Albernaz K C, Silva-Brandão K L, Fresia P, Cônsoli F L, Omoto C
Departamento de Entomologia e Acarologia, Escola Superior de Agricultura 'Luiz de Queiroz', Universidade de São Paulo, Brazil.
Bull Entomol Res. 2012 Jun;102(3):333-43. doi: 10.1017/S0007485311000678. Epub 2011 Nov 30.
Intra- and inter-population genetic variability and the demographic history of Heliothis virescens (F.) populations were evaluated by using mtDNA markers (coxI, coxII and nad6) with samples from the major cotton- and soybean-producing regions in Brazil in the growing seasons 2007/08, 2008/09 and 2009/10. AMOVA indicated low and non-significant genetic structure, regardless of geographical scale, growing season or crop, with most of genetic variation occurring within populations. Clustering analyzes also indicated low genetic differentiation. The haplotype network obtained with combined datasets resulted in 35 haplotypes, with 28 exclusive occurrences, four of them sampled only from soybean fields. The minimum spanning network showed star-shaped structures typical of populations that underwent a recent demographic expansion. The recent expansion was supported by other demographic analyzes, such as the Bayesian skyline plot, the unimodal distribution of paired differences among mitochondrial sequences, and negative and significant values of neutrality tests for the Tajima's D and Fu's F(S) parameters. In addition, high values of haplotype diversity (Ĥ) and low values of nucleotide diversity (π), combined with a high number of low frequency haplotypes and values of θ(π)<θ(W), suggested a recent demographic expansion of H. virescens populations in Brazil. This demographic event could be responsible for the low genetic structure currently found; however, haplotypes present uniquely at the same geographic regions and from one specific host plant suggest an initial differentiation among H. virescens populations within Brazil.
利用线粒体DNA标记（细胞色素氧化酶亚基I、细胞色素氧化酶亚基II和烟酰胺腺嘌呤二核苷酸脱氢酶亚基6），对2007/08、2008/09和2009/10生长季巴西主要棉花和大豆产区的烟芽夜蛾种群进行了种群内和种群间的遗传变异性以及种群历史评估。分子方差分析表明，无论地理尺度、生长季或作物如何，遗传结构均较低且不显著，大部分遗传变异发生在种群内部。聚类分析也表明遗传分化较低。合并数据集得到的单倍型网络产生了35个单倍型，其中28个为独家出现，其中4个仅从大豆田采样。最小生成网络显示出典型的经历近期种群扩张的种群的星形结构。其他种群分析也支持了近期的扩张，如贝叶斯天际线图、线粒体序列间配对差异的单峰分布以及Tajima's D和Fu's F(S)参数的中性检验的负值和显著值。此外，高单倍型多样性（Ĥ）值和低核苷酸多样性（π）值，再加上大量低频单倍型和θ(π)<θ(W)值，表明巴西烟芽夜蛾种群近期经历了种群扩张。这一种群事件可能是目前发现的低遗传结构的原因；然而，在相同地理区域和来自一种特定寄主植物中独特存在的单倍型表明巴西境内烟芽夜蛾种群之间存在初步分化。
