藏北高原湖泊裂腹鱼类资源多态性与生态物种形成研究

The process of speciation and its mechanism is a core topic in evolutionary biology. Ecological-based selection is considered as playing a very important role in the speciation and diversification process, and being a primary driving force of speciation. Those relatively young ecosystems with few species and replicable environments are ideal natural systems for exploring population ecology, morphological divergence, resources polymorphism and ecological-based speciation mechanism. Thus, the present project chooses lake ecosystems in the North Tibetan Plateau as research system, and focus on the schizothoracine fishes, which are highly diverse in morphology. To analyze the distribution pattern and variations in ecological and morphological traits of schizothoracine fishes, different lake environments (saline, brackish and freshwater lakes) and various environmental gradients (benthic vs. limnetic, river vs. lake) are selected. On this basis, correlations between distribution pattern and habitat utilization, ecological conditions for plateau lake fishes can be revealed by combining habitat environmental features, individual preying, trophic ecological niche and genetic structures. And within multiple replicated environmental gradients, the similarities and differences of population characteristics specialization and divergence will empower a joint analysis for exploring parallel and nonparallel evolution pattern, revealing the speciation process and mechanism in plateau lake fishes.

物种形成的过程和机制是进化生物学的核心问题。生态为基础的选择被认为在物种形成和多样化过程中扮演极为重要的角色，是导致物种形成的主要驱动力。相对年轻、物种稀少和具有的重复环境的生态系统是探究种群生态和形态分离、资源多态性以及生态为基础的物种形成机制的理想的研究系统。本项目选择藏北高原湖泊为研究系统，以形态高度多样化的裂腹鱼类为研究对象，分别设置不同湖泊环境（盐湖、咸水湖和淡水湖）、不同环境梯度（浅水底栖—深水浮游、河流—湖泊），系统分析高原湖泊裂腹鱼类生态和形态特征分布模式及其变化规律；在此基础上结合栖息地环境特征、个体摄食和营养生态位以及遗传结构，揭示高原湖泊鱼类特征分布模式与栖息地利用、生态环境的关联；联合分析多个重复的环境梯度中，群体特征特化与分离的共性与差异，探究平行演化与非平行演化模式，揭示高原湖泊物种形成的过程和机制。

物种形成的过程和机制是进化生物学的核心问题。本项目选择藏北高原湖泊为研究系统，以形态高度多样化的裂腹鱼类为研究对象，分别选择河流、淡水湖泊、咸水等3种典型生境，从形态学、生态学和分子遗传等研究层次，采用几何形态学、营养相关性状（鳃耙、下咽齿、肠长、口位、下颌角质以及粘液腔）、食性、碳氮稳定同位素、耳石微量元素、线粒体基因和SSR、转录组以及群体基因组SNP等多种研究方法，系统分析了高原湖泊裂腹鱼形态多态及其形成机制；证实了多个淡水湖泊裂腹鱼存在底栖和浮游型以及与之相应的遗传的平行与趋同进化。底栖型和浮游型裂腹鱼在形态特征，特别是与摄食有关的头部形状，如下颌角质化程度、口位等），生长特征，食性，营养级以及洄游习性等存在一定程度的分化。基因组水平SNP分析也发现两种形态型存在遗传上存在分化；淡水湖泊湖滨带存在可能的空间上分离的产卵场是高原湖泊鱼类形态多态维持的外在环境基础。