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杜父鱼驼形线虫种群生物学和分子生态学的研究
Alternative TitlePopulation biology and molecular ecology of the nematode Camallanus cotti
吴山功
Subtype博士
Thesis Advisor王桂堂
2007-06-09
Degree Grantor中国科学院水生生物研究所
Place of Conferral水生生物研究所
Keyword杜父鱼驼形线虫 种群动态 分子生态学 谱系地理学 共同系统发育 Its Rdna 18s Rdna Coi基因 嗜子宫线虫
Abstract杜父鱼驼形线虫(Camallanus cotti)隶属于线虫纲(Nematoda)旋尾目(Spirurida)驼形科(Camallanidae),该线虫最初发现于日本,现在已经成为世界性分布的淡水鱼类寄生虫。本论文运用形态学和分子生物学技术,研究了杜父鱼驼形线虫的宿主分布、种群动态、分子变异、宿主-寄生虫关系以及寄生虫的种群遗传结构和谱系地理学。 通过对丹江口水库鱼类寄生蠕虫5次大规模的调查,发现杜父鱼驼形线虫寄生于26种鱼类,其中14种是新宿主,而鲤形目鱼类是其最主要的宿主。不同宿主中,杜父鱼驼形线虫的感染率、感染丰度和感染强度差异很大。 对杜父鱼驼形线虫种群动态和成熟过程的研究发现该线虫的感染丰度与马口鱼的体长正相关;其在宿主中呈聚集性分布;它的感染率和平均丰度的周年变化有季节性,表现为夏秋较高,春冬较低;它的发育(成熟)、幼虫的补充和生殖是连续的,而生殖的高峰在冬季。 以ITS rDNA和COI基因为分子标记对我国中南部不同水系杜父鱼驼形线虫种群遗传结构和谱系地理学进行了研究,结果显示长江和闽江水系间的杜父鱼驼形线虫种群间存在广泛的基因交流,而这两个水系与珠江水系间遗传分化很明显;同一水系内不同地点不同宿主中的杜父鱼驼形线虫种群间存在着广泛的基因交流;长江种群是杜父鱼驼形线虫的祖先种群,闽江和珠江种群是由长江种群扩散而形成的;不同水系的杜父鱼驼形线虫种群都经历过最近的扩张事件。 驼形属线虫分子变异的研究说明寄生在我国淡水鱼类肠道内的驼形属线虫只有两个种,即杜父鱼驼形线虫和鲢驼形线虫(C. hypophthalmichthys)。通过寄生虫和宿主系统发育关系的比较,发现不同宿主上的杜父鱼驼形线虫和其宿主的系统发育关系不一致,这种不一致可能是由于杜父鱼驼形线虫短时间内在不同宿主中不断建群、不完全的宿主转移以及随后快速的适应性辐射引起的。 此外,本研究还以ITS rDNA和18S rDNA为分子标记分析了我国淡水鱼类寄生嗜子宫线虫的系统发育关系,结果表明18S rDNA适合于嗜子宫线虫科内系统发育研究;嗜子宫线虫属不是单系。 本研究还通过形态学方法鉴定了嗜子宫线虫一新种-鳜嗜子宫线虫(Siniperca chuatsi),并用分子生物学方法进一步验证了该新种的有效性。
Other AbstractThe nematode Camallanus cotti Fujita, 1927 (Spirurida: Camallanidae), originally reported from the freshwater fishes of Japan, has now become widespread in the world. In the present study, its population biology and molecular ecology was investigated in relation to its host range, population dynamics and maturation cycle, population genetic structure, phylogeography, molecular variation and the cophylogeny relationship between parasites and hosts. During 5 times of extensive investigations into the fish parasite fauna of the Danjiangkou Reservoir, C. cotti was found in 26 fish hosts, of these 14 were new hosts. The cypriniform fishes were typical hosts. The nematode’s mean prevalence, prevalence, mean abundance and intensity of infection varied in different fish species. Distribution of C. cotti in greatly diverse fish species might reflect high adaptation of the parasite to different hosts. However, the difference of infection of the nematode in different hosts indicates a possible host preference. Studies on the population dynamics and maturation cycle of C. cotti (Nematoda: Camallanidae) in the Chinese hooksnout carp Opsariichthys bidens (Osteichthyes: Cyprinidae) revealed that there was a positive relationship between fish length and the number of the parasites on individual host. The dynamics of infection of the nematode showed significant seasonal pattern in changes of mean abundance, and a similar rhythmic pattern was also found in changes of prevalence although it was not statistically significant. The higher levels of infection existed in summer and autumn and the lower in winter and spring. In addition, researches on the development and maturation of the parasite in the Chinese hooksnout carp revealed that continuous development (maturation), recruitment of next generation and reproduction occurred all the year round, although reproduction might be at its peak in winter. The genetic structure and phylogeography of different population of C. cotti collected from 3 water systems in central and southern China were investigated using the mitochondrial COI gene and ITS1 rDNA markers. The results showed that the significant geographical structuring of C. cotti population was only presented between the Pearl River population and the Yangtze River - Minjiang River population. There was no significant differentiation among different host/geographic populations in the same drainage. The Yangtze River geographical population was the ancestral population, which gave rise to the geographical populations of the Minjiang River and Pearl River. The evidence suggested demographic expansions varied among drainages. Molecular analyses indicated that there were only two species of Camallanus found in freshwater fishes in China, i.e. C. cotti and C. hypophthalmichthys. The evolutionary associations of C. cotti strains and their host species resulted from frequent and recent colonization, (incomplete) host-switching events or failure to speciate, and subsequent adaptive radiation and incomplete isolation of the worm in diverse host species, over a short time-span. In addition, phylogenetic relationship of the philometrid nematodes collected from freshwater fishes in China was evaluated by using ITS rDNA and 18S rDNA marker. The results suggested that 18S rDNA was the more reliable marker for analyzing the phylogenetic position of the philometrids. The genus Philometra appeared to be paraphyletic, confirming that the homoplastic evolution of morphological characters of this group was extensive. The current system according to morphological characters didn’t reflect its real phylogenetic relationships. Finally, a new philometrid, Philometra siniperci sp. nov., parasitizing among the pyloric caecum of the Chinese perch, Siniperca chuatsi, was described based on its morphological characters and validated by the molecular data.
Pages125
Language中文
Document Type学位论文
Identifierhttp://ir.ihb.ac.cn/handle/342005/12260
Collection学位论文
Recommended Citation
GB/T 7714
吴山功. 杜父鱼驼形线虫种群生物学和分子生态学的研究[D]. 水生生物研究所. 中国科学院水生生物研究所,2007.
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