The evolutionary mechanisms optimizing neural circuit structure and function for skylight navigation across insect species

昆虫是动物界中最具多样性的类群，具有重要的生态和经济效益。为了成功狩猎，觅食或传播，大多数自由生活的昆虫依赖于相当大的导航技能，他们使用不同的视觉刺激，如天体和天空偏振。尽管昆虫眼睛的形态多样性很大，但最近的数据显示，它们的视网膜马赛克在物种之间表现出显着的相似性。虽然系统的形态学特征已经确定了几乎所有分析的昆虫中偏振天窗的视网膜探测器，但这些结构的规格及其潜在的神经回路实际上是否在进化上是保守的仍然是未知的。此外，它们的结构（连接性）和功能（计算性）如何适应不同昆虫物种的不同生态位，目前尚不清楚。在本研究中，我们计划检验三个假设：（1） 指定偏振天光探测器的分子机制在昆虫中是保守的（2） 转录因子网络的变化使该检测器系统适应物种特异性需求（3） 在下游回路元件中特异表达的基因产物形成进化上保守的神经网络。我们将使用果蝇中可用的分子遗传学工具，结合不同的生物信息学方法，比较昆虫的调控序列，转录因子结合位点，转录因子网络和基因表达谱。这些实验将揭示进化上保守的机制以及昆虫天窗导航神经回路形成背后的物种特异性适应。

Insects are the most diverse group within the animal kingdom and provide both important ecological and economic benefit. For successful hunting, foraging, or dispersal, most free-living insects rely on considerable navigation skills, for which they use different visual stimuli, like celestial bodies and skylight polarization. Despite great morphological diversity of insect eyes, recent data revealed that their retinal mosaics show remarkable similarities across species. While systematic morphological characterization has identified retinal detectors for polarized skylight in virtually all insects analyzed, it remains unknown whether specification of these structures and their underlying neural circuitry are in fact evolutionarily conserved. Moreover, it is unknown how their structure (connectivity) and function (computation) are adapted to the diverse ecological niches of different insect species.In this proposal, we are planning to test three hypotheses:(1) The molecular mechanism for specifying polarized skylight detectors is conserved across insects(2) Variations in the transcription factor network adapt this detector system to species-specific demands(3) Gene products expressed specifically in downstream circuit elements shape evolutionarily conserved neural networks. We will use the molecular genetic tools available in Drosophila in combination with different bioinformatics methods, to compare regulatory sequences, transcription factor binding sites, transcription factor networks, and gene expression profiles across insects. These experiments will reveal evolutionarily conserved mechanisms as well as species-specific adaptations behind the formation of neural circuits for insect skylight navigation.