister to S. eriocaulis, but the relationships among S. pennata s. str., S. borysthenica., and S. tirsa remained unresolved. Within-population genetic variation was extremely low in all species of the S. pennata group (H (e) = 0.0-0.013). In S. pulcherrima, genetic variation was consistently relatively high in the east (Romania, Russia) and declined toward western populations, with many populations at the western range edge lacking genetic variation entirely. Populations were strongly differentiated (F (ST) = 0.762), and this differentiation did not follow a classical pattern of isolation by distance. Bayesian cluster analysis revealed nine gene pools in S. pulcherrima, which were mostly geographically clustered. Overall the results suggest that S. pulcherrima and species of the S. pennata group are characterised by a cleistogamous breeding system leading to extremely low levels of genetic variation and high levels of population differentiation at both the population and species level. Postglacial colonisation, current population isolation, and population bottlenecks at the western range periphery have further reduced genetic variation and obviated gene exchange. Thus, genetic variation can only be preserved by the conservation of multiple populations.
机译：高度自交系的繁殖系统会影响基因流，这可能会影响种群和物种水平上的遗传变异和分化模式。羽毛草（Stipa spp。）是欧亚草原的主要元素，这些草在欧洲中部存在于分散的孤立种群中，具有重要的保护意义。 Cleistogamy在Stipa pennata组中很常见，其系统发育在很大程度上尚未解决。遗传变异的种内模式的特征可以是由于自交而缺乏基因流，而且还可以进行大规模的历史迁移和长期隔离。我们分析了S. pennata组中的5个物种以及在其很大一部分范围内采样的33种Stipa pulcherrima种群。使用AFLP标记，我们评估了S. pennata组的系统发育关系以及种群内部和种群之间的遗传变异模式。 Pennata链球菌群形成了与Capillata链球菌分离的一致枝条。 Stipa pulcherrima是S. eriocaulis的姐妹，但S. pennata s之间的关系。 str。，borysthenica。和S. tirsa仍未解决。在S. pennata组的所有物种中，种群内遗传变异极低（H（e）= 0.0-0.013）。在S. pulcherrima中，东部（罗马尼亚，俄罗斯）的遗传变异一直相对较高，而向西部种群下降，西部范围边缘的许多种群完全缺乏遗传变异。种群之间存在高度差异（F（ST）= 0.762），这种差异没有遵循经典的距离隔离模式。贝叶斯聚类分析揭示了S. pulcherrima中的九个基因库，这些基因库大多在地理上是聚类的。总体而言，结果表明，S。pulcherrima和S. pennata组物种的特征在于，其习性配生繁殖系统导致种群和物种水平的遗传变异水平极低，种群分化程度高。冰川后殖民，当前的种群隔离以及西部山脉外围的种群瓶颈进一步降低了遗传变异并消除了基因交换。因此，遗传变异只能通过多个种群的保存来保存。

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