奥利亚罗非鱼(WZ♀)×尼罗罗非鱼(XY♂、YY♂)杂交子代的性比分析

摘要

在两口4m×2m×1.5m的水泥池中各放入体质量1.4～1.5kg雄尼罗罗非鱼Oreochromis nilotica(XY♂)1尾,体质量0.4～0.6kg奥利亚罗非鱼O.anreus(WZ♀)7尾和4尾,每尾注射0.5个鲤脑垂体(PG)悬浮液催产.另在池塘内两口1.5m×1m×1m的32目网箱中各放入体质量1kg左右的雄尼罗罗非鱼(YY♂)1尾,然后分别放入体质量0.4～0.6kg的雌奥利亚罗非鱼(WZ♀)2尾和1尾,未注射催产剂.各箱配组繁苗20d后,移走亲本,将子代单独饲养至性别鉴定,分析杂交子代的性比,以判断子代中WY型罗非鱼的性别.结果测得3组WZ早×XY♂的子代性比(雌雄比)分别为:114∶111、40∶164和4∶16,1组WZ ♀×YY♂的子代性比为3∶503.卡方分析表明,前3组中有两组子代性比与1∶3的期望值相吻合(P＞0.089和P＞0.79),一组不吻合(P＜0.001);后1组的子代性比与0∶N的期望值相吻合(P=0.92).实验结果推断WY型罗非鱼为雄性,通过探讨导致少数实验值偏离理论值的原因,认为目前构建WY♀-YY♂超雄罗非鱼自繁体系不可行.%One male Nile tilapia (Oreochromis nilotica) (XY♂) with body weight from 1.4 to 1.5 kg was stocked into two cement tanks of each 4 m × 2 m × 1.5 m and induced to cross with 7 or 4 individuals of female blue tilapia (0.aureus) (female WZ) with body weight of 0.4 kg to 0.6 kg by injection of common carp pituitary (PG) suspension at a dose of 0.5 individual per fish.One male Nile tilapia (YY♂) with body weight of about 1.0 kg was stocked into two net cages of each 1.0 m × 1.5 m × 1.0 m and crossed with 2 or 1 individuals of female blue tilapia (WZ ♀) with body weight of 0.4 ～ 0.6 kg without injection of hormone.The parents were removed in 20 days when the hybrid juveniles were reared to determine the sex ratios (female/male) of their hybrids and the sex of the genotype WY in tilapia offspring.The results showed that there were sex ratios of 114 ∶ 111,40 ∶ 164,and 4 ∶ 16 in the hybrids in three WZ ♀ × XY♂ groups,and that there was sex ratios of 3 ∶ 503 in the WZ ♀ × YY♂ group.X2-test analysis indicated that the progeny sex ratios were consistent with 1 ∶ 3 expected (P ＞ 0.089 and P ＞ 0.79) in the two groups and the other group's was not (P ＜0.001) among the first 3 groups.However,in the latter group,the sex ratio was tallied with 0 ∶ N expected (P=0.92).It was conclude that the WY genotype tilapia was indeed male.The reasons that the few test values were deviated from the expected were discussed,and it is suggested that constructing self-reproduction system of WY ♀-YY♂ supermale tilapia is neither feasible nor necessary at present.