金线鲃属洞穴鱼是中国的特有属，它们生活在地下河、湖和岩溶洞穴等黑暗和寡营养的地下水生栖息地中，常发育特殊的身体结构特征，如眼睛退化，生长头角、驼背等非流线型结构。相比于已有深入研究的墨西哥洞穴鱼和美国洞穴鱼，中国金线鲃属洞穴鱼物种多样性和形态多样性更为丰富、灭绝风险更高，但研究起步晚。金线鲃属洞穴鱼分布区域待确定，多样性形成机制不明确，个体对环境的适应性行为及种群发展对环境变化的响应机制不清楚。本文构建了适用于金线鲃属洞穴鱼的生态位模型，模拟和预测了它们的适生区分布。结果表明珠江流域大部分区域均是最佳适生区，金沙江流域下游、嘉陵江与长江的交汇区、以及乌江上游等是中等适生区和边缘适生区，可以作为未来探索洞穴鱼新物种和物种保护的重点区域。地质地貌演化对金线鲃属洞穴鱼在珠江流域内强烈分化的影响一直缺乏明确证据。本文通过协同分析珠江水系发育的地质地貌特征与金线鲃属洞穴鱼的演化特征，发现珠江流域各干、支流的发育过程与地区金线鲃属的分化过程在时间和空间上存在较好的对应关系，阐明了云贵高原的抬升是珠江流域及其临近地区金线鲃属洞穴鱼演化的重要驱动力。本文基于人工神经网络模型开发了可用于弱光环境的鱼类运动轨迹跟踪系统，结合PIV测量技术，实现了对典型洞穴鱼犀角金线鲃的运动行为特征的定量分析。结合3D扫描技术构建了鱼体的真三维数学模型用于水动力模拟，研究结果表明，相比于身体流线型的非典型洞穴鱼，犀角金线鲃的特殊头角结构增加了游动中的阻力系数，同时也增强了感知信号，提升了其侧线系统的感知能力。本文基于种群矩阵模型研究洞穴鱼种群发展对环境扰动的响应。模拟结果表明，典型洞穴鱼和非典型洞穴鱼有不同的生活史策略和不同的环境扰动响应机制；典型洞穴鱼种群发展对于成鱼阶段存活率变化的敏感性更高；非典型洞穴鱼种群发展对幼龄鱼阶段存活率变化的敏感性更高。基于对洞穴鱼的适生区分布、个体行为特性、种群发展机制等的研究认识，进一步构建了种群矩阵模型和栖息地模型相耦合的研究方法和模拟模型，可用于研究河流水文、水动力、水环境变化对洞穴鱼可用栖息地面积和种群规模的影响。
The cyprinid genus Sinocyclocheilus is endemic to China, with a distribution limited to oligotrophic underground rivers, lakes and karst caves. Most of them exhibit troglomorphic traits, e.g. pigment loss, blindness, reduction or total absence of scales, and some of them even evolve the head horn and hump. Compared with Mexican cavefish and American cavefish, Sinocyclocheilus is more valuable in terms of species diversity and body shape diversity, and more vulnerable to extinction. However, research on Sinocyclocheilus, including its suitable growing regions, speciation mechanism, individual behavioral characteristics, and population development in response to environmental disturbances is far less than that of Mexican cavefish and American cavefish.In this study, we investigated the lithological, fluvial and climatic conditions of all reported cavefish collection localities by field measurement and literature research, and further established an ecological niche model. Results suggested that most regions in the Pearl River basin are the most suitable for Sinocyclocheilus inhabitation, and regions in the Lower Jinsha River basin are medium suitable. Confluences in the Jialing River basin, the Yangtze River basin, and the Upper Wujiang River basin are potential regions for new Sinocyclocheilus discovery and preservation in the future. So far, the hypothesis that the tectonic uplift of the Yunan-Guizhou Plateau contributed to Sinocyclocheilus speciation was supported by few reliable evidences. Through the collaborative analysis on the geological and geographical characteristics of the Pearl River basin and the evolution of the Sinocyclocheilus, we found that the Sinocyclocheilus speciation could be correspondance to the fluvial process of the main channel and tributaries in the Pearl River basin in temporal and spatial distributions, which firmly supported that the tectonic uplift facilitated Sinocyclocheilus diversity. A fish movement tracking system based on the artificial neural network was developed and can be applied in low light environment. By combining this tracking system with particle image velocimetry, the Sinocyclocheilus behavior was successfully documented and analyzed. Further, the 3D scanning was applied to build a digital model for S. rhinocerous, and its horn structure was precisely described comparing with the traditional airfoil model. Our results suggested that the horn structure of S. rhinocerous, compared with that of other streamlined cavefish, increased the drag force when coasting and intensified the signal-delta pressure, which benefited the sensing function of lateral line system. In this study, we established a population matrix model for cavefish. Results suggested that different conservation strategies should be intentionally taken for troglobite and troglophile cavefish. For the troglobite, population was the most sensitive to the adults’ survival rate. As for the troglophile, population is the most sensitive to the juveniles’ survival rate.Based on the results obtained from ecological niche predictions, individual behavior measurement, and population development model analysis, we further established a model that coupled the population development matrix and the habitat suitability simulation together, and could be used to analyze the response of fish population as well as inhabiting area to variations in hydrological conditions, hydrodynamics, and water quality.
