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）（禾本科）有32种，分布于世界温带地区.系统发育分析的类群揭示了一个快速和相对较新的辐射内的单系亚组，包括28个物种。大部分的辐射物种出现在沿海和内陆生境的盐影响的土壤。因此，耐盐性的获得可能是这些栖息地定居和辐射的可能触发因素。在这个项目中，我们想研究两个可能的假设，关于大麦快速物种形成。这些是：（1）耐盐性是一项“关键性创新”，它允许受盐影响的生境入侵，并促进生态分化，以规避种下竞争（适应性）;（2）快速辐射是远距离扩散后在偏远生境的异地物种形成（非适应性）。为了调查这些假设，我们将开始一个比较研究的四个种从辐射分支，连同这个组的单一的姐妹分类群。本研究拟利用核微卫星标记和叶绿体单倍型分析来分析群体结构、基因流和地理分布。此外，基因表达研究与cDNA阵列，以及在受控温室条件下的培养实验将被用来了解可能的差异，在遗传背景的耐盐性的物种之间的研究。这些数据将补充生态数据，从自然林分的物种，以揭示生态偏好（小生境）的差异共域发生的物种对。