Evolution of the European alpine flora

杂交和杂种物种形成在显花植物中很常见。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种的形成都是至关重要的，并且已经表明，生殖隔离最常见的是由杂交种与亲本之间的生态分化所赋予的。我们对Sempervivum的系统发育分析提供了证据，表明来自莱茵河峡谷地区（Mittelrhein-、Nahe-、Mosel-、Ahrtal）和中部山区（法国）的该属种群目前均被归类为S. tectorum -分别代表广布和土壤易变（calcicole/calcifuge）S之间的同源倍体和多倍体杂交谱系。tectorum和西南阿尔卑斯和严格钙生S.钙质我们也有证据表明，在W阿尔卑斯山的两个亲本物种之间存在一个混合区。潜在的，这是同倍体和多倍体杂交物种形成从同一对亲本物种的第一次检测，并将代表一个理想的系统，用于比较分析的生态分化的作用，在杂交物种形成。关于莱茵河峡谷、中央高地和阿尔卑斯山西部种群的杂种起源的假说主要是基于杂种材料中有限数量的可变核核糖体基因间间隔序列位置的可加性，以及有限的未知倍性水平的样本，特别是广泛分布的S.顶盖这里提出的项目的主要目的是扩大两个亲本物种的样本，两个潜在的混合血统和混合区人口，并使用基因分型测序方法的高度可变的DNA序列的产生，预计将提供确凿的证据杂交起源。该材料还将用于测定倍性水平。土壤和气候的采样点的特点，所有谱系的生态位将建模。

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.