我国棉铃虫主要地理种群的遗传结构、种群动态和相互关系的初步研究
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该研究工作首先为棉铃虫建立一套多态性高、可用于种内变异分析的微卫星DNA标记，然后利用这套标记对采自全国10个省27个地区的棉铃虫标本进行系统的遗传分析，尝试从进化和遗传角度揭示上述问题的答案.所获得的结果主要包括以下几个方面:1.为棉铃虫建立了一套特异性微卫星DNA标记系统，共得到5个单拷贝、多态性、可用于种群遗传分析的微卫星位点.连锁不平衡检测结果表明，在这些微卫星位点间没有紧密的连锁关系.同时，还为其它6个研究体系的研究对象(包括松毛虫、黑斑蛙、泽蛙、筏蜘蛛、东亚钳蝎、朱鹮)建立了微卫星富集性基因组文库并进行了阳性克隆的序列测定和筛选，其中筏蜘蛛、松毛虫和朱鹮的微卫星标记的引物设计、优化等工作已经完成.2.依据棉铃虫和松毛虫等七个物种微卫星标记系统建立中得到的结果，结合其它实验室已发表的资料，对鳞翅目昆虫基因组中微卫星DNA的情况做了较深入地分析.结果表明，鳞翅目昆虫基因组中含有相对较多的多拷贝微卫星序列和三相重复微卫星，但该类昆虫基因组中微卫星DNA的总体丰度相对较低.3.通过哈迪-温伯格平衡检测，我们发现多数棉花铃虫种群符合哈迪-温伯格平衡，但在几乎所有种群中都存在杂合度偏低的杂合体亏缺现象，在不符合哈迪-温伯格平衡的群体中更为明显，这可能主要是由近亲交配以及瓶颈效应引起的.4.系统性种群遗传分析表明，新疆地区的棉铃虫种群与黄河、长江流域及北部特早熟棉区种群有显著的遗传差别和极显著的地理隔离效应，暗示西北内陆棉区的棉铃虫与东部地区的种群间没有明显的基因交流，相互迁飞的强度和频度应极弱; 新疆地区的棉铃虫不应是由黄河流域和长江流域棉区迁飞过去的，而是可能来自于境外如印度和巴基斯坦地区.5.东部季风区的北部特早熟棉区、黄河流域棉区和长江流域棉区间的各地区种群没有显著差别，表明这三个棉区间存在广泛的基因交流.黄河流域棉区和长江流域棉区间不存在任何地理隔离效应，说明这两个棉区间棉铃虫相互迁飞的强度和频度应该是很大的; 黄河流域和辽宁地区之间存在显著的地理隔离效应，表明棉铃虫在这两个棉区间的迁飞受到一定的限制; 而长江流域和辽宁地区的种群间不存在地理隔离效应，暗示辽宁地区和长江流域棉区间棉铃虫的迁飞强度和频度大于它和黄河流域之间交流.6.研究结果显示，长江流域、黄河流域和北部特早熟棉区的棉铃虫种群间没有显著遗传差别，这些棉区间存在频繁的基因交流.因此，将棉铃虫按棉区或生态型划分种群是不合适的，对虫害治理更有意义、更客观的划分方案可能是以新疆种群为代表的西北种群和由长江流域棉区、黄河流域棉区和北部特早熟棉区的地理种群组成的东部种群。
This study first established a set of highly polymorphic microsatellite DNA markers for Helicoverpa armigera (cotton bollworm) to enable intraspecific variation analysis, then performed systematic genetic analysis on Helicoverpa armigera specimens collected from 27 locations across 10 provinces in China, aiming to reveal the answers to the aforementioned questions from evolutionary and genetic perspectives. The main results are as follows: 1. A species-specific microsatellite DNA marker system was established for Helicoverpa armigera, yielding 5 single-copy, polymorphic microsatellite loci suitable for population genetic analysis. Linkage disequilibrium detection showed no tight linkage between these microsatellite loci. Additionally, we constructed enriched genomic libraries of microsatellites and conducted sequence determination and screening of positive clones for the study subjects of 6 other research systems, including Dendrolimus spp., Rana nigromaculata, Fejervarya multistriata, Dolomedes sp., Buthus martensii Karsch, and Nipponia nippon. Primer design and optimization of microsatellite markers for Dolomedes sp., Dendrolimus spp., and Nipponia nippon have been completed. 2. Based on the results from the development of microsatellite marker systems for Helicoverpa armigera, Dendrolimus spp. and other five species, combined with published data from other laboratories, we conducted an in-depth analysis of microsatellite DNA in the genomes of Lepidoptera insects. The results showed that Lepidoptera genomes contain relatively high numbers of multi-copy microsatellite sequences and triplet-repeat microsatellites, but the overall abundance of microsatellite DNA in the genomes of these insects is relatively low. 3. Through Hardy-Weinberg equilibrium tests, we found that most Helicoverpa armigera populations conform to Hardy-Weinberg equilibrium, but a heterozygote deficit phenomenon with low heterozygosity exists in almost all populations, which is more pronounced in populations that do not conform to Hardy-Weinberg equilibrium. This may be mainly caused by inbreeding and bottleneck effects. 4. Systematic population genetic analysis revealed that Helicoverpa armigera populations in the Xinjiang region have significant genetic differences and extremely significant geographic isolation effects compared with populations from the Yellow River Basin, Yangtze River Basin and the northern extremely early-maturing cotton region, suggesting that there is no obvious gene flow between populations in the Northwestern Inland Cotton Region and eastern regions, and the intensity and frequency of mutual migration are extremely low. Helicoverpa armigera populations in Xinjiang should not have migrated from the Yellow River Basin and Yangtze River Basin cotton regions, but may have originated from overseas regions such as India and Pakistan. 5. There were no significant differences among populations from the northern extremely early-maturing cotton region, Yellow River Basin cotton region and Yangtze River Basin cotton region in the eastern monsoon zone, indicating widespread gene flow among these three cotton regions. There is no geographic isolation effect between the Yellow River Basin and Yangtze River Basin cotton regions, suggesting that the intensity and frequency of mutual migration of Helicoverpa armigera between these two cotton regions are very high; there is a significant geographic isolation effect between the Yellow River Basin and Liaoning region, indicating that the migration of Helicoverpa armigera between these two cotton regions is restricted to a certain extent; while there is no geographic isolation effect between populations from the Yangtze River Basin and Liaoning region, implying that the intensity and frequency of migration of Helicoverpa armigera between Liaoning region and the Yangtze River Basin cotton region are greater than those between it and the Yellow River Basin. 6. The results showed that there were no significant genetic differences among Helicoverpa armigera populations from the Yangtze River Basin, Yellow River Basin and northern extremely early-maturing cotton region, and frequent gene flow exists among these cotton regions. Therefore, it is inappropriate to divide Helicoverpa armigera populations by cotton region or ecotype. A more meaningful and objective division scheme for pest management may be the northwestern population represented by Xinjiang populations, and the eastern population composed of geographic populations from the Yangtze River Basin, Yellow River Basin and northern extremely early-maturing cotton region.
