Evolution of the European alpine flora

杂交和杂交物种形成在开花植物中很常见。杂交种与其亲本物种的生殖隔离对于同倍体和多倍体杂交物种的形成都是至关重要的，有人认为生殖隔离最常见的是杂交种和亲本之间的生态分化。我们对Sempervivum的系统发育分析提供了证据，证明来自莱茵峡谷地区(Mittelhein-，Nahe-，Mosel-，Ahrtal)和中山(法国)的该属种群--目前都被归类为S.tectorum--分别代表了广布的和土壤可变的(钙质/钙隔离)S.tectorum和西南高山和严格的Calcicole S.calcaum之间的同倍体和多倍体杂交谱系。我们也有证据表明，在西阿尔卑斯山的两个亲本物种之间存在着杂交带。潜在地，这是首次从同一对亲本物种中检测到同倍体和多倍体杂交物种形成，并将代表一个比较分析生态分化在杂交物种形成中作用的理想系统。莱茵河流域、中央地块和阿尔卑斯山西部种群的杂交起源假说主要是基于杂交材料中有限数量的可变核糖体基因间隔区序列位置的可加性，以及未知倍性水平的有限样本，特别是广泛分布的顶盖螺旋藻。该项目的主要目的是扩大亲本物种的样本，包括潜在的杂交谱系和杂交区种群的样本，并使用测序分型的方法产生高度可变的DNA序列，这有望为杂交起源提供确凿的证据。该材料还将用于倍性水平的测定。将对样本点的土壤和气候进行表征，并对所有谱系的生态位进行建模。

Hybridization and hybrid speciation are frequent in flowering plants. Reproductive isolation of hybrids from their parental species is of central importance for both homoploid and polyploid hybrid speciation, and it has been suggested that reproductive isolation most commonly is conferred by ecological differentiation between hybrids and parents. Our phylogenetic analysis of Sempervivum provided evidence that populations of the genus from the Rhine Gorge area (Mittelrhein-, Nahe-, Mosel-, Ahrtal) and the Massif Central (France) - both currently classified as S. tectorum - represent homoploid and polyploid hybrid lineages, respectively, between the widespread and edaphically variable (calcicole/calcifuge) S. tectorum and the southwest Alpine and strictly calcicole S. calcareum. We also have evidence for the existence of a hybrid zone between the two parental species in the W Alps. Potentially, this is the first detection of homoploid and polyploid hybrid speciation from the same pair of parental species and would represent an ideal system for a comparative analysis of the role of ecological differentiation in hybrid speciation. The hypothesis of a hybrid origin of the Rhine Gorge, Massif Central and W Alps populations is based mainly on additivity of a limited number of variable nuclear ribosomal intergenic spacer sequence positions in the hybrid material, and on a limited sample of unknown ploidy level particularly of the widespread S. tectorum. The major aim of the project proposed here is to broaden the sample of both parental species, of both potential hybrid lineages and of the hybrid zone populations, and to use a Genotyping-by-Sequencing approach for the generation of highly variable DNA sequences which is expected to provide conclusive evidence on hybrid origin. The material will also be used for the determination of ploidy level. Soil and climate of sample sites will be characterized, and the niches of all lineages will be modelled.