云南鱼类复殖吸虫的分类及分子系统发育研究

In view of characterized by complex life-cycle and internal heteroxenous between Digenea-fish association, Digenea present strikingly special and idealized experimental paradigm in the research field of co-speciation，evolutionary expansion, adaptative radiation and Historical geography. Digenea and their relationship with host fishes play a crucial role to gain further view to indicate and understand the origin and development of parasitism, and leads to new insights on the evolutionary pathways and biological mechanism of co evolution between parasites and their early vertebrate hosts. The biodiversity of class Digenea are widely diverse with their host fishes of Yunnan Province, where has repeatedly been ranked high in terms of species diversity, such as endemic and indigene species fishes. Fishes which distribute endemically in Yunnan Province already represent the unique characteristics of fish fauna. At present, the research backgrounds of the Digenea of fishes of Yunnan province are still not definitive, especially the biodiversity, genetic characteristics and the distribution. The present application focuses on classification and molecular phylogeny of Digenea flatworms parasitizing in fishes of Yunnan Province. The taxa of Digenea, composition of parasite, distribution and host-specificity will be confirmed through field investigation, sample collection and morphological taxonomy. Molecular approaches for investigation based on genetic markers 18S rRNA, 28S rRNA, ITS and cytb gene sequences will extracted as important genetic data to provide proofs for morphological classification results. Phylogenic relationships of closely related taxa within genera, families or even between more distantly related taxa will be reconstructed and analyzed. New taxa described in the research will enrich the fauna Sinica Platyhelminthes. Molecular phylogeny will provide a potent exemplification of Digenea to understanding the phylogenic relationship and evolutionary lineages characteristics of Southeast Asia. The simultaneous analysis composed of morphological classification and molecular phylogeny will distinctively infer the primary mechanism of historical biogeography, the long-standing co evolution and heteroxenous relationship between Digenea-fish. The combination data sets and main results of the basal research application must contribute equivalent signality for drawing the perspective about co-evolution between host-parasite associations.

复杂的生活史和转主寄生的生物学特征，使复殖吸虫成为研究寄生虫-宿主相互关系理想的实验范例，为理解共物种形成、进化扩张、适应辐射及历史地理分布形成提供了新的视角，成为揭示寄生现象起源和发展、寄生虫-宿主协同进化机制的决定性依据。云南具有丰富的鱼类多样性，地方性分布鱼类及土著鱼类吸虫更具独特性。但云南鱼类复殖吸虫的多样性还尚不明确。本项目拟以云南鱼类复殖吸虫为研究对象，采用野外调查、样品采集和形态分类等研究方法，明确其分类单元、种类组成、分布和宿主特异性；提取测定18S rDNA、28S rDNA、ITS及cytb等基因序列，为分类提供分子证据，同时分析不同分类单元的遗传谱系及其分子系统发育关系。本项目虽属基础理论研究，但预期成果将对我国吸虫志做出重要的补充，呈现鱼类复殖吸虫分子系统发育的东南亚进化世系特征，为进一步揭示寄生虫-宿主协同进化机制提供新的、必不可少的研究例证。

复殖吸虫是脊椎动物优势的内寄生虫。复杂的生活史和转主寄生的生物学特征，使复殖吸虫成为研究寄生虫-宿主相互关系理想的实验材料，为揭示寄生现象的起源和发展、寄生虫-宿主协同进化机制提供了新的视觉和决定性证据。全球记录复殖吸虫140余科1000余属8000余种。我国记录淡水鱼类寄生复殖吸虫20科35属110余种。云南具有显著的鱼类多样性，地方性分布鱼类及土著鱼类复殖吸虫更具独特性，但云南鱼类复殖吸虫的多样性还尚不明确。. 本研究从鲫鱼（Carassius auratus）、白甲鱼（Onychostoma sima）、云南裂腹鱼（Schizothorax yunnanensis）等12种鱼类宿主的消化道、精巢和膀胱检获复殖吸虫成虫7科9属17种，确定了云南鱼类复殖吸虫的分类单元及其编目，包括新种6种、记录种6种、未记录种5种，其中中国分布新纪录2种；编制了东肌吸虫属（Orientocreadium）、鲫吸虫属（Carassotrema）、外睾吸虫属（Exorchis）、异肉吸虫属（Allocreadium）、棘吻吸虫属（Telorhynchus）、尾睾吸虫属（Urorchis）及Prosorhynchoides的分类检索表，对我国吸虫志做出了重要的补充。从宿主分类阶元科、属、种不同水平上，分析了云南鱼类复殖吸虫的宿主组成和宿主偏好，明晰了17种复殖吸虫及其12种宿主的地理分布、种群组成、自然感染情况等区系特征。基于18S、28S、ITSs和5.8S rRNA基因序列，综合形态学特征提出了7属复殖吸虫稳定的属征和共源性状，重建了东肌吸虫属、鲫吸虫属、外睾吸虫属、异肉吸虫属、棘吻吸虫属、叶形吸虫属和新斜孔吸虫属共7属复殖吸虫在属、种水平上的遗传谱系及分子系统发育关系，补充了中国和东南亚复殖吸虫进化世系的研究数据，为进一步揭示寄生虫-宿主协同进化机制提供新的、必不可少的研究例证。