BACKGROUND The availability of both pedigree and genomic sources of information for animal breeding and genetics has created new challenges in understanding how they can be best used and interpreted. This study estimated genetic variance components based on genomic information and compared these to the variance components estimated from pedigree alone in a population generated to estimate non-additive genetic variance. Furthermore, the study examined the impact of the assumptions of Hardy-Weinberg equilibrium (HWE) on estimates of genetic variance components. For the first time, the magnitude of inbreeding depression for important commercial traits in Nile tilapia was estimated by using genomic data. RESULTS The study estimated the non-additive genetic variance in a Nile tilapia population of full-sib families and, when present, it was almost entirely represented by additive-by-additive epistatic variance, although in pedigree studies this non-additive variance is commonly assumed to arise from dominance. For body depth (BD) and body weight at harvest (BWH), the proportion of additive-by-additive epistatic to phenotypic variance was estimated to be 0.15 and 0.17 using genomic data (P < 0.05). In addition, with genomic data, the maternal variance (P < 0.05) for BD, BWH, body length (BL) and fillet weight (FW) explained approximately 10% of the phenotypic variances, which was comparable to pedigree-based estimates. The study also showed the detrimental effects of inbreeding on commercial traits of tilapia, which was estimated to reduce trait values by 1.1, 0.9, 0.4 and 0.3% per 1% increase in the individual homozygosity for FW, BWH, BD and BL, respectively. The presence of inbreeding depression but lack of dominance variance was consistent with an infinitesimal dominance model for the traits. CONCLUSIONS The benefit of including non-additive genetic effects for genetic evaluations in tilapia breeding schemes is not evident from these findings, but the observed inbreeding depression points to a role for reciprocal recurrent selection. Commercially, this conclusion will depend on the scheme's operational costs and resources. The creation of maternal lines in Tilapia breeding schemes may be a possibility if the variation associated with maternal effects is heritable.

中文翻译：

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母体，加性和非加性遗传效应对尼罗罗非鱼生长和car体性状的基因组解剖。

背景技术用于动物育种和遗传学的家谱和基因组信息源的可用性在理解如何最好地使用和解释它们方面提出了新的挑战。这项研究基于基因组信息估算了遗传方差成分，并将其与仅由系谱估算的方差成分进行了比较，该群体是为估算非加性遗传方差而产生的。此外，研究检查了哈迪-温伯格平衡（HWE）假设对遗传方差成分估计值的影响。首次使用基因组数据估算了尼罗罗非鱼重要商业性状的近交衰退程度。结果研究估计了全同胞家庭的尼罗罗非鱼种群的非加性遗传变异，如果存在，它几乎全部由累加上位的方差表示，尽管在谱系研究中，通常认为这种非累加的方差是由优势引起的。对于体深（BD）和收获时体重（BWH），使用基因组数据估计逐加表位的累加上位表位与表观差异的比例分别为0.15和0.17（P <0.05）。此外，利用基因组数据，BD，BWH，体长（BL）和鱼片重量（FW）的母亲方差（P <0.05）解释了约10％的表型方差，与基于谱系的估计值相当。该研究还显示了近交对罗非鱼商业性状的有害影响，据估计，每增加1％，FW，BWH，BD和BL的纯合子性状就会使特征值降低1.1、0.9、0.4和0.3％。近亲抑郁的存在但不存在显性差异与特征的无穷小显性模型一致。结论从这些发现来看，在罗非鱼育种方案中将非累加遗传效应纳入遗传评估的益处尚不明显，但观察到的近交抑郁症指出了相互反复选择的作用。在商业上，该结论将取决于该计划的运营成本和资源。如果与母体效应有关的变异是可遗传的，则在罗非鱼育种方案中创建母系可能是可能的。结论从这些发现来看，在罗非鱼育种方案中将非累加遗传效应纳入遗传评估的益处尚不明显，但观察到的近交抑郁症指出了相互反复选择的作用。在商业上，该结论将取决于该计划的运营成本和资源。如果与母体效应有关的变异是可遗传的，则在罗非鱼育种方案中创建母系可能是可能的。结论从这些发现来看，在罗非鱼育种方案中将非累加遗传效应纳入遗传评估的益处尚不明显，但观察到的近交抑郁症指出了相互反复选择的作用。在商业上，该结论将取决于该计划的运营成本和资源。如果与母体效应有关的变异是可遗传的，则在罗非鱼育种方案中创建母系可能是可能的。