Size and shape constitute fundamental aspects in the description of morphology. Yet while the developmental-genetic underpinnings of trait size, in particular with regard to scaling relationships, are increasingly well understood, those of shape remain largely elusive. Here we investigate the potential function of the Notch signaling pathway in instructing the shape of beetle horns, a highly diversified and evolutionarily novel morphological structure. We focused on the bull-headed dung beetle Onthophagus taurus due to the wide range of horn sizes and shapes present among males in this species, in order to assess the potential function of Notch signaling in the specification of horn shape alongside the regulation of shape changes with allometry. Using RNA interference-mediated transcript depletion of Notch and its ligands, we document a highly conserved role of Notch signaling in general appendage formation. By integrating our functional genetic approach with a geometric morphometric analysis, we find that Notch signaling moderately but consistently affects horn shape, and does so differently for the horns of minor, intermediate-sized, and major males. Our results suggest that the function of Notch signaling during head horn formation may vary in a complex manner across male morphs, and highlights the power of integrating functional genetic and geometric morphometric approaches in analyzing subtle but nevertheless biologically important phenotypes in the face of significant allometric variation.

中文翻译：

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Notch信号模式在牛头甲虫Onthophagus taurus的头角形状中。

尺寸和形状构成了形态学描述的基本方面。然而，尽管对特质大小的发育遗传基础，尤其是关于比例关系的基础日益了解，但形状的基础仍然难以捉摸。在这里，我们研究了Notch信号通路在指示甲虫角的形状中的潜在功能，该甲虫角是高度多样化的且进化上新颖的形态结构。由于该物种中雄性的角大小和形状范围很广，因此我们将重点放在牛头的甲虫Onthophagus taurus上，以便评估Notch信号在角形状规范中对形状变化的调控的潜在功能。与异体症。利用RNA干扰介导的转录本耗竭Notch及其配体，我们记录了Notch信号在一般附件形成中的高度保守的作用。通过将我们的功能遗传方法与几何形态计量学分析相结合，我们发现Notch信号适度但持续地影响角形，并且对小，中型和主要雄性的角影响也不同。我们的研究结果表明，Notch信号在牛角形成过程中的功能可能会在男性形态之间以复杂的方式发生变化，并突出了整合功能遗传和几何形态计量学方法在分析细微但生物学上重要的表型时所具有的强大功能。 。