Single Geographic Origin of a Widespread Autotetraploid Arabidopsis arenosa Lineage Followed by Interploidy Admixture
Single Geographic Origin of a Widespread Autotetraploid Arabidopsis arenosa Lineage Followed by Interploidy Admixture
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DOI：
10.1093/molbev/msv089
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发表时间：
2015-06-01
影响因子：
10.7
通讯作者：
Bomblies, Kirsten
中科院分区：
文献类型：
--
作者：
Arnold, Brian;Kim, Sang-Tae;Bomblies, Kirsten
全基因组复制导致多倍体，与物种形成和生物新颖性有关。在植物中，许多物种表现出倍性变异，这可能代表了多倍体谱系进化的早期阶段。为了理解这种多倍体系统的进化，我们必须解决诸如多倍体谱系(S)是否具有单一或多个起源，倍性之间是否发生混合，以及倍性变异影响种群进化的时间尺度等问题。在这里，我们使用非参数和参数分析方法，包括基于合并的方法，分析了三个基因组数据集，以研究地理上广泛存在的拟南芥同源四倍体变体的进化史，这是一个新的模型系统，用于理解同源多倍体进化的分子基础。同源四倍体木兰种群广泛分布于北欧和中欧的大部分地区，而二倍体则出现在东欧和波罗的海南部海岸；这两个倍体在喀尔巴底山脉重叠。我们发现，我们采样的广泛的同源四倍体种群可能来自大约11,000-30,000代前的北喀尔巴底山脉的一个祖先种群，今天在那里发现了它现存的最近的二倍体亲戚。之后，四倍体种群分裂成至少四个主要世系，殖民了欧洲的大部分地区。种群历史的重建表明，大量的倍性混合发生在两个方向上，但仅在地理上接近的种群中发生。我们发现了两种情况，其中选择可能作用于一个导入的基因座，这表明持续的倍间基因流动对白杨遗传变异的模式有局部影响。
Whole-genome duplication, which leads to polyploidy, has been implicated in speciation and biological novelty. In plants, many species exhibit ploidy variation, which is likely representative of an early stage in the evolution of polyploid lineages. To understand the evolution of such multiploidy systems, we must address questions such as whether polyploid lineage(s) had a single or multiple origins, whether admixture occurs between ploidies, and the timescale over which ploidy variation affects the evolution of populations. Here we analyze three genomic data sets using nonparametric and parametric analyses, including coalescent-based methods, to study the evolutionary history of a geographically widespread autotetraploid variant of Arabidopsis arenosa, a new model system for understanding the molecular basis of autopolyploid evolution. Autotetraploid A. arenosa populations are widely distributed across much of Northern and Central Europe, whereas diploids occur in Eastern Europe and along the southern Baltic coast; the two ploidies overlap in the Carpathian Mountains. We find that the widespread autotetraploid populations we sampled likely arose from a single ancestral population approximately 11,000-30,000 generations ago in the Northern Carpathians, where its closest extant diploid relatives are found today. Afterward, the tetraploid population split into at least four major lineages that colonized much of Europe. Reconstructions of population history suggest that substantial interploidy admixture occurred in both directions, but only among geographically proximal populations. We find two cases in which selection likely acted on an introgressed locus, suggesting that persistent interploidy gene flow has a local influence on patterns of genetic variation in A. arenosa.