Speciation mechanisms underlying rapid radiations in South American and Central Asian species of Hordeum (Poaceae)

南美洲和中亚大麦（禾本科）物种快速辐射的物种形成机制

• 批准号: 5362813
• 负责人: Dr. Frank R. Blattner
• 金额: --
• 依托单位: Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2002
• 资助国家: 德国
• 起止时间: 2001-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5362813?language=en
• 关键词: Speciation; mechanisms; underlying; rapid; radiations

The barley genus Hordeum (Poaceae) occurs with 32 species in temperate regions of the world. Phylogenetic analysis of the taxa revealed a rapid and relatively recent radiation within a monophyletic subgroup, comprising 28 of the species. A large fraction of the radiated species occurs on salt influenced soils in coastal and interior habitats. The acquirement of salt tolerance thus could have been a possible trigger for the colonization of and radiation in these habitats. In the proposed project, we like to investigate two possible hypotheses concerning rapid speciation in Hordeum. These are: (1) Salt tolerance is a "key innovation" that allowed the invasion of salt influenced habitats and promoted ecological differentiation to circumvent infraspecific competition (adaptive); (2) rapid radiation is caused by allopatric speciation in remote habitats after long distance dispersal (non-adaptive). To investigate these hypotheses we will initiate a comparative study on four species from the radiated clade, together with the single sistertaxon of this group. We intend to analyze the population structure, the gene flow, and the phylogeography with nuclear microsatellite markers and chloroplast haplotype analysis. Additionally, gene expression studies with cDNA arrays, together with cultivation experiments under controlled greenhouse conditions will be used to get insights in possible differences in the genetic background of salt tolerance among the species under study. These data will be supplemented by ecological data from natural stands of the species to reveal differences in ecological preferences (niches) between sympatrically occurring species pairs.

大麦属Hordeum属（Poaceae）发生在世界温带地区的32种。对分类单元的系统发育分析表明，单系亚组中的辐射迅速，相对较新，包括该物种的28种。辐射物种的很大一部分发生在盐和内部栖息地的盐影响土壤上。因此，耐盐的耐受性的获取可能是这些栖息地定植和辐射的可能触发。在拟议的项目中，我们想研究有关霍尔德姆快速物种形成的两个可能的假设。这些是：（1）盐耐受性是一种“关键创新”，允许侵袭盐影响栖息地并促进生态分化以绕过不受欢迎的竞争（自适应）； （2）快速辐射是由长距离传播后偏远栖息地（非自适应）的同种异体物种引起的。为了研究这些假设，我们将与该组的单个sistertaxon一起对来自辐射进化枝的四个物种进行比较研究。我们打算通过核微卫星标记和叶绿体单倍型分析分析种群结构，基因流量和植物地理学。此外，将使用cDNA阵列的基因表达研究，以及在受控温室条件下的培养实验，将用于在研究中的盐耐受性遗传耐受性的遗传背景中的可能差异。这些数据将由物种自然林的生态数据补充，以揭示同性恋发生的物种对之间生态偏好（壁ch）的差异。