Buonaccorsi V P, McDowell J R, Graves J E
School of Marine Science, Virginia Institute of Marine Science, College of William & Mary, Gloucester Point, VA, USA.
Mol Ecol. 2001 May;10(5):1179-96. doi: 10.1046/j.1365-294x.2001.01270.x.
Different classes of molecular markers occasionally yield discordant views of population structure within a species. Here, we examine the distribution of molecular variance from 14 polymorphic loci comprising four classes of molecular markers within approximately 400 blue marlin individuals (Makaira nigricans). Samples were collected from the Atlantic and Pacific Oceans over 5 years. Data from five hypervariable tetranucleotide microsatellite loci and restriction fragment length polymorphism (RFLP) analysis of whole molecule mitochondrial DNA (mtDNA) were reported and compared with previous analyses of allozyme and single-copy nuclear DNA (scnDNA) loci. Temporal variance in allele frequencies was nonsignificant in nearly all cases. Mitochondrial and microsatellite loci revealed striking phylogeographic partitioning among Atlantic and Pacific Ocean samples. A large cluster of alleles was present almost exclusively in Atlantic individuals at one microsatellite locus and for mtDNA, suggesting that, if gene flow occurs, it is likely to be unidirectional from Pacific to Atlantic oceans. Mitochondrial DNA inter-ocean divergence (FST) was almost four times greater than microsatellite or combined nuclear divergences including allozyme and scnDNA markers. Estimates of Neu varied by five orders of magnitude among marker classes. Using mathematical and computer simulation approaches, we show that substantially different distributions of FST are expected from marker classes that differ in mode of inheritance and rate of mutation, without influence of natural selection or sex-biased dispersal. Furthermore, divergent FST values can be reconciled by quantifying the balance between genetic drift, mutation and migration. These results illustrate the usefulness of a mitochondrial analysis of population history, and relative precision of nuclear estimates of gene flow based on a mean of several loci.
不同类别的分子标记偶尔会对一个物种内的种群结构产生不一致的看法。在此，我们研究了约400条蓝枪鱼（Makaira nigricans）个体中14个多态性位点的分子变异分布，这些位点包含四类分子标记。样本在5年时间里从大西洋和太平洋采集。报告了来自五个高变四核苷酸微卫星位点的数据以及全分子线粒体DNA（mtDNA）的限制性片段长度多态性（RFLP）分析结果，并与之前对同工酶和单拷贝核DNA（scnDNA）位点的分析进行了比较。在几乎所有情况下，等位基因频率的时间变异都不显著。线粒体和微卫星位点揭示了大西洋和太平洋样本之间显著的系统地理划分。在一个微卫星位点和线粒体DNA上，一大簇等位基因几乎只存在于大西洋个体中，这表明，如果存在基因流动，很可能是从太平洋到大西洋的单向流动。跨洋线粒体DNA分化（FST）几乎是微卫星或包括同工酶和scnDNA标记在内的联合核分化的四倍。Neu的估计值在不同标记类别之间相差五个数量级。使用数学和计算机模拟方法，我们表明，由于遗传方式和突变率不同的标记类别，在没有自然选择或性别偏向扩散影响的情况下，预期FST会有显著不同的分布。此外，通过量化遗传漂变、突变和迁移之间的平衡，可以使不同的FST值趋于一致。这些结果说明了线粒体分析在种群历史研究中的有用性，以及基于多个位点平均值的核基因流估计的相对精度。
