Data from: How hot are Drosophila hotspots? Examining recombination rate variation and associations with nucleotide diversity, divergence, and maternal age in Drosophila pseudoobscura

Fine scale meiotic recombination maps have uncovered a large amount of variation in crossover rate across the genomes of many species, and such variation in mammalian and yeast genomes is concentrated to <5 kb regions of highly elevated recombination rates (10–100x the background rate) called “hotspots.” Drosophila exhibit substantial recombination rate heterogeneity across their genome, but evidence for these highly-localized hotspots is lacking. We assayed recombination across a 40 Kb region of Drosophila pseudoobscura chromosome 2, with one 20 kb interval assayed every 5 Kb and the adjacent 20 kb interval bisected into 10 kb pieces. We found that recombination events across the 40 kb stretch were relatively evenly distributed across each of the 5 kb and 10 kb intervals, rather than concentrated in a single 5 kb region. This, in combination with other recent work, indicates that the recombination landscape of Drosophila may differ from the punctate recombination pattern observed in many mammals and yeast. Additionally, we found no correlation of average pairwise nucleotide diversity and divergence with recombination rate across the 20 kb intervals, nor any effect of maternal age in weeks on recombination rate in our sample.

精细尺度减数分裂重组图谱已揭示众多物种的全基因组范围内交换率存在广泛差异；在哺乳动物与酵母基因组中，这类差异集中于重组率远高于本底水平（为本底速率的10~100倍）、长度小于5kb的区域，这类区域被称为"重组热点（recombination hotspots）"。果蝇（Drosophila）的全基因组同样存在显著的重组率异质性，但目前尚未发现这类高度定位的重组热点的相关证据。我们对伪暗果蝇（Drosophila pseudoobscura）2号染色体上一段40kb的区域进行了重组率检测：其中一段20kb的区间以5kb为步长进行采样检测，相邻的另一段20kb区间则被均分为两段10kb的片段进行检测。我们发现，这段40kb区域内的重组事件在各5kb和10kb区间内分布相对均匀，并未集中于某一个5kb的区域内。这一发现结合其他近期相关研究，表明果蝇的重组格局或许与众多哺乳动物和酵母中观察到的点状重组模式存在差异。此外，我们未在20kb区间内发现平均两两核苷酸多样性、核苷酸分歧度与重组率之间存在相关性，同时在本次样本中也未观察到以周为单位统计的母本年龄对重组率的影响。