基于微卫星的中国红火蚁种群遗传结构的研究

背景]自入侵中国之后,红火蚁已给农林业、健康卫生、生态环境等造成了危害。红火蚁在中国的入侵、扩散路径及方式等仍然是待解决的问题。方法]利用微卫星分子标记,对来自国内14个地区和国外1个地区共15个红火蚁地理种群的遗传多样性水平及种群遗传结构进行了研究。结果]应用7对微卫星引物共检测到28个等位基因,15个红火蚁种群在各微卫星位点的基因型频率均符合Hardy-Weinberg平衡。各种群的平均表观杂合度HO、预期杂合度HE、Shannon信息指数Ⅰ、基因多样性指数Nei＇s和多态位点百分率P分别为0.2848、0.2708、0.3174、0.2629和43.63%,研究结果表明这15个红火蚁种群具有比较丰富的遗传多样性。种群间平均分化系数FST为0.4258,说明有42.58%的变异来源于种群间,表明红火蚁各种群之间有较高程度的分化,且遗传分化可能是由地理隔离和基因流障碍（Nem=0.7442）共同引起。遗传距离D显示,河源种群与其他种群间的遗传距离均相对高于其他各种群间的遗传距离,表明河源种群与其他地理种群之间存在较大的遗传差异,可能是较为原始的类型。结论与意义]短距离的种群主要通过自然扩散方式传播,地理距离与亲缘关系有一定的相关性;长距离的种群主要依靠人为传播,因此地理距离与遗传距离不成正比。对于长距离的入侵事件,监控与检疫是关键的预防措施。

Population genetic structure of Solenopsis invicta Buren in China based on microsatellite

Background ] As a notorious invasive species, the red imported fire ant （Solenopsis invicta） has important economic con- sequences as it causes losses to households and businesses including agriculture since its introduction in China. However, little is now about the sources of introduced populations and their entry paths. Method ] The genetic diversity of 15 populations of S. invicta collected from 14 regions in China and one from United States of America were investigated using microsatellite molecular marker SSR （simple sequence repeat）. Result] Two to six alleles were found at each microsatellite locus （total 28 alleles at seven loci）. The mean observed heterozygosity （Ho ） and expected heterozygosity （HЕ） were consistent with Hardy-Weinberg equilibrium. A medium level of genetic diversity was revealed ： Ho = 0. 2848, HЕ = 0. 2708, I = 0. 3174, Nei＇s = 0.2629 and P = 43.63%. The mean genetic differentiation index FST was 0.4258, indicating that 42.58% of the total molecular variance was attributable to popula- tion divergence. The high level of genetic differentiation might be caused by geographic isolation and barriers to gene flow （ Nem = 0.7442）. The genetic distance D showed that the genetic distances between Heyuan population and the other populations was rela- tively higher than any other two populations, suggesting that Heyuan population might be the or/ginal source among all the Chinese populations. On the basis of UPGMA cluster analysis, genetic differentiation was mainly due to geographic separation and trade movement. Conclusion and significance] Based on our results, there was a significant relationship between genetic distance and ge- ographic distance for close populations but not for populations far apart. The results suggest that monitoring or quarantine programs targeting source areas or key transportation routes are crucial for long distance invasion events.