Macpherson J Michael, González Josefa, Witten Daniela M, Davis Jerel C, Rosenberg Noah A, Hirsh Aaron E, Petrov Dmitri A
Department of Biological Sciences, Stanford University, USA.
Mol Biol Evol. 2008 Jun;25(6):1025-42. doi: 10.1093/molbev/msn007. Epub 2008 Jan 16.
A beneficial mutation that has nearly but not yet fixed in a population produces a characteristic haplotype configuration, called a partial selective sweep. Whether nonadaptive processes might generate similar haplotype configurations has not been extensively explored. Here, we consider 5 population genetic data sets taken from regions flanking high-frequency transposable elements in North American strains of Drosophila melanogaster, each of which appears to be consistent with the expectations of a partial selective sweep. We use coalescent simulations to explore whether incorporation of the species' demographic history, purifying selection against the element, or suppression of recombination caused by the element could generate putatively adaptive haplotype configurations. Whereas most of the data sets would be rejected as nonneutral under the standard neutral null model, only the data set for which there is strong external evidence in support of an adaptive transposition appears to be nonneutral under the more complex null model and in particular when demography is taken into account. High-frequency, derived mutations from a recently bottlenecked population, such as we study here, are of great interest to evolutionary genetics in the context of scans for adaptive events; we discuss the broader implications of our findings in this context.
一种在群体中几乎但尚未完全固定的有益突变会产生一种特征性的单倍型构型，称为部分选择性清除。非适应性过程是否可能产生类似的单倍型构型尚未得到广泛研究。在这里，我们考虑了5个群体遗传数据集，这些数据集取自北美黑腹果蝇品系高频转座元件侧翼区域，每个数据集似乎都符合部分选择性清除的预期。我们使用溯祖模拟来探究纳入物种的种群历史、针对该元件的纯化选择或该元件引起的重组抑制是否会产生假定的适应性单倍型构型。虽然在标准中性零模型下，大多数数据集会被判定为非中性，但只有在更复杂的零模型下，特别是考虑种群统计学因素时，有强有力的外部证据支持适应性转座的那个数据集似乎才是非中性的。像我们在此研究的那样，来自近期经历瓶颈效应群体的高频衍生突变，在适应性事件扫描的背景下，对进化遗传学具有极大的研究价值；我们在此背景下讨论了我们研究结果的更广泛意义。
