Song S V, Anderson C, Good R T, Leslie S, Wu Y, Oakeshott J G, Robin C
School of Biosciences, University of Melbourne,Victoria,Australia.
MRC Human Genetics Unit,MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital,Edinburgh,UK.
Bull Entomol Res. 2018 Dec;108(6):817-830. doi: 10.1017/S0007485318000081. Epub 2018 Feb 5.
Over the last 40 years, many types of population genetic markers have been used to assess the population structure of the pest moth species Helicoverpa armigera. While this species is highly vagile, there is evidence of inter-continental population structure. Here, we examine Z-chromosome molecular markers within and between Chinese and Australian populations. Using 1352 polymorphic sites from 40 Z-linked loci, we compared two Chinese populations of moths separated by 700 km and found virtually no population structure (n = 41 and n = 54, with <1% of variation discriminating between populations). The levels of nucleotide diversity within these populations were consistent with previous estimates from introns in Z-linked genes of Australian samples (π = 0.028 vs. 0.03). Furthermore, all loci surveyed in these Chinese populations showed a skew toward rare variants, with ten loci having a significant Tajima's D statistic, suggesting that this species could have undergone a population expansion. Eight of the 40 loci had been examined in a previous study of Australian moths, of which six revealed very little inter-continental population structure. However, the two markers associated with the Cyp303a1 locus that has previously been proposed to be a target of a selective sweep, exhibited allele structuring between countries. Using a separate dataset of 19 Australian and four Chinese moths, we scanned the molecular variation distributed across the entire Z-chromosome and found distinct blocks of differentiation that include the region containing Cyp303a1. We recommend some of these loci join those associated with insecticide resistance to form a set of genes best suited to analyzing population structure in this global pest.
在过去40年里，许多类型的群体遗传标记已被用于评估害虫棉铃虫（Helicoverpa armigera）的群体结构。虽然该物种具有高度的迁移性，但有证据表明存在洲际群体结构。在这里，我们研究了中国和澳大利亚群体内部以及群体之间的Z染色体分子标记。利用来自40个Z连锁基因座的1352个多态性位点，我们比较了两个相距700公里的中国棉铃虫群体，发现几乎不存在群体结构（n = 41和n = 54，群体间差异的变异小于1%）。这些群体中的核苷酸多样性水平与之前澳大利亚样本中Z连锁基因内含子的估计值一致（π = 0.028对0.03）。此外，在这些中国群体中调查的所有基因座都倾向于稀有变异，有10个基因座的Tajima's D统计量显著，这表明该物种可能经历了群体扩张。在之前对澳大利亚棉铃虫的研究中，对40个基因座中的8个进行了检测，其中6个显示出几乎没有洲际群体结构。然而，与之前被认为是选择性清除目标的Cyp303a1基因座相关的两个标记，在不同国家间表现出等位基因结构。利用一个由19只澳大利亚棉铃虫和4只中国棉铃虫组成的单独数据集，我们扫描了分布在整个Z染色体上的分子变异，发现了不同的分化区域，其中包括包含Cyp- 303a1的区域。我们建议将其中一些基因座与那些与抗药性相关的基因座结合起来，形成一组最适合分析这种全球害虫群体结构的基因。
