基于线粒体COⅠ基因黑唇苜蓿盲蝽种群遗传结构与遗传多样性分析

Population genetic structure and genetic diversity of Adelphocoris nigritylus based on mt DNA COⅠ gene sequence variation

【目的】黑唇苜蓿盲蝽Adelphocoris nigritylus Hsiao作为一种植食性昆虫,近年来越来越多的个体有转向农作物取食危害的趋势。本研究旨在探讨黑唇苜蓿盲蝽在中国北部地区的种群遗传结构、遗传多样性、系统发育和种群历史动态。【方法】针对10个地理种群256头个体线粒体COⅠ基因片段(893bp)进行种群遗传分析。【结果】共检测到33个单倍型,确定1个祖先单倍型H5和3个高频率单倍型。Mantel检测显示种群间遗传距离与地理距离没有显著的相关性。中性检验和Beast分析显示种群整体经历了扩张。AMOVA和种群间成对Fst分析表明种群间遗传差异整体较低。Migrate分析显示种群间存在大量的基因流。BI单倍型系统发育树和Network网络中介图分析显示种群在整体扩张的同时,部分种群个体已经出现了遗传分化并形成独立的遗传支系,虽然各种群遗传单系还没有形成。【结论】作者推测人为干扰可能是导致黑唇苜蓿盲蝽整体扩张的主要原因;种群间高水平的基因流是导致低遗传差异的重要原因;廊坊种群与其它种群间存在显著的遗传差异和低的遗传多样性,可能是由于该种群在扩张过程中发生了遗传漂变。

[Objectives] Adelphocoris nigritylus Hsiao is a phytophagous insect that feeds on a wide variety of plants and in recent years has damaged agricultural crops. This study aims to explore the population genetic structure, genetic diversity, phylogeny and demographic history of this species in North China. [Methods] We applied the population genetic approach to analyze variation in the mitochondrial DNA COⅠ gene fragment（893 bp） of 256 individuals from 10 populations. [Results] A total of 33 haplotypes were found, including one source haplotype（H5） and three high frequency haplotypes. A Mantel test indicated no significant correlation between genetic and geographic distance among populations. A Neutrality test and Beast analysis indicated that all populations may have experienced population expansion. An AMOVA and paired Fst values revealed relatively low genetic differentiation among populations, and Migrate indicated a high level of gene flow among populations. A BI phylogenetic tree and Network analyses indicated evidence of overall population expansion, but also of distinct genetic clades in some individual populations and sub-regions, although monophyletic groups have not yet developed. [Conclusion] We speculate that human activity may be the main reason for the apparent population expansion of A. nigritylus in north China. The relatively low genetic differentiation among populations is probably due to the high level of gene flow between them. The significantly high genetic differentiation between the Langfang population and other populations, and the relatively low genetic diversity in the Langfang population, suggests that genetic drift may have occurred during the process of population expansion in this population.