利用ITS1和Cyt b位点的DNA单链空间构型多样性研究黑脚硬蜱的种群结构

摘要

黑脚硬蜱(Ixodes scapularis)是莱姆病的主要传毒媒介.本文利用从12个不同地点采集的853个样本,采用DNA单连构型多样性的分子技术(DNA single strand conformation polymorphisms)对黑脚硬蜱的种群结构进行了分析.线粒体细胞色素b(Cyt b)和核糖体rRNA基因的内部转录空间ITS1被用为种群目标分子标记位点.在Cyt b位点上,总共发现7个单倍基因型.在ITS1位点上,共发现13个基因型.基因型频率分析结果显示,沿美国东海岸分布的黑脚硬蜱隶属于两个不同的南北种群,但是基因流在地理区域间频繁发生.尽管蜱自身的迁徙扩散能力有限,但地理区域内个体间的遗传变异程度仍然较大,这可能与黑脚硬蜱寄主动物的频繁迁移有关.另外,本研究资料显示,南方种群的遗传变异程度明显大于北方种群[动物学报50(2):176-186,2004].%The population genetic structure of the blacklegged tick Ixodes scapularis was analyzed using 853 individual ticks collected from 12 sites along the eastern seaboard of the United States. PCR-based DNA single strand conformation polymorphism (SSCP) was used for analysis of one haploid locus, the mitochondrial cytochrome b (Cyt b ), and one diploid locus, the internal transcribed spacer 1 (ITS1) of nuclear ribosomal RNA. Seven haplotypes in the Cyt b locus and 13 genotypes in the ITS1 locus were identified. Population differentiation and isolation by distance were found. Distribution of haplotype and genotype frequencies across geographic regions suggests that two distinct populations exist along the Eastern Coast of the US. However, genetic variation among individuals within regions was large. This degree of variation suggests frequent gene flow between regions. Moreover, overall genetic diversity among individuals was much higher in ticks from the southern population [Acta Zoologica Sinica 50 (2): 176 - 186, 2004].