基于线粒体COI基因序列的黄胫小车蝗不同地理种群的遗传分化及基因流分析

Analysis of genetic differentiation and gene flow among different geographic populations of Oedaleus infernalis ( Orthoptera: Acrididae) based on mtDNA COI gene sequences

黄胫小车蝗OedaleusinfernalisSaussure是一种在我国分布广泛、对农牧业生产危害严重的经济害虫。本文对黄胫小车蝗10个地理种群的线粒体COI基因序列进行测序和分析，利用DnaSP5．0和Arlequin3．5．1．2软件对该蝗虫种群问的遗传多样性、遗传分化程度、基因流水平及分子变异进行了分析，建立了单倍型贝叶斯系统发育进化树和单倍型网络图。结果表明：在所分析的144个序列样本中，共检测到21种单倍型，其中1种单倍型为10个地理种群所共享。总群体的单倍型多样性指数为0．653，各地理种群单倍型多样度范围在0．423～0．790之间。总群体和各种群的Tajima’sD检验结果皆不显著，说明该种害虫在较近的历史上未经历群体扩张。总群体的遗传分化系数Gst为0．04436，固定系数Fst为0．05255，基因流Nm为9．01。AMOVA分子方差分析结果表明，黄胫小车蝗的遗传分化主要来自种群内部，种群间的遗传变异水平较低。各地理种群的遗传距离的大小与其地理距离间没有显著的相关性。贝叶斯系统发育进化树与单倍型网络图显示，黄胫小车蝗各地理种群中的单倍型散布在不同的分布群中，分布格局较为混杂，未形成明显的系统地理结构。研究结果揭示，黄胫小车蝗各种群间的基因交流并未受到地理距离的影响。

Oedaleus infernalis Saussure is one of the most important agricultural and grass forage pests, which is widely spread in China. The partial sequences of mtDNA COI gene in 10 geographic populations of O. infernalis were sequenced and analyzed. The genetic diversity, genetic differentiation, gene flow and molecular variance were analyzed using DnaSP 5.0 and Arlequin 3.5.1.2. Bayesian inference （BI） phylogenetic tree and the haplotype network of COl haplotypes were constructed. The results showed that a total of 21 haplotypes were defined among 144 gene sequences, including one haplotype shared by ten populations. The total haplotype diversity of all populations was 0. 653 and the range of haplotype diversity of different populations was 0. 423 - 0. 790. The Tajima＇ s D test indicated that there might be no population expansion for the total in recent history. The total Gst was 0.04436, Fst was 0. 05255 and the gene flow Nm was 9.01 among 10 populations. Molecular variance analysis （AMOVA） demonstrated that observed genetic differentiation mainly occurs within populations and just a little differentiation exists among populations. The genetic distance among populations was not correlated with the geographic distribution. The Bayesian inference （BI） phylogenetic tree and haplotype network showed that haplotypes were distributed in different clades and no obvious geographical structure formed. The results suggest that the gene flow among O. infernalis populations is not affected by the geographical distance.