Discovery of Tanichthys albonubes Lin 1932 (Cyprinidae) on Hainan Island,and Notes on Its Ecology

A wild population of the globally restricted and highly threatened freshwater fish Tanichthys albonubes Lin was recently discovered on Hainan Island, China. Prior to the present study, native populations were only known from isolated pockets in Guangdong Province of China and Quang Ninh Province of Vietnam; the Hainan record thus represents the first insular and southernmost distribution of this little-known species. Thus far it is known only from a single site in Hainan, despite repeated surveys of similar habitats throughout the island. The Hainan population occurs in a clean, sluggish coastal stream with abundant hydrophytes, and is sympatric with 20 fish species. Due to the unique geographic distribution of the Hainan population, and the conservation significance of the species, studies of its phylogenetic relationships with conspecifics populations elsewhere are underway. The exact locality of the newly discovered Hainan population cannot be revealed, but relevant government authorities have been notified and we are working to protect the site.

唐鱼养殖种群与广州附近4个野生种群的遗传关系

唐鱼(Tanichthys albonubes)是为数不多的几种原产中国的世界性观赏鱼类之一。自2003年以来,多个唐鱼野生种群相继被发现,其濒危状态和等级由野外灭绝降为极危。为研究唐鱼养殖种群与广州附近野生种群之间的遗传关系,本文分析了唐鱼3个代表性养殖种群和4个野生种群,共计186个样本的Cytb基因、2个核基因(ENC1和RAG1)以及13个微卫星位点数据。基于K2P模型的遗传距离结果显示,唐鱼野生种群间的遗传距离在0.005–0.015之间,养殖种群间的遗传距离为0.001–0.009。系统发育分析表明,唐鱼养殖种群包含4个单倍型谱系分支,其中2个分别与广州附近2个野生种群聚在一起,另外2个分别独立成支。单倍型网络亲缘关系分析显示,清远种群只有1个单倍型且与芳村养殖种群共享,芳村养殖种群拥有最多的单倍型。基于微卫星数据的STRUCTURE分析表明,所有种群最佳分簇数为2,清远种群与养殖种群聚为一簇,良口和石门种群聚为另一簇。主成分分析结果显示,养殖种群高度重叠并能与野生种群分开,清远种群与养殖种群存在部分重叠。利用IMa3的基因流分析表明,存在清远种群至芳村养殖种群的单向基因流。综合本文结果,作者认为唐鱼养殖种群应起源于广州附近多个野生种群。清远种群来源于养殖种群中的芳村养殖种群。建议在未来唐鱼的保护策略中,应禁止不规范的放流活动并且禁止将不同野生种群补充至养殖种群,同时加强唐鱼养殖种群和野生种群的遗传资源管理和持续监测。