Molecular evidence for recent founder populations and human-mediated migration in the barley scald pathogen Rhynchosporium secalis
Molecular evidence for recent founder populations and human-mediated migration in the barley scald pathogen Rhynchosporium secalis
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DOI：
10.1016/j.ympev.2009.03.002
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发表时间：
2009-06-01
影响因子：
4.1
通讯作者：
McDonald, B. A.
中科院分区：
文献类型：
--
作者：
Linde, C. C.;Zala, M.;McDonald, B. A.
Rhynchosporium secalis 是全球大麦的重要病原菌。对从 37 个野外种群中采样的 1664 个 R. secalis 分离株进行了 14 个多态性微卫星分析，以推断其种群历史。结果推翻了 R. secalis 与其在中东的大麦宿主共同进化的假设。来自斯堪的纳维亚半岛的人群具有显着更高的等位基因多样性、最多数量的私人等位基因和最高的基因型多样性。与等位基因的数量相比，除了三个之外，所有分析的种群都具有过多的基因多样性，这与最近的种群瓶颈相一致。其余种群存在基因多样性缺陷，这与过去 +/- 100 年最近出现种群瓶颈后的种群扩张一致。合并分析显示，所分析种群的基于 θ 的有效种群规模相对于其祖先种群而言较小，这表明祖先种群中存在的多样性中只有一小部分传递到了当前种群中。这些发现与大麦上的病原体种群经历了由宿主和/或创始种群施加的选择瓶颈的假设是一致的。迁移率的平均估计值为 2.2（平均 90% 置信区间 = 1.3-3.1）。在相距很远的人群中确定了主要的迁徙路线，例如南非和澳大利亚之间，以及北非、中东和加利福尼亚之间，这表明受感染的大麦种子在当代进行了交换。与早期的发现相反，大多数种群表现出显着的配子不平衡，这可能是遗传漂变的结果。我们得出的结论是，大多数 R. secalis 种群都经历了人类介导的迁徙，导致世界各地发生了大量且相对较新的创始人事件。 (C) 2009 Elsevier Inc. 保留所有权利。
Rhynchosporium secalis is an important pathogen of barley globally. Fourteen polymorphic microsatellites were analyzed for 1664 R. secalis isolates sampled from 37 field populations to infer their demographic history. The results falsified the hypothesis that R. secalis co-evolved with its barley host in the Middle East. Populations from Scandinavia had significantly higher allelic diversities, the greatest number of private alleles and the highest genotypic diversities. All but three of the analyzed populations had an excess of gene diversity compared to the number of alleles, consistent with a recent population bottleneck. The remaining populations had a gene diversity deficit consistent with a population expansion following a recent population bottleneck in the last +/- 100 years. A coalescent analysis revealed that the effective population sizes based on theta, of the analyzed populations were small relative to their ancestral population indicating that only a fraction of the diversity present in the ancestral populations was transmitted into current populations. These findings are consistent with the hypothesis that the pathogen population on barley experienced a selection bottleneck imposed by the host and/or are founder populations. The mean estimate of migration rates was 2.2 (avg 90% confidence interval = 1.3-3.1). Major migration routes were identified among populations separated by long distances, eg between South Africa and Australia, as well as among North Africa, the Middle East and California, suggesting contemporary exchange of infected barley seed. In contrast with earlier findings, most populations exhibited significant gametic disequilibrium, probably as a result of genetic drift. We conclude that the majority of R. secalis populations have experienced human-mediated migration that led to numerous and relatively recent founder events around the world. (C) 2009 Elsevier Inc. All rights reserved.