斑点叉尾鮰基础群体生长和存活性状遗传参数估计

研究估计了斑点叉尾基础群体(G0)体质量、体长和存活性状的遗传参数,为制定育种目标、综合选择指数和选择方法提供基础参数。实验利用5个斑点叉尾引进群体,通过双列杂交和巢式交配设计,产生全同胞和半同胞家系。每个家系内的稚、幼鱼经过中间暂养、个体标记等阶段后,混合放入一个池塘进行生长和存活测试。利用两性状动物模型和公母畜阈模型分别估计生长和存活性状的方差组分和遗传参数。通过最佳线性无偏预测法估计所有个体生长和存活性状的育种值。斑点叉尾基础群体收获体质量和体长遗传力分别为0.41±0.074和0.32±0.064,属于高遗传力水平,并且统计检验显著(P<0.05)。尽管在两性状动物模型中设置标记体质量和标记体长作为协变量进行校正,但是由于加性遗传效应和共同环境效应混淆在一起无法剖分,遗传力估计值偏高。收获体质量和收获体长的表型和遗传相关系数分别为0.93和0.97,表现为高度线性正相关。存活性状的遗传力为0.037±0.016,表现为低遗传力,但统计检验仍达到显著水平(P<0.05)。家系生长(收获体质量和收获体长)和存活性状育种值间的相关系数分别为0.065和0.100,表现为低度线性遗传正相关,并且统计检验不显著(P>0.05)。因此在制定育种方案时,生长和存活性状都可纳入育种目标,利用多性状选择指数方法同时选择。

Genetic parameters for growth and survival of the base population in channel catfish(Ictalures punctatus)

Genetic parameters were estimated for growth and pond survival of channel catfish Ictalures punctatus using full-sib and half-sib families from cultured brood females collected from five different populations of the United States.The fry and juvenile were reared,tagged,and thereafter communal-reared in one pond.Variance components and genetic parameters for growth and survival were estimated using a two traits animal model and a sire-dam threshold model.The estimated breeding values of all animals were calculated using best linear unbiased prediction.The heritability estimates for harvest body weight and harvest body length in the base population were high(0.41±0.074 and 0.32±0.064,respectively)and were significantly different from zero(P<0.05).These estimates are likely biased upwards due to the common environmental effect other than additive genetic effect,although tagging body weight and tagging body length was fitted as a covariate in the mixed model to remove this effect.There was a high phenotypic and genetic correlation between harvest body weight and harvest body length(0.93 and 0.97,respectively).Heritability of pond survival was low(0.037±0.016)but still significantly different from zero(P<0.05).The correlation between family breeding values for growth(harvest body weight and harvest body length)and pond survival were low(0.065 and 0.10,respectively)and not significantly different from zero(P>0.05).Therefore,growth and survival must be included as breeding objective and simultaneously selected in the future generations by using a multiple trait selection index method.