狭义光唇鱼属的两性异型及进化

Acrossocheilus s.str. includes a group of small- to medium-sized, bottom-living and rheophilic freshwater fish species currently known from the Yangtze River basins and river basins of South China south of this river. It has a high degree of endemism in its known occurrence range and shows a remarkable sexual dimorphism in many aspects. Thus, this genus is a suitable candidate group in studies of South China biogeography and other evolutionary biological issues. The proposed project tries to systematically investigate and compare sexual dimorphism among species of this genus, reconstruct interspecific relationship of included species using the mtDNA and nuclear genes, and use the phylogenetic comparative approach to analyze character evolution of sexual dimorphism. This project is predicted to enrich the data of basic biology by unveiling the diversity of sexual dimorphism in Acrossocheilus, accumulate the evidence for the analysis of systematic position of the genus among the tribe Barbini and present a phylogenetic framework for the biogeographic analysis, and provide a valuable clue for underlying mechanism of sexual dimorphism by partitioning phylogenetic constraints and adaptive evolution of character showing sexual dimorphism.

狭义光唇鱼属是一类在山涧溪流和江河中上游等急流环境中栖息的中小型淡水鱼类，广泛分布于长江及长江以南各水系。此类群在此分布区域内物种区域性分化强烈，且具有非常显著的两性异型，既是生物地理学的理想类群，也是进化生物学问题研究理想材料。拟立本项目对其两性异型性状进行系统的分析和比较；基于线粒体和核基因序列，构建其种间系统发育关系；进而采用系统发育比较方法，研究两性异型性状的进化。此项目研究狭义光唇鱼属两性异型多样性揭示可以丰富进化生物学的基础资料；多基因型种间系统发育关系的构建可为研究此类群在鲃亚科的系统位置探讨积累证据，为其生物地理学的研究提供系统发育框架；两性异型性状的系统发育限制性和适应性进化的区分，可为两性异型的维持机制的探讨提供有价值的线索。

狭义光唇鱼属鱼类具有非常显著的两性异型，性选择压力和适应性进化是导致两性异型产生的两个最主要的原因。本研究以狭义光唇鱼属10种光唇鱼的两性异型性状为研究对象，对10个两性异型性状的状态进行划分。然后基于线粒体和核基因序列，构建其种间系统发育关系，并在此框架下，分析了各个两性性状的演化规律。采用系统发育比较方法检测狭义光唇鱼属两性异型性状演化与系统发育间的关系。