【作者】 曾宪坤；

【导师】 吴婷婷；

【作者基本信息】 南京农业大学 ， 水产养殖， 2002， 硕士

【摘要】 罗非鱼是联合国粮农组织重点推广的水产养殖品种，它在国际贸易中成为继大马哈鱼和对虾之后的第三大水产品。在我国，罗非鱼的产量年年递增，到2000年我国罗非鱼产量已达63万吨，占世界产量的60％以上。在实际生产过程中，一般利用罗非鱼的正交一代（尼罗♀×奥利亚♂）进行养殖，但由于杂交罗非鱼很容易混在亲本纯种中，导致罗非鱼的二次杂交，如正交一代的兄妹间杂交、正交一代与奥利亚间的回交，由于二次杂交引起后代基因的分配不均匀，导致生产性能不均匀，影响了整体的产量和生产水平。在以往的实验中我们也发现，兄妹间杂交子代与回交子代在增重率，饵料转化率都没有正交一代高，且规格上出现严重的不整齐。 本论文试从形态学和分子水平研究三种不同杂交方式的杂交罗非鱼后代与纯种尼罗罗非鱼及奥利亚罗非鱼之间的遗传关系。比较正交一代、回交子代、兄妹交子代三种杂交鱼与纯种尼罗罗非鱼和奥利亚罗非鱼之间的种内、种间相似系数、遗传距离。从分子水平检验杂交鱼是否具有杂交优势，从分子水平解释三种杂交鱼生产性能存在的差异。同时在形态学上利用最新的统计学技术和软件对纯种鱼和杂交鱼进行区别，并建立新的形态学分析方法，对杂交鱼和纯种鱼进行区别，为选育和培养高品质的罗非鱼养殖品种打下理论基础和提供实践方法。 结果表明：尼罗罗非鱼和奥利亚罗非鱼之间有着较大的遗传距离，使正交一代基因杂合性增加，使其更有可能获得杂交优势，且正交一代与父母本间的种间相似系数没有明显的亲本偏向性，更进一步证明了其正交一代的杂交优势。回交子代和兄妹交子代与奥利亚有着更大的种间相似系数，在种质上更偏向于奥利亚罗非鱼，由于奥利亚在生产中表现出生长速度较慢、饵料转化率较低。故解释了回交子代、兄妹交子代生产性能较差的原因。同时建议对回交子代、兄妹交子代需进一步的选育和杂交，以其获得更高程度的基因的杂合性和优良的性状。 筛选出引物S₃₂₃可以作为尼罗罗非鱼和三种杂交鱼的分子标记；引物S₃₂₆和引物S₃₃₆可以作为奥利亚和三种杂交鱼的分子标记，可用来鉴定纯种和杂交鱼。 如何在外部形态上区分纯种和各种杂交鱼，在实际生产中有十分重要的意义。本研究表明：用聚类的方法可以将尼罗和杂交鱼、奥利亚和杂交鱼区分开来。尼罗和奥利亚在体形上有着较大的差别，三种杂交鱼在体形上更偏向于奥利亚。其中回交子代和兄妹交子代的体形最相似。更多还原

【Abstract】 This study studied the genetic relations between three kinds of hybrid tilapia and oreochromics niloticus and O.aureus at the level of morphology and molecule. In order to detect the heterosis of three kinds of hybrid and to explain the difference of capability of production at the level of molecule we compared the between-population index of similarity and between-population genetic distance of three kinds of hybrid to oreochromics niloticus and O.aureus. At the same time we distinguished the hybrid from oreochromics niloticus and O.aureus.by new statistic technology and software in morphology and established new means of morphology. This study grounded for breeding and culturing of tilapia theoretically and practically.The results of this experiment showed that there were great between-populationdistance between oreochromics niloticus and O.aureus. which indicated the gene oforeochromics niloticus ♀ × O.aureus ♂ was more heterozygous and showed the heterosisin oreochromics niloticus ♀ × O.aureus ♂ . The between-population index of similaritybetween oreochromics niloticus ♀ × O.aureus ♂ and oreochromics niloticus andO.aureus were equal nearly which also certified the heterosis of oreochromics niloticus♀ × O.aureus ♂ .there were high between-population index of similarity between(oreochromics niloticus ♀ × O.aureus ♂ ) ♀ × O.aureus ♂ and O.aureus whichindicated that (oreochromics niloticus ♀ × O.aureus ♂ ) ♀ × O.aureus ♂ resembledO.aureus in idioplasm.it was the same to (oreochromics niloticus ♀ × O.aureus ♂ ) 　?×(oreochromics niloticus ♀ × O.aureus ♂) ♂. the result of this experiment explained thepoor quality of (oreochromics niloticus ♀ × O.aureus ♂ ) ♀ × O.aureus ♂ and(oreochromics niloticus ♀ × O.aureus ♂ ) ♀ × (oreochromics niloticus ♀ × O.aureus♂ ) ♂ .for example, slow growth, poor food transformation etc. The results of thisstudy suggested that (oreochromics niloticus ♀ ×O.aureus ♂ ) ♀ × O.aureus ♂ and(oreochromics niloticus ♀ × O.aureus ♂ ) ♀ × (oreochromics niloticus ♀ × O.aureus♂ ) ♂ need more selective breeding and hybridization in order to improve the quality ofthem.In addition, products of 8323 were found to be molecular markers for identifying oreochromics niloticus and three kinds of hybrid tilapia.products of 8326 and S336 were found to be markers for identifying O.aureus and three kinds of hybrid tilapia.It is great meaningful to distinguish pure strain tilapia and hybrid in morphology. The results of this study showed that we could distinguish hybrid tilapia from pure strain tilapia by clustering conducting on metric characters, three kinds of hybrid resembled O.aureus from the result of clustering conducting on metric characters.更多还原