地栖脊椎动物听觉平衡觉的适应性进化：基因、结构、功能和行为

The ecological relationship is the prey and predator between rodents and snakes whose auditory and vestibular systems specialized adaptively. In general, similarity of ecological patterns correlated with convergence of functional gene sequences, for instance, prestin gene. There are some missed intermediate procedures from genes to ecological patterns, which are of importance for understanding adaptive mechanisms while less studied. Both rodents and snakes are very sensitive to seism while rodents are sensitive to sounds and snakes not. We hypothesized that rodents and snakes shared largely inner ear structures while were different in structures of middle and outer ears. Similar inner ears would result from analogous sequences of genes that are involved in development of hair cells and/or basilar papilla. Diversity of middle and outer ears might adapt largely to variability of habitats. Our project will be conducted logically along gene, structure, function and behavior for inner ears and structure, behavior and ecological pattern for middle and outer ears. By using theory of Evo-Devo biology and techniques of behavioral and neural biology, we will investigate the correlations of differences between gene sequences and inner ear structures, and between ear structures and ecological patterns. The aim of this study is to elucidate adaptive mechanisms of auditory and vestibular systems, i.e. open the black box between genes and adaptation, which will benefit the research on hearing disability of human beings with providing theory, method and animal model.

啮齿类和蛇类互为猎物与捕食者的生态关系，其听觉平衡觉产生了适应性特化。研究显示，相似的生态类型具有趋同的功能基因结构。然而从基因到生态适应之间的环节，是理解适应机制的关键，却少有研究。啮齿类和蛇类都对震动极其敏感，但啮齿类对声音敏感而蛇类对声音不敏感。我们的研究假说：啮齿类和蛇类具有相似的内耳结构和差异的中耳及外耳结构；蛇类无法将声音灵敏地传至内耳。二者相似的内耳结构（毛细胞）可能源自趋同的基因序列（在啮齿类和蛇类却执行相反的生态功能）；中耳和外耳则是适应环境的结果。本项目中的内耳研究沿基因、结构、功能和行为展开；中耳和外耳因没有相关基因报道，沿结构、行为、生态型展开。借助于Evo-Devo理论以及行为学和神经生物学技术，探讨功能基因正常的序列差异与耳结构差异之间的关系，及结构差异与行为和适应的关系。本研究将阐明听觉平衡觉的适应机制；也为人类的听障研究提供动理论、方法和动物模型。

本研究严格按照项目计划书，开展了如下的实验：1）研发本实验必需的地面震动信号发生器和检测系统，以及生态学研究需要的多传感系统，申请专利2个；2）在野外对不同质地的地表进行振动信号的传导效率测量；3）完成建立二个隔音的行为实验室；4）检测了几种地栖/树栖物种的听觉脑干反应（ABR）；5）完成了肥尾心颅跳鼠 (Salpingotus crassicauda) 的中耳和内耳做显微CT扫描以及短尾蝮（Gloydius brevicaudus）头部MRI成像，正在进行三维重构；6）比较解剖了几种地栖物种的基底乳突（Basilar Papilla）；7）克隆了几个听觉相关的基因；8）构建了游蛇科和蝮蛇科的系统树，基于线粒体基因；9）检测了动物对声音刺激的行为反应。..针对项目的关键科学问题，我们的研究从形态、功能和基因的角度，探讨听觉/平衡觉的适应性进化机制。发现针对环境的改变，外周系统（耳）的变异大于中枢神经；听觉系统变异大于平衡系统。针对同一个性状，选择压力在某一个方向增强，同时释放另一个方向的压力。已经获得专利1个（另有申请1个），发表论文3篇，正在发表1篇，后续将发表3篇。在项目设计阶段由于考虑不周，正如一位评审人指出的那样：涵盖面过大，任务过多，难以在执行期间内全面完成。在本项目的基础上，项目组成员通过其它渠道申请经费（如中国科学院国际合作等），全面研究动物感知系统（包括视觉和红外觉）的适应性进化。