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（禾本科）有32种，分布在世界温带地区。对该分类群的系统发育分析表明，在一个单系亚群内，该亚群包括28个物种，发生了快速而相对较近的辐射。辐射物种的很大一部分发生在沿海和内陆栖息地受盐影响的土壤上。因此，获得耐盐性可能是这些栖息地的殖民化和辐射的可能触发因素。在提议的项目中，我们想调查两种关于Hordeum快速物种形成的可能假设。它们是：(1)耐盐性是一种“关键创新”，允许受盐影响的栖息地入侵，促进生态分化，以规避种下竞争（适应性）；(2)快速辐射是由异地物种在远距离扩散（非适应性）后形成的。为了验证这些假设，我们将对来自辐射分支的四个物种以及该群体的单个姐妹分类单元进行比较研究。利用核微卫星标记和叶绿体单倍型分析对其种群结构、基因流动和系统地理进行分析。此外，利用cDNA阵列进行基因表达研究，并在受控温室条件下进行栽培试验，以了解所研究物种之间耐盐遗传背景的可能差异。这些数据将由物种自然林分的生态数据加以补充，以揭示同地发生的物种对之间的生态偏好（生态位）差异。