光唇鱼属物种的宏进化与微进化: 亲缘地理模式

Acrossocheilus is a genus of ray-finned fishes in the family Cyprinidae that are native to freshwater in South China (including Taiwan), Laos, and Vietnam. There are 26 valid species within this genus. Besides, some species have sometimes been moved to other genera, but it has yet to be widely accepted. However, the previous studies were almost based on the typological and phylogenetic species concepts. The inter- and intra-species diversities are still uncertain. Accordingly, our study examines the phyloeograpphy, a bridge between population genetics (microevolution) and systematics (macroevolution), to observe speciation and differentiations of the genus Acrossocheilus, and to understand the diversity, origins and colonization history of the Acrossocheilus species within Taiwan and Hainan Island. For these purpose, we will use the sequences from multiple mitochondrial and nuclear genes, and the single nucleotide polymorphism (SNP) to examine the phylogeny and population genetic structure. Besides constructing the phylogenetic tree and network, estimating the genetic variations and evolutionary times, and determining the statistical support for ancestral ranges reconstructions and the directions of migrations, this study also uses the approximate Bayesian computation (ABC) approach to reconstruct the unknown history of the genus Acrossocheilus. Moreover, the ABC approach will help to understand whether the different genetic markers reveal the same historical signal when they showed discordant population structures. In additions, the ABC approach could combine different genetic markers as one dataset to determine how the complex geological history in South China influence the phylogeography of the genus Acrossocheilus. The results of this project will help to inform the systematics and conservation management policies.

光唇鱼属为鲤科的䰾亚科、生活于河流中上游的中小型鱼类，分布于南中国、老挝及越南。过去关于光唇鱼属的分类及进化问题的探讨，是以模式物种观念与亲缘物种观念为基础，目前对其属内物种多样性及种间的亲缘关系仍存在着争议。因此，本研究拟由分析能够联系宏进化（种及种以上）及微进化（种内）的亲缘地理研究，利用多个线粒体、核基因序列及单核苷酸多态性(SNP)为分子标记进行亲缘关系和种群遗传结构分析，了解各遗传标记的变异分布模式、重建种间及种内亲缘关系、估算进化时间及祖先种群的分布区，并利用approximate Bayesian computation（ABC法）分析不同遗传标记是否呈现相同的进化信息，以及种化及种群分化历史与南中国地质历史的相关性，来厘清整个光唇鱼属的种化及分化过程，并了解台湾及海南岛内光唇鱼属物种的多样性、起源及拓殖路径，以期有助于光唇鱼属鱼类的分类及保护。

光唇鱼属为鲤科的䰾亚科、生活于河流中上游的中小型鱼类，分布于南中国、老挝及越南。过去关于光唇鱼属的分类及进化问题的探讨，是以模式物种观念与亲缘物种观念为基础，目前对其属内物种多样性及种间的亲缘关系仍存在着争议。本项目在通过大范围的分布地调查获得大量光唇鱼属标本的基础上，采用线粒体和核基因为分子标记，弄清了长江及以南地区光唇鱼属的物种多样性及各物种分布范围；以线粒体基因组和多核基因序列构建了光唇鱼属的系统发育关系、估算了各物种的分化时间及祖先种群的分布区；利用Approximate Bayesian computation（ABC法）分析了大陆东南部光唇鱼属的种化及种群分化历史与南中国地质历史的相关性。项目取得了一系列重要的研究结果：首次澄清了大陆长江、浙江-福建、珠江以及海南岛四大华南亚区主要分布13种光唇鱼；光唇鱼属存在两个单系支，分布于长江中上游和元江水系的物种是原始的物种；该属物种有两条不同的扩散路径，一条是从长江向南到武夷山以北的中国东南部，另外一条是从长江上游向南到元江、珠江和海南岛，向东至武夷山脉以南和台湾，南岭山脉和武夷山脉是其扩散和分化的主要地理壁障；浙江的光唇鱼种类由长江的克氏光唇鱼分化而来，武夷山脉和仙霞岭的隆起作为主要壁障，而非第四纪冰期引起的海平面升降导致该区域的光唇鱼属物种分化，对于浙江地区光唇鱼属物种的保护，应将仙霞岭两侧作为各自独立的管理单位（MUs）。研究结果有助于我国淡水鱼类的分类及多样性保护。