中国沿海牡蛎寄生才女虫属复合体的物种多样性与系统进化研究

"Polydora complex" are those species characterised by having a modified fifth setiger within the family Spionidae Grube, 1850. They are widespread polychaete parasites with broad host range.They are the main shellfish parasites, which affect shellfish's growth and development,even lead to their hosts' death,severely threaten the development of shellfishery．Through the survey of "Polydora complex" species parasites in the oysters, this study compares their species diversity among different offshore marine areas, different host species of oyster, and different habitat types. At the same time, nuclear genes and mitochondrial genes as molecular markers, this study explores the validity of morphologic classification about "Polydora complex", reveals the genetic relationships within them, elucidates their phylogenetic relationships, thus infers their systematic evolution and origin.The aim of this study is to to explore the mutual relationships between the formation of species diversity and host type, geographic position and habitat type. Oyster parasites,"Polydora complex", as model organism, this study explores evolution of biogeographic relationships and formation of species diversity,which has important theoretical significance on the elucidation of speciation and evolution of "Polydora complex" species. Furthermore, the study about the identification and geographical distribution of "Polydora complex" parasite species is helpful to the establishment of measures for preventing and controlling shellfish diseases.

才女虫属复合体是多毛纲、海稚虫科中第五刚节发生变形的所有种类的合称，是世界性分布的、宿主广泛的多毛类动物，是危害贝类养殖的主要寄生虫种类，能影响贝类生长和发育，甚至导致死亡。本项目拟通过调查牡蛎寄生才女虫属复合体的种类，比较其在不同海域，牡蛎宿主，栖居环境下的物种多样性；同时，以核基因与线粒体基因为分子标记，探讨才女虫属复合体形态分类依据的合理性，阐明属种亲缘关系，弄清其种系发生关系，进而分析系统进化关系，探索物种多样性的形成与宿主种类、地理位置、栖居类型等三个因素之间的关系。 本研究以牡蛎寄生虫（才女虫属复合体）为模式生物，探讨生物地理亲缘关系演化以及物种多样性的形成，对阐明才女虫属复合体的物种形成（speciation）与演化（evolution）具有重要理论意义；同时，才女虫属复合体寄生种类的鉴定及地理分布研究，也有助于病害防控措施的制定。

本项目不仅顺利完成了对牡蛎寄生的才女虫的物种多样性调查，还对其他贝类寄生的才女虫种类进行了研究；形态学和分子生物学相结合对一些有害才女虫种类进行了详细鉴定和描述，厘清过去中国海域报道的才女虫的错误鉴定或混淆的种类，发现1种新种；对才女虫的宿主特异性、地理区系分布、栖居类型进行了一系列的探索；应用核糖体18S和线粒体COI基因序列重构才女虫的系统进化树，阐明了部分才女虫种类的亲缘关系。. 本项目从形态和分子水平研究了中国沿海贝类寄生才女虫的物种多样性，并筛选了线粒体COI基因为DNA条形码，用于辅助才女虫的形态相似种的鉴定。本研究得到如下主要结果：中国沿海贝类才女虫物种多样性调查中，共发现10种才女虫，分别为短触手才女虫（Polydora brevipalpa）、威氏才女虫（P. websteri）、陵水才女虫（P.lingshuiensis, sp.）、哈氏才女虫（P. haswelli）、艳丽才女虫（P. aura）、短鳃伪才女虫(Pseudopolydora paucibranchiata)、弯钩小蛇稚虫（Boccardiella hamata）、才女虫未定种1（Polydora sp1）、才女虫未定种2（Polydora sp2）、才女虫未定种3（Polydora sp3）。其中，P. brevipalpa与P. lingshuiensis为养殖贝类中的致病种，分别能导致虾夷扇贝和马氏珠母贝严重病害。P. lingshuiensis与Polydora sp1属广温性生物，其分布范围广，在莆田、深圳、阳江、陵水等地的海区均有发现。P. brevipalpa、P. aura、B. hamata属狭温性生物，只在北方海区的贝类中发现，适于低水温环境。多数才女虫的宿主特异性低，宿主广泛。分子标记方法分析表明，基于18S与COI序列的才女虫系统进化树的拓扑结构基本一致，而与基于COB序列的拓扑结构差异很大。基于分子标记发现的“分子物种”的数量远多于“形态物种”。