青藏高原鱼类DNA条形码系统构建研究

Species identification is the most basic step of biodiversity protection and the sustainable utilization of biological resources. The fish fauna of the Qinghai-Tibet Plateau is a special group of fish species that have adapted to extreme environments of plateau. These fishes are difficult to be identified based on traditionally morphological methods owing to their extensive morphological variations. Hence, it is necessary to develop fast and accurate molecular methods for species identification. In this project, the morphological, geographical and ecological characteristics will be collected from 2000 specimens that belong to at least 100 fishes from the Qinghai-Tibet Plateau. Their COI sequences will be obtained by direct sequencing of the PCR products, and their DNA barcoding system will be established. Based on COI sequences, their Kimura two-parameter genetic distances and phylogenetic tree will be analyzed, which would be used to clarify their taxonomic status. The results of this project would provide the foundation for identification and protection of fishes in the Qinghai-Tibet Plateau, and be useful in the supplement of traditional taxonomy and the verification of new species.

物种的准确鉴定是生物多样性保护和生物资源可持续利用的最基本环节。青藏高原鱼类是适应于高原极端环境条件的特殊生物资源。由于形态多变性，该地区鱼类的形态学鉴定比较困难，因此，需开发快速准确的分子鉴定方法。本项目拟收集青藏高原至少100种2000个鱼类样本的形态、地理和生态位等信息，并为这些鱼类构建基因组库。然后利用PCR测序的方法获取这些样本的线粒体COI基因序列，构建青藏高原鱼类的标准DNA条形码数据库。分析种内和种间COI基因的遗传距离，构建系统发生树，澄清物种的分类地位。本项目构建的DNA条形码数据库为青藏高原鱼类的鉴定和保护提供基础，基因序列分析数据为传统分类学的补充完善、挖掘隐存种和新种提供依据。

青藏高原的鱼类正面临生物多样性丧失、生物入侵等严峻的生态问题。本项目开展了青藏高原鱼类DNA条形码研究，旨在为高原鱼类的生态监测和保护提供基础，取得了如下研究进展：（1）采集了青藏高原82个样点共2057个鱼类样品，设计了用于扩增裂腹鱼类和高原鳅COI基因的高效引物，获得包含青藏高原129种鱼类2310个DNA条形码的数据库。（2）系统开展了DNA条形码研究，结果显示80%的物种存在明显的DNA条形码间隙，能够有效地进行物种鉴定；部分物种如色林错裸鲤、热裸裂尻鱼、拉萨裸裂尻鱼、错鄂裸鲤等没有明显的DNA条形码间隙，系统发育树也显示它们聚成一支，表明存在同种异名的现象。（3）利用形态特征值分析了异尾高原鳅湖泊和河流群体间的适应性歧化，利用DNA条形码序列分析了群体间的遗传分化，结果表明，河流和湖泊分布的异尾高原鳅群体间已经存在显著的形态差异和遗传分化。本项目首次构建了青藏高原DNA条形码数据集，为高原鱼类的分子鉴定及未来的环境DNA监测提供了基础数据，也为部分物种的起源和分化研究提供了参考。