Nadler S A
J Nematol. 1996 Sep;28(3):277-85.
Molecular markers have been used only rarely to characterize the population genetic structure of nematodes. Published studies have suggested that different taxa may show distinct genetic architectures. Isoenzyme and RAPD markers have been used to investigate geographic variation of Ascaris suum at the level of infrapopulations (nematodes within individual hosts), within localities, and among geographic regions. Independent estimates of genetic differentiation among population samples based on isoenzyme and RAPD data showed similar patterns and substantial correlation. Heterozygote deficiencies within infrapopulations and large values for inbreeding coefficients among infrapopulations suggested that the composition of these populations was not consistent with a model of random recruitment from a large panmictic pool of life-cycle stages. Both isoenzyme and RAPD markers revealed moderate levels of genetic differentiation among samples representing infrapopulations and localities. Of total gene diversity, 9.4% (isoenzyme) and 9.2% (RAPD) was partitioned among infrapopulations. Geographic localities accounted for 7.8% (isoenzyme) and 6.2% (RAPD) of total diversity. Only infrapopulations from the same farm had low levels of differentiation.
分子标记很少被用于描述线虫的群体遗传结构。已发表的研究表明，不同的分类群可能表现出不同的遗传结构。同工酶和随机扩增多态性DNA（RAPD）标记已被用于研究猪蛔虫在亚群体水平（单个宿主体内的线虫）、局部地区内以及地理区域之间的地理变异。基于同工酶和RAPD数据对群体样本间遗传分化的独立估计显示出相似的模式和高度的相关性。亚群体内杂合子缺失以及亚群体间近交系数的高值表明，这些群体的组成不符合从一个大型随机交配的生命周期阶段库中随机招募的模型。同工酶和RAPD标记都揭示了代表亚群体和局部地区的样本间存在中等程度的遗传分化。在总的基因多样性中，9.4%（同工酶）和9.2%（RAPD）分布在亚群体之间。地理区域占总多样性的7.8%（同工酶）和6.2%（RAPD）。只有来自同一农场的亚群体分化程度较低。
