In the last 240,000 years, males of the Drosophila simulans species clade have evolved striking differences in the morphology of their epandrial posterior lobes and claspers (surstyli). These appendages are used for grasping the female during mating and so their divergence is most likely driven by sexual selection. Mapping studies indicate a highly polygenic and generally additive genetic basis for these morphological differences. However, we have limited understanding of the gene regulatory networks that control the development of genital structures and how they evolved to result in this rapid phenotypic diversification. Here, we used new D. simulans/D. mauritiana introgression lines on chromosome 3L to generate higher resolution maps of posterior lobe and clasper differences between these species. We then carried out RNA-seq on the developing genitalia of both species to identify the expressed genes and those that are differentially expressed between the two species. This allowed us to test the function of expressed positional candidates during genital development in D. melanogaster. We identified several new genes involved in the development and possibly the evolution of these genital structures, including the transcription factors Hairy and Grunge. Furthermore, we discovered that during clasper development Hairy negatively regulates tartan (trn), a gene known to contribute to divergence in clasper morphology. Taken together, our results provide new insights into the regulation of genital development and how this has evolved between species.

中文翻译：

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揭示果蝇物种之间雄性生殖器快速多样化的遗传基础。

在过去的 240,000 年中，雄性拟果蝇物种进化枝的表皮后叶和扣环 (surstyli) 的形态发生了显着差异。这些附肢用于在交配过程中抓住雌性，因此它们的差异很可能是由性选择驱动的。测绘研究表明，这些形态差异具有高度多基因和一般加性遗传基础。然而，我们对控制生殖器结构发育的基因调控网络以及它们如何进化以导致这种快速的表型多样化的理解有限。在这里，我们使用了新的D. simulans / D. mauritiana3L 染色体上的基因渗入线，以生成更高分辨率的后叶图和这些物种之间的锁扣差异。然后，我们对两个物种的发育中的生殖器进行了 RNA-seq，以识别表达的基因和两个物种之间差异表达的基因。这使我们能够在黑腹果蝇生殖器发育过程中测试表达位置候选的功能。我们确定了几个与这些生殖器结构的发育和可能进化有关的新基因，包括转录因子 Hairy 和 Grunge。此外，我们发现在 clasper 发育过程中，Hairy 对格子呢（trn)，一种已知有助于锁扣形态差异的基因。总之，我们的研究结果为生殖器发育的调控以及物种间的进化提供了新的见解。