The factors that drive the rapid changes in abundance of tandem arrays of highly repetitive sequences, known as satellite DNA, are not well understood. Drosophila virilis has one of the highest relative amounts of simple satellites of any organism that has been studied, with an estimated >40% of its genome composed of a few related 7-bp satellites. Here, we use D. virilis as a model to understand technical biases affecting satellite sequencing and the evolutionary processes that drive satellite composition. By analyzing sequencing data from Illumina, PacBio, and Nanopore platforms, we identify platform-specific biases and suggest best practices for accurate characterization of satellites by sequencing. We use comparative genomics and cytogenetics to demonstrate that the highly abundant AAACTAC satellite family arose from a related satellite in the branch leading to the virilis phylad 4.5-11 Ma before exploding in abundance in some species of the clade. The most abundant satellite is conserved in sequence and location in the pericentromeric region but has diverged widely in abundance among species, whereas the satellites nearest the centromere are rapidly turning over in sequence composition. By analyzing multiple strains of D. virilis, we saw that the abundances of two centromere-proximal satellites are anticorrelated along a geographical gradient, which we suggest could be caused by ongoing conflicts at the centromere. In conclusion, we illuminate several key attributes of satellite evolutionary dynamics that we hypothesize to be driven by processes including selection, meiotic drive, and constraints on satellite sequence and abundance.

中文翻译：

---

果蝇基因组中丰富的7 bp卫星的进化动力学。

导致高度重复的序列串联阵列（称为卫星DNA）的丰度快速变化的因素尚未得到很好的理解。果蝇（Drosophila virilis）是所有研究过的有机体中相对数量最高的简单卫星之一，估计其基因组的40％以上是由一些相关的7 bp卫星组成的。在这里，我们使用维氏梭菌作为模型来理解影响卫星排序的技术偏见以及驱动卫星组成的进化过程。通过分析来自Illumina，PacBio和Nanopore平台的测序数据，我们确定了平台特定的偏倚，并提出了通过测序准确表征卫星的最佳实践。我们使用比较基因组学和细胞遗传学方法来证明高度丰富的AAACTAC卫星家族起源于该分支中的相关卫星，导致该分支中的毒株门呈4.5-11 Ma，然后在某些进化枝中大量爆发。最丰富的卫星在着丝粒附近区域的序列和位置上是保守的，但是在物种之间的丰度差异很大，而离着丝粒最近的卫星的序列组成正在迅速翻转。通过分析维氏梭状芽胞杆菌的多个菌株，我们发现两个着丝粒近端卫星的丰度在地理梯度上是反相关的，我们认为这可能是由于着丝粒处的持续冲突引起的。结论，