Development and evolution of eyes in Araneae

大多数节肢动物有两个独立的视觉系统：正中眼和侧眼。果蝇有一对外侧复眼，这是主要的光学器官，以及一组三个正中眼窝。相比之下，蜘蛛通常有四对简单的眼睛；中间的一对眼睛通常是最大的，因此是主要的光学系统。蜘蛛属于海龟类，在节肢动物的底部分枝。因此，蜘蛛是有用的模型，可以用来研究发育的各个方面是否是节肢动物共同祖先以及潜在的其他后生动物的祖先或起源。研究蜘蛛眼发育的分子和遗传基础将加深我们对视觉系统进化中发育途径的保护和/或重组的理解。此外，在不同的蜘蛛家族中，蜘蛛眼睛的数量、位置、大小和功能都有差异。这种多样性为研究视觉特化的遗传基础提供了机会。此外，蜘蛛保留了祖先全基因组复制(WGD)事件中的许多重复基因；其中包括属于果蝇视网膜决定基因网络(RDGN)的转录因子和几个Wnt配体。Tepidariorum的正眼和侧眼分别发育，表现出一种独特的RDGN对偶组合。因此，祖先的基因复制可能在蜘蛛眼睛的进化、发育和多样化中发挥了作用。我的目的是研究RDGN类似物和关键的信号通路在tepidariorum发育头部眼睛的建立和发育中的作用。

Most arthropods have two separate visual systems: the median and lateral eyes. Drosophila have a pair of lateral compound eyes, which are the main optical organs, and a group of three median ocelli. In contrast, spiders typically have four pairs of simple eyes; the median eye pair are usually the largest and thus, the main optical system. Spiders belong to the chelicerates, which branch at the base of the Arthropoda. Thus, spiders (namely Parasteatoda tepidariorum) are useful models to study whether aspects of development are ancestral or derived with respect to the arthropod common ancestor, and potentially other metazoans. Investigating the molecular and genetic underpinnings of spider eye development will deepen our understanding of the conservation and/or retooling of developmental pathways in the evolution of visual systems. Moreover, across spider families there is variation in the number, placement, size and function of spider eyes. This diversity presents an opportunity to study the genetic bases of visual specialisations. Furthermore, spiders have retained many duplicated genes from an ancestral whole genome duplication (WGD) event; this includes transcription factors belonging to the Drosophila retinal determination gene network (RDGN) and several Wnt ligands. The median and lateral eyes of P. tepidariorum develop separately and express a unique combination of RDGN paralogs. Therefore, ancestral gene duplicates could have played a role in the evolution, development and diversification of spider eyes. I aim to investigate the role of RDGN paralogs and key signalling pathways in the establishment and development of the eyes in the developing head of P. tepidariorum.